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Shorter Cranks

Old 05-12-22, 02:44 AM
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sjanzeir
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Shorter Cranks

I've been wanting to experiment with this for a while: Running shorter crank arms than the usual 170-175-millimeter OEM ones that come on most bikes in my frame sizes (15-17.5/S-M.) Nothing wrong with some experimenting; I'm 5'3" inches/160 centimeters tall; and the Wise Oracle that is the internet says that ideally, I should be running 150-155mm cranks - which is totally ridiculous.

What was perhaps a little foolhardy on my part, though, is that I went ahead and up(down?)graded not one, but both of my folding bikes to 165mm cranks. I did not expect to be having this creeping desire to want to go back to the stock 170mm cranks.

All I expected was for there to be a subtle difference in cadence and power at worst. It turns out, the differences really weren't all that subtle. Now my legs tend to spin up faster - and spin up to a significantly higher cadence they do - than I'm accustomed to, in lower gears than I'm used to, with a little less torque than I had come to expect. Simple physics; no surprise there.

It's been a week or so and I've only ridden the bikes a few times, and just around the neighborhood at that. So I should probably give them more time so as to fully figure out exactly how I feel about this and what I need to do.

In the mean time, I'd really appreciate some of your experiences with running shorter cranks!

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Old 05-12-22, 03:08 AM
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Do you actually ride around in the Kingdom of Saudi Arabia in Jeddah??

I worked there for a while, it gets really hot esp this time of the year and bound to get hotter in July, as high as 120F!! Still hot even very early in the morning!. I actually miss the place, great food (the bbq Kabsa chicken especially and the "burritos"), fun times!

My inseam is 83cm and matched for 170mm crank. But I can hold higher effort zones for longer periods with 150mm crank.

To be honest, my very first experience being a roadie at a very young age, I went with 170mm. I don't recall having an issue about it apart from saddle soreness. But then my next bike had 150 mm. I spent a lot more time riding on the 150mm crank bike. Now I'm back to 170mm size crank and now my legs are complaining.

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Old 05-12-22, 04:03 AM
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Originally Posted by sjanzeir View Post
I've been wanting to experiment with this for a while: Running shorter crank arms than the usual 170-175-millimeter OEM ones that come on most bikes in my frame sizes (15-17.5/S-M.) Nothing wrong with some experimenting; I'm 5'3" inches/160 centimeters tall; and the Wise Oracle that is the internet says that ideally, I should be running 150-155mm cranks - which is totally ridiculous.

What was perhaps a little foolhardy on my part, though, is that I went ahead and up(down?)graded not one, but both of my folding bikes to 165mm cranks. I did not expect to be having this creeping desire to want to go back to the stock 170mm cranks.

All I expected was for there to be a subtle difference in cadence and power at worst. It turns out, the differences really were a little less subtle. Now my legs tend to spin up faster - and spin up to a significantly higher cadence they do - than I'm accustomed to, in lower gears than I'm used to, with a little less torque than I had come to expect. Simple physics; no surprise there.

It's been a week or so and I've only ridden the bikes a few times, and just around the neighborhood at that. So I should probably give them more time so as to fully figure out exactly how I feel about this and what I need to do.

In the mean time, I'd really appreciate some of your experiences with running shorter cranks!
Yeah, that's the reality with shorter cranks i.e. you have to spin more to create the same power (since power = pedal force x crank length x cadence). The advantage of shorter cranks is that you are less likely to exceed your range of comfortable joint articulation (i.e. knee extension/compression, less hip impingmement etc). So they can be good for endurance and reducing the risk of injury. But there's no free lunch here. At 5'3" I would give the shorter cranks a bit more time. 165 mm is not that short in relation to your height (presuming your legs are in typical proportion). Learning to spin faster is generally a good thing too.
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Old 05-12-22, 05:38 AM
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I run 165mm cranks on my fixed gear bikes. They provide a little more clearance when cornering and allow a faster cadence on downhills without blowing out my knees. My wife has joint issues, and uses 155mm cranks on her bike to limit knee range of motion when pedalling.
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Old 05-12-22, 07:01 AM
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Originally Posted by couldwheels View Post
Do you actually ride around in the Kingdom of Saudi Arabia in Jeddah??

