How Significant Is A Change In Pedal Length?

Solomander said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

Remember that 5mm is about 1/6 of an inch..not much. make sure the BB
cenyter to seat height takes the 5mm less into account...raise the
saddle 5mm with the shorter cranks...otherwise it really isn't a big
deal at all. I had a customer that had two different crank lengths on
her bike for 4 years...and didn't know it....original builder did it by
mistake.

Qui si parla Campagnolo said:

Solomander said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Quoted message said:

Remember that 5mm is about 1/5 of an inch..not much. make sure the BB
cenyter to seat height takes the 5mm less into account...raise the
saddle 5mm with the shorter cranks.

Agreed. My three bikes have crank lengths of 165, 170, and 175 mm and
I switch between them without really noticing much of a difference. I
tend to have a slightly higher cadence using the 165s compared to the
175s, but am comfortable using any of the lengths.

On 13 Jul 2006 05:57:33 -0700, "Solomander" <[email hidden]>

Quoted message said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

My first long distance bike was 170mm and I put many thousand of miles
on it. My next one had 175's and just didn't feel right even after
several hundred miles. I put 170's on it and it just seems to spin
better. In my case, I think my legs just had gotten "worn in" with the
shorter crank.

Per Solomander:

Quoted message said:

I am happily riding a bike with 175 mm pedals.

Dem be some beeeeeeg pedals....
--
PeteCresswell

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

In the past week I have switched from bikes that have the followin crank
lengths:
160
170
172.5
175

I only noticed a difference when riding the 160's. The others were basically
unoticeable.
-------------
Alex

R Brickston said:

On 13 Jul 2006 05:57:33 -0700, "Solomander" <[email hidden]>

Quoted message said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

My first long distance bike was 170mm and I put many thousand of miles
on it. My next one had 175's and just didn't feel right even after
several hundred miles. I put 170's on it and it just seems to spin
better. In my case, I think my legs just had gotten "worn in" with the
shorter crank.

Unless someone is particularly large or small, all cranks withing the
"normal" range will be fine. It's mostly a personal preference, much as
stem length. There is no "wrong" stem length.

Yesterday I was helping a friend with sizing for a bike we are going to
build for him. He is 6'6" (2m) with an inseam of 41" (104cm). His seat
height is 96cm (38"😉 from the BB for anyone who wants to take a tape
measure to their own bike to see just how big that really is. He took a
test drive on a bike with 175mm cranks and it looked ridiculous. He
looked like he was on a kid's bike and was just flapping his feet.

Someone like that would like long ones, but normal people will do fine
with regular cranks, and in that context, the difference between
165-175 is pretty minimal.

Joseph

On 13 Jul 2006 05:57:33 -0700, "Solomander" <[email hidden]>

Quoted message said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

Dear Joel,

A normal rider's hips, knees, and ankles can easily handle whirling
his feet around a 3% smaller circle.

Most people don't even notice that their legs are different lengths
until the mismatch reaches 20mm:

http://www.orthoseek.com/articles/leglength.html

Ordinary riders from 5'4" to 6'4" are generally happy with 165mm to
175mm pedal arms.

This means that a group whose height and presumable leg length
increases from 64 to 76 (19%) is happy with pedals that increase from
165 to only 175 (6%).

I suspect that you didn't spot the shorter pedal arms on the bike that
you want to buy. It's far more likely that the owner mentioned the
length or that you peered at the markings.

Notice that you didn't even think to give your height when you asked
for advice.

Even if you can tell the difference (as opposed to just worrying about
it the way that we all do when we're mesmerized by numbers), you'll
probably get used to it within a week.

In the unlikely event that you're so tall that 175mm is the absolute
minimum that you can comfortably use, you can easily replace the dwarf
170mm pedal arms.

Cheers,

Carl Fogel

Solomander said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

Hi,

I'm also a recreational rider that's played with crank length, most
recently with 177,5 contra 172,5. My inseam length is 85 cm (33,5 in) so
I'm probably one of the shorter riders to try this longer length.

