Cranks make me cranky

GriffterUK

Hi All,

Just looking for a bit of advice on a new chainset......long story short, I borrowed a bike for my first triathlon and half-way through the bike course the drive crank axle snapped. Yep first triathlon, borrowed bike, and unbeknownst to me a really expensive crank at that - a Shimano Dura-Ace FC-7900 10-speed 175mm 53/39.

Anyway my question is for all you wonderful helpful peeps is can I replace a 53/39 chain-ring with a 52/39 one without needing to change anything else? Basically I've seen a Shimano Dura-Ace FC-7900 175mm 52/39 but wondered if one less cog tooth made any difference at all? I checked it wasn't a typo on the website.

Thanks for your help all.

Griffter

964cup

Yes, it will fit, and you could always swap the 53 ring from the old crankset onto the replacement if it mattered enough to you.

GriffterUK

964Cup wrote:

Yes, it will fit, and you could always swap the 53 ring from the old crankset onto the replacement if it mattered enough to you.

Thanks for the advice 964Cup - much appreciated

fenix

You snapped a crank ??

Have you taken it back to the shop ? That's pretty blooming rare - must be a defect.

GriffterUK

Fenix wrote:

You snapped a crank ??

Have you taken it back to the shop ? That's pretty blooming rare - must be a defect.

Well the bike was borrowed, and owner get 1,000's of miles out of it. LBS said they'd only had 3 instances of such a thing in over 20 years so yeah pretty rare! To be clear though it was the crank axle that snapped.

One thing though I did have the LBS change the pedals recently - could that have weakened the axle?

webboo

Unless they fitted them using a sledge hammer, I doubt it.

svetty

GriffterUK wrote:

Fenix wrote:

You snapped a crank ??

Have you taken it back to the shop ? That's pretty blooming rare - must be a defect.

Well the bike was borrowed, and owner get 1,000's of miles out of it. LBS said they'd only had 3 instances of such a thing in over 20 years so yeah pretty rare! To be clear though it was the crank axle that snapped.

One thing though I did have the LBS change the pedals recently - could that have weakened the axle?

Seems quite possible that they had to use excessive force to remove the old pedals and in so doing cracked the spindle which then gave way some time later when you were riding. This is a more likely scenario than the spindle just giving way solely due to pedalling torque.