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Discussion Starter · #1 ·
Seeing that the crank arm length thread is closed, probably for the irrational trolling and flaming, I wanted to post some practical experience I have with crank length. Hopefully this does not open a can of worms...

I have both 170 and 165 cranks and my PRACTICAL and PERSONAL experience has been the following:

- I do feel the difference, even if they blindfolded me.

- The shorter cranks do spin more easily, but as such put more stress on the cardiovascular system.

- The shorter crank length might force you to shift down on climbs or against headwind, whereas, with the longer cranks, you maybe could have mashed the bigger gear just long enough to get over the top of the hill or untill the next corner to get out of the wind.

- The longer crank length allows you at times to use a slightly higher gear, but has implications on your RPM's.

- The longer cranks keep your cardiovascular system steady, but might put more strain on your muscles.

- The human body has a very high degree of adaptability. I ride the different crank lengths every week and after a couple of kilometers, you quite get the hang of it.

WHICH IS FASTER?

- It isn't possible to give a rational explanation to this as I believe weather plays a much bigger role on the speeds I develop on my training circuit than crank length. I would probably prefer the shorter cranks on a windy day and the longer cranks for climbing.

- I personally think that there is probably a sweetspot between the pros and cons of every crank length in the range of 170-175 for most riders, hence industry standards tend to offer most availability of cranks in those lengths.

- I believe that much of this is related to RPM's and that again, there might be a zone of healthy RPM's for most people comprised between 70 and 90, i.e. not taking into account extreme situations such as sprints or climbs. I do think that lately "spinning" quickly has probably been overrated by some. There are disadvantages to this as well: it wears down the body, and unless one has a super (or doped) engine, it might not be the most efficient way to ride. Mashing big gears then again may cause injuries or leg cramps.

- It seems having a constant style of pedaling, gently turning circles is more important than the RPM's one develops.

ABOUT SADDLE HEIGHT.

- Again, I know from experience that a difference of 5mm can be felt and even lead to injuries in certain cases.
 

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Agree with much of your post, matchmaker. As to the causes of injuries, it's impossible to be too specific because most change is exponential and effects a host of other variables. But I can only conclude that those who say that they can't notice even 5mm differences couldn't ride that much, as everyone I've ever raced or trained with was hyper-sensitive to even the tiniest of changes.
 

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I'm 5'6" with a 30" inseam, and I rode 175mm cranks from '98 until a year ago. I never tried anything else because I didn't really think there was a need to. Anyway, a year ago, I ended up with a SS road bike with 165mm cranks, and I've progressively gone up to larger chainrings as my legs have gotten stronger (currently push 82GI up even huge hills). I used to occasionally get knee pain in my right knee on rides over 35-40mi, and now with the shorter cranks, I can finish up any length ride and, though my legs are tired, I still feel fresh overall, and never have any pain during the ride.

Last week, I hopped on my MTB and did a 111mi ride, seated the entire time, pushing my 175mm cranks. My knees hurt a little, and I generally felt like I was doing more work to get through the larger arc required by the longer cranks. Obviously, you can get better leverage with longer arms, but I wonder if it's worth the effort considering how much more travel is required.
 

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Discussion Starter · #4 ·
For SS, I would think that 165mm has its advantage, because your leg pace changes continually. On a road bike, gears can make up for changes in resistance.

Anyway, I just hope people are less biased against different crank lengths. I think it is mainly a personal thing. I ended up trying the shorter ones because of a knee injury and I have no regrets. I do enjoy riding the normal length cranks also now my knee is back to normal.

IMO, people should go with what works for them and staying injury-free is probably the most important thing in any sport. You don't improve much by sitting at home with ice packs. For certain people shorter cranks can certainly alleviate knee problems and once they get used to it, they won't even notice the change anymore.

One can only lament the limited availability of different crank length, especially from a certain prestigious brand. Whereas it might be true that 170-175 caters to most, there are also many shorter people (many women are getting into road biking) and taller people that could respectively be served by 165 and 180 cranks.
 