After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that
- I indeed spin faster on the shorter ones (cadence 105 instead of 92)
- I'm slower when climbing, sitting or standing, on the shorter cranks
- It's less effort to climb, standing, on the shorter cranks
- It is slightly less strain on the lower back and glutes, with the
shorter cranks.

YMMV but I'm now used to the longer cranks and will be doing *no*
serious riding with anything shorter, though I may settle on 175 as a
compromise.

Maybe you could borrow the used bike and do a day tour with it, swapping
over pedals and seat. Perhaps you won't notice any perceptible
difference, but then maybe you might.

/Robert

On Thu, 13 Jul 2006 20:29:42 GMT, Robert <[email hidden]>

Quoted message said:

Solomander said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

Hi,

I'm also a recreational rider that's played with crank length, most
recently with 177,5 contra 172,5. My inseam length is 85 cm (33,5 in) so
I'm probably one of the shorter riders to try this longer length.

After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that
- I indeed spin faster on the shorter ones (cadence 105 instead of 92)
- I'm slower when climbing, sitting or standing, on the shorter cranks
- It's less effort to climb, standing, on the shorter cranks
- It is slightly less strain on the lower back and glutes, with the
shorter cranks.

YMMV but I'm now used to the longer cranks and will be doing *no*
serious riding with anything shorter, though I may settle on 175 as a
compromise.

Maybe you could borrow the used bike and do a day tour with it, swapping
over pedals and seat. Perhaps you won't notice any perceptible
difference, but then maybe you might.

/Robert

Dear Robert,

The crank length shrank from 177.5 to 172.5mm, about 2.8%.

Your cadence rose from 92 to 105, about 14%.

Unless you also dropped several gears, you would have been going 14%
faster.

For the same effort from the rider, this isn't a likely explanation,
unless your legs are so short that you were wretchedly uncomfortable.
(There has to be a length where a crank becomes awful.)

You may have been experiencing the well-known new-toy effect.

For a week or two, almost any change that we think is worth trying is
likely to show surprising improvement because we improve when we're
paying more attention than usual in hopes of noticing improvement.

If it still feels better and is still faster after a week or two, then
the effect is probably mechanical, not psychological.

But we're awfully good at fooling ourselves. A 14% cadence increase
from a 5mm crank change is startling.

Regardless, glad that you found something that you like better.

Cheers,

Carl Fogel

In article <[email hidden]>,

Alex Rodriguez said:

In article <[email hidden]>,
[email hidden] says...

Quoted message said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5
mm change in pedal length would be for a recreational/charity rider
such as myself and how changing pedal length would affect riding
comfort and efficiency.

In the past week I have switched from bikes that have the followin
crank lengths:
160
170
172.5
175

I only noticed a difference when riding the 160's. The others were
basically unoticeable.

That's consistent with my experience, too. I don't really notice the
difference between 167.5 and 175. I also didn't feel a difference with
180s but it sure aggravated the torn meniscus in my knee.

In article <[email hidden]>,

Quoted message said:

Yesterday I was helping a friend with sizing for a bike we are going
to build for him. He is 6'6" (2m) with an inseam of 41" (104cm). His
seat height is 96cm (38"😉 from the BB for anyone who wants to take a
tape measure to their own bike to see just how big that really is. He
took a test drive on a bike with 175mm cranks and it looked
ridiculous. He looked like he was on a kid's bike and was just
flapping his feet.

LOL! There's a heckuva mental image.

5mm change in crank length doesn't make much difference. I have a friend
whose Trek 520 tourer came with 175mm Shimano 105 cranks. He wanted to use
smaller chainrings (particularly the middle ring) than the 105 allowed, and
as I had a drive side XTR 170mm crank that was orphaned after the LH crank
was bent in a crash, I offered it to him, pointing out that he would be
riding with left and right cranks that were 5mm different in length. That
didn't worry him, and he has been riding for about the past 18 months on a
175mm LH crank and a 170mm RH crank without any problems.

