Crank Arm Length

A Muzi said:

Quoted message said:

http://www.roble.net/marquis/crank.length

It isn't that formulaic.

Looks like you missed the note about "general rule of thumb". I
tried to stay away from formulas. There are already too many
different formulas and none of are broadly applicable in my experience.
I sometimes take into account inseam length but the problem is that
there are far more variables than anyone has been able to measure
to date.

I was living at the Olympic Training Center in CO Springs back in
'80 when they were measuring riders for the "Fit-Kit (TM)". We all
got measured, some several times, but when the kit came out a couple
of years later many who were "fitted" were told to lower their
saddles as much as 2cm! An unfortunately large number of riders
also purchased frames that were the wrong size as a result of the
Kit's recommendations.

Quoted message said:

Try a different length if you are so inclined. Reasonable
men differ in this.

Agreed.

Quoted message said:

The downside is dramatically overstated in that opinion
piece. Why?

Overstated? Have you ever had knee problems? Ever worked with
riders who had knee problems? Had friends end their racing careers
due to knee problems? Ride regularly with a sports physician? See
<http://www.roble.net/marquis/knees> for more on that.

--
Roger Marquis
http://www.roble.net/marquis/

Roger Marquis said:

Tim McNamara said:

Quoted message said:

Sad that those with no coaching or racing experience dismiss such
large sample populations as "myth and lore" without presenting any
support for their own opinions.

And sad that those who depend on the superiority of "wisdom" and
reject factual data when it contradicts the wosdom of the ages.

Wisdom? Wosdom? I think not. I'm talking about the performance of
competitive cyclists, don't know what you're talking about here Tim.

You seem to be talking about subjective impressions, myth and lore.
All of which abound among cyclists and masquerades as knowledge. But
that's an old discussion in this newsgroup and your position is well
known.

Quoted message said:

Quoted message said:

example, Greenspeed recently compared cranks ranging from 150 mm to
175 mm and found that there is a slight advantage to long cranks at
low speeds and a slight disadvantage to long cranks at high speeds.
They compared heart rate vs. road speed with different length
cranks.

Advantage as measured by heart rate, what good is that? Unless
their HR data was part of a multi-factorial analysis (ANOVA) which
included the race results of a large number of competitive cyclists
it's no more than garbage-out.

You should contact Greenspeed about this, then. I'm sure they'll
appreciate your correction of their ignorance. You can also query
them on their measurement of peak power output across the range of
crank lengths. And you can also compare this to Zinn's findings. I
am sure, however, that you will find all of these measurements
lacking in comparison to your own.

Quoted message said:

Problem is, heart rate is not an accurate measure of performance
(see <http://www.roble.net/marquis/coaching/hrm> and
<http://www.cptips.com/hrmntr.htm>😉.

I am aware of the limitations of heart rate as a measure of
performance, although in this case the issue was heart rate as a
measure of effort not performance. While not entirely accurate, it's
accurate enough that heart rate forms the foundation of most cycling
training programs since few cyclists have the equipment to measure
serum lactate, for example. Even professionals base their training
around heart rate.

The point I was mentioning is that, as actually measured, the
performance effects of different crank lengths appears to be equivocal
at best. As is often the case with rules of thumb, reality may
confound expectation and belief.

Tim McNamara said:

You seem to be talking about subjective impressions, myth and lore.
All of which abound among cyclists and masquerades as knowledge.

You can label coaching "subjective impressions", "myth and lore",
or other such FUD but there's a far higher correlation between
racing performance and good coaching than heart rate or ergometer
testing.

If ergometers could be used to predict performance we'd surely have
seen team selection based on HR, VO2, or ergometer tests by now.
Yet all pro and national teams still base their training camps and
rider selection on the same old "myth and lore".

I wonder what "ancients" like Eddie B, Mike Neel, or Walter Godefroot
would think of Tim's characterization of coaching as "subjective
impressions"?

Quoted message said:

The point I was mentioning is that, as actually measured, the
performance effects of different crank lengths appears to be equivocal
at best.

Perhaps on an ergometer but not in the real world. In a race like
Mt. Hamilton or Nevada City a 2.5mm crank length difference can be
worth several places.

--
Roger Marquis
http://www.roble.net/marquis/

<[email hidden]> a écrit dans le message de :
news:[email hidden]...

Quoted message said:

Roger Marquis writes:

http://www.roble.net/marquis/crank.length

Quoted message said:

No, these rules of thumb are a result of working with many coaches
and riders over 3 decades, across 3 continents, in thousands of
events, and seeing how they perform in competition with different
crank lengths.

