# Rim out of round?



## Sean (May 28, 2013)

Both of the rims on my fastback seem to be out of round. I pulled them apart to clean and whe I relaced them they both have a "bump" in them that goes up and down when you spin the rim. Any idea if that is a spoke related issue? They don't move right to left just up and down.


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## jpromo (May 28, 2013)

That's likely just in the truing of the spokes. A bump is a bit more of a pain to get out than a wobble, and a little more of a crapshoot in my experience. Try loosening a handful of spokes opposite the high point, then tightening a handful on the side that was high. Best to do with the tire off as a tire that's bead has seated off center can give this same effect.


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## partsguy (May 28, 2013)

The last rim I had with a flat spot was a Schwinn (yes Schwinn!) S7 on a 1977 Hollywood. The rim didn't look bad until I took the bike apart for an overhaul and I noticed it on the bench test. I couldn't fix it, I scrapped it and got another.


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## SirMike1983 (Jun 6, 2013)

Rim hop is the product of the spokes being mal-adjusted or the rim itself having a defect. The former is corrected by adjustment, the latter by replacing the rim.

To adjust: tighten the spokes at the point of the hop. If the rim is true left and right, make sure you adjust the spokes from each side of the hub equally. You want to pull the rim down without moving it from side to side, so make sure the adjustments are the same. For a large hop you may have to adjust 4 spokes, for a small one, just the 2 where the small hop is. Always adjust spokes in pairs for this job, and adjust them evenly. Adjust and re-check as needed.

If after adjusting and adjusting there is still a hop, it may be a damaged rim. These are replaced usually.


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## Sean (Jun 11, 2013)

Thanks everyone.


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