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Any reasons not to go with shorter cranks?
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I've done reading about crank length and arguments for and against shortening up, but up to this point it's been just academic curiosity -- I have 175mm cranks on both my road and tri bikes and haven't really been bothered by them so never felt there was a convincing enough argument to push me to spend on a switch.

But this winter I plan to upgrade my Tiagra road bike to 105, meaning I have the opportunity to choose a different crank for my tri bike (would move current tri bike 105 crank to roadie and put whatever new one on the tri bike), and am wondering again if I should shorten my crank.

So the question: Are there any very compelling reasons I should consider not dropping from 175 to, say, 170(?) on my tri bike? And then, since I'm doing all this wrench work anyway, might it behoove me to switch lower on my roadie as well?

Thanks for the help.
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Re: Any reasons not to go with shorter cranks? [icecubes] [ In reply to ]
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I would try 160mm or shorter.
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Re: Any reasons not to go with shorter cranks? [icecubes] [ In reply to ]
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I went shorter for a while and didn't like it. I'm 6'3" with a slower cadence and longer cranks feel more natural, while shorter ones feel like I'm wasting energy short-stepping on a run. Just like 29" mountain bike wheels feel more natural for taller people than 26" ones do, crank length can affect how your pedaling feels due to how long your legs are.

Another factor is I have plantar fasciitis and a longer lever reduces the amount of force I have to apply to my arches at any moment to turn the pedals over.
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Re: Any reasons not to go with shorter cranks? [icecubes] [ In reply to ]
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How tall are you?

Assuming your bike frame fits you properly and you have a proper fit, there is no reason to change lengths.
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Re: Any reasons not to go with shorter cranks? [TurboVette] [ In reply to ]
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I'm 6'0" (185cm) with a long torso and short legs for my height. I agree generally in the "don't fix what ain't broke", but since I have a chance to consider a change I'm wondering. I have the real estate on my tri bike (i.e. not a max/min position) to accommodate the other changes to cockpit/etc that come along with a crank shortening.
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Re: Any reasons not to go with shorter cranks? [icecubes] [ In reply to ]
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The only real way to answer this question is to have a fit done by a competent fitter, and find out through experimentation. The main benefit of a shorter crank arm is the ability to raise your saddle by the amount you shortened the crank. This might (or might not) result in a better position, and allow you to rotate forward around the bottom bracket. Or it might not. It totally depends on your own body's geometry.
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Re: Any reasons not to go with shorter cranks? [g_lev] [ In reply to ]
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The "competent" piece is subjective.

There are "competent" fitters out there that their first suggestion is to shorten the crank. To get in a "proper" position.

However, there are anterior and posterior tilts of the pelvis, some particular fitters believe everyone should have an anterior tilt to their pelvis, with that said Tony Martin has a posterior tilt and wins world time trial championships.

For the OP, if you're only 6'0" and shorter legs, a 175 might be a bit long but not by much.
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Re: Any reasons not to go with shorter cranks? [g_lev] [ In reply to ]
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I think the other (and perhaps bigger) benefit of shorter cranks is a more open hip angle at the top of the pedal stroke.
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Re: Any reasons not to go with shorter cranks? [icecubes] [ In reply to ]
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I use 145mm and have no issues.

Feel odd if iv not ridden my TT bike for a few weeks but after first couple of rides it's perfect. Really helps my position.

I would go 165mm, if you're going to try shorter cranks then may as well make it count.
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Re: Any reasons not to go with shorter cranks? [Mario S] [ In reply to ]
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I'm 6'3" with long legs, I went from 172.5 to 165 on my Trek SC and haven't looked back. For me it was all about getting into a better position. With a shorter crank you can raise the seat and get less hip flexion throughout the cycle. I'm not flexible so that was a big limiter for me to get into a decent position. I barely noticed the difference while pedaling but the difference in positional comfort for me was significant. At my height I probably wouldn't want to go much lower though.
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Re: Any reasons not to go with shorter cranks? [Crentist] [ In reply to ]
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Crentist wrote:
I'm 6'3" with long legs, I went from 172.5 to 165 on my Trek SC and haven't looked back. For me it was all about getting into a better position. With a shorter crank you can raise the seat and get less hip flexion throughout the cycle. I'm not flexible so that was a big limiter for me to get into a decent position. I barely noticed the difference while pedaling but the difference in positional comfort for me was significant. At my height I probably wouldn't want to go much lower though.

