Rear wheel skip - why?

[vifferman]

But the sudden loss of control in good conditions is pretty unsettling.

But were you 'out of control'? Or merely a wee bit unsettled by a strange new feeling?
Take a look at the MotoGP (or any) racers when they're approaching a corner: the back wheel is often off the ground, floating around, yet they're still fully in control, despite looking all out of shape.
It's normal, and when you get used to it, not so unnerving.
I'm no racer, but I've had the back wheel skip around on a bike going into a corner, or spin up/slide going around it, or the front wheel up in the air exiting it. Kinda alarming the first time, but when nothing bad happens as a result, you realise it's OK.

Sorry - didn't mean to get all preachy.

One other thing - it's possible that some minor tweaking of your suspension is required, to reduce rear end lift under hard braking, if it doesn't have quite enough compression damping in the front.

[dipshit]

Yes I do use engine braking combined with the front brake normally and probably rely on engine braking a lot because it is so effective.

But do you blip the throttle on down shifts? It is one of the basics - but i see so many riders that don't do it.

And also giving the rear end a fraction more sag will help the back wheel feel more planted when decelerating.

[Winston001]

But do you blip the throttle on down shifts? It is one of the basics - but i see so many riders that don't do it.

And also giving the rear end a fraction more sag will help the back wheel feel more planted when decelerating.

No, don't blip the throttle ordinarily so I'll try that.

After looking at the Ducati MS forum I'll check the tie-rod between the frame and the swinging arm too. That will lower the back end which is negative for handling but positive for stability. The Ducati ST4 has plenty of weight already on the front - heavy steering compared with other bikes, so lengthening the wheelbase slightly and lowering the back end won't do any harm. I'm going to be a nana for a while....

McJim - I'll set up the camera as promised Winston - I will then film you as you try to replicate the incident and we can see what happened

Mate - the irony is at the time I was thinking about showing you this short piece of road which we could have some fun on provided the local farmers don't call the constubles.....

[sinfull]

back it into that corner bro !!!
http://www.kiwibiker.co.nz/forums/sh...95&postcount=1

[madbikeboy]

Okay, a lot of riding is about being smooth, and firm with the controls. What you're describing has been covered well by a few people here - as you you change down, your rear tire is coping with the engine slowing it down, if you let the clutch out hard instead of feeding it out with feel, the back will start to lock, and it will dance a little. This dancing will be worse if your suspension has too little damping, or your chain is tight, or incorrect tire pressures.

The bike isn't out of control, but you need to settle it down before tipping into the corner - if you don't the bike will likely tell you off a little in a pretty physical way.

Practice progressive braking and letting the clutch out (also progresively).

[Winston001]

But were you 'out of control'? Or merely a wee bit unsettled by a strange new feeling?
Take a look at the MotoGP (or any) racers when they're approaching a corner: the back wheel is often off the ground, floating around, yet they're still fully in control, despite looking all out of shape.
It's normal, and when you get used to it, not so unnerving.
I'm no racer, but I've had the back wheel skip around on a bike going into a corner, or spin up/slide going around it, or the front wheel up in the air exiting it. Kinda alarming the first time, but when nothing bad happens as a result, you realise it's OK.

You are probably right but I'm lightyears behind a MotoGP rider. Seen them and simply marvelled at their skill.

Having said that, how many riders have we seen highside on the track? It certainly happens even to the experts.

I'm not likely to try and do this again on purpose so I can't honestly say if the bike was out of control. Another rider might have grinned and won. However for me, it was out of control. A bit like a tank-slapper except from the rear end. It was kind of like the bike was trying to slap the handlebars in a sense, but not actually doing that.

It was all over in possibly 2 - 3 seconds so accurately remembering is hard.

I didn't make it around the corner.

[henry]

I used to do this all the time on my GB500 and then one day it decided it had had enough and chucked me into the ditch at the side of the road.

[OutForADuck]

No, don't blip the throttle ordinarily so I'll try that.

