MidlandSpinner

Hello

I recently bought a bike with Ulterga 6800 and 172.5mm cranks.

I would like to change the cranks for 170mm (I don't want to start another bike-fit discussion so let's just put that to one side).

What is the cheapest and easiest way to achieve this? I can buy an Ultegra crankset for about £120 but this comes with chainrings, axle, etc which i don't need.

Is it possible to change only the cranks while keeping the same chainrings etc, and is it possible to buy only cranks? What is the compatibility of Ultegra 6800 with non-Ultegra cranks?

Thanks in advance.

alcjphil

The "axle" that you think you don't need is part of the right hand crank arm and cannot be separated from it. As far as I know, Shimano does not sell cranks without chainrings. Changing to a different brand of crank would also involve changing your bottom bracket

HillRider

The "cheapest and easiest" way to get a 170 mm crank is to buy a complete 170 mm crank. Your 6800 crank is a Hollowtech II design and the spindle is part of the crank arm. Either sell the 172.5 mm crank or keep it's chainrings to install on the new 170 mm crank when it's chainrings need to be replaced.

MidlandSpinner

Thanks very much for your replies. I had kind of figured out all of these things since posting.

I'm resigned to buying a full crankset and then selling the left-overs.

dedhed

Bought it new from a shop? Inquire about a swap. Or look for a used one that may have rings that aren't as nice ans swap yours on.

JamesInSJ

Do this. You'll do just fine reselling too.

McBTC

But, why not 165 mm cranks?

andr0id

Buy the replacement crank arm with "other size" chain rings and you can use them when you need them.
They're easy to swap and having more sizes can be useful if you travel to other terrain.

shelbyfv

Great idea!

CliffordK

E-Bay?