Titanium and Frame Size
skim500
longer "fun" rides. I do love to get out of the saddle on the hills.
Considering these great makers, I have heard rave reviews about all of
them. Interestingly, I seem to notice alot of the owners all pretty
big guys, over 6', more than 200. I am wondering if my size and riding
style are not as appropriate for titanium because of the larger tubes,
and in particular those bikes using the more attractively priced
straight tubes.
Any guys more my size (or even not) have thoughts on this? Would
quality steel (am riding an 853 Lemond now) serve just as well? I'd
love to have a bike that soaks it up like my current, but felt faster
and quicker on the hills. Most of my desire is rational, but of course
there is always a degree of "bike sickness."
I understand fit is most important, and of course all can custom fit.
Thanks in advance, and may the petulant not flame.
skim
jim beam
in your size, quality steel will be fine. but why go custom? unless
you have many $k's to burn, consider something off the shelf. i got a
bianchi ev3 at the begining of this season, and it's been fantastic.
very very light, responsive, comfortable, stiff... and only ~$1k for
the frame. unless you need to make a wealth statement, i don't think
frames like this can be beat. and just in case you wonder, i /do/ know
what high end custom is like also - i have a della santa. it's a great
fit and was undoubtedly the best frame i'd ever tried until i rode the
bianchi.
Qui si parla Campagnolo
big guys, over 6', more than 200. I am wondering if my size and riding
style are not as appropriate for titanium because of the larger tubes,
and in particular those bikes using the more attractively priced
<< Any guys more my size (or even not) have thoughts on this? Would
Steel is a wonbderful material, will ride well and last formyears and years. Ti
has few advantages over good steel. Not much other than no corrosion(not a big
deal with steel if ya take care of it) and perhaps a wee bit l;ighter(3.5 lb
steel frames are common as are to frames).
Fit is key, don't expect ti to make for a magical difference in your ride.
Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"
Bruni
gauge option on ride criteria.
Tom
--
Bruni Bicycles
"Where art meets science"
brunibicycles.com
410.426.3420
Qui si parla Campagnolo <vecc...@aol.com> wrote in message
news:20040830085155...@mb-m11.aol.com...
skim500
My "need" to go custom is based upon these lines:
Weird body. Very short legs to long torso. I am riding a 51cm Lemond
Zurich with a 53+ cm top tube. TT is great, but I have zero crotch
clearance. I felt perhaps a custom builder could accommodate this.
Not to open a can of worms, but my thoughts were the builder could
slope the TT to some degree. Although I prefer the traditional look,
it would give me more clearance, and my experience (and mine only!) is
that the sloped TT makes no ride difference on the flats, but has a
very quick and nimble feel when on the hills, particularly out of
saddle.
Anyway, not to open the issue to sloping geometry per se, but really
to give my thoughts on custom vs. stock.
skim
Blair P. Houghton
>Steel is a wonbderful material, will ride well and last formyears and years. Ti
>has few advantages over good steel. Not much other than no corrosion(not a big
>deal with steel if ya take care of it) and perhaps a wee bit l;ighter(3.5 lb
>steel frames are common as are to frames).
Why are Ti frames not much lighter than steel frames?
Ti is much stronger for the same weight than steel is,
and Ti is much lighter for the same strength than steel
is (although it will still take up more volume due to
the its lower density, so like aluminum it will have
oversized tubes).
So if anyone is making a titanium frame and not using
the strength/weight advantage to reduce the weight
significantly, they're missing the point.
>Fit is key, don't expect ti to make for a magical difference in your ride.
Training makes the magical difference in a ride.
--Blair
"I have proof."
Mike Jacoubowsky
> longer "fun" rides. I do love to get out of the saddle on the hills.
> Considering these great makers, I have heard rave reviews about all of
> them. Interestingly, I seem to notice alot of the owners all pretty
> big guys, over 6', more than 200. I am wondering if my size and riding
> style are not as appropriate for titanium because of the larger tubes,
> and in particular those bikes using the more attractively priced
> straight tubes.
No particular reason why larger guys are riding on Ti bikes; in fact, I'd
say the opposite would be true if you surveyed people in my area. If
appropriately constructed, frame material isn't much of a consideration,
especially for middle-of-the-road sizes. Steel and Ti, as used by most
(not all)frame builders, may be a bit flexy in larger sizes. This can be
dealt with by using larger-diameter tubing, but not too many people do that
(partly because it gets costly and the materials may simply not be readily
available in non-standard sizing, and partly because of the added weight).
