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Need help from wheel building/Repairing experts.(6 posts)

Need help from wheel building/Repairing experts.Len J
Jul 18, 2002 4:33 AM
This definatly fall under the topic of "Stupid Bike tricks"
Had to drive to Phila for a meeting yesterday, rushing back to make the Wed night hammerfest. Get home, quick Change, Quickily put bike on roof rack, lean wheel against car, wife asks me a question, I get in car & back over the wheel. D'oh.

It seems to be about 1/2 inch out of true on one side.

How do I bring up to true?
How will I know if Rim needs to be repaired? It's not kinked,Just twisted (I think).
I suspect I can get back to true by working on spoke tension, How do I keep from overtensioning spokes around section of rim that was run over?

Any other tips & techniques? (Besides taking my time when loading bike so I don't do it again.)

Thanks in advance,

Len
re: Need help from wheel building/Repairing experts.eddie m
Jul 18, 2002 5:53 AM
IF you bent the rim that much it probably needs to be bent back before you true it. Look at the spokes at the bent part of the wheel. If the rim is bent to the right, the left side spokes will be too tight and the right side will be too loose. No amount loosing/tightening will true the rim if this is the case until you bend the rim back to more or less straight. You could try to bend the rim back, but if you want a perfect wheel you will probably end up rebuilding it soon.
eddie is likely correct...sprockets2
Jul 18, 2002 8:43 AM
you may need to de-spoke, rim straighten or toss, and do a complete rebuild. YOU DROVE OVER THE WHEEL. They are not designed to bounce back from that kind of assault. You should not use spoke tension to repair damage to your rim.
I don't qualify as an expert, but I do true my wheels...Lone Gunman
Jul 18, 2002 6:05 AM
A 1/2 inch does not sound like a large amount, I think it is a good opp for you to get know how to true wheels. You have not said how well you do this. Hey the worst that can happen is you mess it up big time and have to buy a new rim and relace by a shop.

I would start by just trying to bring it back to true by tighten loosen method and not going more than 1/4 turn of a spoke per session. Then detension the wheel by placing on it's axle on a bench or floor and pressing down on it alternating hand positon on the rim and doing this on both sides. My thoughts are gently bringing it back to true by this method as opposed to getting it done quickly and letting off or applying too much spoke tension that may make the problem worse. I think the best route is start by loosening spokes first and tension second as you work the bent section. By doing the detension thing while the rim is on it's side, you might move it further into true than just loosen/tightening spokes will do and this will help keep spoke tension even.
Go at the rim without spoke tension to start.Quack
Jul 18, 2002 6:54 AM
Before you start twisting on those nipples, look at the eyelets of the rim in the area that the bend occurred. If you see stress cracks around them (usually white spiderweb-like lines), I would put on a new rim. If the eyelets look OK, make marks on the rim with marker indicating the area of the rim that needs to bend back. Detension the wheel so that all the spokes are slack, bend the rim back as close as you can using feet, hands, anything you think might do the job and not damage the rim. Hammers and vices are dangerous unless you know how to use them without inflicting further damage. Once the rim is bent back close to true, tension it back up again and make it true and round. Chances are good that the spokes in the area of the repair will not match tone with the rest of the wheel but you can probably get close. If you find that the spoke tensions are seriously lopsided in the area of the repair compared to the rest of the wheel, chuck the rim and possibly the spokes, and get a new one. Repairs like this on tacoed wheels should be considered temporary until new rims can be mounted. I never trust them again. Yours doesn't sound like it's tacoed so you're probably OK.

Good luck!
re: backing over wheel.Fredrico
Jul 18, 2002 11:59 AM
When a rim takes a hit like that, it bends, takes a "cold set" as it were. Trueing with spokes won't really work. The tightest spokes, trying to hold the bent rim straight, will eventually break, like when you hit a bump a few months' down the road.

I have done the following and know others who have taken the rim off the spokes and bent it back more or less true by hand, then respoked it and trued it. It never comes out perfect.

If the rim is "pretzeled" in a symmetrical potato chip, almost always from a head-on impact, a big bounce, the tire acting as a shock absorber, often all you have to do is lay the wheel on the ground and jerk it back close to true by hand. Amazing how often this works!

But a crushing blow from the side, as from the wheel of a car running over the rim, almost always leaves a dent, which can't be completely taken out by the spokes. The best repair would be to replace the rim.

Good luck!
Fredrico