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hiya,

I was recently thrown off my ZXR when I accellerated to 25 in first, then went to change gear. The back wheel wobbled quite violently and threw me off. I bust my wrist and dislocated my femur! OUCH! Broken bits include: rear set, rear seat panel, mirror, clutch lever and bent clip on.

I had noticed that it wobbled a few times during down shifts, especially at quite high revs (6500-9000rpm). Quite un-nerving at the time, but put it down to damp under trees etc?

Bike has Dunlop Sportsmax tyres with about 800 miles on them.

What do you think caused it?

I think it may be that the clutch was out of adjustment and just came in too quick. I thought the slipper clutch should soak up any hard shifts?

PS those R & D crash protectors worked a treat in protecting the main fairing and forks.

Thanx

ouch! Thats really unusual!

How were the tyres? If the only had 800 miles on them you might have caught a bit of the tyre that hasnt yet scrubbed in yet? Was this in a straight line or on a corner? Otherwise you right in saying that the slipper clutch should have soaked up any lock ups unless its had had it.

macman1 wrote:hiya,

I was recently thrown off my ZXR when I accellerated to 25 in first, then went to change gear. The back wheel wobbled quite violently and threw me off. I bust my wrist and dislocated my femur! OUCH! Broken bits include: rear set, rear seat panel, mirror, clutch lever and bent clip on.

I had noticed that it wobbled a few times during down shifts, especially at quite high revs (6500-9000rpm). Quite un-nerving at the time, but put it down to damp under trees etc?

Bike has Dunlop Sportsmax tyres with about 800 miles on them.

What do you think caused it?

I think it may be that the clutch was out of adjustment and just came in too quick. I thought the slipper clutch should soak up any hard shifts?

PS those R & D crash protectors worked a treat in protecting the main fairing and forks.

Thanx

I've read this several times and still don't understand what you've done? You fell off while changing up from first to second at 25mph? Presumably while cornering because I can't see how that would happen in a straight line.

A slipper clutch will do nothing to 'soak up' clumsy upshifts, only downshifts. Depending on who you listen to, the KBATL clutch doesn't really do anything on downshifts either. And it's not fitted to all ZXRs.

I apologise if this sounds unsympathetic - I am really sorry to hear you've come off and I hope both you and the bike mend quickly - but I think you need to hold your hand up to rider error on this one. A badly adjusted clutch wont help, but the real solution is don't change gear while leant over in the weather/road conditions we've got at the moment - it's always going to unsettle the bike.

Good luck fixing it.

agree with what Deviant says but check your rear spindle is done up properly and rear wheel is aligned, also check the cush drive is all there are in good condition.could be a number of things, cold tyres, weather conditions, but all worth checking.

Strange...

We need more details, really - was the road dry/wet/icy?

Were you leaning over or in a straight line?

How did the bike go down? Did the back step out and flick you off when it gripped again?

From the initial post, a few ideas came to mind. First, it sounds like your rear wheel bearings have collapsed. This would cause the bike to weave when you come off the throttle at the very least. Grab hold of your rear wheel and see if it's loose in any direction.

800 miles on the tires should easily be enough to scrub tyres in an any weather, but it did make me think of my bike a few weeks ago. I'd just put a brand new shiny set of Avons on, but it was pelting down with rain and I just couldn't get any heat into them even after 40 miles on the motorway. I found that changing up from 1st to second the rear was losing grip and snapping out on me. But bear in mind that's on a ZX9-R, which has a clunky 1st-2nd change anyway plus a shedload of power, and that wasn't really enough to cause a major drama...

deviant wrote:
I've read this several times and still don't understand what you've done? You fell off while changing up from first to second at 25mph? Presumably while cornering because I can't see how that would happen in a straight line.

A slipper clutch will do nothing to 'soak up' clumsy upshifts, only downshifts. Depending on who you listen to, the KBATL clutch doesn't really do anything on downshifts either. And it's not fitted to all ZXRs.

I apologise if this sounds unsympathetic - I am really sorry to hear you've come off and I hope both you and the bike mend quickly - but I think you need to hold your hand up to rider error on this one. A badly adjusted clutch wont help, but the real solution is don't change gear while leant over in the weather/road conditions we've got at the moment - it's always going to unsettle the bike.

Good luck fixing it.

Agree with Deviant.

Another thing you should check is your chain and sprockets - tight spots in the chain, hooked teeth on your sprockets are not going to help things

Thanks for the feedback. More info as requested!

The tyres were cold, but it was a mild, dry night with no frost. I'd only ridden about 30 yards.

I was going straight and not cornering or leaning.

The tyres are nicely scrubbed over the full width of the tread.

I was upshifting and it does have the KBATL clutch.

There is no play in the wheel bearings or cush drive and no grinding when I turn the wheel. I assume the alignment is okay, depends if the length of wood I used to check is true. Spindle is tightly done up as it was after tyre change, I assume it was torqued correctly.

The chain is quite taught with about 1.5 cms of play in the middle, but has no tight linkages and the sprocket's teeth are good and deep.

Basically the back wheel 'wobbled' and then slid out to the right, throwing me to the left.

I don't change gears or use the brakes whilst cornering - slow in - fast out!

Hope this helps!!??

PS. Does anyone know how to remove the bar from in the clip-on? I don't want to have to remove the top yoke. it comes out so far, but it just twists and won't come out?

i would say you hit something slippy on the road ie. diesel, gravel etc
gem

Who changed the wheel?

There's a spacer that can easily fall out of the inside of the sprocket carrier, everything seems fine until you ride the bike, but even then I managed to get into the lead of a race with the wheel getting worse and wobbling like crazy, then thought I'd better pull in, nothing seemed wrong until I took it all apart, by that time the bearings were knackered !

However, how the hell anything like that would cause you to fall off I don't know. It makes absolutely no sense to me

macman1 wrote:PS. Does anyone know how to remove the bar from in the clip-on? I don't want to have to remove the top yoke. it comes out so far, but it just twists and won't come out?

Because it's waisted, you won't get it past the fork. Another way of getting it off is to drop just the fork, if you don't want to get the yoke off. (you obviously have to get the wheel out and mudguard off first)

Actually, thinking about it, if the tyres were stone cold, and you were a bit ham fisted on the throttle, maybe combined with a bit of a greasy road, the rear could have just let go and you're on your @rse before you know what happened

Yeh, maybe I was just unlucky, I haven't been back to the road to see if there were any man hole covers, greasy spots or whatever. Doesn't seem to be any mechanical reason?

Is it possible to lower both fork legs simulanously? I have it on paddock stands at the moment so it is pretty stable. I would only need to lower it by a couple of inches to get the clip on off.

im sure its simpler to take the top yoke off, the bike doesnt need to be on any stand, it only takes one person to do and taes about 15 minutes.

macman1 wrote:Yeh, maybe I was just unlucky, I haven't been back to the road to see if there were any man hole covers, greasy spots or whatever. Doesn't seem to be any mechanical reason?

Is it possible to lower both fork legs simulanously? I have it on paddock stands at the moment so it is pretty stable. I would only need to lower it by a couple of inches to get the clip on off.

Yeah, probably a bit tricky though, I've never tried it. TBH it's probably easier getting the top yoke off, I'm guessing your problem is not having a socket big enough for the stem nut?

I use a large adjustable spanner for mine.