Nick

"Solomander" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Quoted message said:

On Thu, 13 Jul 2006 20:29:42 GMT, Robert <[email hidden]>

Quoted message said:

Solomander said:

I am happily riding a bike with 175 mm pedals. I am interested in a
used bike that has 170 mm pedals. I am wondering how big a deal a 5 mm
change in pedal length would be for a recreational/charity rider such
as myself and how changing pedal length would affect riding comfort and
efficiency.

Thanks for your advice.

Best,

Joel Solomon

Hi,

I'm also a recreational rider that's played with crank length, most
recently with 177,5 contra 172,5. My inseam length is 85 cm (33,5 in) so
I'm probably one of the shorter riders to try this longer length.

After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that
- I indeed spin faster on the shorter ones (cadence 105 instead of 92)
- I'm slower when climbing, sitting or standing, on the shorter cranks
- It's less effort to climb, standing, on the shorter cranks
- It is slightly less strain on the lower back and glutes, with the
shorter cranks.

YMMV but I'm now used to the longer cranks and will be doing *no*
serious riding with anything shorter, though I may settle on 175 as a
compromise.

Maybe you could borrow the used bike and do a day tour with it, swapping
over pedals and seat. Perhaps you won't notice any perceptible
difference, but then maybe you might.

/Robert

Dear Robert,

The crank length shrank from 177.5 to 172.5mm, about 2.8%.

Your cadence rose from 92 to 105, about 14%.

Unless you also dropped several gears, you would have been going 14%
faster.

Of course I would be putting out roughly the same amount of power
regardless of crank length, so naturally I would use a shorter gear with
the higher cadence. I'm not one of these people who can produce extra
power for nothing, just by using longer cranks.

Quoted message said:

For the same effort from the rider, this isn't a likely explanation,
unless your legs are so short that you were wretchedly uncomfortable.
(There has to be a length where a crank becomes awful.)

You may have been experiencing the well-known new-toy effect.

Re-read my post. I switched from short cranks to longer ones, spent a
year on them, got used to them, then tried the shorter ones last week
and found I didn't like the short ones as much. So I will stay on the
longer ones. New toy effect, you say?

Quoted message said:

For a week or two, almost any change that we think is worth trying is
likely to show surprising improvement because we improve when we're
paying more attention than usual in hopes of noticing improvement.

Sure, and that's the effect I had last year when I went to the longer
cranks. Found myself doing my favourite courses at much higher average
speed. Just got enthusiastic. But it was causing muscle pain in lower
back / upper gluteus max area and it took me a while to understand that
I had to raise the bars 15 mm to eliminate the discomfort. Once that was
done, things have worked well.

My temporary switch to the shorter ones was to see if I could ride as
well with them, which I didn't. If I had done, then this would have
aroused my suspicions of new toy effect.

Quoted message said:

If it still feels better and is still faster after a week or two, then
the effect is probably mechanical, not psychological.

Quite right. My switch from 172,5 to 177,5 has been for one year so far.

Quoted message said:

But we're awfully good at fooling ourselves. A 14% cadence increase
from a 5mm crank change is startling.

Try something - a very easy test to do with a trainer (back wheel
driving an electromagnetic brake). Set up a fixed resistance (I chose
200 watts) and find the gear / cadence combination that feels most
comfortable. Ride 10 minutes and divide the number of pedal revolutions
(which are counted on the Tacx Cycleforce Flow) by 10 to get average
cadence. Repeat test for different crank lengths, adjusting the gear to
attain the same level of comfort.

I've actually tried this, with the results I posted earlier. And indeed
I prefer a markedly slower cadence with the longer cranks. Which is good
for some of the rides I do, which are often long (e.g. 300 km in 10 hours).

Quoted message said:

Regardless, glad that you found something that you like better.

Thanks, it is indeed a suprise that 5 mm has made a difference for me.

But back to the OP's question. What I am trying to say is that while
some notice no real difference between cranks, there are others that do
notice the difference and it would be good for the OP to test the
shorter cranks before buying the used bike on offer.

