Rockingham 4th June 2008 - vid - it went a bit wrong!

Originally Posted by Blue_SV650S

At first I thought it was just the tyres were not up to full temp.
...
Again, having now looked closely at the video footage, I simply think I just lent that bit too far that lap and the front 'tucked' (knew the front had tucked, just for a different reason than I first thought - I was annoyed with myself at the start!). Looking at the footage, it certainly isn't that many more degrees over from when I was riding it to when it was sliding on its side!!

You were really cranked over when it let go.

Does the front tyre have any chicken strips? Might you have rolled off the edge?

I've lowsided my bandit 400 a couple of times (http://www.youtube.com/watch?v=dxwz-Sa7l18 and http://www.youtube.com/watch?v=-iw6THazM7g skip to 2:50), first time I thought it was cold tyres but after the second time (not on the same day...) one of the marshals suggested I might be rolling off the edge of the rear. The tyres are GT501's and there's no chicken strips on the rear so I think he might've been right. I'm going to change to sport demons on the bandit because I think they've got a better tyre profile.

If you did roll off the edge, maybe different tyres would give you more lean? Or just make sure you hang off a bit more so the bike stays more vertical?


Looks like you're going real quick. Makes me look forward to taking my sv to the track (and a bit worried about crashing it...!).

[yorkie_chris]

Originally Posted by northwind

this is what trackbikes are for right? Bending, hammering straight again, and not caring...

eh? That's how I treat my road bike

Originally Posted by erik

...

Here are some pics of the front tyre - (I have taken it off now)

Plenty of Chicken strip left!! ... but chicken strip isn't always a great indicator of if you have gone 'off the edge' ... i.e. depending on bike/tyre the geometry/angles are such that you are not getting a big enough 'footprint' to hold the bike up, before getting to the edge.

Tyre (notice the loss of profile on RHS (I should have replaced it before that day - but the RHS profile was nothing to do with the incident in question))




RHS Chicken strip (notice the loss of profile on RHS)



LHS Chicken Strip (it was a LHS crash, so this is the important one)





Looking at your vids (what camera gear do you have BTW?) The first one to me looks like it was too much welly cranked over (indeed perhaps cold tyres too) and the rear end let go, the second was the front, but surely just where it was wet/damp? ... it looked like you were riding in a rain cloud, that can't be good for traction!!

I have no idea what GT501s are the Supercorsas I use are great, but the bike/tyres do have limits, I am normally pretty good at judging these (I am not a 'crasher' by nature) ... but on the day I was evidently just a bit too keen on this occasion and overstepped the mark, its a fine line! I should have also replaced the front tyre before that trackday as it has seen a fair bit of use already so that didn't help! But it was the RHS that was worst, so I just took it that it easyer on the rights ... the LHS was good to go

To be honest I didn't think I was pushing it THAT much more than I had done on that corner dozens of times already that day ... obviously there wasn't as much left as I thought!

As for 'getting off the bike' ... there is only a certain amount of that you can do, you are already 'on the floor' .. as the speed builds further, the bike needs to be lent more to increase corner speed ...

p.s. good to see another inappropriate trackbike out there mixing it up!!

Originally Posted by erik

You were really cranked over when it let go.

Does the front tyre have any chicken strips? Might you have rolled off the edge?

I've lowsided my bandit 400 a couple of times (http://www.youtube.com/watch?v=dxwz-Sa7l18 and http://www.youtube.com/watch?v=-iw6THazM7g skip to 2:50), first time I thought it was cold tyres but after the second time (not on the same day...) one of the marshals suggested I might be rolling off the edge of the rear. The tyres are GT501's and there's no chicken strips on the rear so I think he might've been right. I'm going to change to sport demons on the bandit because I think they've got a better tyre profile.

If you did roll off the edge, maybe different tyres would give you more lean? Or just make sure you hang off a bit more so the bike stays more vertical?


Looks like you're going real quick. Makes me look forward to taking my sv to the track (and a bit worried about crashing it...!).

Your lowsides are a bit bizarre? Blue's bike seems much more cranked over when it loses grip. Your first one was cold tyres maybe and second one it looked misty and wet?? Odd though, didn't look like you had leant too far, overcooked it, or suddenly whacked open the accelerator. I'd just get a different bike with different tyres if I were you

Originally Posted by Blue_SV650S

Plenty of Chicken strip left!! ... but chicken strip isn't always a great indicator of if you have gone 'off the edge' ... i.e. depending on bike/tyre the geometry/angles are such that you are not getting a big enough 'footprint' to hold the bike up, before getting to the edge.

