I'm interested in hearing from people who have switched to shorter cranks on their road bike. I think Jo has done this, but I'm not sure if anyone else has.
Steve Hogg recommended I go to 160mm or something crazily short like that, which I didn't do as I couldn't afford to at the time. I do feel soo much better on my fixie and track bike and I am wondering if it's to do with the 165mm cranks on these bikes compared to the 172.5mm's on my roadie.
So to Jo and anyone else who has changed - what was the most noticable difference? Does climbing feel much different?
Changing crank lengths
I moved from the 175mm crank that came with my Bianchi to 170mm when I built my Ridley, and then changed the Bianchi to 170mm also. I felt good on the shorter cranks, at least I think I can spin better. I can't promise whether that's because I am deliberately choosing smaller gears or because of the shorter cranks.
My take on this is that although lacking objective proof of being "better", shorter cranks for shorter legs is logical, as well as standardising across one's steeds.
My take on this is that although lacking objective proof of being "better", shorter cranks for shorter legs is logical, as well as standardising across one's steeds.
My steel Cecil Walker has 175 mm on the left and 172.5 mm on the right.
When I had it built I had a big discrepancy in leg length, hence the asymetric crank length.
This has since been partially corrected.
The Scott has 175 mm both sides.
I don't notice any difference in the feel of the bikes, but maybe that says something about my pedalling style.
Paul
When I had it built I had a big discrepancy in leg length, hence the asymetric crank length.
This has since been partially corrected.
The Scott has 175 mm both sides.
I don't notice any difference in the feel of the bikes, but maybe that says something about my pedalling style.
Paul
There was a time when I used 175mm cranks on my race bike, 172.5mm cranks on my commuter bike, 170mm cranks on my training bike, and 165mm cranks on my track bike.
Now I use 170mm cranks on all my bikes, and all the other crank lengths feel wrong.
I can recommend investing in the correct length crank. The correct length crank allows the rider to raise the seat height, which results in much more efficient pedalling. The corollary allows you to deetermine the correct crank length: The correct crank is the longest crank you can tolerate where your hips don't rock on the saddle at maximum seat height (for most efficient pedalling).
175mm was way too long for me. 172.5mm is still too long, although I can make it work with the seat dropped a tad. There is no way Orphic should be riding with 175mm cranks. I would guess 165 would be close to optimal, but it's probably worth trying 160mm. You can get thingies that effectively shorten standard cranks which are much cheaper than buying new cranks.
On a separate note, having different crank lengths each side is not recommended, and will usually cause more problems than they solve. Much better to put chocks under the cleats on the short leg to acheive symmetry. That way the hips stay level on the saddle instead of rocking.
Now I use 170mm cranks on all my bikes, and all the other crank lengths feel wrong.
I can recommend investing in the correct length crank. The correct length crank allows the rider to raise the seat height, which results in much more efficient pedalling. The corollary allows you to deetermine the correct crank length: The correct crank is the longest crank you can tolerate where your hips don't rock on the saddle at maximum seat height (for most efficient pedalling).
175mm was way too long for me. 172.5mm is still too long, although I can make it work with the seat dropped a tad. There is no way Orphic should be riding with 175mm cranks. I would guess 165 would be close to optimal, but it's probably worth trying 160mm. You can get thingies that effectively shorten standard cranks which are much cheaper than buying new cranks.
On a separate note, having different crank lengths each side is not recommended, and will usually cause more problems than they solve. Much better to put chocks under the cleats on the short leg to acheive symmetry. That way the hips stay level on the saddle instead of rocking.
Have you read this article by Steve?
I was particularly impressed by his thoughts on relating crank length to femur length. This concurs with my own research and calculations, although I would ad one more thing...
Females tend to have longer femurs than males, and shorter lower legs. So even if a female has the same inseam as a male, the female will probably be able to tolerate a longer crank than a male with the same inseam, and may even benefit from a (relatively) longer crank length.
I was particularly impressed by his thoughts on relating crank length to femur length. This concurs with my own research and calculations, although I would ad one more thing...
Females tend to have longer femurs than males, and shorter lower legs. So even if a female has the same inseam as a male, the female will probably be able to tolerate a longer crank than a male with the same inseam, and may even benefit from a (relatively) longer crank length.
Last edited by Toff on 03 Jun 2010, 22:21, edited 1 time in total.
I've got 165s on my bike. They've always been that length so nothing much to compare it with. My new bike will have 165s too although there is a view that 160s might optimal (all other things being equal, which of course they are not).
Unfortunately there's no evidence out there that can fully substantiate this "correct length" claim. Sheldon denies it, no experimental data to support a proposed correlation b/n crank length and performance, and pro-peloton preference statistics can't substantiate it. They are all hypotheses through logic or others, not proof.I can recommend investing in the correct length crank. The correct length crank allows the rider to raise the seat height, which results in much more efficient pedalling. The corollary allows you to deetermine the correct crank length: The correct crank is the longest crank you can tolerate where your hips don't rock on the saddle at maximum seat height (for most efficient pedalling).