After looking at the Ducati MS forum I'll check the tie-rod between the frame and the swinging arm too. That will lower the back end which is negative for handling but positive for stability. The Ducati ST4 has plenty of weight already on the front - heavy steering compared with other bikes, so lengthening the wheelbase slightly and lowering the back end won't do any harm. I'm going to be a nana for a while....



Mate - the irony is at the time I was thinking about showing you this short piece of road which we could have some fun on provided the local farmers don't call the constubles.....

Dude don't worry about anything else.. you have gone down a gear too many without the right technique... its probably never happened before because of a combination of speed, gears gone down, amount of braking and road surface.

NET NET you need to learn how to shift with synchronised engine revs (Blipping the throttle) ST4 from memory does not have a slipper clutch and you would get away with it if it does.. but do you really want the bike to compensate for a skill you have not learnt.

I would guess that you are not getting into the correct gear for exiting the corner if you have not seen this before and are not "blipping" the throttle.

Also back end skipping under breaks? no big deal...just make sure its hooked up before pitching it in.

[vifferman]

I didn't make it around the corner.

Oh...
So it wasn't just a "WTF was that?!? Oh well - it's stopped now... " moment.

[Bass]

It was all over in possibly 2 - 3 seconds so accurately remembering is hard. :

Aint that the truth.
However, if as you say, this was all prior to the corner then it sounds to me like you are doing the slowing down in the right place.
This one, as many others have said, is not really a major and there are ways out of it. The problem is of course that screwing up your entry speed is probably what got you here in the first place and so the stress levels are already pretty high without having to think about what to do next.
Since I took up adventure riding, I find myself provoking this situation and getting the arse out going into the corners in the gravel. (Everyone does; it just takes me longer than most)
Haven't had the balls to deliberately try it on the seal yet - probably never will

I didn't make it around the corner.

Any damage?

[Winston001]

Yeah....

I haven't told the whole story - cos I'm still shaken by it.

I got hurt. Not badly, bike was fine (lots of soft grass), rode home. Later I found the thread about Grub....

My wrists, thumbs and chest are still sore and I'm wondering if my right hand should be x-rayed. It doesn't feel as if it would support me on a bike.

I really appreciate all the posts here and thanks for your advice and experience. I've tried to be dispassionate and concentrate on the logical problem, because other people come off bikes and shrug it off. But I have to say that the two motorcycle deaths last weekend hit home in a serious way.

[Bass]

Yeah....
But I have to say that the two motorcycle deaths last weekend hit home in a serious way.

You are not alone there.
Can I be so rude as to suggest that if you have any doubts at all, go and get the medical attention. It gets the ACC process activated before it's too late - just in case - y'know what I mean?

[AlBundy]

Yeah....

I haven't told the whole story - cos I'm still shaken by it.

I got hurt. Not badly, bike was fine (lots of soft grass), rode home. Later I found the thread about Grub....

My wrists, thumbs and chest are still sore and I'm wondering if my right hand should be x-rayed. It doesn't feel as if it would support me on a bike.

I really appreciate all the posts here and thanks for your advice and experience. I've tried to be dispassionate and concentrate on the logical problem, because other people come off bikes and shrug it off. But I have to say that the two motorcycle deaths last weekend hit home in a serious way.

Sorry to hear...

Question... Did you panic brake and look for a place to crash, or did you look through the corner and try and make it through.

Often people are actually going slow enough to make the corner but focus on the outside of the corner and crash, instead of through the corner, where they can easily make it.

It sounds like you are usually a conservative rider and got caught with the change of pace (A lot of us have been there, so know what it's like, hence trying to help out).

[The Pastor]

actually thinking about it when i brake hard on the rear i often hear a lound clanking noise - it sorta sounds liek teh chain is slipping on the sprocket (but i dont think it could?)

this has happend on every bike i've ridden. What causes it and why.

Nothing to do with down change or blipping.

[vifferman]

actually thinking about it when i brake hard on the rear i often hear a lound clanking noise - it sorta sounds liek teh chain is slipping on the sprocket (but i dont think it could?)

Sounds like the rear wheel chattering, but it could be the chain flapping about as the rear wheel locks up.