Return of the high side??

[phil]

As regular BBC 606 debators will know this is not an original topic for one and not my original thread either.
But in light of Dani Pedrosa's high side and subsiquent hospitalisation on monday i think the question is worth debate and perhaps someone more knowledable than me can answer. Why?
http://www.crash.net/motorsport/motogp/ ... _test.html
After years of low sides being the norm this year we do seem to be seeing more high side's.
Rather than re-word it here is the link from which i blatantly stole this topic from:
http://www.bbc.co.uk/dna/606/A35679036
and here's the copy and pasted version:

Return of the highside?
Moto GP
by yzr-m1 (U6065771) 07 May 2008

After looking at the stills from Lorenzo's spill at the weekend, I'm wondering whether we could be returning to the 500cc days of bonecrunching highsides.

http://www.motogp.com/en/videos/200...
(click on the picture to get the full sequence of images)

This isn't the first time this year we have seen the rear end let go and grip again and I'm suprised it seems to be happening more often with the advent of traction control.

We seem to have had a good few years where highsides haven't been an issue but has the current mix of tyres, chassis and engine made the problem return?

[Albert]

Thanks for that motogpphil - good reading!
I never was a regular over on 606 (a little too much F1 for my taste) but I enjoyed reading some of the debate.

It seems that the highside is making it's unwanted return despite the advent of electronics -- and is it coincidence that the ones who've suffered the most are the ones who were the front runners in 250's?

Having said that, Dani is into his 3rd season of 4 stroke racing so it must be just coincidental. (I hope!)

[carty]

Ok, I was looking through some of the old topics and came across this one started by Phil part way in to the 2008 season. Why have I resurrected it I hear you cry? Well the key line that stood out for me was in Albert's reply when he said 'is it coincidence that the ones who've suffered the most are the ones who were the front runners in 250's?' I think that even though this topic didn't get many replies at the time, the incidence of highsides has remained higher since 2008 than the period between about 2005-2007. Particularly, a certain recent ex-250 rider highsided out of the Assen race on Saturday (albeit slowly) and Stoner also highsided over the weekend.

My point is, that a lot of ex-250 riders are still having highsides one way or another and I wondered if this is an idiosynchrosy with regard to the adaptation to the electronics in MotoGP bikes, or if it is attributable just to a 'cold tyre' and there's nothing more in it.

I've seen a heck of a lot of riders having big 'moments' in all sessions as well, that were almost highsides that were saved. There seems to have been more of these recently.

I'm not really sure what I'm getting at, I just thought it was an interesting old thread to bring up!

Cheers,
Matt

[RatsMC]

OMG, someone used incidence correctly. I don't think I have ever seen that before.

Anyway, it is interesting that this topic came up as I was thinking about the fact that highsides do seem to be increasing when you would think that electronics would continue to become more and more sophisticated and better able to prevent them.

[brigdonia]

Forgive my ignorance, but isn't the lack of available grip for the tire partially responsible for causing a high side? Obviously power delivery pays a massive part (i.e if you were to crack the throttle open coming out of a corner at full lean on a 500 2 stroke will end badly) but I thought ultimately it occurs when the rear tire stops gripping and then grips again brutally changing the direction of momentum/motion, resulting in flicking the rider over the side?

If this is the case, then perhaps the change to one tire manufacturer for the series has slowed down the development of super grippy compounds? ...Or most likely the loss of made to order tires has meant some people can't get the right compound for how they ride (i.e Elias) and thus are pushing it too hard...and crashing.

* I would also like to add that: I don't pretend to know much about bike physics but I'm always willing to learn new things if someone was willing to explain...

[tom]

Perhaps the traction control is being wound up 2 much at the moment (Casey's high side may be just down to conditions). I know this should mean that there would be fewer high sides but I wonder if there is a tipping point where the traction control actually turns a nice slide into a high side.

I think its fair to say that the bikes are becoming more and more like 250 racing where the wheels are always in line and this I would imagine is a factor of the electronics getting better limiting rear wheel steering to practically nothing. There seemed to be a large amount of leeway with the older traction control systems, they seemed to allow a fair amount of wheel spin. The modern systems seem to cut in a lot earlier and cover a lot wider range of conditions.

So what happens now when traction is lost? i.e. when the rider input or an unexpected (so not programmed in) condition is beyond the ability of the traction control? perhaps the traction control kicks in and stops wheel spin a lot earlier than the older systems did. This would turn a rear end loose that would be traditionally be rode out by the rider keeping the rear spinning and bringing traction back slowly, to the traction control coming back in suddenly and going 'Woooah buddy I got confused there for a moment on that slippery bit but now I'm back in familiar territory' and stopping all wheel spin.

So perhaps the new systems are better at preventing a rider loosing the rear but also as an unintended consequence better at catching it again when the rear is lost and thus causing high sides.

[oldboyonrgv]

Bridgestone... core temps take quite a long time to come up. One tyre for all those different types of bikes.....