Front Wheel bobbing up and down

[scra99tch]

Between 20-40 mph I get a bobbing motion, tried adjusting the compression rebound on the California vintage and that does not help.  Wheel spins true when on center stand.  Does have a slight drag from brake but it is ever so slight.  Could it be a warped rotor?  I get no shuddering when either linked brakes are applied or front brake.  I had the mechanic who put the tire on recheck balance on his machine and it is still balanced (has three sticky weights on one side and 2 directly on opposite side). 

This really started to happen when I put the new tire on so I suspect the tire is truly the problem.  Too late to return or get a refund. 

Any ideas?  Think tire beads would help?


 

[SportsterDoc]

Is there a section with the bead not fully seated?

Perhaps tire itself is out of round?

[yogidozer]

run your hand around the outside of the tire. any uneven wear or bumps? if it was a brake problem, you would only feel it when braking.
if not, have a different guy check the balance.....on the tire not you 

[rocker59]

Between 20-40 mph I get a bobbing motion, 

This really started to happen when I put the new tire on so I suspect the tire is truly the problem. 

The first thing I'd suspect is balance.

The second thing would be a bead seat issue.

The third would be an out of round tire.

You DID balance the tire, right ???

[Rich A]

Also make sure that the forks are aligned--both the same height above the triple tree.

Rich

[oldbike54]

 What brand and model of tire ? Also look for any flat spots on the rim .

 Dusty

[guzzisteve]

Find a different shop to balance wheel. Sounds like it was put on w/o notice the balance dot or mark. I never end up w/weights on both sides. They should start w/o any weights on rim. This is why I do all my own wheels. Mine end up w/few weights on at all, but I buy quality tires and watch what I'm doing.  Hey, It's your ass on the tire.

[scra99tch]

I just changed fork oil (bobbing happened before messing with forks) measured that the forks were even above top clamp.

I looked at periphery of wheel apex when spinning also and did not see any high spots.  I may just take wheel off and have someone else re-balance.  I saw him put the wheel on the machine and come up with 0-0 on the digital readout.  So maybe the machine was out of whack? 

I'll look closely for bead issue.

Thanks for replies.

[scra99tch]

Metzler ME880

[rocker59]

Metzler ME880

Those are good tires.  I'm going to put my money on bad balance job at the shop.

[kingoffleece]

Could be the tire.  I just installed my third front Michelin pilot of the front as the first two were out of round.

[scra99tch]

I did try move the forks with it on the center stand to check if there was any bearing lash, none that I could feel.

[Sheepdog]

My Vintage developed a lateral runout problem on my front wheel after a ham fisted tire installer (me) bent a bit of the wheel flange with a too-long tire lever. It balanced, but exhibited some scary behaviors at various speeds. Once I diagnosed it, I sent it to Woody's Wheel Works in Denver for repair. It turned out to be a $200 mistake...

I have also had tires fail to fully seat to the bead. My last Michelin Activ front tire took lots of lubricant and over 80 lbs of pressure before it finally popped into place. It also balanced, but hopped as the bike gathered speed. I had to re-install it...

[scra99tch]

Turns out it was the tire. 

Put it on balance machine (as we did not have a magnetic base to check rim runout) crouched down and spotted a point on far side of balance machine and rim looked good as the rim to point did not move that much.  But looking at tire there was a definite high spot.  Pulled tire and remounted thinking it was the bead and got the same high spot. 

So the Mechanic called his distributor and they took the tire back even after ~1500 miles on it.

 

 

[Sheepdog]

Seems like a happy ending. New tire yet?

[azguzzirep]

Great news! Glad you got it figured out.

My EV gets a new front tire next week. Last week's ride to the Guzzi rally had a few scary parts because of wet slick back roads and curves!!😨😨

[dl.allen]

Sounds like you got it solved.
If not check balance on back tire.  I had a back tire that could not feel out of balance but would make front forks jump up and down at certain speeds

[azguzzirep]

Great news! Glad you got it figured out.

My EV gets a new front tire next week. Last week's ride to the Guzzi rally had a few scary parts because of wet slick back roads and curves!!😨😨

A thing of beauty!  Sure handles better now!