170mm cranks for 5ft 10.5inch rider?

Discuss light weight issues concerning road bikes & parts.
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by Shrike

Also have a 31inch inseam. Industry standard seems to be 172.5mm, but would like to try 170mm.


Seems most recommendations are a bit shorter than industry standard.

Also apologies for question spam recently :P

by Weenie

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by LloydP

I'm very close to your proportions and use 170mm cranks. It works fine for me. Try it and see!

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by AJS914

I'm 6 ft tall and love 170s with a low enough gear that I can spin up hills.

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by Shrike

Nice, that's reassuring thanks guys!

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by joec

170 used to be basically the standard for road bikes, dunno why its changed.

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by RyanH

I have a 32" inseam and have used 175 and 165 back to back for a good portion of last year and never noticed a difference. I use 165 primarily now because it gets me a high saddle position, so more drop and theoretically allows me to get lower without running into issues with cutting off breathing or knee hitting the chest.
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by Geoff

It is all personal preference. I ride 172.5s road, but have tried 175s and 170s. Going longer was weird, while going shorter was just horrible. Try them and see!

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by jmagoulas

Always had 172.5 at 5'9. May try 175 on the winter build up.

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by Shrike

I had 175's on all summer, really liked it when getting in the most aero position on the hoods and sitting on the nose of the saddle. Also felt nice climbing out of the saddle.

Never really felt right most of the time though. Odd that I'd even notice it.. was sort of glad to sell it on.

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by GambadiLegno

I've had a Fuji SL1 RC with 175mm cranks, at the same time a Trek 8500 MTB with 172,5mm cranks, and at the same time a cyclocross Scott with 170mm cranks....So I guess there's no problem.

Now I only have my BH G6 with 172,5mm hehe.

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by AJS914

The fact is that the difference between 170mm and 172.5mm is very small. If you already have 172.5 cranks, I wouldn't even bother upgrading.

One thing I like about going from 175s to 170s was the decreased hip angle. I raised the saddle and left the bars where they were so I was more aero and there was more room between my tummy and thighs.

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by topflightpro

I'm about your height, and I have pretty long legs for my height. I run 172.5 on most of my bikes, but have 167.5 on the track bike. I don't notice the difference at all. In fact, I'd kind of like to go to 170s on the road bikes to decrease hip angle, but I just haven't done it yet.

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by stormur

Is thickness of all road shoes equal ? Or can vary even 3-4mm ? insole thickness ? Sock ? Pedal stack ? Inseam vs height ?

Being 182/85 inseam ( saddle height 75.5 from BB c ) I rode 170, 172,5 and 175 . Going directly from 170 to 175 and backwards ( same bike, shoes & pedals ) I felt some difference, but got use to it very fast. Cadence will drop a bit on longer crank (2-3rpm on 5mm difference ), that's it.

BTW didn't Wiggins change crank length from 177 to 170 recently ? / being 190-ish /
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by plag


Most people will never notice unless your going from one extreme to another .

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by 11.4

There's a huge thread on this forum about crank arm lengths. And some very good discussion of issues in it. You might take a look at that. It covers the whole topic pretty exhaustively.

by Weenie

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