Whether one's hip rocks has nothing to do with the crank length. It has to do with the pedal to saddle distance. If the pedal is longer, then it's a matter of lowering the saddle by a corresponding amount. At the end of the day, the variance is quite small.
At the end of the day, one may be more comfortable in one or the other. Those formulae are not absolute but a consideration.
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mikesbytes
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I'm running 172.5 on the focus and 170 on everything else and my legs are longer than yours. Go 165.
BTW Hip rock, particularly in females can be for a number of reasons, of which seat height is one.
BTW Hip rock, particularly in females can be for a number of reasons, of which seat height is one.
Thanks for the input everyone. It's actually 170mm cranks on my roadie, but still too long I think. 5mm difference is a lot.
One point that Christian had is that longer cranks can provide greater leverage for climbing - which is my major weakness. One thing I have noticed is that climbing out of the saddle on my road bike is much more uncomfortable than on my fixie. Now part of this will be to do with the difference between riding fixed/free, but I thought that maybe part of it would be to do with the rotation of having to pedal a larger circle with longer cranks. I have nothing to base that on so I may just be making stuff up.
One point that Christian had is that longer cranks can provide greater leverage for climbing - which is my major weakness. One thing I have noticed is that climbing out of the saddle on my road bike is much more uncomfortable than on my fixie. Now part of this will be to do with the difference between riding fixed/free, but I thought that maybe part of it would be to do with the rotation of having to pedal a larger circle with longer cranks. I have nothing to base that on so I may just be making stuff up.
Greater leverage can be better controlled by selecting smaller gears and the crank length argument is only relevant if comparing single speeds with identical gearing.One point that Christian had is that longer cranks can provide greater leverage for climbing - which is my major weakness. One thing I have noticed is that climbing out of the saddle on my road bike is much more uncomfortable than on my fixie. Now part of this will be to do with the difference between riding fixed/free, but I thought that maybe part of it would be to do with the rotation of having to pedal a larger circle with longer cranks. I have nothing to base that on so I may just be making stuff up.
The Circumference (distance travelled by pedal arc) difference b/n 170mm and 165mm is 10.pi ie. Just over 3cm over 106.8cm circumference (approx 3%). A longer crank will also require a slightly greater range of hip and knee joint movements. Some people prefer or are used to one over the other, it's your choice.
As stated earlier, I don't argue against 165mm in this situation and standardisation across your steeds, but the reason is not one based on solid proof, but one of theory and logic and personal preference.
Apart from saddle-pedal distance and gross mis-fit of saddle, what other reasons are you aware of that's relevant in this context?BTW Hip rock, particularly in females can be for a number of reasons, of which seat height is one.
He's still fixated with those high heel clip-ons...
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shrubb face
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Pelvic instability can often be the cause hip rocking in cyclists. Any time you are putting power though the pedals it has to be counteracted further up the body, if your core / pelvic strength is the weak point then you will get hip rocking.Apart from saddle-pedal distance and gross mis-fit of saddle, what other reasons are you aware of that's relevant in this context?
Going back to the original discussion, I think 170mm cranks are certainly too long for you Vic. Probably best to start of with 165's and see how you go from there. You have to remember that cycling was (still is?) a very male dominated sport, the concept of putting 170mm+ cranks on a bike is something that has grown out of the male cycling tradition and certainly doesnt mean that they are the right lenght for girls.
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mikesbytes
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high heels increase the logical length of the foot, so if Vic was to use them she could stick to her current cranks. And what's wrong with a bit of style.
While it is true that longer cranks give greater leverage, that is largely compensated by using a lower gear, higher cadence. We get back to gain ratios.
In indoor spin sessions I see a lot of females and the occasional male utilise their hips and sometimes upper body to push the pedal down. In most cases it is due to putting all the power into the down stroke, ie not rotating the pedals. In some cases its due to the pelvis being rotated too far back. The hip rock isn't as noticeable on road bikes as the bike rocks left and right, which is the same effect.
While it is true that longer cranks give greater leverage, that is largely compensated by using a lower gear, higher cadence. We get back to gain ratios.
In indoor spin sessions I see a lot of females and the occasional male utilise their hips and sometimes upper body to push the pedal down. In most cases it is due to putting all the power into the down stroke, ie not rotating the pedals. In some cases its due to the pelvis being rotated too far back. The hip rock isn't as noticeable on road bikes as the bike rocks left and right, which is the same effect.
Quite so, Mike. I've always wondered why the size (length) of a person's foot is almost never discussed as a factor in this particular (long-time) debate.high heels increase the logical length of the foot, so if Vic was to use them she could stick to her current cranks.