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Interesting article about Hinault

matchmaker said:
For SS, I would think that 165mm has its advantage, because your leg pace changes continually. On a road bike, gears can make up for changes in resistance.

Anyway, I just hope people are less biased against different crank lengths. I think it is mainly a personal thing. I ended up trying the shorter ones because of a knee injury and I have no regrets. I do enjoy riding the normal length cranks also now my knee is back to normal.

IMO, people should go with what works for them and staying injury-free is probably the most important thing in any sport. You don't improve much by sitting at home with ice packs. For certain people shorter cranks can certainly alleviate knee problems and once they get used to it, they won't even notice the change anymore.

One can only lament the limited availability of different crank length, especially from a certain prestigious brand. Whereas it might be true that 170-175 caters to most, there are also many shorter people (many women are getting into road biking) and taller people that could respectively be served by 165 and 180 cranks.
http://le-grimpeur.net/blog/archives/18

The intention was to get the 1.73-cm tall Hinault sitting further back but also higher. As such, his saddle height was raised from 72.8 cm to 73.5 cm, but gradually over a 3-year period from 1979 to 1982 to as not to place too much strain on him, particularly his knees (Greg LeMond also endorsed this higher riding position).

Unfortunately, during one stage of the 1983 Vuelta, his saddle was accidentally set at 74 cm, and this exacerbated the strain on his right knee, which had been causing him trouble since 1980 and he had dropped out of that year’s Tour because of it. In the summer of 1983 it was operated on, causing him to miss the Tour for that year.
The new riding position was partially to allow Hinault to climb better in the saddle. He had a reputation for pushing large gears while climbing, often out of the saddle for long stretches, which was attributed by some as the cause of his knee problem.
This was a sensitive issue for Hinault and he maintained that he always had a smooth cadence, but that he would “choose his gears according to the pedalling cadence that suits me – above this cadence I get out of breath too quickly; below it, my muscles are too contracted”. For him, that optimal cadence was between 70 and 90 rpm, a fairly generous range.


I see this thread got started after the other closed. My POV is that a lot of this stuff is very subjective and I'm of the opinion that going from a 172.5 to 175 crank is not all that much of a difference. Blindfolded I don't know whether I could detect a difference.

I'm 175 cm tall and have an 85 cm inseam which would necessitates a 75 cm saddle height according to the LeMond .883 x inseam formula. I like my saddle lower though so I can ankle a decent amount. I wear a 45 or 46 shoe and have strong lower legs.

I prefer a saddle height of around 73.5 to 74. I could ride 75 but the saddle feels like it's weighted too much and down around 73 I feel my knees are too flexed but I think I could ride the lower height rather than the higher one if I was forced to choose the extremes.

Could I tell the difference in a blindfolded test, between saddles .5cm difference? If I had a direct comparison, yes, most likely, but if I just got on a bike with an unknown .5 cm increase/decrease, I might sense something was slightly off.

It's interesting in the article that Hinault went from a 54.5cm top tube to a 56.5 cm tt. The article doesn't mention the STA but the 55cm Seat tube KG381 I'm riding has an approx 56.5tt. That would be considered a big bike nowadays.

By contrast Contador is riding a 52 Specialized with 53.7 cm tt.
Critical measurements

Rider's height: 1.77m (5' 10")
Rider's weight: 62kg (137lb)
Saddle height, from BB (c-t): 748mm
Seat tube length, c-t: 490mm
Head tube length: 120mm
Top tube length: 537mm
Total bicycle weight: 6.80kg (14.99lb)
 

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First off, I'd like to thank Blackjack (non-sarcastically, to be clear) for researching around instead of merely going, "Nuh uh, not in my opinion." This is valuable, and I intend to be reasonable/nice, assuming that others are.

For further background on the incident mentioned, here is a passage from the presumable original source, Hinault's own book, Road Racing Techniques & Training:

The year of 1983 was marked by a knee operation, after a mistake in setting [Hinault's] saddle during the Tour of Spain. This mistake– which was the final provocation, if not the actual cause– forced Hinault to pedal on a saddle raised to 74cm for the whole long mountain stage in which he assured his final victory.

