Riding different length cranks

[professerr]

I've always used 170 cranks, but mistakenly bid and won on ebay a set of 172.5s that I purchased for a second road bike I'm building up for riding on crappy dirt/fire roads.

Bad idea to have two road bikes with different length cranks? Do you feel the difference, and if so would my brain adjust when switching back and forth day to day?

[Ken Robb]

I can feel 5mm but not 2.5mm difference. My pal can feel a 2.5mm difference. I switch between 170 and 175 with no problem as long as each bike is set up correctly for me. I had a bike with 180mm and it made my knees ache slightly.

[ultraman6970]

Lower the saddle 2.5 mms and problem fixed.

Personally i was able to feel the difference but at some point the slight pain in one of my knees (the shorter leg) stopped. I have 170 in one bike and 172.5 in the other one.

[mike s]

guess it should matter if you are trying to mirror each bike setup

[rustychisel]

same experience as others. I can feel the difference but it becomes irrelevant after 3 ~ 4km riding if the bikes set up correctly. By which I mean saddle to pedal measurements and saddle setback (to which I'm susceptible).

In an average week I'll ride a fixed gear 167mm cranks, road bike 172.5mm, fixed gear 170mm and road bike 170mm

[cuda2k]

3 bikes with 172.5, 2 with 170, I find that I spin a little easier on the 170's, but accelerate faster on the 172.5's... or it's all in my head. Either way, never had a problem with any pain or anything once I got each bike's fit dialed in.

[witcombusa]

You can have shoes with more than a 2.5mm sole difference.

Just ride it

[Chance]

Bad idea to have two road bikes with different length cranks? Do you feel the difference, and if so would my brain adjust when switching back and forth day to day?

No, maybe, and yes. Although it's not just the brain adjusting to the longer cranks. However, even if it made a difference why is that necessarily a bad thing?

If a runner trains on both dirt and concrete paths it’s almost certain he/she will notice the difference but the variety itself is not a bad thing, right? It seems silly to suggest the exercise activity has to be duplicated precisely in order for it to be correct, or do more good, or prevent injury, and so on. In my opinion having some variety in crank length can be a good thing.

[echelon_john]

it's unlikely you would ever notice 2.5mm in a blind test.

it's virtually the difference between a thick chamois with tights over your shorts and a think chamois in a pair of shorts alone.

[Gummee]

it's unlikely you would ever notice 2.5mm in a blind test.

it's virtually the difference between a thick chamois with tights over your shorts and a think chamois in a pair of shorts alone.

I'll disagree with that. I can feel the difference between thick socks and thin socks on a day-to-day basis. Things just fit differently.

AFA the OP: It depends. If you're 'one of those guys' like me then yeah, you'll feel it. Otherwise? I've had lots of buddies that switch back and forth and couldn't tell one way or another.

...and yeah, after a little bit of riding, the feeling goes away. Its those first few pedal strokes that get ya.

M

[sjbraun]

Try it, if you are plagued to suffer like the princess and the pea (like the poster who can feel the difference in his socks,) then I guess it won't work.
My rather insensitive arse moves between bikes with cracks that vary from 170 (on the fixie,) to 175 (the tandem and mtb,) with three 172.5 cranks in between.

I never notice a difference as I switch between bikes and I may ride four different bikes in the course of a week.

Steve

[Chance]

I'll disagree with that. I can feel the difference between thick socks and thin socks on a day-to-day basis. Things just fit differently.


My guess is that you don’t feel the difference in sock thicknesses as they influence crank length or reach to pedals, right?

With shoes that are tight on my feet the difference between thin and thick socks is also very noticeable. But if we look at it as a fixed gap between foot and shoe for ideal comfort, then the difference between thin and thick socks may be 100 percent or more in filling that gap. And that should be very noticeable to anyone. It’d be like comparing 100 mm to 200 mm cranks. Granted shoes are someone adjustable but you get my point.

The difference between 170 and 172.5 mm is more like the same socks after going through the wash a few times. Yeah, they’d get a tiny bit thinner but would it be that different? Not to me.

My bikes range from 170 to 175 and the difference is noticeable at the extremes, although the variety feels good. Not only that but repetitive motion in a very defined range of motion seems like a really bad idea to me. Many here preach it and for me it’s something to avoid.

[Gummee]

Try it, if you are plagued to suffer like the princess and the pea (like the poster who can feel the difference in his socks,) then I guess it won't work.
My rather insensitive arse moves between bikes with cracks that vary from 170 (on the fixie,) to 175 (the tandem and mtb,) with three 172.5 cranks in between.

I never notice a difference as I switch between bikes and I may ride four different bikes in the course of a week.

SteveI freely admit I'm anal-retentive about my saddle height. S'why I try and stick to the same things: socks, shoes, shorts, etc. for everything. Also why I posted a WTB for some Bont shoes in the classifieds.

When I don't ride every day, it gets to be less of an issue. Its still an issue, but less of one.

M

[professerr]

No, maybe, and yes. Although it's not just the brain adjusting to the longer cranks. However, even if it made a difference why is that necessarily a bad thing?

If a runner trains on both dirt and concrete paths it’s almost certain he/she will notice the difference but the variety itself is not a bad thing, right? It seems silly to suggest the exercise activity has to be duplicated precisely in order for it to be correct, or do more good, or prevent injury, and so on. In my opinion having some variety in crank length can be a good thing.

Interesting perspective, thanks. I seem to break fairly easily, and try to avoid repetitive motions in other sports and activities. Cycling is one of the few sports I've done for without some sort of overuse injury, but I do like your idea of mixing it up slightly to stay healthy.

Thanks all for your thoughts.

[Not the Slowest]

I had a few of my road bikes fitted by a local guy here in NYC. Over time I started to buy some older bikes that I used as my commuter/rainy day bikes which for me can mean 5000 miles on them a year. In anycase I always knew I was using a 175 crank on my "road" bikes but until I parted out one of my commuter bikes I was unaware that it was a 170mm crank.

My current commuter has a Biopace crankset and you may feel that for the first few yards but after that, just feels natural.

Of course this is only a judge of feel vs Suggested Correct length.

[martinrjensen]

I have 3 bikes with 172.5, one bike with 175. Really can't tell the difference. Ever.