Crank movement

Hi all,
It’s been a while but I’m back!
I got a second hand Nimbus muni and it was all sweet for a number of rides but I noticed a slight clunk from the right hand side crank on my last ride… Thinking the bolt just needed a tighten I pulled out an Allen key and tried to crank it up but it won’t tighten any more. Loosened and retightened to make sure but still no joy.
Could the spindle/crank be worn and do I need new cranks or what else can I check or do to fix it?
Thanks in advance!

Hi Jono,

Is the crank arm square taper or isis drive (looks like a multi point star) ?
Is the crank bolt actually doing up tight now?

It’s Isis drive - sorry! I should have mentioned that.
It’s as tight as it’ll go on but there’s still movement :pensive:

Im thinking maybe you might get away with a thinner spacer behind the crank arm.

If you can get the arm off take out the spacer and put the arm back on with the bolt back in. literally nip the bolt up so the arm is mounted nicely on the crank then measure the gap behind, i use metric drill bits layed in the gap. That is the size spacer you need.

hopefully that makes sense.

That sure does make sense. Thank you!
I’ll give that a go this week and see how I go.
Thank you :slightly_smiling_face::slightly_smiling_face:

You can get an assortment of spacer washers at UDC.

The standard instruction for determining the required spacer thickness is to push the crank on by hand and then select a spacer about 3 to 5mm less then the space from the bearing to the crank. With the correct spacer the crank will fit tight on the tapered ISIS spline and against the bearing when the attaching crank bolt is tightened.

Here is a video that calls for 2mm space but the official ISIS spec is 3 to 5mm preload that is specified by the crank manufacturer.


Awesome! Thank you :slight_smile: