I’m new to unicycle maintenance so I will ask the experts. I did try searching the forum first, but a lot of the answers are not quite exactly what I’m seeing so thought I would ask.
OK. Nimbus II street unicycle 26" with ISIS hub.
I noticed an odd sound/feeling on my last ride like the cranks were rubbing on fine sandpaper. So, I thought I would open bearings and add grease since I have not done that since buying UNI in April 2015.
Removed cranks and frame to get a look at them.
Both bearings had a moderate amount of grease… not loaded.
The left bearing spins easily - one flick of the finger and it spins 8-12 times. The right bearing will not spin. You can give it a flick, but it is only going to turn about 1/4 turn and stop. I’m suspecting this is the source of the rough feeling I was getting.
So, should I just order some new bearings from UDC? or is this something you can take off, clean out, repack and it be okay?
I would actually say that the bearing that spins 8-12 times is your problem. A bearing loaded with grease should not spin freely but spin very smoothly.
I’ve never had luck repacking cartridge bearings so I’d recommend replacing.
well - in that case I might go put some grease in the one that is spinning too much.
My process was a bit goofed. I opened up the right bearing without spinning it… put the grease in and noticed it didn’t spin much. Then, tried spinning the left one BEFORE adding any grease. So, that might have been the problem all along that I didn’t have enough grease in there. It seemed to only be BETWEEN each bearing and not as much between the bearing and the walls.
Id go with replacing them both just to be on the safe side. If you roll the bearing between your thumb and forefinger you should be able to feel if it is gritty or not. If one of the bearings doesn’t feel gritty, keep it as an emergency spare.
By any chance have you cleaned the uni with a hose recently? That is the cause for my last bearing replacement. The pressure drives water (and the crud carried in it) through the bearing seals.
Once you have a bearing puller, removing and installing bearings is no harder than doing the same to cranks.
I’m thinking that the friction I was feeling during the ride was the bearings rubbing on the walls because of lack of grease.
I’m going to order a replacement set and a bearing puller from UDC to have ready to go when I need it. Will try a ride today/tomorrow to see how the grease does.
Went for a ride today. Still had the same feeling. Kinda like when you ride a bicycle and the brakes are dragging against the wheel. I’m going to order two sets of bearings (one for a spare) and the bearing puller.
Let us know if you are able to source a bearing puller for a reasonable price. The one on UDC is $45 which make me wonder if any ol bearing puller would do.
You need to remove the adjuster bolts, and hold the side arms in place by hand until the centre bolt tensions against the crank bolt.
After a bit of creaking and cracking, the 42mm bearing came off my ISIS hub OK.
One thing is pulling the old bearing off - but how do you press the new one on? Just good to know, if I have to replace some bearings - a couple of my unis are several years old.
The easiest way is to just put all the spacers in the right place and install the crank arm. It should slide on enough that you can get the bolt started, then when you tighten the crank it will install itself. You can also carefully tap it on with a piece of tubing over the hub, but if you use that method, the medal tubing should only touch the inner bearing holder, and not the side of the bearing. You’ll need a tube with a ~23mm interior hole.
I went ahead and bought two sets of bearings + the $45 puller. I know… pretty $$$ for a puller and I could have gone cheaper going to an auto store - but, didn’t want to mess with something that could potentially goof up the bearings + plan on keeping it for years to use on other UNIs.
Anyway - replaced the bearings. The puller works great - slips on one way only and holds bearing very secure while pulling it. To install the new bearings I put all spaces in place and used the crank along with a few taps from a rubber mallet to seat them.
I checked the old bearings and with them off and in your hand turning them you can’t feel any friction. They seem to be the same as the new ones. I weigh 225 lbs so I’m sure there is a bit of difference with full weight on them VS just moving them in your hand.
Anyway - I put the new bearings on and went for a few rides. I did not notice the metal on metal feeling anymore - however, it still feels like it is “dragging” as if a brake is lightly applied (no, I don’t have brakes).
I’m beginning to think that the shoes I’m wearing (mid-top) are rubbing on the frame/cranks as I ride. I’m trying to focus on moving my feet to the outer edge to prevent this.
What about:
-trying another pair of pedals if you have one
-checking that the wheel is True and spokes are tight enough so trat the tire doesn’t rub against the frame
Just mentioning that having the bearing cup bolts too tight will cause the condition you describe. The bolts don’t need to be very tight. It’s the nature of the thing that the hub will bind if the bolts are too tight.
