2009 Shimano XTR Crank Problem

gbrnole

Hi,

I finished a ride this evening, riding round from my car to my back gate did my usual bunnyhop up the kerb but as i was about to hop off there was a big old clang and my drive side pedal had stripped out of the crank threads. It wasnt even on the landing but as i was lifting the rear.

Its a straitline flat pedal, just appears to have sheared away the first 4 threads in the crank arm.

Cranks were bought last October so going to contact the shop tomorrow for a warranty- has anyone heard of this happening before? Am i likely to be challenged on having abused the cranks? I weigh 14 stone for the record, cranks were on a mojo.

The pedals were 100% fully threaded in - I'm amazed that a pedal can rip out of its threads?

stu8975

alex.hulme wrote:

The pedals were 100% fully threaded in

Were they 100% tight though? sounds as though they might of been slightly loose to me, not sure on a warranty but should be easily fixed with a helicoil, did you fit the pedals?. If the shop sends them back to shimano (Madison), you may be waiting a good few weeks as they're not that quick on turnaround time.

nicklouse

if you have pulled out 4 threads then that is how many were in contact.

if the pedal was fully screwed in then it would have pulled out as many threads as the pedal axle has.

so it only had 4 thread turns? sounds like poor design

bomberesque

XTR cranks ... straitline pedals .... Mojo

I hate you already

seriously though, like they said, sounds like the pedal was not in fact fully screwed into the crank but was only in 4 turns. Perhaps it had come loose during the ride? If so I don't see it being a warranty issue.

pictures might help.

oh, and those pedals won't be any good anymore (microcracking in the thread, read it on the interweb be very afraid etc etc) so just send them to me and I'll make dead sure no-one hurts themselves with them

gbrnole

Pedals were definately fully threaded, I had the bike on the stand earlier in the day to clean the cranks as the non drive side was filthy making a grating noise from sand/grit.

I find it hard to believe myself, only thing I can assume is that the drive side pedal came loose on my ride, how that would happen with a reverse thread again I cannot believe?

I'll degrease the threads and get some pics up

bomberesque

it's pretty unusual for them to come loose on a ride, IME, but if they weren't cinched up tight enough it's still possible, even though the thread maybe reversed

anyway, if the pedal pulled 4 threads out and left the rest in the crank then I can't think of another answer except that the pedal came loose during the ride.

gbrnole

Pedal thread (note torn thread from crank)





Crank thread


From anyone else looking at the pics I have to say that the easy answer is the pedal was not fully inserted, however I'm so sure this wasn't the case. I cant see anyway this could have come loose; having just ridden 10 gnarly miles I would have noticed and it was tight before I started the ride.

bomberesque

I'd bet some beer that that came loose during your ride and twisted out.

anyway, good luck convincing your LBS otherwise, I'll be interested to hear what they say

Anonymous

definitely wasn't fully screwed in when it ripped the threads out.

Dazzza

If all else fails you 'might' be able to have a threaded insert pressed in very tightly, i know race face has such things on their dh cranks, could be worth looking into.

And that definitely came loose along the ride and twisted out, you can see that from the damage on the threads.

Anonymous

It also looks to me like you weren't using the washer that comes with the cranks inbetween the pedal axle and the crank arms.

supersonic

Have to agree, it must have come loose and unthreaded a bit.

gbrnole

Yep gotta admit defeat on this one, the pedal had to have backed out somehow. The bearings in my pedals are stiff so that cant have helped.

Got the lbs fitting a helicoil for £20 so all good!

pvtpile

those pedals dont have bearings inside, they use polymer bushers

bomberesque

alex.hulme wrote:

Got the lbs fitting a helicoil for £20 so all good!

:shock: wow, that is a cheap fix! :shock:

I've not had that done before but honestly thought your shiny crank was all but dead

nice one!

gbrnole

pvtpile wrote:

those pedals dont have bearings inside, they use polymer bushers

Right, i remember the marketing hype on these. They do have play in them, bushings are tight - they feel as though they are rocking underneath my feet when im standing on the pedals coasting.

pvtpile

you can get a new set from straitline think there fairly cheap

gbrnole

Lol ive only had them 2 months!