Ladies and Gents,

I am trying to chase a bobble down. Tire pressure is not the issue. Spokes are tight and wheel visually looks in round. The bobble happens at around 45 mpg on deceleration. High speed the bike is fairly smooth. Again it ONLY happens at 45 and on deceleration. Stem bearings are torque to specifications. Fall away seems reasonable. I even added an 8th turn for good measure. Front end on jack feels solid... no indication of anything loose. Fork pinch bolts torque to spec. Both tires are stock with 5k each. I wonder of new rubber would cure the problem. Also I noticed there is no zirk fitting for grease like on my Fatboy.

Here is the question:
Has anyone else experienced this and found the answer that corrected their problem? If so Please describe what you found.

Ride safe,
Mike

 

I'll try again... Thinking it could be tire cupping...

 

A few things I'd try is jack the front wheel off the ground and she it the front wheel feels loose side to side. Then spin the wheel and see if there's any bumps or wobbles as it goes round and round.

Next would be to take the front wheel and have it balance again. I had a new tire installed on a 21 inch wheel and when I got over 60 it would start boucing, it was never balance.

Jack up the rear wheel and see if it's loose and also check the swingarm too. Also check rear wheel alignment with a coat hangar.

Good luck

 

+1 with racingjake, also would be helpfull to know if this just started or always been this way or any mods at the same time this started?

 

Thanks guys... The problem was just noticable a thousnad miles or so. Tonight, I checked fall away, loosened one fork tube and checked .5 inch from fork tube cap, played with air pressure.

I note the side of the tire is wearing more than the center. I feel this is primarly due to more breaking into turns. I am wondering if as the rubber wears on the sides, the center begins to bulge more. At 40 psi, problem is nasty comming down from 50 to 40 mph. At 20 psi, it is far less noticable. at 30 psi, it is tolarable.

Wheel is solid, neck bearings are good. Fall away is about 2.5 inches with clutch cable removed. rear swing arm is solid on the jack. No signs of oil out of fork tubes.

Funny thing is I have the same stock tire on my fatboy. going into a left turn is good. going into a right turn give the shakes. I can see why as the tire seam moves in and out while looking down at the pavement. I am beginning to think these dunlap "harley" tires are crap. With the wear on the sides, I see mild cupping on the center tread that alternates left right, left right at 2 inch intervals. Hmmmm.... New rubber......hmmmm.

thx,
mike

 

BTW, 5400 miles, 4 year or more old tire.

 

Is this "bobble" up and down, or side to side?

 

side to side with light hanlebar touch...

 

I've recently stated to experience a side to side bobble. Mine is more at low speed, and most noticeable in a right had turn. Tires are fine.

 

thats the tire seam... probably if you look down at the tire while riding (be careful) you will see the tire move in and out a bit. My other bike is real bad on the right side.