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I read with interest every thread I could find on front end shimmy, which was endemic to my '07 since new. Speculation about early frames being the culprit were moot in my case. I tried many fixes: removing my leatherlyke hardbags, increasing rear shock preload, running 38 psi in the front (suggested by Performance Triumph's lead tech Brian), and even mounting a 4 lb Parabellum Scout fairing seemed to help a little, but I could never completely eradicate that off-throttle wiggle. It looked like a steering damper was in my future.

Until I replaced my tyres a few days ago with Metzeler ME880 Marathons front & rear, and the shimmy is GONE. 100% hands-free-riding gone daddy gone! I don't know if it's the different tread pattern or compound, slightly larger 140-section rear, or not mixing bias/radial like the stock Lasertec/MEZ2 combo, but she's a completely different bike. More aggressive profile on the ME880 too, which eases turn-in but does increase recovery effort a little. Traction seems to have improved as well, but they're not completely scrubbed in so I haven't tested the limits yet. Either way, my last reservation about the bike is completely gone!

Some errata: when changing tyres at 14.2k miles I also replaced the chain/sprockets & brake pads. EBC HH pads offer a marked improvement in braking feel and power IMO. I also discovered why Triumph wants $80 for their 18t countershaft sprocket - it has vibration damping weights, whereas the $20 aftermarket ones do not. I went with a 17t from British Customs, but can barely tell the difference - no discernible vibration increase, and my tacho/speedo needles are still more or less parallel in top gear. I may be able to tell more when I install/break in my new Barnett clutch kit & am able to really romp on it again sans slippage. The BC 43t rear sprocket in black looks trick too.

I really liked running Marathons on my old Magna (3 sets at about 12k miles apiece after I wore out the OEM Dunlops), and am glad I read about the possibility of them fitting the Bonnie in this forum. For anyone curious, they mount up and fit just fine. I'll post again when I hit the wear indicators, but if they outlast the OEM Metzelers you'll have to be patient!
 

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Indeed. My front wheel had a bit of a wobble to it when I first had the bike. It wasn't disastrous so I didn't worry unduly. When I replaced the front tyre this was totally eliminated. Basically I think it's a matter of getting the wheel balanced properly. I replaced the front Metzeler ME33 with another ME33, and the second one is so solid I can take my hands off the bars. I could never do that with the first one.

When experiencing a wobbly front end, the first thing to look at is the wheel in my opinion - balance and trueness.

Good info, thanks for the post.
 

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Fork mounted fairings

It's good your wobble is gone now, glad you've got it solved.

For the record, fairings/large windshields that mount TO THE FORKS will not relieve wobbles, sticktion or headshake, they will universally aggravate rather than allieviate any pre-existing problem. Just a word to the wise: If your front end has any shakes or wobbles, get it solved before you mount that bigbad fairing.
 

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I have read of a couple of Thruxtons with major front end wobble problems and this was only resolved with new wheels. Usually, front end wobble like you describe is due to a manufacturing defect in the tire itself. The rims are not heavy enough when compared to the tire which is also at a greater distance from center, to be the root cause of this problem, IMHO. Someone who knows something about tire balance and has a good machine could possibly get the dynamic balance such that there was no wobble; however, after a little tire wear, it would most likely reoccur. This solution may be OK on an auto; however, I would want the tire replaced on a bike. Most tire balancer techs have no idea of what they are really doing to achieve balance, and most spin balance machines only do a static balance, not both a static and dynamic balance. Static balance keeps the tire from bouncing up and down. Dynamic balance keeps the tire from wobbling from side to side. Most motorcycle tires only need a static balance, IMHO. If they need a dynamic balance, there is enough problems with the belts, that I would not want to ride on them at speed.

The reason the balance weight is "halved" and one is placed on the opposite side of the wheel from the other (at the same radial location) when a static balance is done is to keep from disturbing the dynamic balance. When a tire is in perfect dynamic and static balance, there should be only one weight on each side of the rim. If there is more than one weight on a side, the tire balancer did not do his job, and you will have balance problems before you wear out the tire. When this occurs with todays tire balance machines, the tire has manufacturing problems and should be replaced, IMHO. The operator of the machine has no knowledge of what he/she is doing other than they are doing what they were taught to do--place the weight where the computer tells them to.

Before computers, tire balancing was an art, and most tire balancers had some knowledge of what they were doing. A properly calibrated bubble balancer can achieve just as good a static balance as the most expensive computer balancer sold, IMHO. Among the first spin balancers--the Hunter Balancer--was a good balancer that could do both a static and dynamic balance; however, most techs only did a static balance with this balancer. It spun the tire on the car and there was all kinds of advertising claims as to this being much better than taking the tire off the auto. It's demise was the disc brake system. The Hunter could not spin the tire fast enough to achieve proper static balance because of disc brake drag. Their solution was to replace the motor with a much larger motor which helped some, but, did not completely resolve the problem. Many tire shops reverted back to their cheap, simple, and accurate bubble balancers to get away from all the customer complaints.:D
 
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