There you have it. "Believe me. Just look at my credentials." I
prefer to quote a man who was good at explaining such things in
understandable terms and with substantive evidence (Richard Feynman):
"If you can't explain it in plain English, you don't understand it
yourself." I think that applies here.

Let me see if I understand -

When J Brandt asks us to believe his personal, anecdotal experience in
annual Alpine rides, that qualifies as "substantive evidence" -

And when R Marquis offers summary results of THOUSANDS of observations, with
multiple subjects, multiple locations, multiple points of reference, then he
is just full of hot air -

Got it !

BTW, Roger, I don't like you because you were always much too fast for me
....
--
Bonne route,

Sandy
Paris FR

Roger Marquis said:

Tim McNamara said:

You seem to be talking about subjective impressions, myth and lore.
All of which abound among cyclists and masquerades as knowledge.

You can label coaching "subjective impressions", "myth and lore", or
other such FUD but there's a far higher correlation between racing
performance and good coaching than heart rate or ergometer testing.

Good coaches make use of those tools.

Quoted message said:

If ergometers could be used to predict performance we'd surely have
seen team selection based on HR, VO2, or ergometer tests by now.
Yet all pro and national teams still base their training camps and
rider selection on the same old "myth and lore".

And yet many pro teams- Mapei was one- use all of that equipment
to make team selection, devise training programs, monitor fitness
and effectiveness of training... you're living in the dinosaur age,
Roger, but the world has moved on.

Quoted message said:

I wonder what "ancients" like Eddie B, Mike Neel, or Walter
Godefroot would think of Tim's characterization of coaching as
"subjective impressions"?

I suppose you could ask them. Of course, all three of them use heart
rate monitors, ergometers, SRM cranks, etc. in an effort to benefit
from the science and to avoid the useless devotion to unprovable myth
and lore.

Quoted message said:

Quoted message said:

The point I was mentioning is that, as actually measured, the
performance effects of different crank lengths appears to be
equivocal at best.

Perhaps on an ergometer but not in the real world. In a race like
Mt. Hamilton or Nevada City a 2.5mm crank length difference can be
worth several places.

Neglecting, apparently, that ergometers are part of the real world.
And neglecting also the impossibility of proving such assertions as
"In a race like Mt. Hamilton or Nevada City a 2.5mm crank length
difference can be worth several places." Claims such as yours are
simply specious.

Tim McNamara said:

Quoted message said:

You can label coaching "subjective impressions", "myth and lore", or
other such FUD but there's a far higher correlation between racing
performance and good coaching than heart rate or ergometer testing.

Good coaches make use of those tools.

Never said they didn't, but they use these tools as adjuncts to
race results.

We obviously disagree on this point i.e, that lab tools are poor
predictors of performance. But what I'd like to know is why. What
racing, coaching, or testing experiences form the basis of your
lab-centric opinions Tim?

Quoted message said:

you're living in the dinosaur age, Roger, but the world has moved on.

I'm aware of your method Tim, present no evidence other than insult.
Perhaps just once you could actually cite what team and what lab
results were used to successfully predict competitive performance
and do so without name calling.

As an example of exactly how worthless ergometer testing can be see
my description of "ergometer monsters" who failed to place and
national champions who failed to test well at
<http://www.roble.net/marquis/coaching/max_v02_myth.2>.

--
Roger Marquis
http://www.roble.net/marquis/

Roger Marquis said:

Tim McNamara said:

Quoted message said:

You can label coaching "subjective impressions", "myth and lore",
or other such FUD but there's a far higher correlation between
racing performance and good coaching than heart rate or ergometer
testing.

Good coaches make use of those tools.

Never said they didn't, but they use these tools as adjuncts to race
results.

Ummm, no, Roger. They use those tools to train their riders to
obtain race results. Race results are the outcome of training.

Quoted message said:

We obviously disagree on this point i.e, that lab tools are poor
predictors of performance. But what I'd like to know is why. What
racing, coaching, or testing experiences form the basis of your
lab-centric opinions Tim?

It's not like there hasn't been a lot of published information about
this in the past 15 years. Even an "ancient" like Eddy B. made
reference to it in his book years ago.

Quoted message said:

Quoted message said:

you're living in the dinosaur age, Roger, but the world has moved
on.

I'm aware of your method Tim, present no evidence other than insult.

No insult, just pointing out some of the fallacies in your thinking.

Quoted message said:

Perhaps just once you could actually cite what team and what lab
results were used to successfully predict competitive performance
and do so without name calling.

I mentioned one already: Mapei. They were only moderately
successful, I suppose, but at least they made the effort. There's
lots of information about their training approach out there in the
world.

Quoted message said:

As an example of exactly how worthless ergometer testing can be see
my description of "ergometer monsters" who failed to place and
national champions who failed to test well at
<http://www.roble.net/marquis/coaching/max_v02_myth.2>.

