Re: My thoughts on seat position, crank length, and cleat position

[Jim Martin]

Ron Ruff wrote:
> The ranges are usually quite large... I think 120-220mm in one test
> that I recall.

Yup, that would be my study. Minor differences in maximal power from
120-220mm (see Euro JAP 2001 and for the hard science verson see J
Biomechanics 2000). In a follow up study (JAP 2002, First author John
McDaniel), no difference in efficiency on cranks ranging from 145 to
195mm. Do a Google scholar search for "Martin, JC" AND crank and you
should find them.

The bad news is that no crank will give you a magical improvement.

The good news is that you are free to ride the crank length you LIKE the
best. The one that makes you FEEL the best. Chances are the better you
like the way your bike feels the better you will ride. Call it placebo
effect, but if placebo effect wasn't imporant, we wouldn't need to
control for it in studies would we?

Ride what makes you happy,

Jim

 

[[email protected]]

Jim Martin wrote:
> Ron Ruff wrote:
> > The ranges are usually quite large... I think 120-220mm in one test
> > that I recall.
>
> Yup, that would be my study. Minor differences in maximal power from
> 120-220mm (see Euro JAP 2001 and for the hard science verson see J
> Biomechanics 2000). In a follow up study (JAP 2002, First author John
> McDaniel), no difference in efficiency on cranks ranging from 145 to
> 195mm. Do a Google scholar search for "Martin, JC" AND crank and you
> should find them.
>
> The bad news is that no crank will give you a magical improvement.
>
> The good news is that you are free to ride the crank length you LIKE the
> best. The one that makes you FEEL the best. Chances are the better you
> like the way your bike feels the better you will ride. Call it placebo
> effect, but if placebo effect wasn't imporant, we wouldn't need to
> control for it in studies would we?
>
> Ride what makes you happy,
>
> Jim

I just read your "Determinants of Metabolic Cost During Submaximal
Cycling" and an abstract of "Determinants of maximal cycling power:
crank length, pedaling rate and pedal speed." (I couldn't find the full
text freely available)

Those are quite interesting. It always made sense to me that the
cardio-vascular system was the weak link in maximal power, and thus
relative ineficiencies related to crank length would have no real
effect. But what about duration of sustainable maximum power? This is
probably in the full text article, but was that affected by
crank-length? How was seat height determined for the various crank
lengths?

In the submaximal article the weights of the 9 riders is mentioned, but
nothing about their heights. Is it possible that these findings do not
scale upward? In other words, might rider size or build magnify some of
the effects? I don't understand fully how the distinction between pedal
speed and force applied to the pedal is made. It seems to me this is
what the crank arm length issue boils down to: the tradeoff between
pedal speed and pedal force, with your research suggesting that the two
essentially cancel each other, but perhaps this trade-off (if indeed it
is a trade-off) is very dependant on rider build.

What do you think would happen were you to do these experiments with
more fine-grained crankarm lengths? It seems to me the jump from 170mm
to 195mm may mask a lot of interesting info, particularly when the test
subjects are all of somewhat normal size. It might also be interesting
to see what happens with riders of similar height, but drastically
different builds. Was this 170-195 jump due to logistic/budget issues,
or was there some other reason?

Placebo, or mechanical benefit, I'll take the extra watts and reduced
metabolic costs!

Any chance of you doing more research of this type any time soon?

Joseph

 

[Jim Martin]

[email protected] wrote:
> But what about duration of sustainable maximum power?

I'm not sure what you mean by this. something like time trial power? If
so, that gets to be a difficult thing to measure. So far we have stayed
away from performance trials.

This is
> probably in the full text article, but was that affected by
> crank-length? How was seat height determined for the various crank
> lengths?

We set the seat ht from seat to pedal, at its most extended position,
the same for all crank lengths.

> In the submaximal article the weights of the 9 riders is mentioned, but
> nothing about their heights. Is it possible that these findings do not
> scale upward?

I suppose that's possible but I really doubt it. Also, for the max power
studies, I specifically recruited the tallest and shortest cyclists I
could find. The means may not be impressive but the range was pretty large.

> What do you think would happen were you to do these experiments with
> more fine-grained crankarm lengths?

If there's no difference in an inch there will not likely be any
difference in 2.5mm


> Placebo, or mechanical benefit, I'll take the extra watts and reduced
> metabolic costs!
>
> Any chance of you doing more research of this type any time soon?

Possibly. We have some indication that the ability to excite and relax
the muscle (pedaling rate) may be more subject to fatigue than muscle
force-velocity characteristits (pedal speed) and we'd like to take a
look at that. Keep in mind that my students and I do not study cycling.
We use cycing as a model to get at more basic questions of neuromuscular
function.

