Unbalanced front wheel symptoms?

[chsonnu]

I balanced my new front wheel by spinning it on the axle (without the brake calibers attached of course) and attaching weights until the spins appeared random.  Now when I ride along at about 15-25 MPH, I can feel the tire wobbling a bit, but not at speeds lower and higher.  My first instinct is to attempt another balance job but I feel like I got it right.  Anybody experience this before?

[Atesz792]

I had an out of balance combo of tires this year. It felt like riding on a real bumpy dirt road at and above 130kph/80mph. Also my gauges looked like they'd shake off any minute. Real scary sh*t, I can tell you. Please get it properly balanced by someone who has that machine attached to a computer, my wheels required 50 grams each, and they'd been balanced before (with the mothod you described above).

[Big Rich]

Look real close at the bead of the tire. If the bead isn't seated properly around the wheel, it will feel like the tire is severely out of balance. There's a ring of lines on the tire that should be about 1/4" away from the rim the entire way around.

[The Buddha]

Chsonnu: The balancing method you used is - well if this is what you did, I'll say OK - Spin it. attach weitgh @ the top when it stops. Repeat till it stops different location 3 consequent times.
Then its OK.
Atesz792: That far out of balance ? I've not bothered to balance many of my tires. I've had nothing close to your experience. Yea check what ig Rich said.
Cool.
buddha.

[Old Mechanic]

Assuming the wheel-tire spins freely.

Spin the assembly and let it come to a stop, several times. I take the wheel off and use a piece of steel rod between two support 4x4s in my garage but it should work on the bike without brake drag.

Mark the top position where it stops. If it does not stop in the same place consistently the the wheel is already balanced with no weight added.

If it stops in the same place, even reverses rotation to go back to that same spot, then that point (top) is where the assembly is lightest.

Add weight and repeat the process, until the place where you put the weight is between 60 and 120 degrees of the new top position.

Add a smaller weight to the new top position. If it still stops in one place change the smaller weight until it does not stop in the same place.

regards
mech

[Old Mechanic]

I have balanced thousands of auto wheels and the principle is the same.

There is the primary "light spot"and the secondary "light spot". The way to KNOW you have put the right amount of weight in the right spot is the 60-120 degree rule. Basically you are doing the first balance, call it the gross balance. Then the second or fine balance.
You should only need two weights and they should be close to 90 degrees apart (emphasis on close).

The first weight will always be a larger weight. If you add too much weight the ckeck spin will leave the weight outside of the 60-120 range. Too light less than 60 degrees, too heavy more than 120 degrees. If the weight you added makes the check spin bring that weight to more than 120 degress (closer to the bottom) you have too much weight added. It it does not reach 60 degrees you have too little weight added. It should take no more than two weights to get it balanced properly. The weights can be taped in place until you have them in the proper position.

All of this drivel aside (both posts) I think if you are feeling a vibration at 15 MPH, it's more likely due to a bent rim or an improperly seated or defective tire. It should be easy to see when you spin the assembly and look at the tread and rim.

regards
mech

[Old Mechanic]

In most cases the larger weight is somewhere close to opposite the valve stem. Many tire manufacturers mark the light spot of their tires which should be near the valve stem when the tire is mounted.

regards
mech

[chsonnu]

Thanks guys.

Old Mechanic, I'll definitely try out the 60-120 degree 2nd weight system you have there.  Do you bother putting weights on both sides of the wheel?

[BockinBboy]

Just one side - I'm not aware of any application that would require each side.  I'd imagine that would introduce another variable and make it harder to hone in the correct weight to use.

- Bboy

[Old Mechanic]

A dymanic car wheel balancer tells you wich side of the rim to put the weight on. On a bike I would go for the center of the wheel if practical. If I was doing it on the bike, I'd back off the axle bolt tension a bit.


regards
mech

[gsJack]

I balanced my new front wheel by spinning it on the axle (without the brake calibers attached of course) and attaching weights until the spins appeared random.  Now when I ride along at about 15-25 MPH, I can feel the tire wobbling a bit, but not at speeds lower and higher.  My first instinct is to attempt another balance job but I feel like I got it right.  Anybody experience this before?

I mounted my own tires without balancing them on the four old 400-750 cc Hondas I had before the GSs and never had a problem with any of them because I never went over about 70 mph with them.  Atesz792 reports above that he had out of balance tires that felt like riding on a real bumpy road above 80 mph.  That's what I'd expect from out of balance bike tires, bumpy or bouncy not wobbly or wobling at higher the speeds.

First thing that comes to mind is a bead not properly seated like Rich mentioned above, did you check the bead line like he suggested?  I would not expect out of balance  bike tires to be a problem at 15-25 mph unless they were really badly out.

Only time I've experienced anything like you describe was years ago on my 97 GS when I put a 110/70 BT010 supersport radial on the front with a 140/80 AV36 sport touring radial on the rear and it felt what I called twitchy at the slow speeds your having wobble.  Twitchy or wobbly not bumpy or bouncy like imbalance.  What kind and size are your tires involved here?

[The Buddha]

Out of balance tires dont always get worse with increasing speed. I've heard 45 mph and 65 mph are 2 speeds where these seem to peak in their ill effects.
Who knows, I've never had it personally.
Cool.
Buddha.