Are you seriously suggesting that someone like me, with a VO2 max of
53 ml/kg/min could successfully compete with someone with a VO2 max of
88 ml/kg/min? Dang, it's too bad I don't know where my old testing
results from back when I raced are. We could go through them and you
could try to tell me that I could have been a pro if I'd only had you
for a coach.

When the parameters identified through lab testing are reasonably
close, other factors can come into account in terms of race results.
But it's fallacious to state or imply- as you are doing- that things
like VO2 max, power to weight ratio, power at lactate threshold,
etc. are of no meaning and that any disadvantages in these parameters
can be overcome.

Tim McNamara said:

Quoted message said:

We obviously disagree on this point i.e, that lab tools are poor
predictors of performance. But what I'd like to know is why. What
racing, coaching, or testing experiences form the basis of your
lab-centric opinions Tim?

It's not like there hasn't been a lot of published information about
this in the past 15 years. Even an "ancient" like Eddy B. made
reference to it in his book years ago.

So I take it by this non-answer that you have no substantive rational
for dismissing the crank length recommendations of many experienced
coaches as "myth and lore"?

Quoted message said:

I mentioned one already: Mapei. They were only moderately
successful, I suppose, but at least they made the effort. There's
lots of information about their training approach out there in the

I haven't read anything substantially different about Mapei's use
of HR, VO2, ergometers, etc than other teams i.e, as a minor adjunct
to race performance. Velo magazine (FR) has excellent technology
and physiology articles, far more in-depth than anything I've found
in English language magazines, but even they haven't covered this
alleged Mapei practice. If you're referring to something other
than team physician research and monitoring, at best successful in
catching over-training and sickness in riders that might have reasons
not to admit to fatigue, please do post *specific* sources.

Quoted message said:

Quoted message said:

As an example of exactly how worthless ergometer testing can be see
my description of "ergometer monsters" who failed to place and
national champions who failed to test well at
<http://www.roble.net/marquis/coaching/max_v02_myth.2>.

Are you seriously suggesting that someone like me, with a VO2 max of
53 ml/kg/min could successfully compete with someone with a VO2 max of
88 ml/kg/min?

Or are you seriously dismissing the volumes of research documenting
the extent to which training and weight loss can improve VO2max or
is this just another comical straw-man misrepresentation?

Quoted message said:

When the parameters identified through lab testing are reasonably
close, other factors can come into account in terms of race results.
But it's fallacious to state or imply- as you are doing- that things
like VO2 max, power to weight ratio, power at lactate threshold,
etc. are of no meaning and that any disadvantages in these parameters
can be overcome.

Specifically which test(s) would indicate rider A, with several top
20 placings, be preferred over rider B with several top 10 placings?
Please be specific as your continued vague generalizations reflect
poorly on the lab-centric argument.

--
Roger Marquis
http://www.roble.net/marquis/

Roger Marquis said:

Tim McNamara said:

Quoted message said:

We obviously disagree on this point i.e, that lab tools are poor
predictors of performance. But what I'd like to know is why.
What racing, coaching, or testing experiences form the basis of
your lab-centric opinions Tim?

It's not like there hasn't been a lot of published information about
this in the past 15 years. Even an "ancient" like Eddy B. made
reference to it in his book years ago.

So I take it by this non-answer that you have no substantive
rational for dismissing the crank length recommendations of many
experienced coaches as "myth and lore"?

If you had been paying attention, Roger, you'd know that had already
been given. There are at least two systematic systematic studies
that have been done on this issue, both of which show that crank
length is a equivocal factor and not all that important. The same
riders can perform as well both in the lab and on the road with 150
mm cranks and 180 mm cranks. Please to make some attempt to keep up.

Quoted message said:

Quoted message said:

I mentioned one already: Mapei. They were only moderately
successful, I suppose, but at least they made the effort. There's
lots of information about their training approach out there in the

I haven't read anything substantially different about Mapei's use of
HR, VO2, ergometers, etc than other teams i.e, as a minor adjunct to
race performance. Velo magazine (FR) has excellent technology and
physiology articles, far more in-depth than anything I've found in
English language magazines, but even they haven't covered this
alleged Mapei practice. If you're referring to something other than
team physician research and monitoring, at best successful in
catching over-training and sickness in riders that might have
reasons not to admit to fatigue, please do post *specific* sources.

Roger, you're the expert here by your own admission. I wouldn't
presume to do your work for you.

Quoted message said:

Quoted message said:

Quoted message said:

As an example of exactly how worthless ergometer testing can be
see my description of "ergometer monsters" who failed to place and
national champions who failed to test well at
<http://www.roble.net/marquis/coaching/max_v02_myth.2>.

