crankbolt keep coming loose

[cycleguy12345678]

Hi to all.

 

I have a truvativ stylo gxp crankset with a left crankarm that keeps coming loose. The first time it felt loose I only tightened it and it was allright and then it came loose again and replaced the crankbolt. it lasted for about 2 months, when I went for a weekend outride the left crank arm just fell off. I took it to the lbs and had it tightened with torque wrench and then 2 days later it fell off again. after some examination of the bolt I saw it was stripped . So I put the original one back on because I had a race that weekend and couldn't found one in time and it actually lasted a long time but now it is loose again... I searched the problem and found quite a lot of people having the same problem with that crankset. also my chain slips when it is on the first two chainrings when accelerating, so I am thinking about coverting my bike to a 2x9 and fit it with shimano slx crankset. Is this the best option or should I buy two new chainrings and try to fix the bolt again?

Edited March 30, 2014 by cycleguy12345678

[Flowta]

If there has been some movement before, the splines on the non - drive side arm could be worn.

 

This then accentuates the situation causing the bolt to undo itself easier.

 

The Shimano crank might be the better option IMO. Though your lbs might be able to order just the arm. (Had the same problem and did this before with a FireX crank)

Edited March 30, 2014 by Flowta

[droo]

If there has been some movement before, the splines on the non - drive side arm could be worn.

 

This then accentuates the situation causing the bolt to undo itself easier.

 

The Shimano crank might be the better option IMO. Though your lbs might be able to order just the arm. (Had the same problem and did this before with a FireX crank)

 

Sounds about right. If you've fitted a new bolt and torqued it up properly and it still comes loose, it's most likely that the spline on the crank and / or axle are worn.

 

Unfortunately the only solution if this is the case is replacing the crankset. Shimano SLX would be your best option - the BB will last longer and the crank will never give trouble.