Not arguing, just trying to understand. This means you raised your seat 7.5mm, but the shorter "top" crank arm gives you 15mm more room (less pinch) in the flexed hip? And you can feel that 15mm? That just seems like an insignificant change.
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Re: Any reasons not to go with shorter cranks? [HVP] [ In reply to ]
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And you can feel that 15mm? That just seems like an insignificant change. //

When you get right down to the spot where you are almost there, the last change of course will seem small, but not insignificant.
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Re: Any reasons not to go with shorter cranks? [monty] [ In reply to ]
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I'm 6'-0" I downsized from 172.5 to 165 when I invested in a stages powermeter crank. It made the the fit work much better and had no detrimental effects on my power output.

"They know f_ck-all over at Slowtwitch"
- Lionel Sanders
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Re: Any reasons not to go with shorter cranks? [HVP] [ In reply to ]
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HVP wrote:
Crentist wrote:
I'm 6'3" with long legs, I went from 172.5 to 165 on my Trek SC and haven't looked back. For me it was all about getting into a better position. With a shorter crank you can raise the seat and get less hip flexion throughout the cycle. I'm not flexible so that was a big limiter for me to get into a decent position. I barely noticed the difference while pedaling but the difference in positional comfort for me was significant. At my height I probably wouldn't want to go much lower though.

Not arguing, just trying to understand. This means you raised your seat 7.5mm, but the shorter "top" crank arm gives you 15mm more room (less pinch) in the flexed hip? And you can feel that 15mm? That just seems like an insignificant change.

The number may seem small in relation to overall height or leg length, but it's huge. Give it a try and let us know how it feels.

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Re: Any reasons not to go with shorter cranks? [brider] [ In reply to ]
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People have tried to reinvent pedals and shoe fitments to gain a pedal stack improvement.

So why is a free 10mm on a crank such a tough sell?

Shoot, 175 is already longer than ā€œstockā€ anyway.

It doesnā€™t make sense until youā€™ve done it.
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Re: Any reasons not to go with shorter cranks? [brider] [ In reply to ]
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brider wrote:
HVP wrote:
Crentist wrote:
I'm 6'3" with long legs, I went from 172.5 to 165 on my Trek SC and haven't looked back. For me it was all about getting into a better position. With a shorter crank you can raise the seat and get less hip flexion throughout the cycle. I'm not flexible so that was a big limiter for me to get into a decent position. I barely noticed the difference while pedaling but the difference in positional comfort for me was significant. At my height I probably wouldn't want to go much lower though.

Not arguing, just trying to understand. This means you raised your seat 7.5mm, but the shorter "top" crank arm gives you 15mm more room (less pinch) in the flexed hip? And you can feel that 15mm? That just seems like an insignificant change.

The number may seem small in relation to overall height or leg length, but it's huge. Give it a try and let us know how it feels.

Yea, in short my answer is "yes" it's quite noticeable. As the others mentioned, when you're trying to get lower in front that "little" extra margin makes a huge difference. I think it would be obvious if you can A/B test in the shop.
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Re: Any reasons not to go with shorter cranks? [brider] [ In reply to ]
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brider wrote:
HVP wrote:
Crentist wrote:
I'm 6'3" with long legs, I went from 172.5 to 165 on my Trek SC and haven't looked back. For me it was all about getting into a better position. With a shorter crank you can raise the seat and get less hip flexion throughout the cycle. I'm not flexible so that was a big limiter for me to get into a decent position. I barely noticed the difference while pedaling but the difference in positional comfort for me was significant. At my height I probably wouldn't want to go much lower though.


Not arguing, just trying to understand. This means you raised your seat 7.5mm, but the shorter "top" crank arm gives you 15mm more room (less pinch) in the flexed hip? And you can feel that 15mm? That just seems like an insignificant change.


The number may seem small in relation to overall height or leg length, but it's huge. Give it a try and let us know how it feels.

