Morning all

Hopefully a simple question.

I currently run 175mm crank arms, been offered some new ones at decent money, but they are only 170mm. Will 5 mm make that much difference to my bike and the way it rides?

is there any benefits to shorter cranks?

cheers

No.

Depends how long your legs are!

I am 6'2 and have to run my seat at around max height.

I found with 170mm cranks I had to run the seat a little higher, so i swapped back to 175mm cranks.

I'm 6'2" with a 32/33" inside leg

suppose I just crank the seat up 5 mm to compensate

Sounds like your legs are long enough to drive 175's, but you'll probably be fine with 170's. Shorter cranks are supposed to be easier to spin fast.

David – so it threw the way you felt on the bike out alot then?

aye have no problems pushing em round, will be running just the middle and inner plush bash. not so bothered about cranking out some speed

I found with 170mm cranks I had to run the seat a little higher,
so i swapped back to 175mm cranks.

at first this sounded crazy but then I realised the lower pedal is nearer if the arm is shorter 🙂

Try this:

http://www.machinehead-software.co.uk/bike/cranks/cyclist_crank_length_calculator.html

unless you're the kind of person who can't get to sleep if there's a pea under your mattress, I doubt you'll notice

I can't feel any important difference between 165 and 180 – and neither makes me a pro-level rider so there's clearly nowt to the "power" theory

I have run 165 and 175 on the same bike, with the same gearing, that's pretty noticable back to back.

My commuter bike has 170s
My mountain bike had 172.5s but it now has 180s

I can't tell the difference but I like to think the 180s make it easier to get up hills singlespeeding.

It's just the emperor's new chainset.

I had different lengths either side (170/175) and couldn't tell 🙂

David – so it threw the way you felt on the bike out alot then?

Not alot, but the seat was being run at about max height anyway, so i couldnt really put the post any higher to compensate for the shorter cranks.

Also, if you run the saddle higher to compensate, it means its a bit more (5mm?) in the way when your riding downhill.