But you're talking middle-of-the-road stuff here, so Steel, Aluminum, Ti &
Carbon can all be used to build an extremely nice frame without modification
from normal building practices.
> Any guys more my size (or even not) have thoughts on this? Would
> quality steel (am riding an 853 Lemond now) serve just as well? I'd
> love to have a bike that soaks it up like my current, but felt faster
> and quicker on the hills. Most of my desire is rational, but of course
> there is always a degree of "bike sickness."
Steel builds a very nice frame, but your weight floor (the lightest you can
build something that's very durable) is about 3.5 lbs or so. With Ti you
can get down to just over 3 lbs. Using aluminum, my experience is that the
floor is about 2.8 lbs, while Carbon Fiber can get you down to 2.4 lbs,
maybe even a bit less. There are plenty of people building bikes from these
materials with lighter weights, but experience shows that doing so carries
costs in terms of overall lifespan and durability under adverse conditions
(crashing).
> I understand fit is most important, and of course all can custom fit.
> Thanks in advance, and may the petulant not flame.
In a later post you mention that you have a longer torso and shorter legs,
which, with modern sloping-top-tube bikes, is very easy to accommodate.
Don't buy a custom bike because you think it's going to magically fit you
better; my guess is that the current Klein & LeMond bikes, with their
moderately-sloping top tubes, would work great.
The reason for getting a custom bike, for most people, is to have something
that offers a sense of uniqueness, a bike that was built for you and which
nobody else has the exact same thing. Some people put a high value on
uniqueness, and even prefer something that costs more because that, also,
enhances its exclusivity. Hey, if that's what it takes for you to want to
ride more, go for it. But don't assume it's necessary for the best-possible
ride. In fact, by going custom you often give up technologies that don't
lend themselves to one-up craftsmanship (such as the manner in which TREKs
OCLV carbon bikes are built).
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
"skim500" <ski...@mindspring.com> wrote in message
news:a1209d19.04082...@posting.google.com...
Qui si parla Campagnolo
They are not. A 'standard' ti frameset, like a Moots or Serotta or Litespeed,
is about 3.3 pounds, some are heaver(Dean). Most of the steel framesets we
sell-Waterford, Nobilette, Torelli are in the 3.3 to 3.7 pound range. There are
very light ti framesets but they are extremely thin walled, have their own
problems(like a Merlin with a crimped seattube from the front der clamp).
Blair<< Ti is much stronger for the same weight than steel is, >><BR><BR>
Yes it is but you imply that steel is somehow weak when applied to a bicycle
frameset. Ti is way overbuilt.
Blair-
<< So if anyone is making a titanium frame and not using
the strength/weight advantage to reduce the weight
significantly, they're missing the point.
>><BR><BR>
I guess all the ti frameset makers, like Serotta, Seven, Litespeed, Moots, etc
are missing the point then.
Four thing make for a better performing cyclist
-fit
-fat
-fitness
-finesse
skim500
out the romanticsm and dogmatism that is a real part of our
enthusiasm, especially when I believe most of it!
Based upon these posts, I have a real feeling that custom is not a
necessity, but perhaps still viable for me. Seven in particular seems
to be an incredible company. If you never seen their brochure, I am
sure it is responsible for a significant part of their sales,
especially "on the fence-er's" like myself. I am not touting them per
se, just reporting. The technical end is impressive to me,
notwithstanding the fact that they publish the weights of each frame
in each size. E.G. "52cm Axiom steel: 3.70 lbs, Axiom Ti: 2.68 lbs".
(These are the "Signature" Seven geometries). Check out their
brochure, it is a marketing masterpiece.
Will a pound help me, particularly considering the typical $1200
surcharge? Okay, I'm not naive to believe that. But as the "dream
bike" I'm still thinking about it. Which leads me to this question:
I understand that tube diameter/wall thickness is what actually
contributes to strength and weight more than material. That being so,
as the typical Ti tube is thicker than steel, I am wondering what you
think contributes to what I have experienced is a "quieter" feeling. I
would think the wider tube diameter would contribute to a harsher
feel.
