Cranks rubbing frame! Help!

So, about two weeks ago my new Nimbus ISIS 29er arrived. It’s fulfilled all my hopes and dreams and more.

However, there seems to be an issue. After about a week of riding, one of the cranks started rubbing against the frame/bearing holder thingy. It was causing a LOT of friction, which as we all know, isn’t good.

Looking at it, it was clear the one of the bearings had moved AWAY from the hub, and the other TOWARD the hub. This caused the tire to not line up under the middle of the frame, and created the friction described above.

I took the uni to my LBS, and they took the cranks off (which I hadn’t done yet) and carefully pounded down the bearing until it was flush with the hub. Problem solved! (or so I thought!).

I just got in the mail the 100mm Qu-Ax cranks I ordered. After one ride around the parking lot, I love them! Anyway, I was putting them on 20 minutes ago, and after I finished, I noticed the exact same thing…the crank rubbing against the frame, causing a lot of friction.

I imagine I could take the uni back to my LBS and have them do the same thing again, for another $10, but how can I fix this problem permanently?

It almost seems as if the frame fork is too wide, slowly forcing one of the bearings away from the hub. Maybe not though, since it still fit OK when the bearing was set closer to the hub by my LBS.

I’ll add photos later tonight if needed, I’m on campus right now in a computer lab and don’t have my camera.

Thanks for any help! :slight_smile:
(And yes, I searched for about 5 mins before posting - found nothing.)
(If this doesn’t work out, I think I’m gonna call UDC tomorrow and see what they recommend.)

is there any spacers between the hub and bearing, and the bearing and the crank??

yea…there should be spacers in there to not let the bearing move. and if there is spacers, one or both of your cranks must be coming loose…allowing the bearing & spacers and everyyything to have wiggle room. But i suspect you need some more spacers to not let the bearing wiggle around.:wink:

I’m 99% sure the cranks are NOT coming loose. I tighten them hardcore.

Where can I get spacers? Do I want to install them on both sides of each bearing? Won’t the spacers rub against the rotating crank?

I guess I’m a little confused still. The one bearing is staying in place just fine. The other other is moving AWAY from the hub, meaning I would need a large spacer to put between the bearing and the crank. But wouldn’t the spacer just rub against the crank, too?

I’ll post pictures in 2 hours or so…

Thanks for your help so far!

there should be spacers on there already, i dont think you can buy them seperatly, if they are missing id tell udc and they might replace it

no, it wont rub or anything against your crank. it will be smushed tight between your crank and your bearing, spinning with the crank as it goes around. So…the bearing will just spin around like its supposed to, inside the bearing clamps on your frame, and everything else will be tight in place, spinning as one. ya know? So id say just try 1 spacer between your crank and bearing on the side thats wiggling out. you might need more than 1. you should see how many are on the other side of your hub, between your crank and bearing. because whatever spacers you have on that side, it seems to be good, right?

I might be able to tell more by the pictures to say for sure.

and you cant buy spacers seperately, if that one side is indeed short a spacer causing the wiggle of the bearing. go to a hardware store or something. I got some extra spacers for my profile hub at an auto shop. they aren’t specific UNI spacers ofcourse, but a spacer’s a spacer.

I don’t know about Nimbus 29s because I haven’t seen one, however I do know that Nimbus 26s do not require spacers - and I’d think they’re pretty similar? Maybe it depends on the cranks? (however I doubt it…).

As a last resort, GENTLY stand on one of your frame legs and bend it in, untill it fits over the bearings without forcing them out of position.