170mm crank arms, will I die??

Hi,
Firstly, happy Friday everyone!!
What length crank arms do you guys run?…I’ve always used 175 for no other reason than that’s what came on a bike when I first got into this stuff and I’ve always stuck with it, any opinions out there?

Cheers, Paul

How tall are you? 170mm probably a good thing under about 5’8/9 and a not brilliant idea above that

Yes, you’ll die. However, death is very unlikely to be connected to crank length. I’m just making the switch to 170 after riding 175 since forever. I think I’m just on the cusp. Will 175 might do me some damage long term, I can’t see any down side to 170 health wise.

Aren’t cranks on road bikes often shorter anyhow?

I’m 5ft 10 and I’ve had 170/172.5/175 and you don’t really notice the difference unless you were perhaps riding them back to back.

Normally run 175’s but have thought about buying some 170’s just for a fraction extra ground clearance. If there were some cranks going cheap that I wanted then so long as the length was between 170-175, I wouldn’t worry.

The only real feeling I felt making the change is that its easier too accelerate but you dont get quite the same torque.

Just my opinion of course.

Only if you`re on a SPECIALIZED FSR rockskelper… 165mm the only way forward

I inadvertently got some 170s as a replacement for 175s on my singlespeed. I am certain I noticed the difference for a couple of weeks or so while I got used to them. Now I don’t.

I’ve never noticed the differnce

I inadvertently got some 170s as a replacement for 175s on my singlespeed. I am certain I noticed the difference for a couple of weeks or so while I got used to them. Now I don’t.

Same here

I have both, don’t notice the difference.

Other people ride my bikes, they never comment so I think don’t notice either.

Presumably crank length should be related to inside leg measurement? Anyone know what the accepted wisdom is?

I have just two bikes, but just acquired some oldskool XT cranks for a retro rebuild and was pondering if they’d be ‘alright’ in use compared to what i’m used to.

The XTRs on my mtb are 175mm, the XTs on my commuter (ex mtb) are 175mm……………….or so i thought. It turns out they are infact 170mm and i have’nt noticed since buying them in 2006 and swapping between bikes.

Draw your own conclusions from my experience if you like!

Happy Friday!

I have nothing to say about your cranky thingymajigs.

There’s a bit on Sheldon Brown about it. His figures say I (5’7″) should be on 170.

I’ve no idea if that’s right but I do know it seems a bit daft that me, and the guy I ride with who’s 6’2″, are both on the same cranks. You’d think at least on of us has to be wrong.

Crank arm length is largely personal preference. There are people out there with short legs that prefer long cranks, and people out there with long legs that prefer short ones. For some disciplines like track cycling, and DH, it makes much more sense to run short (165mm or sometimes even shorter) cranks, for singlespeeding many people like to run longer cranks

The accepted “old skool” wisdom used to be that you want to run a crank length as close to 21% of the length of your inside let measurement as possible. For me with a 32.5″ inside leg, that means 173.5mm cranks. Which don’t exist. But 170’s and 175’s are readily available and 172.5’s are common for roadie cranksets too.

My personal preference is for a 170mm crank though, I’m more of a spinner than a cranker. One thing shorter cranks are also better for is your knees, longer cranks lead to increased knee pain or problems if you’ve ever had any issues with them. I was suffering on 175’s years ago, and going to 170’s improved things quite a lot for me personally.

Mike Burrows says
http://www.ctc.org.uk/file/member/200801047.pdf

I’m 6ft and run 165’s due to a low BB. I ride lots of different bikes, all with different length cranks & I can’t tell the difference.

+1 for personal preference + joint health in some circumstances.

I have in the past accidentally run 175 and 170 on the same bike simultaneously without noticing the difference. More recently, I’ve tried short cranks to combat knee pain (since diagnosed as osteoarthritis) with a large measure of success. Initially tried 155s, which worked a treat, so fitted some 152s to the other bike and found them a bit short! I’ve since picked up some 160s for that bike, and they also feel about right. I’m 6ft tall.

One interesting point: I find I can crank a higher gear with short cranks than with longer ones… The leverage is lower, but I’m pushing with a straighter leg, which (for me) appears to improve the biomechanics by a greater factor than any reduction in leverage at the crank.