Strange "wandering" feeling at rear wheel??

[FredL]

My 2002 Sprint RS occasionally exhibits some very strange handling characteristics. It only has 8k miles on the odometer, and about 400 miles on a new set of ContiMotions, which I had mounted at a local shop. Every so often I get a very disconcerting feeling that something is loose under me, to where the bike feels "squishy" while riding straight ahead at relatively low speeds, 25 to 40 mph, as if I just hit a small patch of greased ball bearings. I have checked my tire pressure, which I run at 42R/40F, and neither was low. I don't have a center stand, but gave everything a good shake while it was on a lift at the shop, and felt no play on the rear wheel or swingarm. The weird thing is that it doesn't do it all the time! Anybody have any idea what could be causing this? It is a very bad feeling, which doesn't inspire confidence at all, even though it generally feels solid. Any ideas would be most appreciated, thanks!

PS. the previous owner treated the bike terribly, and dropped it on both sides at least once.

[Triumphforever]

Sounds like it's probably the surface of the road, but check to see if they put the tires on in the right direction and whether one fork seal is leaking.
Chris

[roadrunsl]

I believe it is the new rear tire. I have the same problem after changing the tires two months ago. I felt this when I rode the bike very slowly - with 10 to 20 mph. When I put the bike on it central stand and rotated the rear tire, I noticed that the tire was "jumping" at one place. The tire had some kind of little geometric distortion. After this I talk with a guy at the tire shop and he told me that it is common thing with some new tires. After some time of running, when the tire will slightly wear out, this jumping will disappear.

[Mickea]

Originally Posted by roadrunsl

I believe it is the new rear tire. I have the same problem after changing the tires two months ago. I felt this when I rode the bike very slowly - with 10 to 20 mph. When I put the bike on it central stand and rotated the rear tire, I noticed that the tire was "jumping" at one place. The tire had some kind of little geometric distortion. After this I talk with a guy at the tire shop and he told me that it is common thing with some new tires. After some time of running, when the tire will slightly wear out, this jumping will disappear.

roadruns, that sounds like a poorly a fitted tyre and a guy that cant be bothered to fix it!
However, that and the road surface would account for the symptoms.
Does the issue occur on the same sort of road or is there any other common ground? Good luck with sorting it out anyway.
Rgds Mick

[KitNYC]

First thing I would do is drop the front to 36 PSI; max recommended pressure is 36 front/42 rear, and a lot of people find that 10% below that is good.

Cheers,
-Kit

[DaveM]

I agree and 36 and 42 are maximum pressures.

ie max load = rider + pillion = luggage

[triplestrength]

Please get a second opinion on the tyre, new tyres should look and "feel" perfect if they don't something is amiss.
Triumph recommended pressures are good for all conditions loaded or not, these are Radials not cross or bias belted tyres.
At least get the tyre remounted on the rim with plenty of tyre soap. It sounds like it could be mounted slightly off and ossilating as you ride.
Was it balanced?
Are you positive there is no play in wheel bearing?
Tyler ( ex tyre tech)

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[triplestrength]

I reread your post again, it's possible in mounting the tyre, the beadwire could be damaged please get it looked at ASAP.

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[DaveM]

Originally Posted by triplestrength

Triumph recommended pressures are good for all conditions loaded or not, these are Radials not cross or bias belted tyres.
( ex tyre tech)

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I would not agree with that comment but you believe that if you like.

Of course loads make a difference to tyre pressures and performance, no matter what any vehicle manufacturer recommends (usually on the high side in my experience).

Any tyre with more pressure than the respective load requires will perform differently in handling, braking, grip and wear.

I'll leave it at that

Cheers
Dave

[triplestrength]

I'll agree to disagree:-)

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