Maybe Not Carbon Fiber

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It's birthday week for host Tom Butler, and he is gearing up for another year of adventure! Join Tom as he reflects on the transformation cycling has provided for him over the last year as he gets ready for a new ride to celebrate another year.

Tom also contemplates a once-a-year opportunity to cycle one of the most scenic highways in the U.S. – car-free! The challenge will be big but also will be the opportunity to prepare for this season’s challenge to bike across Washington State. 

Tom welcomes Garren Miler, the official mechanical engineer of Cycling Over Sixty, for a technical discussion about bike frame materials. Steel, aluminum, carbon fiber – what's the best choice? Tom revisits his decision to go carbon fiber and, with Garren's expert insights, evaluates the trade-offs and benefits of different materials.

Whether you're a seasoned cyclist or just starting your journey on two wheels, this episode offers a perfect blend of reflection, inspiration, and technical knowledge. Tune in and discover what lies ahead for Tom and Cycling Over Sixty, and get ready to celebrate life, adventure, and the freedom of the open road!

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Show music is "Come On Out" by Dan Lebowitz. Find him here : lebomusic.com

Episode Transcript

Tom Butler (00:04):
This is the Cycling Over 60 Podcast, season 2,
episode 30, maybe not carbonfiber and I'm your host, tom
Butler.
In a few days I will be turning61 years old.

(00:26):
I am coming up on a year sinceI started out my cycling over 60
journey with a 60-mile ride onmy 60th birthday.
That led to many awesomemoments of cycling last year,
including the Cascade BicycleClub Seattle to Portland ride.
I am celebrating my birthdayagain with a ride.
This time it is only 33 miles,but with more climbing.

(00:47):
The beautiful ride we did lastyear had about a thousand feet
of climbing and this year I willbe doing the chilly, hilly ride
that has twice the elevationand half the miles.
I like that a lot because hillsare a real struggle for me.
So I feel like, even thoughthis is a short route, it is a
bigger challenge over lastyear's ride.
That is one of the things thatI would love to demonstrate with

(01:09):
my cycling over 60 journey.
I want to show that I can stillget stronger and take on bigger
challenges as I get older.
At some point I will slow down,I know, but I bet I'm a long
way from that, so this is a newperspective for me.
In the last year.
I wish I had my wife on with mebecause she could testify to
the fact that a few years ago Istarted seeing my life as

(01:30):
winding down.
I was facing health issues thatI had seen heavily impact my
father and his siblings, and Iwas losing hope that I would
continue to have quality of life.
So it is a big deal for me tosee how much stronger and
healthier I am now Because ofthe gains I've made this last
year.
I have no doubt that I will beable to handle the hills on this
ride.

(01:51):
I might have to step off on thesteepest climb, but I will
definitely be able to get backon and finish.
Another difference over lastyear is that I will be
celebrating my birthday thisyear with a ride both with my
son-in-law and with my daughter.
Next year, I'm committed toinclude my wife as well.
My vision is that my birthdayweekend will become a family

(02:13):
cycling trip.
The biggest obstacle is thefact that my wife has only a
year to figure out how she candress in a way that she will
enjoy biking in February in thewet and cold Pacific Northwest.
It is possible that we mightneed to travel south if she's
going to join in, but thatdoesn't sound too bad.

(02:34):
I registered my email with theWashington State Department of
Transportation to get updates onwhen Washington Pass will be
cleared of snow.
That is the pass on Highway 20,the North Cascades Highway,
which is also US Bike Route 10.
This is the route that Iplanned to ride across
Washington State in September.
I'm excited because there is ashort period of time between

(02:56):
when they clear the pass of snowand when they open it up for
cars, so you can bike up to thepass on one of the most scenic
routes in all of the US withoutworrying about any cars.
In addition to just a greatcycling adventure, I will also
be experiencing a verychallenging section of the ride
I want to do in September.

(03:16):
The route is about 69 milesround trip, with 67,000 feet of
climbing For 30 miles.
It is almost a constant 2-6%grade.
Yes, this will be a big test,but is the best way to see what
kind of challenge it will be forme to go over the Cascades in
September.
A quick note on my healthprogress.
I think I'm going to have tostart wearing the continuous

(03:39):
glucose monitor again.
I find that I'm slacking offway too often without the
feedback of the CGM.
I'm still maintaining themajority of the habits I
developed when I wore it before,but I'm just not as compliant
as I should be.
I'm very proud of my son-in-law, garan, for a lot of things.

(04:04):
One of them is that he excelsat his job as a mechanical
engineer.
I have been thinking a lotabout bike frame materials
lately and I asked Garan to joinme for a conversation about the
benefits of the differentmaterials.
Here is our discussion.
I'm here again with Garan Myler.
Thanks for coming on, garan.

Garren Miler (04:22):
Yeah, thanks for having me.

Tom Butler (04:23):
Garan is the official mechanical engineer for
the Cycling Over 60 podcast,also my son-in-law, so he pretty
much has to come on, but I dothink you enjoy talking about
bike tech, is that right?

Garren Miler (04:35):
Oh, absolutely yeah.
I think it's a really greatapplication of engineering and
it's a lot of fascinating waysto look at it.

Tom Butler (04:41):
McKenna, your wife, my daughter, just got a new bike
and so we were looking at bikesagain, which it seems like
we're finding plenty of excusesto look at bikes.
There's always a reason.
Yes, that's right.
It got me thinking about bikeframe materials again.
I wanted to have you come on.
I've spent about a year nowthat you've been looking at

(05:03):
bikes, have been dealing withbikes.
As an engineer, I know thatyou've been thinking about bikes
in that part of your brain andthat part of your life.
I thought it would be good tobring up some things about
frames that I'm interested inand just have a dialogue To give
some framing to this discussion.

(05:25):
I'd like to first have you talkabout some terms that, as an
engineer, you would have in mindwhen you're evaluating a
bicycle frame.
Could you do that?

Garren Miler (05:39):
Yeah, definitely.
My flavor of engineering that Ido at my job is marine
engineering, so I work a lot onboats.
So material selection is at theforefront of a lot of what we
do, because we're not justcombating the strength and the
durability of the material, butwe're also combating corrosion
and other factors like that.
Combating my materials issomething that I'm more than
happy to dive into.

