Crank arm wobbling

My new Nimbus Muni’s ISIS crank arm is wobbling considerably despit the fact that everything is in tight. What causes this?

dunno what caused it , but the same happened to mine. (Nimbus ISIS)

I think perhaps it works loose and knackers the splines up. If the splines are wrecked then it will wobble even if it is tight.

I’ve put KH Moments on mine now and keep checking them all the time.

unibob may be right, take it off and have a look at the splines.

At 45 lbs my DX cranks sometimes wobble. If I tighten them to 65 lbs (I think the max) w/ red Loctite, I get no issues.

My theory is that the spacers on the axle prevent the crank from going on fully and result in a loose crank which will quickly slop out. ISIS has a taper and therefore in my mind should not have spacers.

If you want spacers use a pinch bolt system.

Why do the ISIS hubs come with spacers anyway?

Problem solved. Just shook loose, had to beat it back on with a rubber mallet.

It keeps shaking loose again. Any other ideas?

I think this is right

I have an '05 KH with the old style straight splines. It has come loose a few times, but tightened up ok with the bolt. It didn’t need a crank puller, the straight splines will slide off when the bolt is removed.

MY new ISIS '07 KH has a tapered spline, and the Nimbus is the same. I need a puller to get these off. Grease the spline, and bang it on with a plastic mallet, or wood block. It should feel zero play even before you install the retaining bolt.

If you can’t bang it on tight, I think you should check Sasc’s point ^ about a spacer. If there is a spacer behind the crank that won’t let the taper spline seat tight, find out why. Maybe use a thinner spacer, or leave it out.

If you run to long with play in the splines, this may junk the cranks, hub axle, or both.

A tapered spline (as opposed to the '05 KH, and I think the Torker dx) should bang on tight, if it can’t, you have bad parts, or a spacer preventing the splines from seating tight like they are designed to. Loctite will not fix this, the crank must bang on tight.

If there make to high spec then there shouldn’t be a problem.

I have worked with two Nimbus ISIS hubs and I do not believe they are made to high specs. On both hubs, one side was much easier to put the crank on, and it didn’t matter which crank you used - the splines were actually slightly different on each side. On both hubs, one side was so tight, that you could not actually tighten it all the way to the spacer using a long lever. I have not had this experience with a KH hub, even though they are supposedly identical except for the cutouts. I know that two is not a good sample size, but my guess is that this is a manufacturing problem. I don’t believe with todays level of precision that they can’t get both sides to be the same.

hmmm that interesting, I only have experience with the kh hub (which is fine). Mabey its time to start a poll to get more acurate results?


Anyone else having problems with tolerance and stuff?

I’ll start a thread about nimbus isis vrs kh at some point, be interesting to compair them.

Also, is the crank is loose on the splines and the problem hasnt been sorted, try using white plumbing insulation tape stuff (the rubbbery tape) and wrap it around the spines on the hub before you whack the crank on… this usually works. (with knackered bike bottom brackets)

Also putting loctite on the hub splines will have the same effect, just make sure you leave it for upto 24 hours or what ever it says on the tub for the stuff to dry.

The loctite is probably the better option as plumbing tape on splines can be hard to wrap aroundd + fill the dips in the splines.