Are you seriously suggesting that someone like me, with a VO2 max of
53 ml/kg/min could successfully compete with someone with a VO2 max
of 88 ml/kg/min?

Or are you seriously dismissing the volumes of research documenting
the extent to which training and weight loss can improve VO2max or
is this just another comical straw-man misrepresentation?

There's very little that can be done to affect VO2 max substantially
other than weight loss, as long as that weight loss is fat and not
lean. Cecchini has done a lot of work on this in Europe, with
reasonably good results with Bjarne Riis. Or are you perhaps
delusional enough to claim that you could take my 53 ml/kg/min VO2 max
up to 88 ml/kg/min?

Quoted message said:

Quoted message said:

When the parameters identified through lab testing are reasonably
close, other factors can come into account in terms of race results.
But it's fallacious to state or imply- as you are doing- that things
like VO2 max, power to weight ratio, power at lactate threshold,
etc. are of no meaning and that any disadvantages in these
parameters can be overcome.

Specifically which test(s) would indicate rider A, with several top
20 placings, be preferred over rider B with several top 10 placings?
Please be specific as your continued vague generalizations reflect
poorly on the lab-centric argument.

No more so than your mindless repetitions of myth and lore, the vast
majority of which are completely unprovable and in the realm of faith
rather than reality. As the old saying goes, one measurement is
worth a dozen expert opinions.

Tim McNamara said:

Quoted message said:

So I take it by this non-answer that you have no substantive
rational for dismissing the crank length recommendations of many
experienced coaches as "myth and lore"?

If you had been paying attention, Roger, you'd know that had already
been given. There are at least two systematic systematic studies
that have been done on this issue, both of which show that crank
length is a equivocal factor and not all that important. The same
riders can perform as well both in the lab and on the road with 150
mm cranks and 180 mm cranks. Please to make some attempt to keep up.

You're proposing that two lab studies invalidate the results of
hundreds of thousands riders multiplied by an equal number of races.
It doesn't take a background in statistics to see the flaw in that
logic.

If 150mm cranks worked as well as 180s surely we would all be riding
150s and saving a fair amount of rotating weight. In reality the
cranks of two similarly built riders of the same racing level rarely
differ by more than 2.5mm. You can measure that with a vastly
larger sample size and incontrovertible statistical significance.

Claims that a rider would perform the same with 150mm vs 180mm
cranks in anything but the most ill-designed ergometer test are so
absurd that I'm embarrassed for Tim for even citing such "systematic
studies".

--
Roger Marquis
http://www.roble.net/marquis/

Tim McNamara said:

Quoted message said:

There are at least two systematic systematic studies
that have been done on this issue, both of which show that crank
length is a equivocal factor and not all that important. The same
riders can perform as well both in the lab and on the road with 150
mm cranks and 180 mm cranks. Please to make some attempt to keep up.

Roger Marquis replied:

Quoted message said:

You're proposing that two lab studies invalidate the results of
hundreds of thousands riders multiplied by an equal number of races.
It doesn't take a background in statistics to see the flaw in that
logic.

If 150mm cranks worked as well as 180s surely we would all be riding
150s and saving a fair amount of rotating weight. In reality the
cranks of two similarly built riders of the same racing level rarely
differ by more than 2.5mm. You can measure that with a vastly
larger sample size and incontrovertible statistical significance.

Claims that a rider would perform the same with 150mm vs 180mm
cranks in anything but the most ill-designed ergometer test are so
absurd that I'm embarrassed for Tim for even citing such "systematic
studies".

I'm not so convinced of the absurdity of this. The problem with the
anectodal data you refer to is that it doesn't control for Gain Ratio*,
and racers generally use equipment with a very limited choice of gear
options.

It is indisputable that if you fit longer cranks
_without_changing_gearing_ you'll be able to climb easier, because you
will have lowered the Gain Ratio. However, you will also find that you
won't be comfortably able to spin as fast, so your top end will be
limited, again, for the same gearing.

For a comparison to be valid in evaluating the biomechanical aspects of
longer cranks, it must equalize gain ratios, otherwise it's just looking
at bikes with different effective "gearing."

When I did my own subjective fixed-gear experiments with 150 cranks
instead of my usual 165s, I maintained my usual 5.8 Gain Ratio by
selecting appropriate sprocket sizes. I found no performance
difference, the only thing I noticed was that I didn't like having to
sit 15 mm higher off the ground.

Sheldon "Gain Ratio" Brown

*Gain ratio is a new system for measuring bicycle gearing.
It is explained in detail on my Web site at:
http://sheldonbrown.com/gain.html
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