(05:59):
If I'm choosing a material andI'm especially in the context of
a bike frame the first thingyou want to know is the weight
to strength ratio.
That's going to be determinedby the density of the material,
which is directly proportionalto its weight, but also by the
tensile strength and the yieldstrength of the material.
Tensile strength and yieldstrength are both measurements

(06:20):
of the overall strength of amaterial, but they mean very
different things From theperspective of design.
You have to understand thedifference in order to know just
where you can push your productto where the limits are.
So the tensile strength of anitem is the absolute overall
strength, the maximum amount offorce that you can put on it
before it breaks.
The yield strength is how muchforce you can put on something

(06:42):
before it starts to deform, andthis is really important when
you're deciding between aductile material like an alloy
or a brittle material likecarbon fiber.
The tensile strength of amaterial is not actually super
relevant to engineers inday-to-day life because we
always design things based ontheir yield strength.
Yielding is really importantbecause it lets you know that

(07:04):
the metal is about to break.
If you're in a building and yousee that a metal beam is
sagging, then you know that it'sunder more stress than it
should be under and you need tohave mitigating support for it.
So along with those two items issomething called the modulus of
elasticity.
That's a bit of a deep dive ifyou want to know exactly where
that number is derived from.
There's quite a bit of theorybehind it and it's kind of

(07:27):
almost an entire semester ofengineering schools devoted
towards relating the modulus ofelasticity to the tensile
strength and to the yieldstrength of different materials.
But overall it measures thestiffness of a material.
It's a measurement of thatmaterial's ability to bend and
then bounce back to its originalshape.
In alloys, the modulus ofelasticity is relatively high.

(07:48):
Modules can take quite a bit offorce before they start to bend
, and if they do bend they'llkind of boing back into shape,
which is why you make springsout of them and things like that
.
Carbon fiber has an excellentmodulus of elasticity, but it's
a lot higher.
It can bend, but when it getsto its breaking point it will
break catastrophically.
It's not going to stretchitself into a spaghetti noodle

(08:10):
like a piece of metal wouldbefore it snaps.
It's just going to break withno warning.

Tom Butler (08:15):
Now, when you talk about yield strength, it seems
like there are materials outthere you know, just talking
about material properties ingeneral where you actually
wouldn't be able to see somebending of that material before
it would snap.

Garren Miler (08:31):
Absolutely.
That's what we would call abrittle material, a material
whose primary mode of failure iscatastrophic at the first sign
of damage.
So in that material the tensilestrength and the yield strength
are going to be almost the samenumber, because it breaks just
as soon as it starts bending.
But with things like aluminum,for example, the yield strength
is far below the ultimatestrength and you can stretch

(08:54):
aluminum out quite a bit becauseit's quite a ductile material.
So those numbers are quite abit different.
Fatigue resistance is anotherthing we look at with materials,
but it's actually quitedisconnected from yield strength
and tensile strength and itvaries a lot depending on the
exact composition of your alloy,because not all aluminum are
created equal and we can diveinto that a little more later.
But the fatigue resistance isall about the ability of the

(09:17):
metal to be loaded and unloadedrepeatedly over time.
So if you have a cyclic loadingon something where the load is
applied and then unapplied whichobviously in bicycles is
exactly what you're doing you'recycling hits in the name.
A cyclic loading pattern isgoing to lead to a decreased
overall strength and anincreased amount of brittleness
and in aluminum, for example,that might look like fracturing

(09:39):
or cracking in the metal farbefore it's yielded, and it can
greatly reduce the overalltensile strength of the material
over time.
There's really not a lot ofmitigations for that, aside from
just making sure that you havedone, of course, your homework
and done a lot of producttesting, but also making sure
that you've designed yourproduct to be well below the

(09:59):
threshold and there arenumerical thresholds that you
can calculate based on empiricaldata to know that your product
is not going to build up toomuch fatigue over time over its
lifespan.
The thing that we think aboutmaybe the most as marine
engineers is corrosionresistance.
Of course, the first thing youthink of when you think of
corrosion is rust, and rusthappens to ferrous metals, which

(10:21):
is steel.
Any metal that has iron in itis going to rust when exposed to
air and water.
Things that make rust worse issalt, including the salt that
they put on the roads.
That can easily rust your bikeout.
That being said, steel won'trust if it has a proper coating
on it, it was painted well, orif it has a nice finish.
Stainless steel won't corrodeeither, but it's an expensive

(10:44):
material and probably isn't oneyou'd see.
A bike frame made out ofStainless steel is also very
difficult to weld.
Aluminum does not rust, butthat does not mean that it is
free from the effects ofcorrosion.
Aluminum will build an oxidelayer on it.
It looks like a white kind ofpowdery layer that can build up
on the aluminum.
Rust can be just as bad as rustis for steel.

(11:05):
Over time the oxide layer willeventually eat into the material
and will create a very brittlealuminum that will break on you
without you realizing that it'sgotten to that point, until the
bike is in half below you.
Additionally, here in Seattlewe have a particular risk to
aluminum bikes.
That's that the chemical thatthey use to deice the roads in
Seattle, which I've been told isunique to the Seattle area, is

(11:27):
especially aggressive towardsaluminum itself.

Tom Butler (11:32):
That's handy, it's very convenient.

Garren Miler (11:35):
So people in Seattle oftentimes report that
their spokes eventually, afterriding in bad weather, their
spokes will just pull right outof their wheels, and that's due
to the really aggressivechemical that they use here.
Of course it's better for thecars, which are mostly steel,
but it's not better if you're acyclist.
The way to mitigate that riskin particular is to just make
sure you're rinsing your bikedown after any ride in really

(11:55):
bad weather.

Tom Butler (11:56):
Well, I think that's a great overview of properties
that you would look at whenevaluating materials.
Let's talk about common bikematerials.
I'm going to go through thesein a way that I was exposed to
them.
So the first bike I ever had,and several bikes that I had as

(12:19):
growing up, were made out ofsteel.
Let's talk about the propertiesof steel that make it from
these principles, theseengineering principles.
What is it about steel thatmakes it a typical bike material
?

Garren Miler (12:37):
So steel is really easy to work with and it's the
reason that most of ourbuildings are made out of steel
and that cars are made out ofsteel and overall, steel is easy
to weld, it's very durable, itis very strong and it's actually
quite cheap.
In fact, it's probably thecheapest material we're gonna
look at.
So there's a reason that mostbikes start off in the low end

(12:59):
as steel frames.
Of course, the downside ofsteel is that it's quite dense,
quite a bit denser than aluminum.
So even though it has twice thestrength, it has quite a bit
more weight to it.

Tom Butler (13:10):
When you're looking at weight, then I think it's
fair to say that there's anelement of the alloy that is
used.

Garren Miler (13:18):
Oh, absolutely Within steel.
There's many different flavorsof steel.
Each one's gonna have theiradvantages and disadvantages,
but really the two most commonis gonna be carbon steel, which
is what you might think of asplain steel or regular steel,
and then there's stainless steel.
Stainless steel is gonna be abit more brittle and have a bit

(13:40):
less strength, but it has a verygood corrosion resistance.
However, that does come with abit of a weight cost as well.
It's also not as easy to workwith, it's not quite as ductile
and it's much more difficult toweld than regular steel is, and
that makes it a bit lessattractive of an option for
building a bike.
You might look back at theDeLorean or even the new Tesla

(14:01):
Cybertruck that are madecompletely out of stainless
steel, and none of those carsare successful because stainless
steel is very hard to work with.
There are disadvantages quicklyoutpaced its advantages when
you scale stainless steel up toa larger assembly.