A sudden increase of 5mm– especially in such a difficult stage– couldn't help but damage the tendons of a rider whose position was being adjusted so precisely and gradually. If the saddle had been lowered instead of raised it wouldn't have done the same thing. A saddle that's too low reduces efficiency, but doesn't cause this kind of injury.

From the book, we can see that Hinault's saddle being set 5mm too high did indeed cause him problems, though to be fair to BJ, Hinault had not been completely kind to his knees previously. Still, many riders could be accused of same.

It is also noted in his book that Hinault did, in fact, learn to start pushing smaller gears partway through his career. When exactly he started doing this is not stated:


In the mountains, I now use smaller gears than when I was a young pro. Where I used to ride a 22-tooth cog, standing on the pedals when needed, I now use a 24 and stay in the saddle much longer. I sit further back and pedal much more smoothly.


Far as my own experiences with crank length(s) go, I've ridden 170, 172.5, and 175 extensively, and prefer 172.5s.

I especially A-B'd 172.5 and 175 cranks a lot fairly early on in my cycling, and could definitely tell the difference... my pedaling was smoother and felt better on the 172.5s. Which was surprising/disappointing to me, as I kinda liked the idea of having 175s as my crank size ('more is always better', and all that). The 175s felt 'torquey-er', but just weren't smooth enough. But at an 82cm inseam (178cm tall), I suppose that was pushing it a bit. I do have very long thighs, though.

I like a saddle height of around 72.3 mm, and find that, when playing around with my setup, I notice if I don't have that saddle height dialed in precisely or extremely close.

Far as my personal riding style goes, I think I prefer lower rpms on the flats than most, but higher rpms than most on climbs. I don't understand the guys who try to maintain 100+ on the flats, but then want to grind it out at 60 uphill. To me, the two types of effort aren't so radically dissimilar.

I worry about things like knee and ligament injuries, but, knock on wood, none experienced so far.

// I agree with the OP that it would be nice if more cranks were available in 165mm and 180mm lengths, to fit the short and tall. There's a few, but the majority of cranks don't offer this.
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SystemShock said:
First off, I'd like to thank Blackjack (non-sarcastically, to be clear) for researching around instead of merely going, "Nuh uh, not in my opinion." This is valuable, and I intend to be reasonable/nice, assuming that others are.

For further background on the incident mentioned, here is a passage from the presumable original source, Hinault's own book, Road Racing Techniques & Training:

The year of 1983 was marked by a knee operation, after a mistake in setting [Hinault's] saddle during the Tour of Spain. This mistake– which was the final provocation, if not the actual cause– forced Hinault to pedal on a saddle raised to 74cm for the whole long mountain stage in which he assured his final victory.

A sudden increase of 5mm– especially in such a difficult stage– couldn't help but damage the tendons of a rider whose position was being adjusted so precisely and gradually. If the saddle had been lowered instead of raised it wouldn't have done the same thing. A saddle that's too low reduces efficiency, but doesn't cause this kind of injury.

From the book, we can see that Hinault's saddle being set 5mm too high did indeed cause him problems, though to be fair to BJ, Hinault had not been completely kind to his knees previously. Still, many riders could be accused of same.

It is also noted in his book that Hinault did, in fact, learn to start pushing smaller gears partway through his career. When exactly he started doing this is not stated:


In the mountains, I now use smaller gears than when I was a young pro. Where I used to ride a 22-tooth cog, standing on the pedals when needed, I now use a 24 and stay in the saddle much longer. I sit further back and pedal much more smoothly.


Far as my own experiences with crank length(s) go, I've ridden 170, 172.5, and 175 extensively, and prefer 172.5s.

I especially A-B'd 172.5 and 175 cranks a lot fairly early on in my cycling, and could definitely tell the difference... my pedaling was smoother and felt better on the 172.5s. Which was surprising/disappointing to me, as I kinda liked the idea of having 175s as my crank size ('more is always better', and all that). The 175s felt 'torquey-er', but just weren't smooth enough. But at an 82cm inseam (178cm tall), I suppose that was pushing it a bit. I do have very long thighs, though.