I've been mulling giving it a try for years now; just haven't pulled the trigger (partly because I'm invested in crank power at 172.5mm). I can appreciate the merits. I just wish there was a rough size guide - i.e., you are 70" with "normal" femur length and poor flexibility, then your happy-medium crank length starting place is 1XXmm. It just seems like 15mm isn't very much of a change. And why not drop down to 155mm instead of 165mm? Etc. But this is good dialogue to hear about others' experiences.
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Re: Any reasons not to go with shorter cranks? [HVP] [ In reply to ]
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Not speaking for centrist. But yes, some can feel as little as 2.5mm. I'm old school. We used to ride 175s on our roadies and longer on the TT bike for "better leverage". I had 177.5s on the TT. But I've developed a minor problem with my left knee. At 6ft, It's very uncomfortable for when the knee is full bent riding 175s. But I can ride 172.5s on my roadie at 92 avg cadence with no knee problem or soreness. If I try 175s, I know the difference before 3 revolutions. I ride 170s on the TT now, mostly for a more aero position, but it also keep my quads from beating the hell out of my 22+ pounds of extremely well insulated stomach. I could go shorter, but I don't run, so it's not as big an issue for me.

To the OP: A competent fitter is not subjective. Her or his advice may be. A competent fitter will follow a specified protocol and have the proper equipment to allow you to find your best position, balancing comfort, speed and the ability to run off the bike. One critical piece of equipment is an adjustable crank. This will let you try different lengths so that you can find the one that's best - without buying a bunch of different cranks.

hth
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Re: Any reasons not to go with shorter cranks? [FatandSlow] [ In reply to ]
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FatandSlow wrote:
Not speaking for centrist. But yes, some can feel as little as 2.5mm. I'm old school. We used to ride 175s on our roadies and longer on the TT bike for "better leverage". I had 177.5s on the TT. But I've developed a minor problem with my left knee. At 6ft, It's very uncomfortable for when the knee is full bent riding 175s. But I can ride 172.5s on my roadie at 92 avg cadence with no knee problem or soreness. If I try 175s, I know the difference before 3 revolutions. I ride 170s on the TT now, mostly for a more aero position, but it also keep my quads from beating the hell out of my 22+ pounds of extremely well insulated stomach. I could go shorter, but I don't run, so it's not as big an issue for me.

To the OP: A competent fitter is not subjective. Her or his advice may be. A competent fitter will follow a specified protocol and have the proper equipment to allow you to find your best position, balancing comfort, speed and the ability to run off the bike. One critical piece of equipment is an adjustable crank. This will let you try different lengths so that you can find the one that's best - without buying a bunch of different cranks.

hth

Iā€™ve fit myself in the garage to a super aggressive position and have ALWAYS been able to run off the bike.
In fact Iā€™d challenge anyone on here to chime in if they have NOT been able to ā€˜run off the bikeā€™. (Given some getting used to new position of course).
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Re: Any reasons not to go with shorter cranks? [FatandSlow] [ In reply to ]
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I would also be willing to bet if you had a ā€˜competentā€™ fit in the morning then go across town to another ā€™competentā€™ fitter later in that same day youā€™d end up with different positions.
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Re: Any reasons not to go with shorter cranks? [g_lev] [ In reply to ]
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g_lev wrote:
The only real way to answer this question is to have a fit done by a competent fitter, and find out through experimentation. The main benefit of a shorter crank arm is the ability to raise your saddle by the amount you shortened the crank. This might (or might not) result in a better position, and allow you to rotate forward around the bottom bracket. Or it might not. It totally depends on your own body's geometry.

I get so confused by such a simple thing

So if you go shorter cranks you can raise your saddle?

That would be good for me. I thought it was the other way around

Happy to be educated

Thanks!
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Re: Any reasons not to go with shorter cranks? [thatzone] [ In reply to ]
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thatzone wrote:
FatandSlow wrote:
Not speaking for centrist. But yes, some can feel as little as 2.5mm. I'm old school. We used to ride 175s on our roadies and longer on the TT bike for "better leverage". I had 177.5s on the TT. But I've developed a minor problem with my left knee. At 6ft, It's very uncomfortable for when the knee is full bent riding 175s. But I can ride 172.5s on my roadie at 92 avg cadence with no knee problem or soreness. If I try 175s, I know the difference before 3 revolutions. I ride 170s on the TT now, mostly for a more aero position, but it also keep my quads from beating the hell out of my 22+ pounds of extremely well insulated stomach. I could go shorter, but I don't run, so it's not as big an issue for me.