Tom Butler (14:15):
So what is the term chromoly refer to?

Garren Miler (14:19):
Chromoly is an alloy of steel that it's a
particularly attractive flavorof steel because it has a lot of
the advantages of regular steel, like its affordability and its
ease of welding, but it alsohas much better corrosion
resistance due to the chromiuminfused in it.

Tom Butler (14:39):
What I have here is ranges for a 56-centimeter
bicycle frame that's made ofsteel is 2.2 to 3 kilograms.
Again, there's this corrosionelement to steel that you have
to take care of it.
I mean, I know as a kid like mybike rusted as a kid, just

(15:01):
specifically because I reallydidn't think that much about
taking care of my bike when Iwas a kid.
If the paint gets scratched,gets chipped off or whatever,
then that can lead to an issue.

Garren Miler (15:16):
So I actually have a steel-framed bike.
My Rad bike is steel-framed andI used to take my Rad bike
every single day on a ferry whenI was queuing to work across
the sound and on that ferry itwas sprayed with saltwater
repeatedly every morning, whichis just pretty much the worst
environment you can possiblyimagine for corrosion.
A steel bike being sprayed withsaltwater and the frame itself

(15:37):
actually wasn't the biggest riskfactor.
The paint chipped off in a fewplaces and you'd get some
surface rust, but it was nothingNothing you couldn't just wipe
off with some WD-40 or someother solvent and then retouch
up.
The really difficult part is thelittle tiny bits and pieces
that are inside of yourdifferent components.
I had my brakes go out multipletimes on that bike because the

(15:59):
little springs and the leversinside the handles were not
functioning properly because thelittle tiny pieces were rusting
out.
The frame itself is so big it'seasy to take care of.
It's really the nooks andcrannies where things go wrong
and engineering.
One thing we focus on is theavoidance of what we call faying
surfaces or two surfaces thatare really really close together
, when you have two pieces ofsteel that are basically sitting

(16:22):
on top of each other but aren'tactually adhered.
That's a faying surface in thatcrevice and that is just a
treasure trove for rust to getin there and eat your metal from
the outside in, and you won'trealize until it's too late.

Tom Butler (16:35):
Interesting I ended up which I think is the main
reason why aluminum frames cameabout is that I ended up wanting
a lighter bike and so when Ibought my Trek 1500, we talked
about it a couple of times onthe podcast when I got that on
that frame and so I'm thinkingthis is about 90, 89, someone

(16:59):
there I should probably figureout when that is but right on
the frame it says in boldletters aluminum.
You know they were really atthat time still promoting
aluminum as a new frame materialand again, I believe it was
because it was a lighter framematerial.
Can you talk a little bit aboutaluminum as a frame material?

Garren Miler (17:23):
So aluminum is kind of the next obvious choice
from steel.
It has about half the strength,but it's also substantially
lighter, and it's pretty obviousto tell.
If you have items in your housethat you know are steel, you
know are aluminum, you can pickthem up and it's quite jarring
the difference.
Aluminum also can be formedthrough a couple of different
methods, although it is moredifficult to form than steel is,

(17:44):
it's not quite as ductile and,like we said earlier, aluminum
has an excellent resistance tocorrosion, which makes it yet
another drop in the bucket forwhy you'd want to switch over.
When you're comparing something,say, steel to aluminum, one of
the things you're looking atreally the only thing you're
looking at is the strength toweight ratio, or you could look
at that as the yield strength todensity ratio, because a steel

(18:08):
bike, for example, even thoughsteel itself is heavier, you can
get away with less steelbecause it has more strength,
whereas you're going to needmore aluminum to have the same
amount of strength, but it isalso lighter.
So you have to look at theratio of its density to its
strength in order to really knowwhich material you're going to
want to use.
That being said, aluminum isquite a bit more expensive than
steel and it does come in a lotof different flavors In the

(18:32):
marine industry.
Aluminum is they're picking theright.
Aluminum is vital to makingsure that your craft is going to
build a function in all weatherconditions and in all
environments.
Aluminum does change itsproperties substantially with
temperature.
It doesn't do as well in reallycold temperatures and it has a
lower melting point.
But hopefully your bike isn'tbeing subjected to that.

Tom Butler (18:54):
Yeah, I think I'm going to be stopping biking
before I get to that point.

Garren Miler (18:58):
Yeah, but in really cold temperatures you
will notice that aluminum canbecome brittle.

Tom Butler (19:04):
Now, how cold is cold.

Garren Miler (19:05):
That depends on the flavor, but cold within
reasonable riding conditions forwinter time in the northern
hemisphere.

Tom Butler (19:13):
Really, that's interesting.

Garren Miler (19:14):
Yeah, I mean I would say if it's below freezing
in general you're running a bithigher risk for having a
brittle failure of aluminum.

Tom Butler (19:22):
OK, when I was looking at different frames,
there are these alloys, justlike with steel, and so there's
a 6061 alloy and a 7005 alloy.
I have no idea what those mean,but again, I think that when

(19:42):
they're building aluminum frames, they're taking account that
these alloys are more suited forthe stresses that a bicycle
frame would have.

Garren Miler (19:51):
Yeah, absolutely so.
With steel, steel is, steel issteel, and you can weld it, you
can heat it up and, for the mostpart, its properties are pretty
constant.
With aluminum, that isabsolutely not the case, and so,
moreover, more so than justyour alloy, you have to pay very
close attention to the heattreatment of the aluminum, and
the quality of the welds playsan enormous role in the strength

(20:13):
of the structure.

Tom Butler (20:14):
Now, when you're talking about welding aluminum,
what's that look like as opposedto welding steel?

Garren Miler (20:20):
So when you weld aluminum you obviously have to
heat up the metal quite a bitand, like I said, heating up
aluminum changes its propertiespretty drastically compared to
steel.
So when you weld aluminumyou're going to create localized
areas within the frame that aregoing to have different
material properties than otherareas of the frames that were
cold instead of being welded.

(20:41):
So that means you have tofactor those sorts of stress
concentrations into your designto know that you're not going to
hit a failure point due to theextra heat that was added during
the welding process.

Tom Butler (20:54):
Do you know if there's other ways to bond
aluminum together that's notheat related?

