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rear tyre issue

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by TheForgotten, Jul 8, 2011.

  1. having trouble with my rear tyre.
    On a ride on sunday it felt skitterish, on monday i checked tyre pressure and it was a fair bit down (22psi), pumped it back up to 34 and went about life for a few days, but i took it for a decent ride yesterday and it feels the same. Tyre's a michelin pilot activ, new last november, done maybe 800km.

    it feels fine when cold, but feels crap once it has some heat in it

    any ideas???


     
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  2. You might have killed it... 800km's in almost a year? Or 8000?

    If it's 8000, replace it, if it's 800... It may have gone off...?
     
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  3. I've just solved a major problem with my tyres, being kept (un-intentionally) under-inflated, they felt like they were wandering over the road, like I was on skates at times. Turned out they were badly scalloped and feathered, could be the same with yours, but are you sure they have done only 800K's???
     
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  4. yeah only 800km
    did maybe 400 then crashed, it sat in my shed for around 6 months, then did the rest since getting it back on the road maybe 2 months back
    oh and it was 32psi when i got it on road, the drop in pressure happened over those 2 months.

    i thought about the rubber hardening, but it's easy to manipulate with my fingers, the same way my week old front manipulates
     
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  5. Have you re-checked the pressure? What's it at now?
     
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  6. try pumping it up to 36, to me it sounds like inadequate air pressure.
     
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  7. I agree, 34 seems a bit low for a back tyre, I run mine at 42

    but it does sound like a slow leak, I'd get the thing checked, maybe the valve rubbers have gone hard, try replacing it....
     
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  8. 34
    manual says 33f/34r
    there was no change in pressure over (almost) a week. i know the valve was replaced when i got the new tyre, would it really go hard in such a short time??

    also, what sort of increase should i expect from cold to hot? 2-3psi??
     
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  9. doesn't matter that the manual says some tyres actually require more than what the manual states.
    O my bike for instance running metzelers I have front 38 and rear 40 but it is a heavy bike with telelever suspension.
     
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  10. i just checked, the manual states KG/CM2 and apparently i screwed the conversion. should be 36psi, i'll see how that goes
     
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  11. what bike and what it your pace?
     
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  12. cbr250rr
    trying to learn to crank it up before i upgrade. i would say pace is ~speed limit. trying to push much beyond that through the fun bits is uncomfortable (yeah yeah i know stick to the limit blah blah)
     
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  13. needs a fair bit of air then.

    just double check that your rear end isnt loose or the shock hasnt lost its rebound dampning or something.

    all possibilities.
     
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  14. ok ... you said something about a short ride, and a crash, and a long wait, and then you got back on, and now it doesn't feel right and you think it's the tyres. With you so far.

    Who repaired the bike?
    What had to be replaced?
    Was it an insurance job?
    Was the frame jigged for true? (Checked for straight.)
    Were the forks removed and checked for true?
    Were the steering head bearings replaced?
    Was the front axle removed and checked for true?
    Were the wheels checked for buckles or warps?

    ...

    See, if the tyre is not the problem, but the bike feels bad - Warning Wil Robinson! Danger! Danger!

    Checking the tyre as a first step is a sensible thing, and that's right. Good thinking. But if the tyre's right, and the bike still feels wrong, then get it checked by a pro - and not the one who fixed it.
     
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  15. rear end loose?
    shock is my next thought, but i compared it to another identical bike with a known shagged shock and mine doesn't bounce nearly as much (and the other rider weighs ~20kg less than me)
     
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  16. as in, just double check swingarm bearings, wheel bearings etc. just for play in things that shouldnt have it. not something silly like the rear wheel is out of alignment after a chain adjustment?

    is this shock adjustable for anything, like rebound, compression etc. or is it preload only?

    explain your crash. even though it may have been low speed it can still bend shit.
     
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  17. just checked, no play. wheels appears to be aligned (chain sits evenly over sprocket teeth)
    nah preload only. does not pogo when i bounce on the seat
    clipped the car infront of me at round 10km/h. knew i was in for a ride so i tried to filter but missed. caught the rear bumper using the nosecone/LH fairing as a cushion. bar snapped left full lock, threw me at the tarmac off the right side and laid on the right side snapping bars to right full lock
     
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  18. ... ok, and you've stripped and rebuilt the front end...

    All of which just means that we don't have an obvious cause. And we've checked stuff by eye, to the extent that there's nothing obviously wrong, but we haven't actually measured anything up and genuinely eliminated it as a possibility. And it may even be that it felt shonky before the stack but you're now noticing it.

    LOL - Geez, mate. Don't make it too easy for us, will you? I'd hate get bored by answering these simple questions.

    I don't know - it could be fucken anything! Any one of the 4,321 possible faults with the chassis and suspension could be to blame.

    I'd be looking to maybe get another rider on the bike, pref one who's owned one and ridden it a bit, get his comments. And beyond that ... I don't know. Possibly find out how much it would cost to get at least a basic measure and check of the frame.

    At some point, I think we need to start properly checking things and eliminating them. The fact that everything looks about right, doesn't really do that.

    Sorry I can't be any more help.
     
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  19. well yeah, circumstance depicts i can't ride often outside my 7km work commute, in which time i don't reach speeds or lean angles high enough to notice if it feels wonky. that same circumstance says i can't afford mechanics
    have had an offer of someone else taking it for a run, guess i'll just wait and see what he says
     
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  20. Ah huh. Me too. Well, the povo part.
     
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