Thank you. A side note: Mike J, I am mostly a lurker, but have read
many of your posts throughout the years. I am very impressed by your
willingness to help, knowledge, and able to keep level through "cranky
times". We're close enough to you to consider you a LBS and my wife
has got it in her head she wants a Trek OCLV in the next year
(opposites attract eh?), so I'll give you a call to get her sized up.
skim
Scott Goldsmith
> that offers a sense of uniqueness, a bike that was built for you and which
> nobody else has the exact same thing. Some people put a high value on
> uniqueness, and even prefer something that costs more because that, also,
> enhances its exclusivity. Hey, if that's what it takes for you to want to
> ride more, go for it. But don't assume it's necessary for the best-possible
> ride. In fact, by going custom you often give up technologies that don't
> lend themselves to one-up craftsmanship (such as the manner in which TREKs
> OCLV carbon bikes are built).
>
> --Mike-- Chain Reaction Bicycles
Those technologies also limit how Trek can build their bikes,
if you look at the trail numbers, determined by how many different forks
Trek can afford. The 5xxx bikes vary from 6.2 in small to 5.0 in large
sizes. A small builder would just bend the fork blades to keep consistent
handling across different sizes. If you look the geometry charts you'll
see Treks 23xx frames use the same length chainstays for all sizes,
so you have different weight distribution, more weight on the front end
as bike sizes increases. There are trade offs in using any building
material, and even at the 5$k that Trek charges for some of the OCLV
bikes they can't afford to match fork rake and head angle. Where a small
builder with a big wooden block and a pair of Reynolds fork blades can
precisely match fork rake and head angle and cut chainstays proportional
to frame size. You pays you money and takes your choices.
Scott Goldsmith
(Pete Cresswell)
> I seem to notice alot of the owners all pretty
>big guys, over 6', more than 200.
Can't speak for others, but the reason I bought my "custom" SevenCycles was to
get a frame that fit my too-long bod.
If I were within the normal range of sizes, I would have been just as happy or
happier with one of the several off-the-shelf frames I've owned.
--
PeteCresswell
Mike Jacoubowsky
> if you look at the trail numbers, determined by how many different forks
> Trek can afford. The 5xxx bikes vary from 6.2 in small to 5.0 in large
> sizes. A small builder would just bend the fork blades to keep consistent
> handling across different sizes. If you look the geometry charts you'll
> see Treks 23xx frames use the same length chainstays for all sizes,
> so you have different weight distribution, more weight on the front end
> as bike sizes increases. There are trade offs in using any building
> material, and even at the 5$k that Trek charges for some of the OCLV
> bikes they can't afford to match fork rake and head angle. Where a small
> builder with a big wooden block and a pair of Reynolds fork blades can
> precisely match fork rake and head angle and cut chainstays proportional
> to frame size. You pays you money and takes your choices.
You bring up an interesting point! But it's not about cost that TREK
doesn't have different fork rakes for different sizes anymore; the molds
exist, and they did have the different offsets for some time. But
experimentation with the Postal team (which TREK did, in fact, get a lot of
mileage out of beyond the advertising value) showed that the bike handling
difference was insignificant, if detectable at all. This flies in the face
of everything I've been taught, and I fought the change tooth-and-nail.
But in the end, it appears I'm wrong, because I've ridden the bikes with
different offsets, as well as my customers, and it doesn't appear to matter.
In fact, I have the first-year 5900 (2001) which came with a stock
(unmodified) Klein Aeolos fork. 38mm offset, instead of the 43mm specified
in the catalog (and used on every other 60cm OCLV TREK at the time,
including my prior 5500). 38mm, yikes! For the Klein, with its steeper
head tube, it made sense, but on paper, it seemed, well, wrong for the OCLV.
Does it handle differently than my 5500? Yes. On that first ride, I
noticed it *instantly.* Definitely felt a bit faster/twitchier. But after
the second ride, I no longer noticed any difference and, in fact, could ride
the 5500 and 5900 interchangeably without noticing differences in handling.
Go figure.
Mike Owens
"Mike Jacoubowsky" <mik...@ix.netcom.com> wrote in message
news:x02Zc.14014$hR5....@newssvr29.news.prodigy.com...
stable at speed? Do even experienced and reasonable riders (you) think that
they feel something that isn't there? If true, it's just another indictment
of the clowns who write bike reviews.
-Mike
Mike Jacoubowsky/Chain Reaction Bicycles
> more
> stable at speed? Do even experienced and reasonable riders (you) think
> that
> they feel something that isn't there? If true, it's just another
> indictment
> of the clowns who write bike reviews.