Garren Miler (21:00):
There are some ways to do that.
One of the common ones you seeon old bikes and in fact on that
first bike that you had, theTrek 1500, you'll see it used on
the fork and that's a socketfit.
So they would take the aluminumand they would fit it into a
socket of another aluminum.
That would.
So essentially a tube wouldslide inside of a slightly
larger tube and then they wouldeither they could use epoxy to

(21:22):
put that joint together andthat's what they did on the fork
.
Because when you heat upaluminum it also expands and
contracts a lot more than steeldoes when steel is heated up.
So when you weld, say, a fork,you're much more likely to bring
that fork out of true and havemisalignments.
So when they're assemblingaluminum forks in particular,
they tend to use socketconnections at the top to ensure

(21:44):
that they're not putting anyheat into that aluminum and not
warping that fork.
So they use an epoxy jointinside of a socket to connect
sensitive elements like a forkor with maybe the rear section
of your frame together.

Tom Butler (21:59):
What is TIG welding?

Garren Miler (22:01):
So TIG welding is the type of welding that's more
common in exotic metals is howyou're going to connect titanium
pieces together.
In my industry we use a lot ofcopper and nickel pieces, and
those are connected togetherwith TIG welding and it's a lot
more difficult to carry out, butin the end it creates a much
better end product.
Tig welding can also fusenon-homogeneous metals together.

(22:21):
For example, you cantheoretically weld aluminum to
steel using TIG welding, eventhough you couldn't do that with
other forms, and it introducesa third type of metal, tungsten,
into the mix, and that createsa bond that's stronger and
lighter than if you were to justuse traditional welding methods
.

Tom Butler (22:39):
Interesting.
So, looking at a comparisonagain, what I have here is a
comparison on a 56 centimeterbicycle frame, and this source
was talking about that.
Aluminum is 1.8 to 2.5kilograms as a range, as opposed
to steel being 2.2 to 3kilogram.

(23:00):
You can see the differencebetween 3 kilogram and 1.8
kilogram.
That's a decent difference inweight.

Garren Miler (23:09):
That's a very significant difference in weight
in the bike world, but weightactually isn't the only factor
that might influence you toswitch from steel to aluminum.
The increased ability to formaluminum is really a strong
motivator pushing people intothe aluminum realm.
What I mean by that is steel.
Bikes are almost always madeout of tubes, and tubes actually
are not great at carrying loads, especially in bending.

(23:32):
So the top tube of your bikeall it wants to do is bend when
you sit on the bike right, andtubes aren't particularly good
at taking that.
Really, you want a differentshape, and what that shape is?
There's no one right answer,and many bike companies have
very differently shaped toptubes.
And not only that, but your toptube versus your down tube
versus your seat post are allgoing to be loaded in completely

(23:55):
different patterns from the wayyou sit and pedal the bike.
And steel just being limited totube construction means that
you're going to have a lessefficient shape than if you were
to have a material likealuminum that can be molded into
different shapes that are moreefficient to carry the load
through that particular memberof the bike.
Does that make sense?

Tom Butler (24:13):
Yes, it does, and I want to talk a little bit more
about that later on.

Garren Miler (24:19):
So the advantage of aluminum isn't just its
strength to weight ratio, butit's also the ability for
aluminum to be created into moreefficient shapes that carry the
load with less material overall.

Tom Butler (24:30):
Gotcha.

Garren Miler (24:32):
And, of course, that advantage is what would
bring you straight into theworld of carbon fiber.

Tom Butler (24:37):
And when I was looking at getting a road bike,
then I started looking at acarbon fiber frame, which I
hadn't before, and I reallywasn't considering a carbon
fiber frame.
Frankly, if I could look at theweights again with my 56
centimeter frame comparison,carbon fiber is 0.8 to 1.5

(25:00):
kilograms for the frame.
If you're talking about thelightest aluminum frame at 1.8
kilograms versus a carbon fiberframe, that is 1.5 kilograms.
To me that is not a big enoughdifference to make a difference
for me and my cycling ability.
I really wasn't looking atcarbon fiber before, but I have

(25:27):
to say that when I got the bikeit just felt really good.
So let's talk about carbonfiber as a frame material.

Garren Miler (25:35):
Absolutely.
To understand the advantagesand disadvantages of carbon
fiber, you first have tounderstand exactly what it is,
and in simple terms, it's carbonfibers, and maybe the name is
misleading, because it's reallynot just carbon fiber.
It's carbon fiber suspended ina resin base, and so you might
hear it called composite or apolymer, and it is all of those

(26:00):
things, but the actual fibersthemselves are little tiny
strands that are suspended in amatrix of epoxy resin around
them.
So the fibers are where thestrength comes from.
Now, carbon fiber isessentially like making your
bike out of a million tiny ropes, and so they act really really
good in tension.
You can pull on them all youwant, but you can't push on a

(26:21):
rope, so the epoxy matrix iswhat resists compression in a
carbon fiber material.
So you have the little carbonropes that are holding the
tension and you have the matrixof epoxy that's holding the
compression.
That being said, if you had allyour ropes lined up in the same
direction and you startedpulling on them in that
direction, they'd be very strong.
But if you started pulling themapart, side to side, you would

(26:45):
find out that the ropes wouldjust give way immediately, which
is why, in carbon fiber, theyhave to weave the fibers in
every direction to make surethat you're always pulling the
ropes end to end.
That being said, the quality ofcarbon fiber doesn't just
depend on the very fact that itis carbon fiber, but it depends
on how it was laid out, how itwas designed and how it's loaded

(27:07):
relative to the direction ofall the fibers.
So a well-designed carbon fiberbike will have the fibers
facing in strategicallyadvantageous ways to make sure
that they're best equipped tohandle whatever loads are going
through the frame.

Tom Butler (27:21):
I think that that was something that really
happened in bicyclemanufacturing at one point was
that they got serious aboutreally researching and
developing how to lay the fibersdown in a way that, as a
bicycle is being pedaled overand over again, the stresses

(27:42):
that you get with the pedalstroke when you're standing up
and climbing, the stresses youwould get that would be
different from just pedalingalong on a flat hitting bumps,
the different stresses that thebike would have.
They started getting seriousabout how to lay fibers down to
what you said create a matrixthat can withstand force in a

(28:06):
lot of different directions.

