Front wheel bounce at 40mph  By  bstow (Read 3,292 times)

It is a smooth ride until speed reaches about 40.

Then it bounces and the bounce increases with more speed.

What in the suspension should I check?

I have the same on my EVO 150.
The problem is that the tires are not balanced from the factory, just put on the rims, and pumped up with air.
Let some air go, downto like 10PSI, ride around for a few hundred feet, blow up more, and more, until you get 35PSI.

You could also just keep on riding. usually when the tire seats on the (mostly on alloy) rims, the vibrations will lessen. I have 600km's on my 150, had a very bad oscillation, but now is hardly noticeable. (mechanic told me that the alloy rims and tires (esp the 3.5x wide tires) are self balancing tires.

Mine does the same thing I balanced the tire and its % better.

You get them spun balanced and then you will know what the problem really is if the tire shop is any good. Self balancing only works if the tire and rim are true inside and out and then it is usually a specially coated tire such as one that has had a Rhino treatment otherwise it is just hot air from a mechanic trying to get you to go away without having to fix things. With a good tire and rim you should be talking about 1/2 to 1 ounce of weight to balance a good tire and rim. OEM tire and rims on Chinese bikes are generally the cheapest that can be found so quality can be very inconsistant.

If balancing does not take care of things or reveal a defective tire/rim then you could have a defective front spindle/axle shaft or wheel bearings.

Thanks for the responses.

Will start trying them to see what will work.

I was being sarcastic BTW