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Front wheel imbalance? CM400T

Brad from Lasalle

Veteran Member
Joined
Jun 18, 2021
Total Posts
133
Total likes
1
Location
Lasalle,Ontario,Canada
I purchased a new front tire Kenda K657 challenger 100/90/18 for my bike. The tube was reused. The place I had mount it used beads to balance the tire. When I went for a ride there was a lot of up/down movement in the handlebars around 30 to 40 mph like the wheel is out of round. When I got home I raised the front wheel off the ground and spun the wheel. Then I lowered the jack slowly until the tire just touched the ground. It is touching on 1/3 of the diameter and not on the other side. It seems around the valve stem is the worst. When I looked at the bead seam line along the edge of the tire just above the alum mag edge you could see it was out further in that location so I let the air out and pushed the tire in at that area then reinflated it. The gap was smaller but the out of round still exists. I wonder if the new tire is out of round or the mag? I know this bike has some front end damage as I am still working to correct the crooked steering (upper triple tree plate is due in today!)When I spot a reference point to the mag lip it doesn’t seem it is that bad. I called the place where I had it mounted and he will put it back on the machine on Monday. I would think the machine should catch this condition? I am also thinking it’s either the tire itself is defective or the mag is bent, there really isn’t anything else that could cause this, correct?
 
The thin raised line near the bead should be even all the way around the rim, if it's not then the tire bead isn't seated fully. It may correct with riding but it's best to have it reset at the shop, especially since there's a tube involved.
 
Do you think the front mag wheel can run without a tube or is this rim designed for tube. I see Partzilla calls out tubes and tires but the manual mentions tubeless equivalent tires in them. Just curious.
 
Do you think the front mag wheel can run without a tube or is this rim designed for tube. I see Partzilla calls out tubes and tires but the manual mentions tubeless equivalent tires in them. Just curious.

I believe Comstar mags are imprinted with the word "Tubeless" somewhere on it as this old post by Jim confirms.

Tubeless or not
 
The early Comstars don't say tubeless but the bead safety ridge is there so you can run tubeless. Later wheels are stamped Tubeless.
Tube only wheels don't have the raised bead ridge that keeps the bead from sliding in under low pressure situations.
 
The early Comstars don't say tubeless but the bead safety ridge is there so you can run tubeless. Later wheels are stamped Tubeless.
Tube only wheels don't have the raised bead ridge that keeps the bead from sliding in under low pressure situations.

Thank you Jim, I went to review the rim and did not see any tubeless marking so that would explain it. Wheel is back at the shop this morning and I dropped off the fork tubes to see if they can be straightened. Both will be ready later today . I will update this post later once I see the results.
 
I found out the the rim is out of round slightly. Any advice on how to true it up? If I loosen all the bolts to the hub do you think I could flex it enough to get it closer to round? Or do I need to take it to somewhere with a large press? The tube is running with dyna beads in it but it doesn’t matter due to the out of round condition.
 
The Comstar wheels are NOT designed to take apart. People have done it but they have never answered the question if the reassembly was a success. I would source a replacement wheel. See your PM
 
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