Garren Miler (28:08):
That's why there's a massive quality gap from the
lowest carbon fibers to thehighest and ones, and why you
keep seeing manufacturers eachyear come out with the latest
and greatest carbon fiber,because they're further and
further optimizing their formula.
It's not like metal where youcan just pick an alloy and make
your bike out of it and reallyyou're fine.
Tuning with an alloy is reallytrivial things like its shape

(28:31):
and its form and its weldswhereas with carbon fiber you
can improve the actualproperties of the material
itself over time withoutchanging other design factors.
The biggest advantage of carbonfiber over alloys is the very
fact that you can make the bikeentirely out of a solid chunk of
it.
You don't have to have anywelds or seams or connections,

(28:53):
and that greatly opens up thedesign space for how you can
actually design your frame ifyou want it to be more
aerodynamic or you want to haveit be loaded in a certain way.
One thing we do in engineering,for example, is we avoid having
sharp corners.
That's why airplane windows areround and you'll see a lot of
it and on boats all the doorsare round, because square

(29:14):
corners actually build stressconcentrations and can create a
failure point and can createcracking On bikes.
If you can have your top tubeflow into your down tube and
flow into your seat post, thenhaving big radiuses and swooping
curves on your bike isn't justaesthetic, it's actually helping
to distribute the load moreevenly throughout the whole

(29:35):
frame.
The way that manufacturersapproach this is by using a
method called finite elementanalysis.
That's a really fancy way ofsaying.
It's a computer process thatbreaks your frame down into
little, tiny elements.
It discretizes it and then itsees how each little part would
react and it adds it all up.
You've probably seen picturesof a finite element analysis

(29:56):
performed.
A lot of companies use them totaut their R and D division.
These 3D CAD models usuallyhave a rainbow-looking color on
them, where one part's reallyred and one part's green, the
red denoting really highstresses.
The advantage of finite elementanalysis is that you can follow
the path that stress takesthrough your bike.

(30:18):
Something we talk about a lotas engineers is the load path.
When you sit on your bike,you're sitting on the seat post
and you're putting all yourweight through the seat post,
but then, when it gets down tothe actual frame, it's being
distributed into the down tubeand on the top tube.
You have to know how much of theforce is getting distributed
into the top tube versus thedown tube, how much of it's

(30:39):
going back to your rear tire andhow things are distributing.
That's a very complicatedprocess, which is why we have
these programs that are able tojust compute a massive amount of
data at once to follow thatstress through your bike, to see
where your weight and yourcranks and your hands on your
handlebars, to see where allthat force actually ends up in
the frame.
Sometimes you might find thatif there's an area of your frame

(31:01):
that's all good and all greenand it's not really experiencing
any of the force, well, get ridof it.
You want to make your bike aslight as you can.
Eventually, you start to cutaway portions of your frame that
aren't experiencing much load,while bolstering the parts that
are.
You have a frame that'scompletely optimized for the way
that people are going to ridethese bikes.

Tom Butler (31:23):
When we were looking at the Roubaix.
You ended up getting a roubaixand then you evangelized me and
I ended up getting a roubaix.
One of the things that I likedabout the roubaix and the frame
that we got was that we did notget a high-end roubaix.

(31:46):
I don't know if you would evenconsider what we got to be
middle of the road roubaix.
It depends on if you're goingto look at the S-Works roubaix
as part of the roubaix family.

Garren Miler (32:00):
I don't think they had the S-Works roubaix when I
bought mine.

Tom Butler (32:03):
Oh, is that right Okay?

Garren Miler (32:05):
I think that they released that just after I
bought mine.

Tom Butler (32:08):
Okay, Well, I think.
Actually the S-Works roubaixwas $14,000 when it was released
.
When you compare the differentcarbon frame sets that
Specialized is using, theFACT-10R is what's used on our
bike, which is, I think, areasonably priced entry level.
It's got 105 group set.

(32:28):
It's a reasonably priced entrylevel carbon fiber frame, but
that same frame is used all theway up through their $8,000
Specialized roubaix.
You have to get into theS-Works roubaix before you get
what they call the FACT-12R,which is a higher form of carbon
fiber.
Now I don't know exactly whatthat difference is, but I think

(32:51):
that you're again you'restarting to look at maybe higher
grade modulus fibers.
What do you think about that?
And maybe you even looked atthis?
But if you were just going totheorize the difference between
a FACT-10R and a FACT-12R carbonfiber frame set, what would you
theorize, the difference being?

Garren Miler (33:12):
I think the difference between those is
probably very, very small andI'm guessing closely guarded
differences in their formulasfor their resin and in their the
way that their fiber matrix iswoven inside of it.
It also could have to do withthe way that it's laid up,
because with carbon fiber it'snot just the design of the
material, it's how that materialis actually put together, how

(33:34):
it's laid up in the shape of abike, and by changing the
manufacturing process you changethe end product pretty
substantially.
So it's not just that theFACT-12 might just not be a
better material.
It might just be.
It might also just be that it'smanufactured in a more
efficient way.
That being said, the way thatthese companies name their
materials is all completelyproprietary.
It's their invention.

(33:55):
They invented that type ofcarbon fiber.
They can call it whatever theywant, and so some other company
can invent something verysimilar and call it some other
fancy word that they made up forit, and what that does is it
makes it.
So it's really hard to compareapples to apples across
different companies and say,with aluminum, you know that a
6061 bike is the same if youbought it from this manufacturer

(34:16):
versus that manufacturer.
It's always going to be thesame alloy, aluminum, whereas
when you're comparing the wordthat specialized and made up for
their aluminum, for theircarbon fiber, versus the word
that giant made up for theircarbon fiber, you don't actually
know what those minutedifferences are and if they're
relevant to what you're lookingfor.

Tom Butler (34:36):
You know, I felt pretty confident that whatever
FACT-12R is, that it wasn'tgoing to make a $14,000
difference as far as you know mybike is concerned.
So that was the way that Ijudged those properties.

Garren Miler (34:53):
I would completely agree with that.
I think that the whole carbonfiber versus carbon fiber
discussion is a bit more in theclouds than the average cyclist
really needs to worry about.
Something my dad just made meas a kid was that even the worst
NFL quarterback is still an NFLquarterback and even the worst
carbon fiber is still carbonfiber, assuming there's no

(35:15):
defects or errors in its designor manufacturing.
The carbon fiber is carbonfiber and the advantages of
carbon fiber are always going tobe there.
You're going to have theability to make a complex frame
shape.
You're going to have that greatstrength to weight ratio,
you're going to have the reallyreally light outcome and you're
going to have the really reallynice flexibility that you get
when you're riding a carbon bikethe shock absorption that you

(35:37):
don't quite get from an alloyframe.

Tom Butler (35:40):
So I want to talk about comfort with frames.
I find the Roubaix to be verycomfortable.
A couple episodes ago, Iinterviewed Eddie Holmes, who is
the president of the Gulf CoastBicycle Club and has been
cycling a long time, and Eddietalked about the Roubaix being
the most comfortable bike he'dever ridden.

(36:01):
And there is a property ofcarbon fiber that creates a
comfortable bike.
Can you talk about that a bit?

Garren Miler (36:09):
Carbon fiber has a great ability to absorb shock
and you'll notice thatimmediately when you start
riding a carbon fiber bike.
The primary places that you'regoing to feel this shock
absorption is going to be inyour seat post and in your front
fork, because those are theareas where your weight is
getting transferred down intothe tires.
Most manufacturers produce a Dshaped seat post these days out

(36:29):
of carbon fiber, and it allowsit to bend really well in the
aft direction but still have alot of rigidity in the forward
and downwards directions.
What this does is itessentially puts you on a giant
leaf spring where the roadshocks are being absorbed simply
through the carbon fibermaterial and the shape of the
seat post.
Similarly, front forks aredesigned so that their shape

(36:51):
allows them to bend and absorbshocks when your front wheel
hits a bump, and that eliminatesthe load coming up to your
hands through the handlebars.

