Front Wheel Bounce

[Richard]

Hi All,
I have a gg ec 250 2007.
Riding on the road above 40-50km/h i get front tyre bounce. There are 2 small flat spots in the rim, no buckle. My mate has a 05 with a much bigger flat spot and no bounce. Was wondering if my suspension might be too soft or something like that. I have a rim lock also (possible not balanced?). What is the best way to troubleshoot this issue please?
Thank you for any responses.

best regards,
Richard

 

[ditezz]

Richard,
Every dirt bike I have owned has had the same trait.I would guess as you do it is probably a balance isssue due to the rim lock.Ride it in the dirt and avoid the road then its not an issue .cheers

 

[m555]

If you have a dot on the side wall of your tyre put that opposite your rim lock. It is the heaviest point on the tyre. I had this problem and having worked in the car tyre industry you have a heavy and light point of a tyre( the heavy point is where the tyre is spliced together) i rang the place i bought the tyre from to confirm that its the same for bike tyres.

 

[Neil E.]

My bike was really bad for front tire bouncing. This was with a Tubliss setup with the rim lock/low pressure valve stem close to the high pressure valve stem. I added balance weights to offset this but it improved only slightly. It turns out the factory lacing job was poor and the front wheel had significant run-out.

There was also a low spot in the rim that was compounding the problem. I loosened off a lot of spokes to allow for adjusting. Once I offset the rim to raise the low spot, everything was fine. Truing a wheel is not difficult, it just takes a lot of time. Tighten each spoke only a small amount and go around the rim many times. The hard part is rigging up a pointer to mark where the rim is out of true.

 

[wasp4banger]

Tighten each spoke only a small amount and go around the rim many times. The hard part is rigging up a pointer to mark where the rim is out of true.

I've put a cable tie on the fork leg to use as a guide, zip it up tight and nip it off a couple of mm shy of the rim, spin the wheel and it'll tell you of any vertical or lateral run-out.

 

[skid jackson]

dyna beads .....

 

[rod]

I don't get it, is it doing this 'bounce' thing on glass smooth bitumen, if it is than it probably is a balance issue as others have said.

If it's on a rougher surface than glass smooth, maybe try increasing rebound damping by 1 or 2 clicks. ie: slow the action of the fork.

This might help in either scenario.

 

[Neil E.]

Front wheel bounce starts with runout or tire/wheel imbalance. The suspension won't amplify it unless there is something really wrong with your suspension. Fix the problem, don't try and reduce it some other way.

 

[Dave]

As others have mentioned, it's probably an out of balance front wheel.
Motion Pro makes light weight rim locks (Liteloc) that will help a bit. Skid mentioned Dyna Beads - the folks at advrider.com swear by them.