Looks to me like you were right then when you said "I simply think I just lent that bit too far that lap and the front 'tucked'".

Originally Posted by Blue_SV650S

Looking at your vids (what camera gear do you have BTW?) The first one to me looks like it was too much welly cranked over (indeed perhaps cold tyres too) and the rear end let go, the second was the front, but surely just where it was wet/damp? ... it looked like you were riding in a rain cloud, that can't be good for traction!!

I have no idea what GT501s

The camera is a security ccd bullet camera recording onto a jxd900 portable media player. The microphone was made with bits from an electronics store using approximately this circuit: http://www.reconnsworld.com/audio_singleicpreamp.html and is jammed in a piece of foam in the tail fairing. The JXD900 only records at 320x240 pixels and seems to compress the video quite a bit, but it can record for ages and is good enough quality for youtube.

I don't think the bandit has enough grunt for 'too much welly' to make the rear slip, at least not in the dry at that speed. In the second crash the track was damp and the front does turn in a bit, but I can't tell if it's before the rear lets go or after, it doesn't look like the front slides at all before the rear spins around, so I'm going to continue to think it was me rolling off the edge of the rear (that way I can hope to avoid doing the same thing in the future by getting different tyres).
Dunlop GT501's are a cheap crossply tyre, good for commuting, not so good for track days. I've had Pirelli Sport Demons on there in the past, I think they were better, with them I crashed because the peg dug in and dragged for too long. I don't touch the pegs with the GT501's, I think it gets to the edge of the tyre first.

Originally Posted by Blue_SV650S

p.s. good to see another inappropriate trackbike out there mixing it up!!

Cheers

Originally Posted by Warthog

Your lowsides are a bit bizarre? Blue's bike seems much more cranked over when it loses grip.
...
I'd just get a different bike with different tyres if I were you

A different bike?! I think it's just the tyres.

[yorkie_chris]

I think they make avon viper sports in 150 section if that's what the 400 takes..

This gives me the chance to ask a question. Losing the front and lowsiding is often referred to as the front "tucking". Why tuck? It seems so odd to me. "Tuck" suggests gathering closer or drawing in, or beneath, or securing. Strange to use "Tuck" to describe when the front is about as far from that as possible..........is that the point? Or maybe just one of those sayings that, despite not really making sense, has been around so long everyone knows what you mean anyway. Like "I could care less" in America.

Originally Posted by erik

...

I got a JXD too but the jxd 638, it does 640x480. But I have a devil of a time trying to edit the footage. What software do you use with yours? Do you have special codecs?? I'd love it to just work in windows movie maker and edit i there, but at the mo I have to 'process' it before I can put it in WMM ... and that takes ages

Why are you using commuter tyres on the track? Do you use it as a commuter bike too? ... if you do, I suggest getting a 2nd set of wheels and putting track rubber on there for trackdays

I only have the videos to go by, your behind was in the saddle, but the first one is the back going, the way the revvs pick up it is the rear loosing traction ... it couldn't handle that lean with that power ... so too much lean for the power .. or too much power for the lean ... either way its the same thing!! ... the second one looks like the front going to me, the camera angle/where you are pointing doesn't change at all before you see the front turn/tuck. It looks 'front end' that one to me, not rear.

Originally Posted by sinbad

This gives me the chance to ask a question. Losing the front and lowsiding is often referred to as the front "tucking". Why tuck? It seems so odd to me. "Tuck" suggests gathering closer or drawing in, or beneath, or securing. Strange to use "Tuck" to describe when the front is about as far from that as possible..........is that the point? Or maybe just one of those sayings that, despite not really making sense, has been around so long everyone knows what you mean anyway. Like "I could care less" in America.

Interesting, never really thought about the terminology!! I should imagine it originated by the feeling you get when the bars just suddenly lose tension and turn on you, it is kinda 'folding' ... tuck .. fold ... same thing ... that's my guess anyway ... it is a very distinctive feeling!!

[yorkie_chris]

Originally Posted by Blue_SV650S

Why are you using commuter tyres on the track? Do you use it as a commuter bike too? ... if you do, I suggest getting a 2nd set of wheels and putting track rubber on there for trackdays

I think the curvy front wheel fits some bandits ... I have one for sale by an incredible coincidence...

Originally Posted by Blue_SV650S

Interesting, never really thought about the terminology!! I should imagine it originated by the feeling you get when the bars just suddenly lose tension and turn on you, it is kinda 'folding' ... tuck .. fold ... same thing ... that's my guess anyway ... it is a very distinctive feeling!!

I'll go along with that. It makes just about enough sense..........just