Tom Butler (36:59):
And when you're talking about bend, you're
talking about a pretty minutebend.

Garren Miler (37:03):
I'm talking about an almost imperceptible bend.
This isn't something you'regoing to take with your bare
hands and bend into a rubber.
I mean, this is something thatis measured on the level of
thousands of inches.

Tom Butler (37:14):
Right.
At one point I thought I'mnever going to get a carbon
fiber frame.
And now I have a carbon fiberframe.
Right now my mind I'm thinkingI'm never going to get a
titanium frame.
I don't know.
What do you think about that?
Do you think someday you mightend up with a titanium frame?

Garren Miler (37:28):
I don't think titanium frames offered a
distinct enough advantage overother alloy frames or over
carbon fiber to really be toobig of a market share at any
point.
For starters, titanium is anincredibly expensive material.
It's one of the most expensivemetals that you're going to find
in day to day life.
It's hard to even get yourhands on enough titanium to make
a bike and by the time you doit's going to be quite expensive

(37:50):
.
Titanium is very difficult towork with, very difficult to
weld.
It also suffers from the sameproperty changes due to heat
that aluminum does, where whenyou weld it it changes the local
properties of the metal nearthe weld.

Tom Butler (38:03):
When I'm looking at this chart again that I have for
this 56 centimeter bike frame,it actually says titanium is
heavier than carbon fiber.

Garren Miler (38:14):
That probably depends on the carbon fiber.
I think that they're prettywell neck and neck, but I don't
have specific numbers, I guess.
But in general, I would expectcarbon fiber to be lighter than
titanium.
Is the thing that titaniumreally doesn't solve, that
aluminum didn't solve and thatseal didn't solve and titanium
still doesn't solve is the issueof the shape of your bike being

(38:35):
limited to tubes and limited topieces that are fit together by
joinery, be that a weld, aresin joint, sockets or whatever
.
The advantage of a carbon fiberbike being a single laid piece
that you can shape into whatevershape you want is still a
shortcoming that titanium can'tovercome.
There will still be weldedjoints, no matter how good the

(38:55):
weld is, and that limits how youcan design your bike.
Carbon fiber does not havethose limitations, Even if it is
heavier.
Being able to more accuratelytailor your bike to the loading
pattern that it's subjected tois still enough of an advantage
to go with a carbon fiber bikeover an alloy solution of any
kind.

Tom Butler (39:14):
There's an element here of the shaping that, among
all these frames, it sounds likethe carbon fiber frame can be
laid out in a way that makes itmore aerodynamic.
I've heard you talk aboutbefore that a round shape is not

(39:34):
a very aerodynamic shape andI'd like you to talk about why
that is again.
But then it seems like with acarbon fiber frame you would
have the ability to lay it outin a way that you can make it
more aerodynamic.

Garren Miler (39:53):
Yeah, obviously aerodynamics is a big topic in
the bike world.
When you're talking about theaerodynamics of your frame
itself, your frame is such asmall amount of cross-sectional
area compared to you on top ofthe bike.
You're probably 90% of thecross-sectional area and your
bike is only about 10.
So when you're talking aboutyour bike being more and more
streamlined, that's really notan advantage you're going to

(40:15):
feel unless you're reallypushing the boundaries, which I
think most people on bikes onthe weekends are absolutely not.
So aerodynamics really isn't ahuge concern.
The ability to shape your frameinto different, into more
accurate and more creativeshapes actually has more to do
with making sure that your loadis being distributed evenly
throughout your material,allowing you to shave off any

(40:37):
excess material that you don'tneed and lighten up your bike.
That's really the advantage ofit is that you can shape your
bike into a more efficient shapefrom a mechanical perspective.

Tom Butler (40:49):
Well, yes, I understand what you're saying
and I totally agree that when Isaid on a bike seat, the
aerodynamics of the frame arejust lost.
But that being said, I'm stillthinking that you can create a
more aerodynamic frame,regardless of whether or not
that transitions into anymeaningful performance advantage

(41:10):
.
You're still able to shape abike frame into a more
aerodynamic shape with carpetfiber.
Is that fair?

Garren Miler (41:18):
Yeah, carpet fiber certainly allows you to make a
lot more creative shapes.
That includes some real coolairfoil looking bikes.
You might see them on some ofthe indoor velodrome races where
aerodynamics is key.
It looks like a big flying wingout there and that's certainly
something you wouldn't get awaywith on an alloy bike.
That you have to have themalleability of carpet fiber and

(41:40):
the customizability of thelayup in order to create a bike
that can have anything close tothat kind of shape.

Tom Butler (41:46):
So now I want to come to a point where I talk
about where my mindset is now.
At one point I said I'm nevergoing to have a carpet fiber
bike.
Now I have one, but in thisprocess of looking at McKenna's
bike, there are a few thingsthat I looked at that made me

(42:08):
question having a carpet fiberbike, and so the first of those
things that I will talk about isthis element of hydroforming.
Can you talk about hydroforming?

Garren Miler (42:27):
Yeah, hydroforming is a way to have aluminum sort
of catch up to carpet fiber inthe shape world.
You can take a tube of aluminumand you can fill it with water
and press it into a mold tocreate whatever shape you'd like
.
So on McKenna's bike you'll seethat the top tube does have a
more carbon fiber-esque sort ofoval shape to it.

(42:47):
It's not just a tube, andthat's because they're able to
take the aluminum and form itusing water pressure in a mold,
Similarly to how you would haveinjection molded plastic parts.
They can hydroform the aluminuminto a much better shape that's
more efficient and moreaerodynamic.

Tom Butler (43:05):
McKenna's bike is a live bike which is made by Giant
.
They call their aluminum frameI think it's pronounced Alex,
but it's A-L-U-X-X and so theycall it their Alex grade
aluminum frame.
To me again, what you just saidwas they're able to replicate

(43:29):
some of the advantages of acarbon fiber frame.

