Strange rhythmic shudder at speeds over 65 mph.

[doubletee]

Developed a rhythmic shudder (comes and goes every second or two) at speeds over 65 mph. It's not extremely pronounced, but can certainly be felt, and the rhythm cycle increases with speed. Feel it mostly in the handlebars, but somewhat in the seat, as well. Seems to have started after replacement of the front tire (Avon). My first thought is wheel balance, but I would think the shudder would be constant, instead of intermittent/rhythmic if that was the case. Anyone have any other thoughts?

[BonS]

Perhaps both of your tires have issues with balance or run-out. The slightly different diameter will make them rotate at different rates and the overall vibration will ebb and flow as you go down the road.

[Farther]

Perhaps both of your tires have issues with balance or run-out. The slightly different diameter will make them rotate at different rates and the overall vibration will ebb and flow as you go down the road.

  Good point.  My new Avons don't ride as good as the worn Metzlers they replaced.  Maybe there was a bad batch of Avons.

[Pete]

Last thing changes = first suspect.

Check for out of round or flat spot.
Also gauge the tread all around the tire to see if the tread and tire body are not concentric.
Ie. more or less tread in certain areas.

[sandy]

It is possible that a new tire can cause another issue to surface. Check shock bushings, wheel bearings, etc.

[WintrSol]

Sometimes, the problem with a bad tire is invisible; adding extra air to one like this will sometimes reduce or change the problem. A friend had the dreaded head-shake on his Suzi 1500 from new, which only got worse, and usually means a head bearing replacement with better quality bearings. I convinced him to raise the front tire pressure 5lbs, and the result convinced him the tire was just bad inside; he replaced the tire, and problem solved.

[Karen]

Check the u joints on the drive shaft.