I like a saddle height of around 72.3 mm, and I find that I notice if, when playing around with my setup, I don't have that saddle height dialed in precisely or extremely close.

I worry about things like knee and ligament injuries, but, knock on wood, none experienced so far.

// I agree with the OP that it would be nice if more cranks were available in 165mm and 180mm lengths, to fit the short and tall. There's a few, but the majority of cranks don't offer this.
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Fair enough, the rag fest, back and forth starts getting old anyway.

Someone mentioned that anyone who rides a lot would be able to detect small differences or that they would matter to such a person. I ride about 10k miles per year though, so that's a decent amount of time on the bike and it makes very little difference to me whether I'm running a 172.5 or 175 crank..

The only injury I'm worried about on the bike is my back, which I injured through overuse on the job. What helped make it worse on the bike was getting cut off by a car when I was going 25mph.

A lot of these adjustments are personal preference. For example, moving the cleats back more towards the heel from the ball of the foot. I think even LeMond did this for more power. I myself would never dream of moving the cleats back but then I've never had fatigue in the gastrocnemius or the soleus on a bike. To be able to ankle the pedals like a Boonen provides a lot of my power, which is one of the reasons I like a lower saddle than that which others might feel is more efficient.

One of the things a lot of people don't consider with cranks is the size of their feet. I wear an 11.5 to 12 US at 5'9" which is pretty big. If the cleats are in the same position relative to the ball of your foot, all else being equal, and your foot is a size 8 or 9, that cm or so will alter your pedal stroke somewhat..
 

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blackjack said:
Fair enough, the rag fest, back and forth starts getting old anyway.
Agreed. And I actually don't like being mean.

I ride about 10k miles per year though, so that's a decent amount of time on the bike and it makes very little difference to me whether I'm running a 172.5 or 175 crank.
It's possible that your 'perfect' crank size is about halfway between those two sizes.

Even someone from the 'I notice' camp, such as myself, would not expect you to feel anything odd from cranks that are only 1.25mm off your ideal.

What might be more interesting is how 170s or 177.5s feel to you.

One of the things a lot of people don't consider with cranks is the size of their feet. I wear an 11.5 to 12 US at 5'9" which is pretty big. If the cleats are in the same position relative to the ball of your foot, all else being equal, and your foot is a size 8 or 9, that cm or so will alter your pedal stroke somewhat.
This is quite true, most ppl don't take into account the effects of having small or large feet, relative to your overall body size.

Come to think of it, I'm sure a professional fitter could tell us some very interesting things, if he/she were so inclined to jump into the thread, but of course they have absolutely no financial incentive to give away any of their fitting procedures/'trade secrets'.
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Discussion Starter · #9 ·
blackjack said:
http://le-grimpeur.net/blog/archives/18

The intention was to get the 1.73-cm tall Hinault sitting further back but also higher. As such, his saddle height was raised from 72.8 cm to 73.5 cm, but gradually over a 3-year period from 1979 to 1982 to as not to place too much strain on him, particularly his knees (Greg LeMond also endorsed this higher riding position).

Unfortunately, during one stage of the 1983 Vuelta, his saddle was accidentally set at 74 cm, and this exacerbated the strain on his right knee, which had been causing him trouble since 1980 and he had dropped out of that year’s Tour because of it. In the summer of 1983 it was operated on, causing him to miss the Tour for that year.
The new riding position was partially to allow Hinault to climb better in the saddle. He had a reputation for pushing large gears while climbing, often out of the saddle for long stretches, which was attributed by some as the cause of his knee problem.
This was a sensitive issue for Hinault and he maintained that he always had a smooth cadence, but that he would “choose his gears according to the pedalling cadence that suits me – above this cadence I get out of breath too quickly; below it, my muscles are too contracted”. For him, that optimal cadence was between 70 and 90 rpm, a fairly generous range.


I see this thread got started after the other closed. My POV is that a lot of this stuff is very subjective and I'm of the opinion that going from a 172.5 to 175 crank is not all that much of a difference. Blindfolded I don't know whether I could detect a difference.