Garren Miler (43:34):
The advantages that we see from carbon fiber
bikes are not limited just tofull carbon frames, and that's
what's really nice about themiddle ground that we're able to
strike in today's bike industry.
To use a good analogy, in thecar industry you have supercars
that only a handful of people inthe world own, but the
innovations that come from thedevelopment of those supercars

(43:54):
eventually trickle down intodaily drivers.
For example, conseg, created atone point, was very near the
world's fastest car and it had avery unique transmission system
inside of it, and thattransmission system was then
adopted by other Europeanmanufacturers and it trickled
down into the transmissions ofeveryday cars, and I think

(44:17):
that's what we're seeing withcarbon bikes now.
The advantages that carbonfiber bikes were able to bring
about in the world ofaerodynamics and frame shapes
are now being transferred toaluminum frames through
hydroforming to create moreaerodynamic and more efficiently
shaped aluminum frames.
And the ability of carbon fiberto absorb shock can also be

(44:37):
included on aluminum frame bikesby just making the seat post
and the fork carbon fiber, whichis a common configuration
you'll see these days and it'sthe configuration that's on
McKenna's bike the fork and theseat post isolate you from the
bike and the ground in order tohave all the benefits of the
shock absorption the carbonfiber offers, without needing to
pay the premium price tag thatcomes with buying a full carbon

(44:59):
fiber bike.

Tom Butler (45:00):
Yeah, and McKenna's bike was I don't know half the
price of our bike.
And again, I think that youknow, if I was getting into a
new bike, I'm really happy withmy bike, but if I was looking at
getting a different bike, Ithink I would look at an
aluminum frame.
I think I'd want it to be thelatest design principles as far

(45:21):
as aluminum frames are concernedand I would want to have a
carbon fiber seat, post andcarbon fiber forks.
By the time you do that, if youcan save $1,000 or whatever, at
my level as a cyclist, it seemslike that wouldn't be a bad
choice for me.

Garren Miler (45:38):
I completely agree with you.
Our Rubais size 56, weigh 19.1pounds.
Her live, which isn't sized inthe same system but it's a size
medium weighs 20.7 pounds.
The weight difference for anaverage cyclist is completely
negligible.
In fact you'd be hard-presseduntil the difference just by

(45:59):
picking them up, I think.
Bottom line a carbon fiber bikeis better than an aluminum bike
, but for the weekend warriorit's really hard to justify an
almost doubling of the price fora product that's only
marginally better.

Tom Butler (46:15):
And if McKenna can get you to carry the bike tool,
the tubes, you know, there's notmany things that she would need
to convince you to carry on.
Your bike rides together andyou're riding pretty much the
same weight of bike, rightexactly.

Garren Miler (46:35):
I think it just depends on how much water is in
your water bottle.
I mean, it's really, it's sucha minute difference.
It's been so many cliff bars Ieat at the stop.
I think that the carbon fibercan be utilized in the areas
where it's most needed, withoutthe extra cost of making the
entire bike out of carbon fiber.
Aluminum will do just fine forsomeone who is just getting out

(46:57):
on the weekends getting someexercise or commuting.

Tom Butler (46:59):
Okay, so I want to talk about a different frame
material, and this is a framematerial that I would really
like to have the extra money tojust go out and buy this frame
and that is a frame made out ofbamboo.
Have you ever seen a bike witha frame made out of bamboo?

Garren Miler (47:18):
I've certainly never seen a frame made out of
bamboo.
I think the first thing thatcomes to mind is how much of a
nightmare quality assurancewould be on that, making sure
that you have consistency andthat you know that your bamboo
is not going to fail.
One thing that's difficult withmaterials like bamboo is that
each plant is completely unique.
You can't say, just becauseplant A broke it, this amount of

(47:41):
strength means that plant B isgoing to break it, that amount
of strength.
The only way to know thebreaking strength of a plant is
to break it.
It's a chicken and egg problemwhere you can't break the thing
you're making your bike out ofto test it, but then you don't
know when your bike is going tobreak.

Tom Butler (47:57):
The interesting thing about it is that the 56
centimeter bamboo frame they'resaying weighs 1.8 to 2.5
kilograms.
So comparing to steel 2.2 to 3kilograms it's actually a
lighter frame material thansteel.

(48:17):
And about the range of aluminumframes, I think that's very
interesting.
But again what you're talkingabout, it seems like there's so
much variability even in that inwhat the weight would be.

Garren Miler (48:32):
Absolutely.
I think it depends oneverything from the water
content of the tree to the soilit was growing in.
I don't think that's really youcan control very tightly.

Tom Butler (48:41):
Right, how much sun there was that year.
Whatever, right.

Garren Miler (48:45):
I think that the most obvious advantage of a
bamboo bike is the inherentsustainability of it.
I think if we're trying tobring bicycling to the masses,
that's certainly a direction youmight want to take it.
Our rubes are literally andessentially made out of plastic,
and they'll be here long afterwe're done riding them, be that
in the ground or in our kids'hands.
But a bamboo bike is not onlybiodegradable at the end of its

(49:08):
lifespan and hopefully no soonerbut bamboo is also a really
good carbon sink.
When it grows, it sucks asurprisingly large amount of
carbon out of the area comparedto other plants.
So growing bamboo in and ofitself is also a more
sustainable practice.

Tom Butler (49:24):
I want you to go to Ampro bikes and just look at the
bike and give me yourimpression looking at it.

Garren Miler (49:33):
I got to say that is a pretty awesome looking bike
.
It definitely would catch someattention and turn some heads
cruising that thing down thestreet.
I want to say if I saw it inperson I'd probably have to get
real close to it before I'dbelieve that it was actually
bamboo.
But they don't try to hide it.
I just wouldn't believe thatsomeone would ride a bike around

(49:53):
and just made out of bamboo.
But it's pretty awesome.

Tom Butler (49:56):
Yeah, I think you'd be like is that a really
innovative paint job, or is thatactually in bamboo?

Garren Miler (50:03):
Exactly.
I think it's a.
Really I love the juxtapositionof the really high-tech group
set and everything on it with areally just naturalistic bamboo
that looks like it just gotpicked out of the woods and
slotted with a coat of lacquer.

Tom Butler (50:17):
They show a frame set by itself and it's a $600
frame set, which isn't thatexpensive of a frame, and I
think they're probably usingcarbon fiber to join the
different bamboo together tomake the frame set.
They have a commuter frame set,they have a gravel frame set.

(50:37):
They have some electric bikes.
I find it to be a reallyfascinating thing and I hope to
someday run in these bikes again.
If something happens, I end upwith a bunch of extra money, I
think I'll buy a frame set andbuild it up, because I think
that would just be fantastic.

Garren Miler (50:56):
Yeah, for sure.

Tom Butler (50:58):
If you were going to yes, okay, I'm putting you on
the spot here.
What frame material do youthink has the largest market
share in bicycling?

Garren Miler (51:08):
I think it's aluminum.

Tom Butler (51:09):
Okay, what would you put second?

Garren Miler (51:11):
Probably steel.

Tom Butler (51:12):
Okay, and what would ?

Garren Miler (51:13):
you put, and then only carbon.