> -Mike
The more subtle aspects of cycling beg for "feeling something that isn't
there." A bicycle isn't like a car, where the linkage between the driver
and /acceleration handling is indirect at best. If you're tense while
driving a car, sure, it can affect reaction times and how you steer etc.,
but it has no effect whatsoever on the overall ability of the vehicle to
perform. On the other hand, if you're tense on a bicycle, it has a
tremendous effect on handling... you can actually induce a shimmy, or cause
it not to recover as it ought to after hitting something that knocks a wheel
off track, etc.
So a bicycle actually responds to emotional input in a way that clearly
flavors how someone thinks it handles. Is this a good or bad thing?
Actually, I think it's a good thing. It's cool that a bicycle is more than
just a simple tool, but rather something that, in a way, you bond with. And
the things that affect that bonding aren't limited to what physics would
dictate; how you *feel* about your bike is key, and even how it looks is
going to affect that.
--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
IMBA, BikesBelong, NBDA member
"Mike Owens" <mow...@emory.edu> wrote in message
news:ch2cr2$2ai$1...@puck.cc.emory.edu...
Mike Jacoubowsky/Chain Reaction Bicycles
> many of your posts throughout the years. I am very impressed by your
> willingness to help, knowledge, and able to keep level through "cranky
> times".
Cranky times? Here? Heck, this group is pretty darned civil compared to
some others I sometimes check out. Rec.bicycles.racing makes this group
look quite tame. And rec.photo.digital... just try to ask a question about
the pros and cons of different types of sensors and watch the missiles fly!
And Lord help you if you venture into ba.mountain-folk... (you can hear the
dueling banjoes in the background, even without a sound card).
--Mike Jacoubowsky
Chain Reaction Bicycles
www.ChainReaction.com
IMBA, BikesBelong, NBDA member
"skim500" <ski...@mindspring.com> wrote in message
news:a1209d19.04083...@posting.google.com...
Chalo
>
> Ti is much stronger for the same weight than steel is,
> and Ti is much lighter for the same strength than steel
> is
That depends on both the Ti in question and the steel in question.
All Ti alloys are around 60% as dense as steel alloys, but not all of
them are 60% as strong.
Let's make an example of a couple of strong yet forgivingly workable
alloys. Regular old 3Al/2.5V titanium alloy in its beta annealed
state has a yield strength of 78 Ksi and elongation of 17%. Regular
old tempered 4130 chromoly steel has a similar elongation figure at
16%, but its yield strength is 161 Ksi. So in this comparison the Ti
alloy is 60% as dense, but only 48% as strong as the steel.
If workability and elongation are not as important as utmost strength,
the material choices may be different. Another example: 6Al/4V
titanium alloy has a yield strength of 128 Ksi. A similarly
high-performance steel, tempered 4340 chrome-nickel-moly, has a yield
strength of 225 Ksi. So in this case the Ti is 57% as strong as the
steel-- close to, but not quite equal in strength-to-weight ratio to
the steel.
For comparison, the strongest aluminum alloy in common use for bike
frames (scandium aluminum) has a yield strength of 83 Ksi. That makes
it 37% as strong as the 4340 steel, but only 33% as dense.
If you want to compare the cheap stuff, grade 1 "commercially pure"
titanium has a yield strength of 35 Ksi and a phenomenal elongation of
30%. Cold drawn, stress relieved 1018 mild steel has a yield strength
of 45 Ksi and elongation of 20%. So the Ti in this case is 78% as
strong as the steel and even more ductile. However, it's worth noting
that even the plainest CP Ti is much, much more expensive than mild
steel. For the same cost as a CP Ti bike frame, you could buy a steel
frame of a relatively distinguished alloy, certainly stronger than the
Ti frame for its weight.
> (although it will still take up more volume due to
> the its lower density, so like aluminum it will have
> oversized tubes).
Oversized tubes are a means of dealing with the relatively low modulus
(stiffness) of the material, and have nothing to do with its density.
> So if anyone is making a titanium frame and not using
> the strength/weight advantage to reduce the weight
> significantly, they're missing the point.
As I pointed out, there is no strength-to-weight advantage. Titanium
is desirable for its corrosion resistance and its high-tech glamor,
but has few other properties to recommend it over steel or aluminum
for bike frames.
