crank length, does it really matter?

[oldgreyandslow]

My cranks are currently 172.5mm. am I likely to notice any significant difference changing to either 170 or 175mm long cranks, other than a need to adjust saddle height? I checked the Sheldon Brown gear ration calculator, it seems minimal as far as I can see but it's more a question of "feel" will it feel different?

 

[Angelfishsolo]

What type of riding do you do? If you are on a MTB you will most likely notice that you hit more stones when peddling.

 

[ColinJ]

I can't tell you yet, but perhaps I'll be able to once I've got over my cold and ride my bike again!

I cracked my left 175 mm crank and have replaced it with a 170 mm crank from my junk box. It so happens that my left leg is significantly shorter than my right leg so this shorter crank might suit it better.

I'll report back once I've done a decent ride on the bike. I suspect that I won't notice much difference but a mate of mine used to swear that there was a huge difference between 175 mm and 170 mm in terms of feel. I can't really believe it because it is only about a 3% change in length. We'll see ...

 

[GrasB]

In terms of mechanics not really, if you go shorter you'll spin the pedals faster, if you go longer you'll grind it more. Power production will be the same it's just it'll happen at different rpms.

 

[oldgreyandslow]

Cheers folks, in answer to the above its a road bike with a 34/50 compact set up and 12-25 cassette, instinct tells me it'll make little difference, however if anyones has made the change..............

 

[GrasB]

I ride with 160mm to 175mm cranks. The TT bike runs 160mm & commuter 165mm cranks, my road bike & fixie run 175mm. They will feel different, when you switch over initially you'll feel like your spinning out early or that your natural cadence is to high but that's just acclimatization, it initially took me about 300-400 miles to get used to the shorter cranks & how to ride with them. That said once I learnt how to ride on shorties the transition takes 5 miles to get into the right habits. The longer cranks on the fixie make climbing easier & due to the nature of fixed it's easier to spin up so I'm not so worried about spinning out. On the shorter cranks it's much easier to spin up which means it's easer to hold a given effort level, the downside to this is that there isn't the explosive power I have on the road bike with the 175mm cranks.

 

[oldgreyandslow]

Thanks for that. whichever I go for I'll only be changing +/- 2.5mm rather than 10 to 15mm so I'll probably go with what's available and at the "right" price.

 

[Davidc]

I changed (just cost of replacement) from 175 to 170 on my old Peugeot and couldn't tell the difference it was so slight.

 

[fossyant]

I run 170 what ever..fixed, 2 x road bikes and 1 x MTB. Being Mr Average in height, that's how I've ridden for over 26 years.

 

[fossyant]

Rules are Track 165 - can't ever say I've noticed on the Manchester bikes a change in 5mm at all even from riding fixed 170mm on road.

It's usually track shorter cranks, TT longer cranks than road. Is that right...dunno ? - I've always stuck to 170. If you are tall, then 175 is recommended.

 

[asterix]

No. I ride a 25" frame and am quite happy with 170 or 175 cranks. When the esteemed custom builder, Roberts, built me a bike they used 170. One of my other bikes has 175 and I never notice!

 

[GrasB]

I should add that from what reading I've done it seems like you'll produce the same amount of power across a broad range of crank lengths so go for whatever takes your fancy.