Has anyone else experienced a gradual dishing of the wheel away from the dominant side? I got a used Nimbus 24" about a year ago. The wheel was basically centered in the frame at the time. Then it gradually began to shift off-center. The other day it began to rub the frame, and I had to re-balance it. About one full turn of the nipple on each side, releasing one side and tensioning the other, was enough to bring it almost back to center.
I ride daily on flat roads, mostly, figure fifteen to twenty miles a week.
It’s common for me, happens on my bmx bike since I typically 180 the same way as well as my unicycles from side hopping to the right most often and dishing my wheel off closer to the left side of my frame. It’s good habit on anything with spokes to loosen/tighten often to keep things true.
That really shouldn’t happen from riding on flat roads. I bet your spoke tension was really messed up from the start. You might want to loosen it and re-true the whole wheel just to make sure the tension is even all the way around on both sides.
The only cause I can think of is the way I mount. It is the only unbalanced load on the wheel, I step on the right pedal and put all my weight on it to get up, doing a roll-back. That may put a side-load on the wheel, pressing it toward the left frame member.
It’s more likely that your frame is bending, or if you don’t have spacers, that your bearing is slipping on the axle.
Have you tried flipping the wheel around in the frame and seeing if the wheel is still closer to the same side?
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I’ve not seen a gradual dish to one side, but unicycle wheels being pretty loose from the factory is not uncommon and especially if it was a dished wheel to start with I could picture it dishing more over time towards the tighter disk side spokes.
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Very strange. The second day after centering the rim, it was right back with the tire rubbing the frame. So I first did what Saskatchewanian suggested, I turned the wheel around. Sure enough, now it rubbed the other side. So it’s not the frame. This time I totally loosened the spokes on the offending side and tightened the other side as necessary for balance and even tension. One day later, so far, so good. And by the way, I made a mistake in my original post. The rim did not shift away from the dominant side where I step when I mount, it shifted toward the dominant side. Which makes sense.
Does your wheel have all of it’s spacers installed?Have the bearings slid on the spindle? Stating the obvious, but dish shouldn’t shift, especially that quickly.
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Can you post a picture of the unicycle that you have? As Nimbus have made a number of slightly different unicycles over the years it would be good to know what we’re talking about here.
It sounds like good news if it hasn’t shifted again. It sounds like the spokes could perhaps do with being done up rather tighter than they are/were if nothing has shifted as @saskatchewanian suggests. Modern spokes can typically handle being very tight, and they’re generally far more likely to break being less tight permitting more uneven tension between them when force is applied to the wheel.
Here’s a pic. As for spacers, I do not recall any when I changed the bearings. Still, I just popped the wheel off the other day and it was in rock-solid. It is not dancing around.
Ahh, you’ll likely want to fix that to prolong the life of your cranks if nothing else. It’s pretty easy to over tighten them and deform the ISIS interface without a positive stop.
Maybe there was some hidden defect? Or a breakdown that you were not told about.
Thank you for the suggestions. It is true, I do have one crank that I have to keep on tightening. I am ordering spacers ASAP, I ope I did not ruin that crank. Also, does anyone know what size and pitch tap I need to clean up the threads inside the Isis axle? I mashed them a bit last time I used the crank puller.
To answer JSom’s question, the previous owner was honest. I got the cycle off Craig’s list and he explained what he knew was wrong, but he was not much of a mechanic. As they say in publishing, “any errors are my own.”
Anyway, as for the dishing, after the last re-balancing things seem to have quieted down, and the wheel appears to have stabilized.
I’d install a new set of cranks.
I was afraid someone would say that. Do you think I have already over-tightened these?
I wouldn’t waste my money on new cranks before confirming that the ones you have are actually broken. There is certainly no way to diagnose this without having the unicycle right in front of you, and even if they are worn out, the worst thing to happen is that they are a tiny bit wobbly or a bit creaky, but you can still ride them without damaging anything else while you wait for new ones to arrive. I see zero reason to just blindly throw new cranks at the problem.
In my experience cranks are actually quite sturdy, chances are good that with the correct spacer you will be just fine.
M12x1 is the size of the thread. (Note that is not the standard thread pitch, so you won’t find this size in a normal set of taps.)
Thank you finnspin, I just ordered the 12x1 tap. If Gockie is right, then when I put in the spacers the problem crank will really wobble. I’ll wait and see, I hate to throw things out if they can be rescued. Maybe I can make some wedges out of an aluminum can to make it firm up on the splines.
We are so quick to throw things out here in the West, I am guilty too. But I have been learning from one of my helpers, who was born in India and studied at the University of the Streets. If a screw does not grab, he backs it out, puts a short length of copper wire into the hole, and drives the screw back in, firm as a rock. And he has a million other tricks of the sort.
So we’ll see what it will take to fix the loose crank. Every other day I have to tighten the crank bolt, and it has gotten to the point where it is about as tight as it can get.
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The main thing is that the problem has been solved. I asked a question because there are a lot of dishonest sellers in the world who hide information about serious defects that are invisible at the first inspection.