To the OP: A competent fitter is not subjective. Her or his advice may be. A competent fitter will follow a specified protocol and have the proper equipment to allow you to find your best position, balancing comfort, speed and the ability to run off the bike. One critical piece of equipment is an adjustable crank. This will let you try different lengths so that you can find the one that's best - without buying a bunch of different cranks.

hth

Iā€™ve fit myself in the garage to a super aggressive position and have ALWAYS been able to run off the bike.
In fact Iā€™d challenge anyone on here to chime in if they have NOT been able to ā€˜run off the bikeā€™. (Given some getting used to new position of course).

Iā€™m not understanding

You did your own fit and you can run good off the bike

Do you advocate shorter cranks, longer cranks

What?
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Re: Any reasons not to go with shorter cranks? [thatzone] [ In reply to ]
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thatzone wrote:
FatandSlow wrote:
Not speaking for centrist. But yes, some can feel as little as 2.5mm. I'm old school. We used to ride 175s on our roadies and longer on the TT bike for "better leverage". I had 177.5s on the TT. But I've developed a minor problem with my left knee. At 6ft, It's very uncomfortable for when the knee is full bent riding 175s. But I can ride 172.5s on my roadie at 92 avg cadence with no knee problem or soreness. If I try 175s, I know the difference before 3 revolutions. I ride 170s on the TT now, mostly for a more aero position, but it also keep my quads from beating the hell out of my 22+ pounds of extremely well insulated stomach. I could go shorter, but I don't run, so it's not as big an issue for me.

To the OP: A competent fitter is not subjective. Her or his advice may be. A competent fitter will follow a specified protocol and have the proper equipment to allow you to find your best position, balancing comfort, speed and the ability to run off the bike. One critical piece of equipment is an adjustable crank. This will let you try different lengths so that you can find the one that's best - without buying a bunch of different cranks.

hth


Iā€™ve fit myself in the garage to a super aggressive position and have ALWAYS been able to run off the bike.
In fact Iā€™d challenge anyone on here to chime in if they have NOT been able to ā€˜run off the bikeā€™. (Given some getting used to new position of course).

I don't see an incongruence between an aggressive (or super aggressive) position and the ability to run off the bike. By super aggressive, I'm assuming you mean a very flat back. One can be in the exact same position with longer cranks or shorter ones. The shorter ones make the knees not come up as high, improving comfort for many. I should have said moving forward opens the hip angle and allows for an easier run off the bike. My bad.
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Re: Any reasons not to go with shorter cranks? [thatzone] [ In reply to ]
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thatzone wrote:
I would also be willing to bet if you had a ā€˜competentā€™ fit in the morning then go across town to another ā€™competentā€™ fitter later in that same day youā€™d end up with different positions.

I might be willing to make the same bet. The two protocols that I've seen the most involve having the rider tell the fitter what feels best, so it's possible the different fits would come from what the rider tells the different fitters. But that's a reach. More likely, because the angles are ranges, the different fitters may have different preferences about where you should be in those ranges. So I think your scenario is not only possible, but likely. But that doesn't mean that either is wrong. I just don't think fitting is that exact. That said, every fitter (more than 3) I've used has said try it for a couple of weeks and come back if anything isn't working or doesn't feel right we'll make an adjustment. I've never been charged for an adjustment.
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Re: Any reasons not to go with shorter cranks? [icecubes] [ In reply to ]
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Some fitters have adjustable length cranks to help fit you.

I went from 170's to 150's and I have a 145 in a box. I'm 5'5" and it helped opening my hip and I was having hip flexor issues. I could feel the difference but overall I think it was better for me.

When I raced CX, I would have toe overlap issues. On a short corner I'd have to pedal backwards to avoid hitting my toe on the wheel. Having shorter cranks would have helped.
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