170mm vs 175mm crank arms?

[John Forrest Tomlinson]

On 24 Feb 2006 05:40:27 -0800, "Qui si parla Campagnolo"
<[email protected]> wrote:

>
>only1gear wrote:
>> I beg to differ, and this is based on my own experience as well as
>> others.
>>
>> Put a guy on two different cranks and he will go faster on the longer
>> crank. Period.
>
>Differ all you want. A longer crank won't make you faster,
>automatically.
>
>I rode twice on what I thought were 175 cranks on a bicycle i borrowed
>and 'felt' like I was so much faster, until I discovered they were
>172.5,
>
>By saying the above, in isolation, means anybody, regardless of
>physical perportions, would benefit from longer cranks....not true in
>any way.

Peter, can you get 165s at the same cost as longer cranks? If so, I
think you should use them on the next bike you build up, just to
demonstrate that length doesn't matter.

JT

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[A Muzi]

>>only1gear wrote:
>>>I beg to differ, and this is based on my own experience as well as
>>>others.
>>>Put a guy on two different cranks and he will go faster on the longer
>>>crank. Period.

"Qui si parla Campagnolo" <[email protected]> wrote:
>>Differ all you want. A longer crank won't make you faster,
>>automatically.
>>I rode twice on what I thought were 175 cranks on a bicycle i borrowed
>>and 'felt' like I was so much faster, until I discovered they were
>>172.5,
>>By saying the above, in isolation, means anybody, regardless of
>>physical perportions, would benefit from longer cranks....not true in
>>any way.

John Forrest Tomlinson wrote:
> Peter, can you get 165s at the same cost as longer cranks? If so, I
> think you should use them on the next bike you build up, just to
> demonstrate that length doesn't matter.


I have 165, 167.5 on my most-ridden bike, and 170.
I can't feel a difference.
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

 

[531Aussie]

I once accidentally put myself in a blind experiment: one morning, I dusted off an old bike I hadn't ridden for a couple of years, forgetting that it had 175 instead of the 170s I'd been using. When I got to my usual hills, I couldn't figure out why I was FLYING up them! I felt like Superman!!! I eventually realized I was using longer cranks.

I was riding in jogging shoes (short commute), so, not having a fixed cleat position is probably why I didn't immediately notice the different length.

Ever since that time I was a bit obsessed with longer cranks, and eventually settled on 180s. I don't care what the 'physicists' say, I'm sure I get extra leverage -- the only drawback is the having to be in a lower, slightly weaker position.

 

[Robert]

531Aussie wrote:
> I once accidentally put myself in a blind experiment: one morning, I
> dusted off an old bike I hadn't ridden for a couple of years,
> forgetting that it had 175 instead of the 170s I'd been using. When I
> got to my usual hills, I couldn't figure out why I was FLYING up them!
> I felt like Superman!!! I eventually realized I was using longer
> cranks.
>
> I was riding in jogging shoes (short commute), so, not having a fixed
> cleat position is probably why I didn't immediately notice the
> different length.
>
> Ever since that time I was a bit obsessed with longer cranks, and
> eventually settled on 180s. I don't care what the 'physicists' say, I'm
> sure I get extra leverage -- the only drawback is the having to be in a
> lower, slightly weaker position.

Hi, noticing comment on "lower, slightly weaker position". I'm still
playing with seat position with the longer cranks. Can you say more what
you mean by "weaker", it might give me a hint. /Robert

 

[Qui si parla Campagnolo]

John Forrest Tomlinson wrote:
> On 24 Feb 2006 05:40:27 -0800, "Qui si parla Campagnolo"
> <[email protected]> wrote:
>
> >
> >only1gear wrote:
> >> I beg to differ, and this is based on my own experience as well as
> >> others.
> >>
> >> Put a guy on two different cranks and he will go faster on the longer
> >> crank. Period.
> >
> >Differ all you want. A longer crank won't make you faster,
> >automatically.
> >
> >I rode twice on what I thought were 175 cranks on a bicycle i borrowed
> >and 'felt' like I was so much faster, until I discovered they were
> >172.5,
> >
> >By saying the above, in isolation, means anybody, regardless of
> >physical perportions, would benefit from longer cranks....not true in
> >any way.
>
> Peter, can you get 165s at the same cost as longer cranks? If so, I
> think you should use them on the next bike you build up, just to
> demonstrate that length doesn't matter.
>
> JT

Extremes may make a difference. But the gent implied that is you have
170s, 175s will make you faster, and I don't agree. If I used 165, then
170s would not automatically make me faster.

 

[[email protected]]

A couple of years ago I was experiencing more than the usual knee pain
and swapped out the 175 cranks for 170 on my mountian bike. This didn't
help at all. What did help was to stop riding my commuter which had a
frame that was slightly too small for me, which probably put my knees
too far back from the saddle with the long seat post.