I'm 175 cm tall and have an 85 cm inseam which would necessitates a 75 cm saddle height according to the LeMond .883 x inseam formula. I like my saddle lower though so I can ankle a decent amount. I wear a 45 or 46 shoe and have strong lower legs.

I prefer a saddle height of around 73.5 to 74. I could ride 75 but the saddle feels like it's weighted too much and down around 73 I feel my knees are too flexed but I think I could ride the lower height rather than the higher one if I was forced to choose the extremes.

Could I tell the difference in a blindfolded test, between saddles .5cm difference? If I had a direct comparison, yes, most likely, but if I just got on a bike with an unknown .5 cm increase/decrease, I might sense something was slightly off.

It's interesting in the article that Hinault went from a 54.5cm top tube to a 56.5 cm tt. The article doesn't mention the STA but the 55cm Seat tube KG381 I'm riding has an approx 56.5tt. That would be considered a big bike nowadays.

By contrast Contador is riding a 52 Specialized with 53.7 cm tt.
Critical measurements

Rider's height: 1.77m (5' 10")
Rider's weight: 62kg (137lb)
Saddle height, from BB (c-t): 748mm
Seat tube length, c-t: 490mm
Head tube length: 120mm
Top tube length: 537mm
Total bicycle weight: 6.80kg (14.99lb)
Blackjack, thanks for the link. About not noticing crank length differences, I tend to agree with you that anyone would be hard pressed to notice a 2.5mm difference. But I can share the following story about noticing 5mm changes. There is a static bike at the gym nearby my work, where I sometimes do some intervals. BTW, that machine has a mean program called random, a mode where it will throw any junk at you when you least expect it. But anyway, I noticed that my RPM's on that machine where higher and to still my curiosity, I wrote a mail to the manufacturer of the machine. Guess what, the cranks were 165mm and at that time I had only one road bike with 170mm cranks. So I guess in a way, that is a blindfolded test, as I really did not know how long the cranks were. In all honesty, it took my a couple of months before beginning to wonder. I also got into problems when trying to emulate the high RPM's on the static bike on my road bike that had longer cranks. That, coupled with a questionable cleat mount and other sports I practice at the same time got me a knee tendonitis that kept me away from cycling for more than a month.

Now I have two bikes, one with 165's and the other with the 170 cranks I already had before the injury and I ride them both, but the riding style is different. IME it is not a good idea to try to spin to hard on the longer cranks. Spinning smoothly at reasonable RPMs, yes, but overdoing it, no.

As to saddle height, with the new cranks and also with the new saddle I bought I had to determine my saddle height again. So I went for a ride, armed with wrenches and hexagonal keys to fiddle around until I hit my sweetspot and at one point I wanted to go a little higher, so I moved the saddle by what could not have been more than 5mm and as soon as I got on it I could feel that it was too high and lowered it immediately.

I also remember a ride about a year ago that I had set my saddle too high and I really had to get off the bike 10k before the finish. That is when I decided higher isn't always better.

Recently, I did the bikefit calculation at competitivecyclist.com and I get a saddle height from them around between 77 and 80cm, but I think my saddles are around 75-76, depending on the bike (different geometries and cranks). I don't even know exactly how high my saddle is set, I do know that it is the best for me, as when I set saddle height, I try different positions and pick the best one for me.

The more I think about it, the more I am convinced that there is no such a thing as a universal bike fit, or an ideal top tube length or crank length. I think it really depends on the individual's body and preferences. I changed my stem from 110mm to 100mm on one of my bikes and I can swear it feels a lot better to me. The other bike has a longer top tube, so I put a slightly shorter stem on it (90mm) but for some reason I feel I wouldn't be bothered by an extra 10mm on that bike, probably a lot has to do with geometry.

I indeed think that small details such as stem length, and cleat position, can make a big change in the end, but that depends on riding style and prefererences, as well as on physical constitution. What you say about feet length is absolutely true, a longer foot might have another way of pedaling than a shorter one and therefore cleat position and even crank preferences might be different from a shorter foot.
 
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