crank arm help

GJC

Hi need help just sheared grip (for axle) in left hand crank arm due to retaining plastic bolt fell out felt lateral movement but damage was done. I want order a new crank arm the measurement from pedal to hole is 170mm would i assume this maybe the crank arm length?

Many thanks GJC

cooldad

Centre to centre.
What cranks are retained by a plastic bolt?

Hylol

That's correct. You measure crank arm length from center mounting hole for spindle to center mounting hole for the pedal.

If you're in doubt at all, remove the right hand pedal and measure that crank arm.

Detailed drawing (courtesy of SRM): http://mywheelsandmore.com/Images/bicycleParts/chainset/Bike-Crank-Arm-length-Determination.jpg

GJC

sorry not plastic bolt just plastic retaining screw on shimano slx crank, thanks for the replys just noticed its says the length on the inside of crank arm.

Many Thanks GJC

nicklouse

the preload bolt? just order a new one.

or are you on about the 2 clamping bolts?

cooldad

Once the pinch bolts are tightened the preload bolt won't make any diiference if it loosens.

cooldad

But it shouldn't move if the pinch bolts are done up.

GJC

Thanks for the replies, the preload bolt wont stay in, it makes its way loose and the teeth inside the crank that slides on to the axle is sheared, when preload bolt tighten and pinch bolts tightened there is lateral movement

many thanks GJC

nicklouse

so get a new preload bolt.

or your bearings are dead.

The Rookie

Have you enough spacers? Withe the preload tightened there should be no lateral movement, either it's bottoming on something and not pulling the NDS arm in, or your bearings are too close together.

GJC

Thanks once again for the replys, the only way to fix it is buy left hand crank arm. sorry for the confusion in the crank arm the groves that slide on the axle, these are sheared. no grooves, just smooth so crank cant grip to turn axle when pedalling.

Many thanks Glenn

Chunkers1980

I'd buy a whole new crankset, it'll workout better value.