If anything, the shorter cranks on the mountain bike seemed to cause
more pain and not less. Oddly enough, what finally got me out of the
pain cycle was painting my garage -- something about climbing up and
down a ladder seemed to straighten out the knees. (I also focused more
on stretching excercises.)

Eventually I switched back to the 175mm crank on the mountain bike and
hardly noticed any difference.

My new bike came with 175mm cranks and seems to suit me fine, even on
long road rides. (Specialized uses 170, 172.5, and 175 cranks on the
tricross bike depending on frame size.)

 

[John Forrest Tomlinson]

On 25 Feb 2006 05:40:07 -0800, "Qui si parla Campagnolo"
<[email protected]> wrote:


>Extremes may make a difference. But the gent implied that is you have
>170s, 175s will make you faster, and I don't agree. If I used 165, then
>170s would not automatically make me faster.

I'd take you more seriously if you switched to 165s just to show it
doesn't matter. If the cost is the same to you, you should do it next
time you build up a bike for yourself or change cranks. Nothing to
lose, right?

JT

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[531Aussie]

Hi, noticing comment on "lower, slightly weaker position". I'm still playing with seat position with the longer cranks. Can you say more what
you mean by "weaker", it might give me a hint. /Robert

I've always felt that the best position is one that's slightly on the high side; one that reduces knee flexion. This is probably the best argument FOR short cranks.

When someone gets longer cranks, they'll most likely have to drop the saddle by approx the same amount as the increase in crank arm length. So, if the increase is 5mm, this then means that, relative to the hip, the knee is approx 10mm higher through the top of the stroke. In other words, the saddle is effectively ~10mm lower through the top of the stroke. The knee moves slightly higher from ~the 8 o'clock position, right through to about 4 o'clock on the pedal circle. I reckon this is a small trade-off, but one that's seldom mention by the long crank advocates, such as Zinn and Palm.

I'm such a geek, and I was so obsessed by this, that I drew a scaled down version of the difference between a 175mm pedal circle and a 180mm, relative to MY seat height, with the distance from the saddle to the bottom of the stroke that same.

The black circle is the 180mm crank. Note how the foot is higher right through till about 4 o'clock. That gap at the top of the strokes represents 10, but obviously shortens through the stroke, to about 5mm at 3 o'clock,then, eventually to nothing.
(I'm such a geek )

Also, most people will wanna move to seat forward a little, I felt like I was reaching a bit.

 

[Peter Cole]

John Forrest Tomlinson wrote:
> On 24 Feb 2006 05:40:27 -0800, "Qui si parla Campagnolo"
> <[email protected]> wrote:
>
>
>>only1gear wrote:
>>
>>>I beg to differ, and this is based on my own experience as well as
>>>others.
>>>
>>>Put a guy on two different cranks and he will go faster on the longer
>>>crank. Period.
>>
>>Differ all you want. A longer crank won't make you faster,
>>automatically.
>>
>>I rode twice on what I thought were 175 cranks on a bicycle i borrowed
>>and 'felt' like I was so much faster, until I discovered they were
>>172.5,
>>
>>By saying the above, in isolation, means anybody, regardless of
>>physical perportions, would benefit from longer cranks....not true in
>>any way.
>
>
> Peter, can you get 165s at the same cost as longer cranks? If so, I
> think you should use them on the next bike you build up, just to
> demonstrate that length doesn't matter.

The latest research seems to agree with Peter.

<http://jap.physiology.org/cgi/reprint/93/3/823.pdf>
"Determinants of metabolic cost during
submaximal cycling"

They tested crank length from 140 to 195 and cadence from 40 to 100 and
found no correlation to efficiency and crank size or cadence, but rather
to pedal speed, which is a function of both. IOW, if your cranks are
shorter, pedal faster for the same efficiency. As it was, the overall
variation in efficiency over the entire range of pedal speed was only
around 5%, something so small as to be nearly undetectable without
instruments.

 

[[email protected]]

Peter Cole wrote:
> John Forrest Tomlinson wrote:
> > On 24 Feb 2006 05:40:27 -0800, "Qui si parla Campagnolo"
> > <[email protected]> wrote:
> >
> >
> >>only1gear wrote:
> >>
> >>>I beg to differ, and this is based on my own experience as well as
> >>>others.
> >>>
> >>>Put a guy on two different cranks and he will go faster on the longer
> >>>crank. Period.
> >>
> >>Differ all you want. A longer crank won't make you faster,
> >>automatically.
> >>
> >>I rode twice on what I thought were 175 cranks on a bicycle i borrowed
> >>and 'felt' like I was so much faster, until I discovered they were
> >>172.5,
> >>
> >>By saying the above, in isolation, means anybody, regardless of
> >>physical perportions, would benefit from longer cranks....not true in
> >>any way.
> >
> >
> > Peter, can you get 165s at the same cost as longer cranks? If so, I
> > think you should use them on the next bike you build up, just to
> > demonstrate that length doesn't matter.
>
> The latest research seems to agree with Peter.
>
> <http://jap.physiology.org/cgi/reprint/93/3/823.pdf>
> "Determinants of metabolic cost during
> submaximal cycling"
>
> They tested crank length from 140 to 195 and cadence from 40 to 100 and
> found no correlation to efficiency and crank size or cadence, but rather
> to pedal speed, which is a function of both. IOW, if your cranks are
> shorter, pedal faster for the same efficiency. As it was, the overall
> variation in efficiency over the entire range of pedal speed was only
> around 5%, something so small as to be nearly undetectable without
> instruments.

