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are my cranks too long? does it really make a difference?

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are my cranks too long? does it really make a difference?

Old 07-15-09, 01:30 PM
  #1  
bluenote157
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are my cranks too long? does it really make a difference?

I just picked up some 175mm cranks. I'm 5-7 with 30in inseam. Before I mount them, I figure I would ask. Will I find it difficult to spin?
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Old 07-15-09, 01:43 PM
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Depends on what gears you are using. Crank length provides subtle adjustments to wattage produced , needs equipment to be measured. Average rider would probably never know the difference
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Old 07-15-09, 01:45 PM
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too long IMO
but you'll never know if it fits your riding style until you try it.

at 5'7 and 30in inseam, you should stick to 165~170mm
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Old 07-15-09, 03:28 PM
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I'm 5'8" and i had 175mm cranks on my last bike. Now I have a bike that actually fits and it has 170s. I'm much happier.

anecdotal evidencs YMMV
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Old 07-15-09, 03:32 PM
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cool..thanks.. guess this is going on ebay.
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Old 07-15-09, 03:34 PM
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Originally Posted by bluenote157 View Post
I just picked up some 175mm cranks. I'm 5-7 with 30in inseam. Before I mount them, I figure I would ask. Will I find it difficult to spin?
I'm about the same size and I ride/like 172.5's.
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Old 07-15-09, 03:56 PM
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I'm 5'10 with a 34.75 inch inseam, and I ride 172.5's.

You get used to whatever you have after a while as long as the fit isn't really off.
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Old 07-15-09, 04:30 PM
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i use 160s!
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Old 07-15-09, 04:33 PM
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uh huh huh...huh...huh huh
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Old 07-15-09, 10:14 PM
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Yeah, too long.

170s at the most

I'm 6ft, with a 35.25" inseam; I've have tried every length from 170 to 180 (I even persisted with the 180s for about a year, and I had 165s on a track bike a long time ago), and my favourite length is 172.5

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Old 07-15-09, 11:10 PM
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i'm 5'7", with a 29.3" inseam, and i use 170mm.
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Old 07-16-09, 01:36 AM
  #12  
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On the flip side, too short is definitely noticeable to me. I've test-ridden bikes with 170 and 172.5 cranks which was a change from my usual 175mm cranks. It was exhausting to pedal.. I would spin at a higher rate than I'm used to and then, to compensate, upshift by a cog or two bigger than I was used to. Both felt "wrong"; I couldn't get into that sweet spot that I easily fall into with 175mm cranks.

Proper-sized cranks, FTW.
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Old 07-16-09, 04:56 AM
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One of my two-bit theories is that smaller guys aren't as strong on flat roads, not because they're 'less powerful', which is the common wisdom, but coz they use cranks which are too long. I dunno how anyone under ~5ft5" can use 170s. Yeah yeah, plenty of short guys will say they use 170s with no problems, but have they ever persisted with shorter cranks?

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Old 07-16-09, 05:26 AM
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Heh. Hi Aussie531, my counterpart.

I'm 5'7", 30" inseam (less actually, but that's my jean size), 175s. As I've gotten slower I've gone to longer cranks. 167.5s, 170s, 175s. I went back to 170s last year, failed miserably, returned to 175s. I'm actually at the point where I can count points on my license.

I am also realizing that body style has a lot to do with it. I have a good jump, nothing else. I weigh 180, +/-. I tend to ride seated (which I've observed since Aussie531 pointed something out).

Therefore my riding consists of the following:
- sit on wheel
- gap opens
- 1 or 2 powerful downstrokes to close slight gap ("slight" = 2-3-12 inches)
- relax
- repeat

I'm comfortable now at 100-110 rpms. I ran slightly higher on 167.5s and 170s. When I first got on the 175s, I was slower, like 80s.

Search for me and 175. There's way too much for me to repeat it all, but the above thing on my riding is new. Also my blog (sprinterdellacasa) I expound on long cranks here and there, without yet thinking that my riding style makes me good for long cranks.

cdr
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Old 07-16-09, 05:45 AM
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You get more torque and spin slower, all else equal. Probably a plus for sprinters - you can only spin so fast out of saddle.
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Old 07-16-09, 05:50 AM
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I'm 5'6" and have one bike that has 170 cranks and two bikes that have 172.5 cranks. The difference that I notice... absolutely nothing. Scientific explanations aside, it makes no difference to me comfort wise.
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Old 07-16-09, 06:44 AM
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Originally Posted by bluenote157 View Post
I just picked up some 175mm cranks. I'm 5-7 with 30in inseam. Before I mount them, I figure I would ask. Will I find it difficult to spin?
OK, I'll put in my two bobs worth and we will have ALL the usual suspects responding to such threads.

Based on an actual inseam of 30" I wouldn't be recommending that you use cranks any longer than 165mm and even that would be a tiny bit long in my book.

The problem with long cranks is that they make your knee's rise quite high at the top of the stroke which then makes it VERY difficult to adopt an aerodynamic position. This is one of the MAJOR advantages big guys have on bikes. For all their size its EASY for them to bend into an aero position because their knee's aren't rising into their chests. I also find that long cranks mean that your legs are rubbing MORE against the saddle than if using shorter cranks and on long rides this adds up.

To me 175mm cranks are far too long for a 30" inseam.

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Old 07-16-09, 07:39 AM
  #18  
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Originally Posted by z415 View Post
You get more torque and spin slower, all else equal. Probably a plus for sprinters - you can only spin so fast out of saddle.
Incorrect, good sprinters turn a very high RPM. Also sprinting is about the quick acceleration, which is much easier with a high cadence.


Good track sprinters spin 140 rpms with no problem.
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Old 07-16-09, 08:37 AM
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Take a ruler and mark 170, 172.5 and 175 mm on a piece of paper.

I have no idea why they even bother to make different sizes when they are only 2.5mm apart (a pencil width is about 7mm). You won't notice any difference.
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Old 07-16-09, 08:46 AM
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I have some 175s on a backup bike and Im 5'7''. When I pedal a high cadence they give me an awkward bouncing sensation since my hips can *just* barely rotate the full length.
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Old 07-16-09, 12:23 PM
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Originally Posted by merlinextraligh View Post
Incorrect, good sprinters turn a very high RPM. Also sprinting is about the quick acceleration, which is much easier with a high cadence.

Good track sprinters spin 140 rpms with no problem.
But he was talking about out-of-saddle sprinting. Are you saying that guys sprint at 140rpm out of saddle?
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Old 07-16-09, 12:24 PM
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yes.


Just an example. Mark Cavendish is 5'9" he uses 170mm cranks. He seems to turn a fairly decent cadence.

http://autobus.cyclingnews.com/tech/...lumbia_scott09
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Old 07-16-09, 08:14 PM
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well...on mountain bikes 175s are used more often because they help you power up technical climbs and crap...so that being said I guess if your not much of a spinner and rely on more of a strong pedal stroke 175 might be fine.
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