Chalo Colina
jim beam
> Thank you guys for these informative posts. It isn't easy filtering
> out the romanticsm and dogmatism that is a real part of our
> enthusiasm, especially when I believe most of it!
>
> Based upon these posts, I have a real feeling that custom is not a
> necessity, but perhaps still viable for me. Seven in particular seems
> to be an incredible company. If you never seen their brochure, I am
> sure it is responsible for a significant part of their sales,
> especially "on the fence-er's" like myself. I am not touting them per
> se, just reporting. The technical end is impressive to me,
> notwithstanding the fact that they publish the weights of each frame
> in each size. E.G. "52cm Axiom steel: 3.70 lbs, Axiom Ti: 2.68 lbs".
> (These are the "Signature" Seven geometries). Check out their
> brochure, it is a marketing masterpiece.
>
> Will a pound help me, particularly considering the typical $1200
> surcharge? Okay, I'm not naive to believe that. But as the "dream
> bike" I'm still thinking about it. Which leads me to this question:
>
> I understand that tube diameter/wall thickness is what actually
> contributes to strength and weight more than material. That being so,
> as the typical Ti tube is thicker than steel, I am wondering what you
> think contributes to what I have experienced is a "quieter" feeling. I
> would think the wider tube diameter would contribute to a harsher
> feel.
as far as i've been able to figure out, what seems to make the most
difference is tube wall thickness, tube diameter, wall thickness at the
joints and whether any tubes like seat stays have bends in them. of the
two aluminum frames i ride regularly, the one with straight seat stays
is a beast, the one with curved seat stays, the ev3, is real comfy.
regarding the materials themselves, there's a couple of pdf's available
for download on the reynolds tube web site here:
https://vault2.secured-url.com/reynolds/compproperties.html
https://vault2.secured-url.com/reynolds/downloads/compprop1.pdf
https://vault2.secured-url.com/reynolds/downloads/compprop2.pdf
so, what's best? imo, it depends on the builder. in custom, steel is
comparatively easy to use and a real artisan can produce fantastic work.
but then again, cosmetic beauty does not mean they really understand
the finer points of engineering design. [beware heavily ovalized down
tube at bottom brackets - can lead to really bad torsion!] regarding
ti, it's not my favorite. apart from the cost, welding can be a real
problem - this is not the cosmetics but the metallurgy. beautiful
looking welds mean nothing. look inside any welded parts like bottom
brackets or head tubes to see what color the tube has gone - the inside
part that has not been polished. if it's gone purple or even black,
there was too much oxygen present at welding and i wouldn't buy it.
oxygen is the achilles heel of ti. in aluminum, heat treatment is the
big thing. it needs to be very closely controlled to achieve the right
results, so i'd only buy from a big manufacturer with lots of production
capacity that can both afford the equipment necessary and afford the
reject rate if it's not done right. that pretty much rules out custom.
then, there's carbon. again, i'd only buy from a real volume
manufacturer, so it won't be custom.
i guess this is a long winded way of saying, just ride lots of different
machines and see what you like best!
skim500
Thanks for responding.
skim
Qui si parla Campagnolo
Or Rec.aviation.naval...ya can tell it's an election year.
(Pete Cresswell)
>Pete, did you order Ti or steel from Seven? And which did you ride previously?
I ordered their 'Duo' FS - which only comes in Ti. Given a choice, I'd have
ordered steel - only because people wouldn't say "Oooooh, titanium...!".
Previous bike was (actually is still - anybody intersted?) a 22" Ellsworth Isis.
Nice bike, but I have to do cruel and unnatural things to it to get the
handlebar-near-saddle height that I crave.
Before that, it was a Cannondale Jekyll. A decent bike - and the Lefty fork
appealed to the exhibitionist in my - but also a poor fit.... and my feeling is
that I could have gotten a better bag of parts for the same or lower price by
buying something that used standardized parts.
--
PeteCresswell
Donald Gillies
>As I pointed out, there is no strength-to-weight advantage. Titanium
>is desirable for its corrosion resistance and its high-tech glamor,
>but has few other properties to recommend it over steel or aluminum
>for bike frames.
Aluminum has a "zero" fatigue cycle endurance limit.
An Aluminum frames loses strength every time you ride it. Every
fatigue cycle is above the endurance limit, which is zero. Once you
ride an Aluminum frame enough times, IT WILL CRACK / FAIL.