/Robert
Göteborg, Sweden

On Thu, 13 Jul 2006 23:35:10 GMT, Robert <[email hidden]>

Quoted message said:

Quoted message said:

On Thu, 13 Jul 2006 20:29:42 GMT, Robert <[email hidden]>
wrote:

Quoted message said:

Quoted message said:

Quoted message said:

Hi,

I'm also a recreational rider that's played with crank length, most
recently with 177,5 contra 172,5. My inseam length is 85 cm (33,5 in) so
I'm probably one of the shorter riders to try this longer length.

After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that
- I indeed spin faster on the shorter ones (cadence 105 instead of 92)
- I'm slower when climbing, sitting or standing, on the shorter cranks
- It's less effort to climb, standing, on the shorter cranks
- It is slightly less strain on the lower back and glutes, with the
shorter cranks.

[snip]

Quoted message said:

Quoted message said:

Quoted message said:

/Robert

[snip]

Quoted message said:

Quoted message said:

You may have been experiencing the well-known new-toy effect.

Re-read my post. I switched from short cranks to longer ones, spent a
year on them, got used to them, then tried the shorter ones last week
and found I didn't like the short ones as much. So I will stay on the
longer ones. New toy effect, you say?

Dear Robert,

Here's what you wrote:

"After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that . . ."

This sounds like a couple of days on the shorter crank--that's the new
toy.

Again, an increase from 92 rpm to 105 rpm is not likely to be
mechanically attributable to a 5mm crank difference.

Cheers,

Carl Fogel

Robert said:

Quoted message said:

On Thu, 13 Jul 2006 20:29:42 GMT, Robert <[email hidden]>

Quoted message said:

Solomander wrote:

Quoted message said:

Quoted message said:

Dear Robert,

The crank length shrank from 177.5 to 172.5mm, about 2.8%.

Your cadence rose from 92 to 105, about 14%.

Unless you also dropped several gears, you would have been going 14%
faster.

Of course I would be putting out roughly the same amount of power
regardless of crank length, so naturally I would use a shorter gear with
the higher cadence. I'm not one of these people who can produce extra
power for nothing, just by using longer cranks.

14% sounds like one cog.

My normal cadence on the 170's is about 88 and 81 with the 175s. This is more
than the difference in leverage. It could very well be that even minor changes
result in a large change in cadence without a meaningful change in power output.
I don't ride significantly faster on one than the other. Just tend more toward
spin on the shorter crank.

Ron

Quoted message said:

On Thu, 13 Jul 2006 23:35:10 GMT, Robert <[email hidden]>

Quoted message said:

Quoted message said:

On Thu, 13 Jul 2006 20:29:42 GMT, Robert <[email hidden]>
wrote:

Quoted message said:

Quoted message said:

>Hi,
>
>I'm also a recreational rider that's played with crank length, most
>recently with 177,5 contra 172,5. My inseam length is 85 cm (33,5 in) so
>I'm probably one of the shorter riders to try this longer length.
>
>After about a year on the 177,5's I tried the shorter 172,5's for a
>couple of days and found that
>- I indeed spin faster on the shorter ones (cadence 105 instead of 92)
>- I'm slower when climbing, sitting or standing, on the shorter cranks
>- It's less effort to climb, standing, on the shorter cranks
>- It is slightly less strain on the lower back and glutes, with the
>shorter cranks.

[snip]

Quoted message said:

Quoted message said:

>/Robert

[snip]

Quoted message said:

Quoted message said:

You may have been experiencing the well-known new-toy effect.

Re-read my post. I switched from short cranks to longer ones, spent a
year on them, got used to them, then tried the shorter ones last week
and found I didn't like the short ones as much. So I will stay on the
longer ones. New toy effect, you say?

Dear Robert,

Here's what you wrote:

"After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that . . ."

This sounds like a couple of days on the shorter crank--that's the new
toy.

Again, an increase from 92 rpm to 105 rpm is not likely to be
mechanically attributable to a 5mm crank difference.

