Hollowtech cranks coming loose

tandrews8664
tandrews8664 Posts: 97
edited August 2012 in Workshop
Hi,

I was riding a TT the other day and looked down to see my chainrings wobbling ominously from side to side as i pedalled, having finished the TT i noticed they were almost falling off (knocking when pushed from side to side), although no play in the Bottom Bracket as far as i am aware.

I have since removed crank and then re installed, tightened them as per instructions, i.e gently tightening the end bolt, then tightening the pinch bolts, but it still seems to come loose after about 10 minutes riding.

To give some backgound info bike is about a year old, used in all weathers. Recently whilst riding in the rain, brown rusty looking sludge often washes out of the bb area down the cranks, i fitted new pedals about 2 months ago, and there was a clicking and creaking which started at the same time. I put this down to the new cleats settling in, but this was more than likely the start of the crank play which i have ignored thinking it was the pedals :roll:

Does anyone have any idea what is wrong, and whether this can be fixed, or will the cranks need replacing?

Going to take it to LBS for a service soon, so if it's something i can fix now myself i would much prefer rather than paying extra for LBS to fix it along with service

Thank you

Comments

  • nicklouse
    nicklouse Posts: 50,673
    what cranks?

    as what you say does not sound like HT2 fitting. but your description of the tightening does.

    as the Non drive side arm is the ome that bolts on the chain rings could not of been wobbling. as the two bearings would have still supported the axle and then the rings. they may have been moving side to side?


    if it is HT2 and is now a presistant problem you could well have damaged the splines resulting in the failures.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Moving side to side is perhaps a better description then

    Sora cranks, Tiagra bottom bracket

    so is a damaged spline a new chainset/cranks?
  • keef66
    keef66 Posts: 13,123
    When you refit the drive side crank / chainrings, whack it with the flat of your hand or a rubber mallet to make sure the axle is as far through the BB as possible. Then similarly tap the non drive side crank on to the splined axle and preload the bearings with the little plastic cap, just finger tight. Install the pinch bolts, one from each side, together with the little spacer / retaining clip, then tighten the bolts progressively and alternately to the recommended torque.

    If it comes off again after installing it all properly, I'd say yes, you've probably buggered the splines in the LH crank.

    You can get replacements, but a new chainset is often a cheaper option!
  • Thanks for the advice. Still having problems even after trying the mallet tips. So taken into lbs. hopefully it is just my cack handedness and not something expensive!