Cheers,

Jim

 

[[email protected]]

Jim Martin wrote:
> [email protected] wrote:
> > But what about duration of sustainable maximum power?
>
> I'm not sure what you mean by this. something like time trial power? If
> so, that gets to be a difficult thing to measure. So far we have stayed
> away from performance trials.

I suppose that is what I mean, but in a much shorter time frame. What
do the curves look like for trying to generate maximum power with 100%
effort until exhaustion. How much power? How long? I don't know if this
would be interesting from a neuromuscular angle, but for cyclists it
would be very interesting.

> > In the submaximal article the weights of the 9 riders is mentioned, but
> > nothing about their heights. Is it possible that these findings do not
> > scale upward?
>
> I suppose that's possible but I really doubt it. Also, for the max power
> studies, I specifically recruited the tallest and shortest cyclists I
> could find. The means may not be impressive but the range was pretty large.

What was the height range of subjects?

> > What do you think would happen were you to do these experiments with
> > more fine-grained crankarm lengths?
>
> If there's no difference in an inch there will not likely be any
> difference in 2.5mm

The incremental differences may be insignificant, but maybe between
175mm and 195mm there is room for a significant improvement and
degradation again. Particularly for semi-normal sized folks. Since 195
is regarded as huge, and 170 is normal, pehaps a more intermediate step
would be a worthwhile addition.

> >
> > Any chance of you doing more research of this type any time soon?
>
> Possibly. We have some indication that the ability to excite and relax
> the muscle (pedaling rate) may be more subject to fatigue than muscle
> force-velocity characteristits (pedal speed) and we'd like to take a
> look at that. Keep in mind that my students and I do not study cycling.
> We use cycing as a model to get at more basic questions of neuromuscular
> function.

That sounds interesting. I am glad you and your students find cycling a
good vehicle for your studies, as your findings are very informative. I
know nothing of what sort of facilities you have, but here are some
nice adjustable cranks that may help with these type of experiments:
http://www.hscycle.com/Pages/adjustablecrankset.html

Thanks!

Joseph

 

[Jim Martin]

[email protected] wrote:
> I suppose that is what I mean, but in a much shorter time frame. What
> do the curves look like for trying to generate maximum power with 100%
> effort until exhaustion. How much power? How long? I don't know if this
> would be interesting from a neuromuscular angle, but for cyclists it
> would be very interesting.

Okay I see what you mean. Yes, that is interesting to me and we may get
to that study sometime in the next year or two. It is what I tried to
describe earlier about fatigue mechanisms.

> What was the height range of subjects?

5'4" to 6'6"

> The incremental differences may be insignificant, but maybe between
> 175mm and 195mm there is room for a significant improvement and
> degradation again. Particularly for semi-normal sized folks. Since 195
> is regarded as huge, and 170 is normal, pehaps a more intermediate step
> would be a worthwhile addition.

I don't think so. Your statement implies that the effect of crank
length, if there were one, would have local maxima/minima in between the
lengths we tested. I can't see that happening.

Cyclists really have trouble with our findings that crank length is not
important. I think one reason for that trouble is that cyclists can
detect differences of 2.5 mm and because they can detect such a small
difference they believe it must be important. Its not.

BTW, I am not just a science geek who ONLY uses cycling as a model. I
was a cat 1 track rider and cat 2 road rider, 3 time Texas State
champion and National masters champion on the track.

Cheers,

Jim

 

[[email protected]]

Jim Martin wrote:
> I don't think so. Your statement implies that the effect of crank
> length, if there were one, would have local maxima/minima in between the
> lengths we tested. I can't see that happening.

But it is possible, and not _entirely_ unlikely.

> Cyclists really have trouble with our findings that crank length is not
> important. I think one reason for that trouble is that cyclists can
> detect differences of 2.5 mm and because they can detect such a small
> difference they believe it must be important. Its not.

So in your opinion, my improved performance after switching to 195 from
175 is due to placebo, and/or other factors such as my condition,
weather, etc. What was the range of possible positive effect from
different crank lengths? 2% improvement? 0.02%?


> BTW, I am not just a science geek who ONLY uses cycling as a model. I
> was a cat 1 track rider and cat 2 road rider, 3 time Texas State
> champion and National masters champion on the track.

That's it! You're too strong! Frame-flex, heat disipation from
wheel-spin and other inefficiencies mask just how important crank
length is when you hit the track! ;-)

If any of your students want to ever do some sort of experiment, but
rounding up folks is a problem, they can feel free to contact me. I am
in a team of 30 riders who focus on long distance rides. Our main event
is a 540km race which we intend to do in 13:59 this year. The age range
is 18 to 59. We have acccess to VOmax, AT, and power, as well as the
other things measurable with a Polar at our local health club. Maybe
not ideal conditions with communications, etc, but maybe it would be
interesting for a student interested in a proof-of-concept type
experiment, and anything that has a side effect of helping individual
riders fine-tune their riding would help us reach our sub 14 hour goal.

Joseph