I worked there for a while, it gets really hot esp this time of the year and bound to get hotter in July, as high as 120F!! Still hot even very early in the morning!. I actually miss the place, great food (the bbq Kabsa chicken especially and the "burritos"), fun times!

My inseam is 83cm and matched for 170mm crank. But I can hold higher effort zones for longer periods with 150mm crank.

To be honest, my very first experience being a roadie at a very young age, I went with 170mm. I don't recall having an issue about it apart from saddle soreness. But then my next bike had 150 mm. I spent a lot more time riding on the 150mm crank bike. Now I'm back to 170mm size crank and now my legs are complaining.

You mean like this?



You'll probably hardly recognize the place today. We've got a whole circus running near where we live, complete we scantily clad ladies performing (well, not as scantily clad by Western standards, but still!) We've got women driving their own cars all over the place (and occasionally crashing into you and blaming you for being there )... We've got women hanging around shopping centers in Western clothes with no black gowns or headscarves and no one seems to give a rat's ass anymore ... We've got happier, more cheerful people (well, again, relatively speaking) going about their daily lives... People are living normally for a change, free of the constant erstwhile worry of being chased around by big men with big black beards and big sticks in big black SUVs. It used to be when people felt they had to come to Saudi Arabia because you had to earn a living and somebody gave them a job there. Now they want to come to Saudi Arabia to see the place, and there's plenty to see.

And my wife and I just had kabsah for lunch

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Old 05-12-22, 07:31 AM
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I'd suspect if you have a narrow range of comfortable cadence and it is on the lower side of the spectrum, then you'll not like short cranks.

For those that don't think anything of 70 - 120 rpm, and 80 - 90 being their norm, I'll suspect they might like shorter, but then again they might not.

I gave 170 mm cranks a good try for 4 full months of riding before going back to 165 mm cranks. I'd hope you give yours a fair amount of time to get use to them too before returning to the others.
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Old 05-12-22, 07:35 AM
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Originally Posted by sjanzeir View Post
You mean like this?

You'll probably hardly recognize the place today. We've got a whole circus running near where we live, complete we scantily clad ladies performing (well, not as scantily clad by Western standards, but still!) We've got women driving their own cars all over the place (and occasionally crashing into you and blaming you for being there )... We've got women hanging around shopping centers in Western clothes with no black gowns or headscarves and no one seems to give a rat's ass anymore ... We've got happier, more cheerful people (well, again, relatively speaking) going about their daily lives... People are living normally for a change, free of the constant erstwhile worry of being chased around by big men with big black beards and vig sticks in big black SUVs. It used to be when people felt they had to come to Saudi Arabia because you had to earn a living and somebody gave them a job there. Now they want to come to Saudi Arabia to see the place, and there's plenty to see.

And my wife and I just had kabsah for lunch
I was there last 2016 just before things got crazy. I can't believe I've been missing A LOT of the excitement going on in there! Now I feel bad about leaving!

Your route goes very near where I lived there in Al Faisaliyyah, near the Aziz mall and just across the Electronics University. You ride at 9am up to around 12pm, yeah, that's crazy with those daytime temperatures.

Back in 2016 I rarely saw any cyclists. Occasionally saw few boys riding BMX bikes and few commuters on dutch-style bikes. None on road bikes, not even folding bikes. Everyone is in love with their cars in Saudi but not bicycles.

I really miss kabsah! Anyway, do look for shorter cranks and get used to them. They do make things feel easier when you get used to them. You'll need every bit of efficiency even more in that searing hot climate in Jeddah!
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Old 05-12-22, 07:36 AM
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I notice similar things when going shorter.

Whether it is good or bad depends on the application.

I have run slighly shorter cranks on my Road/Gravel bikes than my MTBs for years. I recently went a bit shorter on the MTB just for kicks as that seems to be the trend lately.

While I feel like the shorter cranks sort of fit better, I dont really like the higher cadence on the MTB. Going to give this some time to make a decision. It is fine on the Road/Gravel bikes, though.
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Old 05-12-22, 08:05 AM
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Originally Posted by couldwheels View Post
I was there last 2016 just before things got crazy. I can't believe I've been missing A LOT of the excitement going on in there! Now I feel bad about leaving!

Your route goes very near where I lived there in Al Faisaliyyah, near the Aziz mall and just across the Electronics University. You ride at 9am up to around 12pm, yeah, that's crazy with those daytime temperatures.

