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Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

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Old 02-24-04, 02:38 PM   #1
crowtee
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balance tires

does anyone know how to balance a tire. When I spin the tire it makes the whole bike move up and down. Is there a certain way to mount the tire on the rim so it is balanced?

Thanks Mike
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Old 02-24-04, 03:00 PM   #2
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Firstly, is your rim completely true and round? I usually find that a rim with a high or low spot will cause an unbalance when spun at a high rate. As for tires, I don't know if there's anything much you could do about them.

George
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Old 02-24-04, 03:19 PM   #3
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What kind of tire? Knobbie, slick? It could have a flat spot from skidding. Other than that, i dunno
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Old 02-24-04, 05:17 PM   #4
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As George said, check the rim-take the tire and tube off and see if that is the problem. If it is not the rim, it could be the tube. If the tube is not the right size for the rim, or if it is stretched and somehow doubled over, it would push the tire up. Befor this though, check first whether the bead of the tire ( the part that should set into the rim wall) is uniformly set in all around the wheel. If it is not, deflate it, and set it properly, and re-inflate. If it pushes the bead out again, see if the tube is correct and not out of shape. If the tube is not out of shape, and if the bead keeps coming out, it is either the tire or the rim with a faulty side wall.
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Old 02-24-04, 05:26 PM   #5
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Take that big white reflector out of the spokes.




Seriously though,
Assuming you have the bike upside down, and when you spin the wheel the bike bounces a bit?

Its probably the extra weight of the valve stem and cap, since there is no counter weight across from it, accept maybe some stickers. If you pull the tube out then the other side of the rim will be slightly heavier since there is no hole in that side.

You can remove the cap or add a counter weight and see if that helps, but frankly I don't think that little of an off balance wheel is going to make any difference.
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Old 02-24-04, 05:37 PM   #6
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Quote:
Originally Posted by Smoothie104
Its probably the extra weight of the valve stem and cap, since there is no counter weight across from it, accept maybe some stickers. If you pull the tube out then the other side of the rim will be slightly heavier since there is no hole in that side.
Actually, the rim opposite the valve stem is usually the heaviest point. Rim manufacturers use steel pins to pin the extrusion at the joint which is usually exactly opposite the valve hole. It's easy to tell on a front wheel just hold it off the ground and see where the wheel stops spinning. I usually put computer magnets on a spoke near the valve stem to minimize the imbalance.
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Old 02-24-04, 06:31 PM   #7
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You know this almost sounds as if he has the tube pinched between the tire and the wheel bead. Try remounting the tire and see if that helps. If it is pinched you are headed for a flat.
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Old 02-27-04, 06:49 PM   #8
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Quote:
Originally Posted by Retro Grouch
Actually, the rim opposite the valve stem is usually the heaviest point. Rim manufacturers use steel pins to pin the extrusion at the joint which is usually exactly opposite the valve hole. It's easy to tell on a front wheel just hold it off the ground and see where the wheel stops spinning. I usually put computer magnets on a spoke near the valve stem to minimize the imbalance.
Yes, my Velomax rims are both heavy opposite the stem. Even the magnet doesn't correct it. The back wheel would make the bike bounce when spun up over 15 mph on a stand. Don't know how significant that is on the road, but suppose in theory it could be using energy and causing uneven tire wear.

I used about 4 inches of lead plumbers solder, wrapped around a spoke on both wheels, to bring them into balance. Not sure if that's recommended by anyone.
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Old 02-28-04, 12:03 AM   #9
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Does it make the bike move up and down while you're riding it? If yes, you have a serious problem. If no, then ignore it.
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