Bike Forums - Wheel balance

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Quote:

Originally Posted by Lemond1985 (Post 20803777)

Your valve stem serves as one. You can always tell your hubs are in good shape when a spinning wheel settles gradually, with the valve stem winding up in the lowest possible spot on the wheel.

I don't think so.

When I worked as a shop mechanic I installed a lot of bike computer wheel magnets. I assumed the bast place on the wheel to install the magnet would be the lightest point so I'd let the front wheel find it's balance point. Most often the lightest point was near the valve stem. If you think about it, when they make a rim, they remove material to make a hole for the valve stem and they add material where the extrusion is joined together.

Quote:

Originally Posted by Marcus_Ti (Post 20804256)

Have you noticed that if you have a friend hold your rear wheel up, you spin the cranks and get the wheel going as fast as the highest gear will allow....the bike doesn't "jump" around in his hand?

Like I said. Pendulums. They are a thing. In a stand driving a wheel hard you excite one.

No. I tried it (with my own hand) & the movement is pretty much the same either way.

I don't really get the pendulum idea since it's rate depends on length. It would have to be very short to swing back & forth multiple times a second

every now and then..
A few times over the years I ran into a "wheel balance" problem it was always the cheap tire/rim not seating correctly. Actually a big problem on motorcycle tires, rarely on bicycles, But it does happen.

Quote:

Originally Posted by HillRider (Post 20803709)

The rotational speeds of bicycle wheels are low enough that the imbalance would have to be rather large to be noticeable. I've heard of some riders carefully balancing their wheels using thin lead strips wrapped around the nipples next to the rims but it's pretty rare.

Out-of-round or unevenly molded tires are the most likely the source of any significant imbalance.

I agree, even with tires if you get one that's a bit off, and this is quite rare by the way, you can turn the tire a 1/4 turn at a time on the rim till the vibration goes away, problem is with doing that you can't index your tire's label to the stem, the best you can do if once you rotated the tire and found the sweet spot you then have to move the other tire to match the position of the other so it looks better for whatever that's worth.

Todays AL rims are machined too which one of the things that does is balance the rim, it's the same principle they do with racing tires, they shave the rubber instead of adding weight. However I've never had an out of balance non machined pinned rim either, so not sure the importance of machining, I read it improves the braking surface but I can't tell any difference.