I brought this up in another thread but figured that maybe I’ll bring it up here as well since I’m sure not everyone reads the progress journal. For those who don’t know, I’m learning and own a 70s era Schwinn uni (with the cottered cranks).
I got back to riding today after my Saturday wipeout when after a couple of rides I noticed a bit of abnormal slop. After bringing it back in and taking a look at it, the wheel seems to have a bit of ‘wiggle room’ now. Doing a further look, it appears to be around the hub and bearing inner sleeve (I don’t quite know the anatomy of a unicycle other than there’s sealed bearings on either side of the hub, held in at the fork and locked in via bearing caps, or in my case, a pair of lock rings on either side of the fork). What would this be anyway? I may go ahead and attempt removing the cotter pins (Wish me luck, I hear they’re a pain) and see more of what’s going on under that crank.
Something definitely doesn’t feel right when I’m sitting on it, and when I pick it up and give the wheel a shove to align the pedals for a mount, I can feel the play…feels like it’s going to fall apart. Any tips?
Try and wiggle the cranks up and down, and see if either moves independently from the wheel. I’ve got a 1967 Schwinn that I learned to ride on, and that exact slop feeling was happening to me, and it wasn’t for a while until I realized that is was the crank that was loose. Check that out before removing the cranks, they are a major pain.
That was actually my first test. The cranks are snug. I just took my seat off and I can definitely see the amount of play between the bearing and hub. I’m not too excited about removing those pins, I’ve already tried tapping them out with nothing happening.
The bearings, are these also a non-standard size much like the rim?
Well, I just removed the crank, the bearing itself actually seems fine. The inner sleeve is snug and rolls smoothly. The hub also appears to be fine so I’m not sure what it could be. I just put everything back together and it feels fine for the time being. Earlier I did make an adjustment on my seat so maybe that had something to do with the extra amount of play, maybe didn’t have the seat post nut tight enough.
As far as removing that cotter pin (I just did 1 crank), after ‘giving up’ and putting it back on, I did a couple idles where I noticed some more slippage going on. During the idling, I was apparently loosening the cotter pin, so afterwards I was able to tap it out the rest of the way.
Something similar to this happened to me ~20-25 years ago. In my case, the bearings were firmly affixed to the frame. There was no slop there. But the bearing cases would slip relative to the axle. With my weight on the seat, torque on the pedals, add a little twist for steering and “ca-chunk ca-chunk ca-chunk”. One of the fork/bearings would slide back and forth on the axle. The way I fixed it was to take off the fork and put the axle up on an anvil. Then I whacked the polished bearing surface with a big hammer several times. This put some dings in the bearing surface of the axle. I popped the bearings back on the axle and with these dings they stuck firmly. No more “ca-chunks”.
Give it a try.
Thanks, I may give that a shot if it starts to feel sloppy again. With mine, my bearings are snug onto the frame. It’s how it sits on the axle/hub where there seems to be some play. However, there’s no stress marks/deformities causing the bearing to have quite a bit of play on it.
So basically, you pounded the axle into the bearing so it would be ‘wedged’ into the axle for better security? I thought that ker-chunk sounds I was getting were from my spokes as that sound went away when I tightened some of the looser-feeling spokes.
Yes, if your cranks are tight, it’s probably the bearing sliding side to side on the axle. Maybe a little annoying, but nothing to worry about. The suggestion above was to beat on the axle, but not on the bearing! The idea was to create some irregularities in the surface where the bearing sits, to hold it a little tighter. But I wouldn’t worry about it. It will not affect performance, and your Schwinn will probably last until you’ve long past outgrown it.
The bearings are replaceable BTW, but locate your replacements first! I’m sure someone has some out there. Use eye protection when you go to remove those snap rings!
Like you, the bearing of my (main-cap style) unicycle was sliding along the axle. I took the bearing off, wrapped about 2 layers of aluminum foil around the axle without any creases or folds and put the bearing back on. It was quite snug and I had to use a pipe the same diameter as the inside bearing to hammer it back on. Thanks to harper (in http://www.unicyclist.com/forums/showthread.php?p=1404096 ) for the idea.
One thing you probably want to do is to use a cotter pin press to set the pins. You can make a press with a “C” clamp, and a small section of tubing that goes around the threaded end of the pin. Back in the day I worked on many, many bikes with cotter pins. One of the reasons people would need new pins was that they tried setting them with a hammer, or just by screwing the nut on. This leads to uneven wear, and looseness in the pin. Luckily they are cheap to replace; although, it’s getting harder to find shops that have them in stock.
UDC used to have the bearings in their catalog, but I don’t see them online at the moment. That could mean that they are out, or that they just don’t have much inventory. You might want to call them if you need bearings.