Studies also show that I have 2.1 kids. ;-)

Not everyone will fit exactly into the norm. Certain people (not that
many, probably) will benefit from non-standard crank-lengths. The
benefits may be more power/efficiency, or "just" better comfort. They
key is not to rule-out the potential significance of crank length.

Joseph

 

[peter]

John Forrest Tomlinson wrote:

> I'd take you more seriously if you switched to 165s just to show it
> doesn't matter. If the cost is the same to you, you should do it next
> time you build up a bike for yourself or change cranks. Nothing to
> lose, right?

My three most-used bikes have 165, 170, and 175mm cranks. Can't say
that I notice any difference in comfort or efficiency, but I do tend to
have a slightly higher cadence with the 165s compared to the 175s.

 

[Peter Cole]

[email protected] wrote:
> Peter Cole wrote:

>>The latest research seems to agree with Peter.
>>
>><http://jap.physiology.org/cgi/reprint/93/3/823.pdf>
>>"Determinants of metabolic cost during
>>submaximal cycling"
>>
>>They tested crank length from 140 to 195 and cadence from 40 to 100 and
>>found no correlation to efficiency and crank size or cadence, but rather
>>to pedal speed, which is a function of both. IOW, if your cranks are
>>shorter, pedal faster for the same efficiency. As it was, the overall
>>variation in efficiency over the entire range of pedal speed was only
>>around 5%, something so small as to be nearly undetectable without
>>instruments.
>
>
> Studies also show that I have 2.1 kids. ;-)
>
> Not everyone will fit exactly into the norm. Certain people (not that
> many, probably) will benefit from non-standard crank-lengths. The
> benefits may be more power/efficiency, or "just" better comfort. They
> key is not to rule-out the potential significance of crank length.

Silly me, I thought the key was science.

 

[John Forrest Tomlinson]

On Sun, 26 Feb 2006 11:57:26 -0500, Peter Cole
<[email protected]> wrote:

>John Forrest Tomlinson wrote:
>> On 24 Feb 2006 05:40:27 -0800, "Qui si parla Campagnolo"
>> <[email protected]> wrote:
>>
>>
>>>only1gear wrote:
>>>
>>>>I beg to differ, and this is based on my own experience as well as
>>>>others.
>>>>
>>>>Put a guy on two different cranks and he will go faster on the longer
>>>>crank. Period.
>>>
>>>Differ all you want. A longer crank won't make you faster,
>>>automatically.
>>>
>>>I rode twice on what I thought were 175 cranks on a bicycle i borrowed
>>>and 'felt' like I was so much faster, until I discovered they were
>>>172.5,
>>>
>>>By saying the above, in isolation, means anybody, regardless of
>>>physical perportions, would benefit from longer cranks....not true in
>>>any way.
>>
>>
>> Peter, can you get 165s at the same cost as longer cranks? If so, I
>> think you should use them on the next bike you build up, just to
>> demonstrate that length doesn't matter.
>
>The latest research seems to agree with Peter.

Great, so next time you have the occasion to get cranks on teh short
side -- say 5mm shorter than what you use now, will you?

JT

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[John Forrest Tomlinson]

On 26 Feb 2006 09:26:34 -0800, "peter" <[email protected]> wrote:

>John Forrest Tomlinson wrote:
>
>> I'd take you more seriously if you switched to 165s just to show it
>> doesn't matter. If the cost is the same to you, you should do it next
>> time you build up a bike for yourself or change cranks. Nothing to
>> lose, right?
>
>My three most-used bikes have 165, 170, and 175mm cranks. Can't say
>that I notice any difference in comfort or efficiency, but I do tend to
>have a slightly higher cadence with the 165s compared to the 175s.

So you'll try 160s next, right?

JT


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[Johnny Sunset aka Tom Sherman]

John Forrest Tomlinson wrote:
> ...
> Great, so next time you have the occasion to get cranks on t[he] short
> side -- say 5mm shorter than what you use now, will you?

I won't speak for Mr. Cole, but I am considering trying out some 150-mm
cranks on my lowracer.