Back in 2016 I rarely saw any cyclists. Occasionally saw few boys riding BMX bikes and few commuters on dutch-style bikes. None on road bikes, not even folding bikes. Everyone is in love with their cars in Saudi but not bicycles.

I really miss kabsah! Anyway, do look for shorter cranks and get used to them. They do make things feel easier when you get used to them. You'll need every bit of efficiency even more in that searing hot climate in Jeddah!
Nah, this was back in January when the weather was much more conducive to a midday crosstown trek just for kicks. There's no way I'd venture out on a bike midday at this time of year!

And 2016 was a very different time!

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Old 05-12-22, 08:14 AM
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Originally Posted by sjanzeir View Post
Nah, this was back in January when the weather was much more conducive to a midday crosstown trek just for kicks!

And 2016 was a very different time!
January would be perfect indeed. I remember November to March where you actually feel cold when you get outside during daytime. It even snowed one time but very rare. 5 months when it's great to do things like cycling and running outdoors, except taking a dip in the beach!
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Old 05-12-22, 11:25 AM
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Originally Posted by sjanzeir View Post
II'm 5'3" inches/160 centimeters tall; and the Wise Oracle that is the internet says that ideally, I should be running 150-155mm cranks - which is totally ridiculous.
Why is it totally ridiculous? People come in a variety of sizes. It's ridiculous to expect everyone to ride on 170mm cranks. Nowadays you can get a Shimano 105 crankset in 160mm. So you don't have to downgrade to some oddball BMX crankset to get shorter.
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Old 05-12-22, 11:39 AM
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Originally Posted by icemilkcoffee View Post
Why is it totally ridiculous? People come in a variety of sizes. It's ridiculous to expect everyone to ride on 170mm cranks. Nowadays you can get a Shimano 105 crankset in 160mm. So you don't have to downgrade to some oddball BMX crankset to get shorter.
Modern physio studies is actually proving we are riding with oversized cranks. Shorter cranks have shown performance improvements across the board.

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Old 05-12-22, 11:54 AM
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I'm a shorty at 5'4. More than a decade ago, I sent a couple cranks to Mark Stonich at BikeSmith Design and Fabrication to have then shortened, an Ultegra triple and a 105 double. The idea was to experiment with shorter cranks than 165. Both cranks were shortened to 148mm.

I immediately put the Ultegra on a favorite folding bike to see how it would work. Short answer? Not great! Spinning was easier, but it seemed I had no leverage, so hills and wind became exponentially harder than I would have expected. After a month of deciding whether I wanted to kill my knees some more, I put my "normal" (165 or 170, can't remember) crank back on and everything felt fine, just like before this little dalliance.

I still have both these cranks, but have never felt a need to re-experience 148 again.
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Old 05-12-22, 11:59 AM
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Originally Posted by icemilkcoffee View Post
Why is it totally ridiculous? People come in a variety of sizes. It's ridiculous to expect everyone to ride on 170mm cranks. Nowadays you can get a Shimano 105 crankset in 160mm. So you don't have to downgrade to some oddball BMX crankset to get shorter.
In a post that he seems to have just deleted, livedarklions responded to you better than I possibly could: like I said in the very first line of the original post, I'm experimenting, so yeah, it would've been totally ridiculous to heed Mother Interwebs' advice and spend the money going all the way down to a 150-155mm crank. Make of that what you will.
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Old 05-12-22, 12:05 PM
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Originally Posted by sjanzeir View Post
In a post that he seems to have just deleted, livedarklions responded to you better than I possibly could: like I said in the very first line of the original post, I'm experimenting, so yeah, it would've been totally ridiculous to heed Mother Interwebs' advice and spend the money going all the way down to a 150-155mm crank. Make of that what you will.

Also, does the fact that these are Dahons factor into this as well? Since I haven't experimented with crank sizes and I don't know anything about Dahons, I decided I really don't know enough to weigh in as heavily I had drafted.
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Old 05-12-22, 12:14 PM
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Originally Posted by bargainguy View Post
I'm a shorty at 5'4. More than a decade ago, I sent a couple cranks to Mark Stonich at BikeSmith Design and Fabrication to have then shortened, an Ultegra triple and a 105 double. The idea was to experiment with shorter cranks than 165. Both cranks were shortened to 148mm.