Steel and Titanium has a "nonzero" fatigue cycle endurance limit.
If you ride a Steel or Titanium frame with stress levels below its
endurance limit, THE FRAME WILL BE IMMORTAL.
- Don Gillies
San Diego, CA
dhk
Correct in theory, except that few people buy a steel or Ti frame that
heavy anymore. I believe that lightweight steel or Ti at anywhere near
the weight of AL will fatigue and fail also. A quality AL frame at 2.5
lbs is going to last most of us longer than we care to ride it. You
could build a 5 lb AL frame that would last forever too, but there's
little market for them. To me, any comparison in life only makes sense
if you're comparing frames of equal weight.
I've got one of those "immortal" steel frames you talk about....a 531
lugged frame on my '74 Raleigh Gran Sport. Probably weighs a good 6
lbs, with a rock-harsh ride to go with it. I'm letting it rust in
peace.
--
dhk
Blair P. Houghton
>
>They are not. A 'standard' ti frameset, like a Moots or Serotta or Litespeed,
>is about 3.3 pounds, some are heaver(Dean). Most of the steel framesets we
>sell-Waterford, Nobilette, Torelli are in the 3.3 to 3.7 pound range. There are
>very light ti framesets but they are extremely thin walled, have their own
>problems(like a Merlin with a crimped seattube from the front der clamp).
>
>Blair<< Ti is much stronger for the same weight than steel is, >><BR><BR>
>
>Yes it is but you imply that steel is somehow weak when applied to a bicycle
>frameset. Ti is way overbuilt.
I'm not implying that. I'm only implying that by using Ti,
you can save a few hundred grams per frame, and it's very
odd that it's not done.
I ride steel. I believe I ride actual Sheffield steel,
as my frame is a Holdsworth. Light, flexy, and sexy.
>Blair-
><< So if anyone is making a titanium frame and not using
>the strength/weight advantage to reduce the weight
>significantly, they're missing the point.
> >><BR><BR>
>
>
>I guess all the ti frameset makers, like Serotta, Seven, Litespeed, Moots, etc
>are missing the point then.
Maybe. The entire DSL networking industry missed the
point, and there are over a hundred years of bicycle parts
designs we'll never see again.
>Four thing make for a better performing cyclist
>-fit
>-fat
>-fitness
>-finesse
I can lose a pound from my middle, or throw my water
bottle into the weeds. Either way, I'll go into the
sprint one pound lighter. If I can start with a lighter
bike without sacrificing any mechanical strength, then
all the better, no?
--Blair
"You left out politics."
Trevor
Mike Owens wrote in message ...
>Shouldn't less offset increase trail and make the bike less twitchy and
more
>stable at speed? Do even experienced and reasonable riders (you) think
that
>they feel something that isn't there? If true, it's just another
indictment
>of the clowns who write bike reviews.
Rider compensates for changes in fork geometry. It is when compensation it
not what is expected to produce desired effect that differences in feel are
noted.
Trevor
(Pete Cresswell)
>If you ride a Steel or Titanium frame with stress levels below its
>endurance limit, THE FRAME WILL BE IMMORTAL.
Maybe so...but I broke my old (steel-and-not-particularly-light) Panasonic road
bike right at the rear dropouts just by riding the heck out of it for several
years.
--
PeteCresswell
Trevor
dhk wrote in message ...
How about its actual weight?
Trevor
Peter Cole
news:ch5msh$8oj$1...@cascade.cs.ubc.ca...
This is a very naive interpretation of the material science. It assumes that
steel/Ti frames are never stressed beyond fatigue threshold, which is
obviously not true since those frames crack and fail in use also. It also
assumes that the (calculated) fatigue life of an aluminum (or carbon fiber)
bike will be short relative to the actual years of potential use, also false,
since there are many old aluminum bikes in circulation that have been ridden
hard for many years. The fatigue curve for aluminum is *very* non-linear, so a
fairly small increase in material extends the fatigue life orders of
magnitude, making fatigue failure happen in relatively "infinite" time.
Lastly, it ignores the pragmatic reality that most frames fail from either a
design or manufacturing flaw, quality control and design soundness loom as
much larger reliability issues than material. Other factors to consider in
longevity are corrosion, impact damage resistance, and cost to repair, the
various materials have different tradeoffs in those areas, none being
obviously better in all respects.