Tom Butler (51:14):
Okay, these are the numbers that I have and this is
from a variety of sources.
Aluminum is number one largestmarket share at 35 to 45%.
Carbon fiber is gaining groundrapidly it said the report that
I read and it's at 30 to 35%.
So steel is 15 to 25%.

(51:37):
I found that to be interestingbecause I would have thought for
sure that steel was at least50% of the market.

Garren Miler (51:45):
Yeah, and you also have to wonder how much of a
role e-bikes play in thesenumbers as well, because a lot
of e-bikes are made out of steel.
Because it's increased strength, it makes it a lot easier to
strap a battery to it and nothave it break, and so I wonder
how much of the steel market ise-bikes as well and what kind of
an impact that would have.

Tom Butler (52:02):
I think that's a really good question.
And then kids' bikes.
I would think that steel isstill the predominant material
in kids' bikes, right?
So I thought that was prettyinteresting.
They estimate around 5% to 10%titanium, and then bamboo is so
small that they don't evenestimate it.
I did want to touch on one thingand I wanted to get your

(52:23):
comment on it.
There was an article that Ifound and I sent over to you,
and it was an outside magazine,so this is a pretty significant
source of information as far asoutdoor sports are concerned,
including cycling, and the titleof the article is there's no
Good Reason to Buy a Carbon Bike.

(52:44):
Again, we've said here that weboth would really consider
aluminum frame in the future,given the carbon fiber seat post
and the carbon fiber forks, youknow, counting in as far as
part of aluminum frame.
But one of the things that thisperson pointed out Eben Weiss,

(53:06):
I believe, is their name is thatcarbon fiber bikes.
And I'm just going to read thissection of this article, and
this was published in theJanuary 27th online.
I don't know it's online, so itwas published January 27th of
this year and then it was, sinceit was updated in January 30th.

(53:28):
I'm not sure what they updated.
There's the statement hereProbably the biggest drawback to
carbon fiber bikes is thatthey're like eggs.
You know how eggs are almostimpossible to break if you
squeeze them from the pointyends, but if you squeeze them
any other way, you'll quicklywind up with a handful of yolk.
Similarly, while carbon bikesare quite strong when used as

(53:50):
designed, what they're designedfor is racing.
They're not designed forcrashing, falling off a hitch
rack, getting knocked over inthe garage by your young
children or any other littlemishaps that befall normal
people's bicycles as part of themessy business of day-to-day
living.
So what I heard this personsaying is that they're so
fragile that it doesn't makesense for people to have them,

(54:14):
unless they're professionalracers where they're constantly
given new bikes.
I sent that over to you.
I know that you've had sometime to think about it.
What do you think about that?

Garren Miler (54:24):
I think the article brings up some good
points, but I also do think thatit exaggerates the fragility of
a carbon bike.
I mean, they certainly aredesigning these bikes with
factors of safety against, forexample, side loads or crashing,
and they're doing crash testson these bikes.
You've got to be sure of it,that they're making sure that
these bikes aren't just going toexplode if it falls over your

(54:45):
garage, for example.
I mean, that's maybe a bit of acatastrophized approach to the
issue, but it is definitely aconcern, and one way that
manufacturers mitigate this iswhen you buy a carbon bike new
and you register with amanufacturer, you get a lifetime
warranty on the frame, andthat's given the fact that
carbon fiber is going to bedifferent layup to layup.
Not all bikes are created equal.
In fact, you can see that onyour bike where it has the

(55:08):
unfinished paint job, you cansee the carbon layup, and if you
were to take another bike withthat same unfinished look, it
would have a completelydifferent pattern on it because
the carbon fiber was laid updifferently.
And so it's very possible thatyou do get a carbon fiber bike
that has a weak point in itbecause something went wrong on
the layup and one day you'releaning on it against a post and

(55:29):
your top tube cracks, andthat's when specialized and
giant and Trek will take thosebikes back.
And it's industry standard togive a lifetime warranty on
carbon bikes and that's one ofthe advantages, of course, of
buying a new bike and that's oneof the ways that they help to
mitigate the concern of anoverly fragile carbon bike.

Tom Butler (55:49):
I haven't seen people writing about I'm never
getting carbon fiber bike again.
I bought this carbon fiber bikeand it cracked and they
replaced it, but it crackedagain I'm just not reading about
that and it seems like theywere as fragile as falling off a
hitch rack or getting knockedover in the garage by your young

(56:11):
children.
If a carbon fiber frame wasthat fragile, you would get
people saying, hey, I had acarbon fiber bike, but it just
kept getting cracked over andover again, and so I just dumped
it and got a limited frame.

Garren Miler (56:27):
It would be hard to imagine carbon bikes having
what was it?
A 30% market share if peoplewere to get a carbon fiber bike.
So we're going to be breakingthem and having to buy new ones
frequently.

Tom Butler (56:37):
But we look at giant producing frames for quite a
long time now.
They've had a lot of years tolook at carbon fiber frames and
they've not been selling thoseframes to only racers.
They're selling that to normalpeople like you and me,
obviously.
And so, yeah, I just carbonfiber would have got popular,

(57:00):
popular, popular, and then itwould have died off.

Garren Miler (57:03):
I'd agree.

Tom Butler (57:04):
Well, Garen, thank you so much for coming on.
We talk about bikes a lot.
I find it to be really fun andI really appreciate your
perspective on it.
I don't know if you haveanything else that you're
looking forward to or thinkingabout as far as frames.

Garren Miler (57:22):
No, I'm always happy to talk about this kind of
thing.
Like I said, I do this for workand I think about it all day
long, and it's fun to get homeand think about it some more.

Tom Butler (57:29):
And you also have some engineer classmates that
are cyclists as well, I think.

Garren Miler (57:35):
Yeah, I had some classmates present senior
projects on different bikerelated problems that they had
solved.
Pretty interesting stuff.
It's kind of a tragic job ifyou're a mechanical engineer.

Tom Butler (57:44):
Yeah, so that's very cool.
And again, thanks a lot andwe'll be riding together soon.

Garren Miler (57:50):
Yeah, thank you, and I'll see you then.

Tom Butler (57:52):
All right, bye now Bye.
I certainly don't regret that Igot a carbon frame bike, and it
is likely that I would havealways wondered what I was
missing if I'd gotten analuminum bike instead, but I do
think I will make a differentchoice if I get another bike in

(58:14):
the future.
What I really want to purchasenext is a bamboo frame bike, and
not because I need it or Iwould even ride it very often,
just because there are certainrides that would be really fun
to show up on a bamboo bike NowI just have to figure out a way
to justify it.
If you have a bamboo bike, Iwould really love to hear from
you, and if you have somethoughts on carbon fiber as a

(58:36):
bike material, please share.
You can find my email and thepodcast, instagram and the show
notes.
Whatever frame you are ridingon, I hope you are experiencing
some beautiful scenery and somewonderful fresh air, and
remember age is just a gearchange.