I immediately put the Ultegra on a favorite folding bike to see how it would work. Short answer? Not great! Spinning was easier, but it seemed I had no leverage, so hills and wind became exponentially harder than I would have expected. After a month of deciding whether I wanted to kill my knees some more, I put my "normal" (165 or 170, can't remember) crank back on and everything felt fine, just like before this little dalliance.

I still have both these cranks, but have never felt a need to re-experience 148 again.
This is my thing--I live by torque and am definitely not a spinner, so I really have no interest in shortening the levers. That's why I'm skeptical that it's just a matter of proportions, these generalizations seem to rely on assumptions of one particular riding style.
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Old 05-12-22, 12:16 PM
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Originally Posted by livedarklions View Post
Also, does the fact that these are Dahons factor into this as well? Since I haven't experimented with crank sizes and I don't know anything about Dahons, I decided I really don't know enough to weigh in as heavily I had drafted.
There's the fact that I tend to ride my two Dahons more often than I do my Trek FXs, and with the Dahons already being 1x, swapping out cranksets is a simpler affair. In fact, I was planning to do the same mod to at least one of the two FXs if this works out.
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Old 05-12-22, 12:35 PM
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Originally Posted by livedarklions View Post
This is my thing--I live by torque and am definitely not a spinner, so I really have no interest in shortening the levers. That's why I'm skeptical that it's just a matter of proportions, these generalizations seem to rely on assumptions of one particular riding style.
I'm skeptical of anything that points to body proportions too. I'm supposed to be on >175 mm cranks based on my 34.5" (≈88 cm) inseam. Yet I ride 165 mm cranks.

Unlike you, I like to spin a fast cadence and put out little torque. So it stands to reason that my choice of cranks will be different than your choice.
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Old 05-12-22, 12:36 PM
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Originally Posted by sjanzeir View Post
There's the fact that I tend to ride my two Dahons more often than I do my Trek FXs, and with the Dahons already being 1x, swapping out cranksets is a simpler affair. In fact, I was planning to do the same mod to at least one of the two FXs if this works out.

Yeah, I just have no experience riding on a bike with 20" wheels and have no idea what that might do to the effects of changes in crank length or even if they have anything to do with each other. I'm thinking that the smaller wheels mean that you get less benefit from increasing your cadence, is that wrong?
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Old 05-12-22, 01:04 PM
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I first started to pay attention to crank length in my teens when I realized that my track bike had 167.5, road bike had 172.5, and mountain bike had 177.5. A more experienced rider told me longer cranks gives you better leverage when climbing, and shorter cranks were easier to spin higher cadences and also cleared the banking on the velodrome. Made sense to me. As for my own observations, I only noticed that going too short made climbing steep grades intolerable.
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Old 05-12-22, 01:41 PM
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Originally Posted by sjanzeir View Post
I've been wanting to experiment with this for a while: Running shorter crank arms than the usual 170-175-millimeter OEM ones that come on most bikes in my frame sizes (15-17.5/S-M.) Nothing wrong with some experimenting; I'm 5'3" inches/160 centimeters tall; and the Wise Oracle that is the internet says that ideally, I should be running 150-155mm cranks - which is totally ridiculous.

What was perhaps a little foolhardy on my part, though, is that I went ahead and up(down?)graded not one, but both of my folding bikes to 165mm cranks. I did not expect to be having this creeping desire to want to go back to the stock 170mm cranks.

All I expected was for there to be a subtle difference in cadence and power at worst. It turns out, the differences really weren't all that subtle. Now my legs tend to spin up faster - and spin up to a significantly higher cadence they do - than I'm accustomed to, in lower gears than I'm used to, with a little less torque than I had come to expect. Simple physics; no surprise there.

It's been a week or so and I've only ridden the bikes a few times, and just around the neighborhood at that. So I should probably give them more time so as to fully figure out exactly how I feel about this and what I need to do.

In the mean time, I'd really appreciate some of your experiences with running shorter cranks!
I much prefer 165 cranks to longer. For whatever reason Im faster.
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Old 05-12-22, 02:00 PM
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Originally Posted by sjanzeir View Post
I've been wanting to experiment with this for a while: Running shorter crank arms than the usual 170-175-millimeter OEM ones that come on most bikes in my frame sizes (15-17.5/S-M.) Nothing wrong with some experimenting; I'm 5'3" inches/160 centimeters tall; and the Wise Oracle that is the internet says that ideally, I should be running 150-155mm cranks - which is totally ridiculous.

