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Discussion Starter · #22 ·
Wettek , What type of cadence do you typically ride at ? I researched this a few years ago and never took the plunge to buy shorter cranks .I have always rode 172.5 and my research indicated I should be on 165 cranks , I am a spinner and find anything under 95 for a cadence feels like I am lugging . I too as I age find my knees aching more .
I would be interested in any other people to chime in on this topic . Thanks
Gidday mate. I like 95-100. I can definitely feel the difference in my knees going to the shorter crank. Previously my knees would have a "dull ache" for a couple of days, that's gone now. I did not think 2.5mm would make as much difference as it has.
 

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Discussion Starter · #23 ·
Went out and did 30 miles this morning, I can say the shorter cranks have definitely made a difference, I feel heaps better after a ride, and my average pace has picked up by about .8 mph. Just goes to show that just because we've done something for the last 35 years, doesn't mean it's still "right". We all get older. (and fatter). 😀
 

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As more data and understanding of bike fit is generated, the industry is definitely trending towards shorter crank lengths. Long-held beliefs about optimal lengths are being rethought and products are evolving to reflect this. Note Shimano now offers multple versions of the latest 12-speed Ultegra and Dura-Ace cranksets in 160mm. In the previous 11-speed road gruppos, you could only get 160mm cranks as a 105 50/34T compact.

Bradley Wiggins started out his career on 177.5mm cranks and won gold in the Team Pursuit in the Rio Olympics using 165s. I believe I read elsewhere that he did his hour record attempt using 170s. He's 6'3".

Guys that have been riding for years may find this a bit of a paradigm shift, but it's not a fad. However, I don't think you should look into changing your crank arm lengths unless you have a compelling reason.

I think these articles do a good job in explaining the benefits and liablities of shorter and longer cranks and align with my exact experience when I switched to shorter cranks (-5mm):

What's the best crank length for cycling?
What is the best crank length for cycling?

The takeaway: There's no right or wrong length, but most people will benefit from using shorter cranks than what has been considered the industry standard.
 

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OP, did you adjust your saddle height? You should have raised your saddle 2.5mm to adjust for the shorter crank length.

My knees have been hurting me (front of the knee). I raised my saddle about 2mm and they feel a lot better. I found that saddles sag after a while, and thus your position becomes lower over time.

Conventional wisdom is if there's front of the knee pain, raise the saddle; behind the knee, lower it.
 

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OP, did you adjust your saddle height? You should have raised your saddle 2.5mm to adjust for the shorter crank length.
Is there really a need to? If yoy have shorter crank arms, you will also be extending less, so it's really a wash.

I would say leave well enough alone and if you still have pain in front of the knees, then raise the saddle a bit.
 

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Is there really a need to? If yoy have shorter crank arms, you will also be extending less, so it's really a wash.

I would say leave well enough alone and if you still have pain in front of the knees, then raise the saddle a bit.
Agree with you that it may well be a wash for this rider. Fit is defiinitely a personal, subjective matter.

However, note that a decrease of 2.5mm in crank arm length will result in a difference of 5mm in the diameter of your overall pedal stroke. Raising the saddle will distribute all of that difference to the top of your stroke, where you gain the most benefit: more open hip angle results in less stress on joints and muscles, more comfortable position on a drop bar bike and it helps with breathing because your torso isn't as compressed.

A -5mm change in cranks will decrease the overall pedal stroke diameter by 1cm. If you are experiencing a problem due to bike fit, this is not insignificant.
 

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Discussion Starter · #28 ·
OP, did you adjust your saddle height? You should have raised your saddle 2.5mm to adjust for the shorter crank length.

My knees have been hurting me (front of the knee). I raised my saddle about 2mm and they feel a lot better. I found that saddles sag after a while, and thus your position becomes lower over time.

Conventional wisdom is if there's front of the knee pain, raise the saddle; behind the knee, lower it.
No, I actually left it where it was. I only changed by 2.5mm, so figured I would leave until I had "settled in" to the new length. Didn't want to change variables too much, then point at the crank length alone as the big change.
 

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As more data and understanding of bike fit is generated, the industry is definitely trending towards shorter crank lengths. Long-held beliefs about optimal lengths are being rethought and products are evolving to reflect this. Note Shimano now offers multple versions of the latest 12-speed Ultegra and Dura-Ace cranksets in 160mm. In the previous 11-speed road gruppos, you could only get 160mm cranks as a 105 50/34T compact.

Bradley Wiggins started out his career on 177.5mm cranks and won gold in the Team Pursuit in the Rio Olympics using 165s. I believe I read elsewhere that he did his hour record attempt using 170s. He's 6'3".

Guys that have been riding for years may find this a bit of a paradigm shift, but it's not a fad. However, I don't think you should look into changing your crank arm lengths unless you have a compelling reason.

I think these articles do a good job in explaining the benefits and liablities of shorter and longer cranks and align with my exact experience when I switched to shorter cranks (-5mm):

What's the best crank length for cycling?
What is the best crank length for cycling?

The takeaway: There's no right or wrong length, but most people will benefit from using shorter cranks than what has been considered the industry standard.
This reinforces everything I have read , in my situation it recommends a drop from 5mm to 7.5mm which in my mind is huge. If you have been riding for a long time most people I think would agree small changes at a time .
One fitter that I follow say's most people will not notice a change of 2.5mm , decisions decisions.
 

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Discussion Starter · #30 ·
This reinforces everything I have read , in my situation it recommends a drop from 5mm to 7.5mm which in my mind is huge. If you have been riding for a long time most people I think would agree small changes at a time .
One fitter that I follow say's most people will not notice a change of 2.5mm , decisions decisions.
I had heard the same thing, but I didn't want to make a "big" jump of 5mm, I figured small changes would find the optimum length for me. Might cost me a few extra dollars, but better than the scatter gun approach of jumping straight to a large change. I have definitely noticed the 2.5mm.
 

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Discussion Starter · #36 ·
Only to promote both sides of this conversation - recently changed from 172.5mm to 175mm. So much better.
Fair enough, but I'm not racing, just doing 25 miles a day for general fitness. If I was serious, I would fine tune my seat position by millimetres, but at the moment I am very comfortable and the crank change has helped. One day I will pay for a professional fit!
 

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As I said, I have not adjusted my saddle height yet. The only 2.5mm change so far is my crank length.
Were you able to find the individual crank arms or did you have to replace the whole crank set?
 

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Discussion Starter · #40 ·
Were you able to find the individual crank arms or did you have to replace the whole crank set?
Searched the internet to see if I could get the drive side spider and non drive side arm separately, but it was by far easier (and cheaper) to get a complete set (chainrings and cranks)
 
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