I don't know why not. The leg driving these things is a fairly complex system
with its own feedback and servo systems. There's surely more to it than the leg
blindly reacting to the cranks. Real ergonomic knowledge is missing from this
discussion. It's a good enough question to deserve some.

Ron

Thanks for everybody's replies. It sounds like a non issue. Peter, if
I ever meet you, I owe you at least a 6 pack.

Best,

Joel

Thanks for everybody's replies. It sounds like a non issue. Peter, if
I ever meet you, I owe you at least a 6 pack.

Best,

Joel

On Fri, 14 Jul 2006 00:48:47 GMT, RonSonic <[email hidden]>

Quoted message said:

Quoted message said:

On Thu, 13 Jul 2006 23:35:10 GMT, Robert <[email hidden]>

Quoted message said:

[email hidden] wrote:
> On Thu, 13 Jul 2006 20:29:42 GMT, Robert <[email hidden]>
> wrote:

Quoted message said:

>>Hi,
>>
>>I'm also a recreational rider that's played with crank length, most
>>recently with 177,5 contra 172,5. My inseam length is 85 cm (33,5 in) so
>>I'm probably one of the shorter riders to try this longer length.
>>
>>After about a year on the 177,5's I tried the shorter 172,5's for a
>>couple of days and found that
>>- I indeed spin faster on the shorter ones (cadence 105 instead of 92)
>>- I'm slower when climbing, sitting or standing, on the shorter cranks
>>- It's less effort to climb, standing, on the shorter cranks
>>- It is slightly less strain on the lower back and glutes, with the
>>shorter cranks.

[snip]

Quoted message said:

>>/Robert

[snip]

Quoted message said:

> You may have been experiencing the well-known new-toy effect.

Re-read my post. I switched from short cranks to longer ones, spent a
year on them, got used to them, then tried the shorter ones last week
and found I didn't like the short ones as much. So I will stay on the
longer ones. New toy effect, you say?

Dear Robert,

Here's what you wrote:

"After about a year on the 177,5's I tried the shorter 172,5's for a
couple of days and found that . . ."

This sounds like a couple of days on the shorter crank--that's the new
toy.

Again, an increase from 92 rpm to 105 rpm is not likely to be
mechanically attributable to a 5mm crank difference.

I don't know why not. The leg driving these things is a fairly complex system
with its own feedback and servo systems. There's surely more to it than the leg
blindly reacting to the cranks. Real ergonomic knowledge is missing from this
discussion. It's a good enough question to deserve some.

Ron

Dear Ron,

Do you know of any studies in which riders were even partially blinded
to the fact that they were using different crank lengths?

This topic does come up now and then, with one group claiming
startling differences for what others in the same thread claim they
don't even notice.

Here we have a rider who attributes a 14% change in cadence from 92 to
105 rpm to a 5mm change in crank length.

But elsewhere in this thread, other experienced riders report that
they can't tell the difference between equally large differences in
crank length--and it seems likely that they'd notice their cadence
rising from 92 to 105 rpm, the need to drop several gears, and so
forth.

Before crediting such large cadence changes to such tiny pedal arm
changes, I'd want to see if the rider reporting the large cadence
change can reliably tell the difference between a dozen different
bicycles with random crank lengths from the local bike shop.

Few of us can tell crank length with a casual glance before getting on
an unfamiliar bike. Stack a dime on top of two nickels to see the
difference between a 170 and a 175mm arm.

I'm willing to believe that something interesting may be going on, but
so far it looks a lot like the new-toy effect. Bicyclists are
notorious for sincerely reporting astonishing differences that turn
out to be largely in our heads.

I don't know of any widespread claims that reducing crank length 5mm
in the 17x range routinely leads to a 14% cadence increase. It sounds
like the kind of thing that numerous local bike shops would be warning
customers about.

But in very specific cases, where someone was right at the edge of the
range of comfortable and efficient length, I suppose that going 5mm
past the extreme could have an exaggerated effect. But then I'd expect
the cadence and power change to be accompanied by complaints about
comfort.

Cheers,

Carl Fogel