Pelvic instability is a specific medical situation that relates to a fractured pelvis, one that's clearly not relevant here. Otherwise as used here, it appears to be a rather generic term that doesn't specify the root cause. Per description here, it sounds to be a case of poor saddle fit and/or over-extension of the leg (ie. Excessive saddle-pedal distance).Pelvic instability can often be the cause hip rocking in cyclists. Any time you are putting power though the pedals it has to be counteracted further up the body, if your core / pelvic strength is the weak point then you will get hip rocking.
Which debate? Saddle-pedal distance or crank length?Quite so, Mike. I've always wondered why the size (length) of a person's foot is almost never discussed as a factor in this particular (long-time) debate.
As a quick take I'd say,
1) It's a small portion of the overall leg length, hence is lost in the resolution.
2) A plantar flexed foot isn't in a good position for power, so the foot returns to its neutral position during the pedal cycle.
3) Good bike fit takes care of it as it assesses the overall rider's position and motion on the bike.
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mikesbytes
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This is one of my faults2) A plantar flexed foot isn't in a good position for power, so the foot returns to its neutral position during the pedal cycle
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shrubb face
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when we sit on a bike, pelvic stability on seat is all important. All important because your pelvis is the foundation of your position. Your legs reach down from and your torso extends out from your pelvis. Any asymmetries or instability of pelvis on seat flows out to the periphery a whole raft of potential problems. Pelvic instability on a bike is both the most common root cause problem and the toughest to solve on the bike. . . I thought I had seen everything. Have a look at this clip. This gent has the greatest amount of pelvic movement I've ever seen on a bike. He wasn't aware of it but doesn't feel any pain either. I'm amazed!
http://www.cyclefitcentre.com/video%20c ... 8.08_o.avi
Thats taken from one of steve hogs articles, of which there is many on the internet.
http://www.cyclefitcentre.com/video%20c ... 8.08_o.avi
Thats taken from one of steve hogs articles, of which there is many on the internet.
How? You still cycle through the range of ankle movements on either side of neutral position. Not as if you keep your foot plantar flexed throughout the full pedal circle.This is one of my faults
If you look closely, that's predominantly a rotational movement in a horizontal plane, one that's also complicated by the amount of soft tissue in the back side of this big guy. All the bony landmarks have been obscured and there's no telling what the bony pelvis is doing. Very different to the pelvic rock we are talking about here relating to saddle-pedal distance.when we sit on a bike, pelvic stability on seat is all important. All important because your pelvis is the foundation of your position. Your legs reach down from and your torso extends out from your pelvis. Any asymmetries or instability of pelvis on seat flows out to the periphery a whole raft of potential problems. Pelvic instability on a bike is both the most common root cause problem and the toughest to solve on the bike. . . I thought I had seen everything. Have a look at this clip. This gent has the greatest amount of pelvic movement I've ever seen on a bike. He wasn't aware of it but doesn't feel any pain either. I'm amazed!
http://www.cyclefitcentre.com/video%20c ... 8.08_o.avi
As much as Steve Hogg wrote about pelvic instability being a root cause, but to what? Root cause of what problem? Otherwise that's but an external observation and he hasn't explained the anatomical/physiological cause (the true root cause) of this observation. For all we know, a wider saddle may sort this big guy out. At the end of the day and given his suggestion that he can do something mechanical to fix it, then clearly "pelvic instability" isn't the true root cause, there's more to it.
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mikesbytes
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That's forward and backwards, I've never seen it that bad before. What causes forward and backwards?when we sit on a bike, pelvic stability on seat is all important. All important because your pelvis is the foundation of your position. Your legs reach down from and your torso extends out from your pelvis. Any asymmetries or instability of pelvis on seat flows out to the periphery a whole raft of potential problems. Pelvic instability on a bike is both the most common root cause problem and the toughest to solve on the bike. . . I thought I had seen everything. Have a look at this clip. This gent has the greatest amount of pelvic movement I've ever seen on a bike. He wasn't aware of it but doesn't feel any pain either. I'm amazed!
http://www.cyclefitcentre.com/video%20c ... 8.08_o.avi
Thats taken from one of steve hogs articles, of which there is many on the internet.
I'm thinking about hips going up and down.
I tend to do it at high cadence.How? You still cycle through the range of ankle movements on either side of neutral position. Not as if you keep your foot plantar flexed throughout the full pedal circle.
I think that's well within range but we should do a video shoot of your ankle movement and play it back in slow motion. It'll be interesting.I tend to do it at high cadence.
Big belly fat? Unrelaxed upper body? Poor style?That's forward and backwards, I've never seen it that bad before. What causes forward and backwards?
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mikesbytes
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BTW Alex, you should of put a NSFW tag on that video
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shrubb face
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id argue that NSFW tags arent required on that link. If your looking at a forum at work, you already doing something wrong, so opening a video such as that isnt going to make it any worse.
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mikesbytes
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Mate that was gross, I'm nearly threw up my lunch.
I've got a set of 90mm cranks if you want to try those.
James
James
LOL! From your childhood?I've got a set of 90mm cranks if you want to try those.
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