--
Tom Sherman

 

[Peter Cole]

John Forrest Tomlinson wrote:
> On Sun, 26 Feb 2006 11:57:26 -0500, Peter Cole
> <[email protected]> wrote:

>>The latest research seems to agree with Peter.
>
>
> Great, so next time you have the occasion to get cranks on teh short
> side -- say 5mm shorter than what you use now, will you?

I'm not sure exactly what you're saying. The article I cited said that
crank length didn't make a difference in efficiency, but pedal speed
did. For the same pedal speed, shorter cranks mean higher cadences. I
don't particularly like higher cadences, so I don't prefer shorter
cranks. I did select shorter cranks for my fixer to avoid pedal strike
problems, and coincidentally, that happens to be the bike I use the
highest cadences with (by far), and it works fine, but wouldn't be my
first choice. At the same time, cranks much larger than 175 would
severely limit my position on a conventional frame (thighs hitting
chest) and increase the risk of pedal strike, so that's an impractical
solution. I'd go to the bother of setting up "proportional" cranks (for
my 6'10" height), but I haven't seen any research that would justify the
trouble and expense.

 

[John Forrest Tomlinson]

On Sun, 26 Feb 2006 13:29:58 -0500, Peter Cole
<[email protected]> wrote:

>John Forrest Tomlinson wrote:
>> On Sun, 26 Feb 2006 11:57:26 -0500, Peter Cole
>> <[email protected]> wrote:
>
>>>The latest research seems to agree with Peter.
>>
>>
>> Great, so next time you have the occasion to get cranks on teh short
>> side -- say 5mm shorter than what you use now, will you?
>
>I'm not sure exactly what you're saying.

What I'm saying is that I'd like people who suggest crank length
doesn't matter to back up their suggestions by riding shorter cranks.

JT



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[peter]

JohnFT wrote:
> >My three most-used bikes have 165, 170, and 175mm cranks. Can't say
> >that I notice any difference in comfort or efficiency, but I do tend to
> >have a slightly higher cadence with the 165s compared to the 175s.
> So you'll try 160s next, right?

No, since I saw no advantage for any of these crank lengths relative to
the others I'll continue to stick with whatever length happens to come
with bikes that look like decent deals in other respects and that feel
ok after a short test ride.

 

[Andrew Lee]

John Forrest Tomlinson wrote:
> On Sun, 26 Feb 2006 13:29:58 -0500, Peter Cole
> <[email protected]> wrote:
>>I'm not sure exactly what you're saying.
>
> What I'm saying is that I'd like people who suggest crank length
> doesn't matter to back up their suggestions by riding shorter cranks.
>
> JT

I'm interested in what you think about crank length because I have already
seen some answers to your question - some people have said that they have
ridden more than one crank length and some prefer the shorter or shortest of
the range that they have tried, some don't prefer the shortest of the range
that they have tried, and some have no preference. Do you have a point?

Other than cranks on the kids bikes that I had a long time ago (and which I
had no complaints about except for the 3" or so cranks on my "Big wheel"
trike), I have only used 170 on my road bike(s) and 175 on my mountain bike.
I can definitely feel a difference in length and much prefer the 170 length.
The feel is good enough that I don't see a need to explore crank lengths
further, especially after seeing the results or non-results of all the
studies over the years.

 

[Sandy]

Dans le message de news:[email protected],
Peter Cole <[email protected]> a réfléchi, et puis a déclaré :
> [email protected] wrote:
>> Peter Cole wrote:
>
>>> The latest research seems to agree with Peter.
>>>
>>> <http://jap.physiology.org/cgi/reprint/93/3/823.pdf>
>>> "Determinants of metabolic cost during
>>> submaximal cycling"
>>>
>>> They tested crank length from 140 to 195 and cadence from 40 to 100
>>> and found no correlation to efficiency and crank size or cadence,
>>> but rather to pedal speed, which is a function of both. IOW, if
>>> your cranks are shorter, pedal faster for the same efficiency. As
>>> it was, the overall variation in efficiency over the entire range
>>> of pedal speed was only around 5%, something so small as to be
>>> nearly undetectable without instruments.
>>
>>
>> Studies also show that I have 2.1 kids. ;-)
>>
>> Not everyone will fit exactly into the norm. Certain people (not that
>> many, probably) will benefit from non-standard crank-lengths. The
>> benefits may be more power/efficiency, or "just" better comfort. They
>> key is not to rule-out the potential significance of crank length.
>
> Silly me, I thought the key was science.

Silly isn't it. But it's more than the mechanical advantage from cleat to
tire patch. And there's science that looks at the backward path. When you
present that with equal authority, then we'll have something to look at
seriously, like a much more complete picutre.
--
Bonne route !

Sandy
Verneuil-sur-Seine FR