What was perhaps a little foolhardy on my part, though, is that I went ahead and up(down?)graded not one, but both of my folding bikes to 165mm cranks. I did not expect to be having this creeping desire to want to go back to the stock 170mm cranks.

All I expected was for there to be a subtle difference in cadence and power at worst. It turns out, the differences really weren't all that subtle. Now my legs tend to spin up faster - and spin up to a significantly higher cadence they do - than I'm accustomed to, in lower gears than I'm used to, with a little less torque than I had come to expect. Simple physics; no surprise there.

It's been a week or so and I've only ridden the bikes a few times, and just around the neighborhood at that. So I should probably give them more time so as to fully figure out exactly how I feel about this and what I need to do.

In the mean time, I'd really appreciate some of your experiences with running shorter cranks!
Choose your cranks based on biomechanics (how much your knees and hips like to flex) and maybe your preferred cadence - the gears will even out the power output. Since power is essentially torque x RPM (with some constants thrown into the equation), if you use shorter cranks, you might lose some torque, but you can compensate with higher cadence (which the shorter cranks will favor) and a lower gear - you should manage similar power output. The only time the added torque of longer cranks become an advantage is when you're run out of gears and long cranks might be the difference between grinding up a steep climb and walking.
Years ago, when I started paying attention to bike sizing (when size selection became more involved than "can you stand over it? Good - it's the right size"), I used an online bike fitting guide which suggested that 172.5mm cranks were appropriate for my height (5'8"). Thinking back, a crank calculation based on inseam might have been a better starting place, but I've used 172.5s for the last ~30 years with no issues, so I guess the height-based method is fine for people of average proportions.

Last edited by Litespud; 05-12-22 at 02:09 PM.
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Old 05-12-22, 02:13 PM
  #23  
sjanzeir
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Originally Posted by livedarklions View Post
Yeah, I just have no experience riding on a bike with 20" wheels and have no idea what that might do to the effects of changes in crank length or even if they have anything to do with each other. I'm thinking that the smaller wheels mean that you get less benefit from increasing your cadence, is that wrong?
It's more right than wrong. The smaller wheel size is primarily compensated for with a bigger chainring (52t om my Hemingway and 53t on my Mu, but plenty of folding bike riders swap 8n even bigger ones.)

With that being said, part of fun of smaller wheels is that the quicker acceleration. It's a great feeling when you find yourself up to speed in a couple of spins of the crank. With geared small-wheelers, the ability to throw three or four gears in quick succession as you peel off adds to the joy.
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Old 05-12-22, 02:54 PM
  #24  
livedarklions
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Originally Posted by Litespud View Post
Choose your cranks based on biomechanics (how much your knees and hips like to flex) and maybe your preferred cadence - the gears will even out the power output. Since power is essentially torque x RPM (with some constants thrown into the equation), if you use shorter cranks, you might lose some torque, but you can compensate with higher cadence (which the shorter cranks will favor) and a lower gear - you should manage similar power output. The only time the added torque of longer cranks become an advantage is when you're run out of gears and long cranks might be the difference between grinding up a steep climb and walking.
Years ago, when I started paying attention to bike sizing (when size selection became more involved than "can you stand over it? Good - it's the right size"), I used an online bike fitting guide which suggested that 172.5mm cranks were appropriate for my height (5'8"). Thinking back, a crank calculation based on inseam might have been a better starting place, but I've used 172.5s for the last ~30 years with no issues, so I guess the height-based method is fine for people of average proportions.

My suspicion is that we develop our legs in certain ways when we have longstanding habits like always the same size cranks so that even if our biomechanics might favor something else if it were a clean slate, we've probably adjusted them to fit the hardware size in certain consequential ways.
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Old 05-12-22, 04:52 PM
  #25  
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Originally Posted by Iride01 View Post
I'm skeptical of anything that points to body proportions too. I'm supposed to be on >175 mm cranks based on my 34.5" (≈88 cm) inseam. Yet I ride 165 mm cranks.

Unlike you, I like to spin a fast cadence and put out little torque. So it stands to reason that my choice of cranks will be different than your choice.
To borrow Sheldon Brown's analogy, it's a lot easier for a tall person to climb small steps than it is for a short person to climb tall steps.
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