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Crash at Turn 10 in Buttonwillow

ACA

ACA

Member
Joined
Jul 17, 2006
Location
Berkeley
Moto(s)
FJ09, FZ1,
Ninjette,
SV650, CRF250L, Ruckus!
Name
Charles
BARF perks
AMA #600767
Thought I'd post a vid of my crash last Saturday morning. Group 2, first practice end of second lap.

The bike is a GSXR 450 cripple/triple (600 with a disabled cylinder). Pirelli rear slick at 28 psi cold.

http://vimeo.com/60954017

I thought it was a weird place to crash.

I heard some people saw it from trackside and thought my rear went flat pre-crash, but I didn't feel anything strange and was getting decent drive.

Even though I had tire warmers and it was almost the end of the second lap, I'm guessing cold tires/pavement. Thoughts?
 
Ummm....throttle wide open...add lean angle...ask the bike to turn....crash....
 
Nobody ever talks about this, probably because it's too simple and most people like the really complicated explanations, but it did appear that you were a little off-line in that corner.

There's less grip off-line, period. Having said that, that corner is one that you should be able to get away with that, as it's not a very tight radius corner on a bike that has less than 90hp, so... :dunno
 
ACA said:
Even though I had tire warmers and it was almost the end of the second lap, I'm guessing cold tires/pavement. Thoughts?
Click to expand...

I can't tell if you are serious or not. Care to clarify?
 
Enchanter said:
I can't tell if you are serious or not. Care to clarify?
Click to expand...

I am serious, that is my best guess at failure mode though it wasn't a particularly cold day, and it was dry. Usually you get a little warning (stepping out and re gripping) but there was none of that. (Thank god the rear didn't hook up though).

For the previous posts, throttle was definitely wide open, bike dynoed at 69hp last Wednesday. Is this not a WOT turn?

Agree on missed apex.
 
Cold tires had nothing to do with it...It may be a wide open throttle turn on your bike, but not with other bikes with more power.

Ken
 
Pretty sure Chris recommended 25psi cold for the rear. Not saying that's what caused your crash...
 
Too much throttle for sudden lean angle
 
afm199 said:
Too much throttle for sudden lean angle
Click to expand...

I didn't think I had the arm strength for that.

So for next time:
1. hit the apex the turn
2. steer more gradually
3. consider less throttle
4. get right air pressure
 
Mmmm...how smoothly does a bike with one disabled cylinder deliver smooth power to the pavement?

Could that be part of it?
 
GAJ said:
Mmmm...how smoothly does a bike with one disabled cylinder deliver smooth power to the pavement?

Could that be part of it?
Click to expand...

Poorly? kidding.

I thought about this too, with all the talk of "big bang" in MotoGP back in the day. But at such low HP, will it make a big difference?
 
ACA said:
I didn't think I had the arm strength for that.

So for next time:
1. hit the apex the turn
2. steer more gradually
3. consider less throttle
4. get right air pressure
Click to expand...

How about "exit direction".....

Ken
 
I think Ken means get the bike turned. Hitting the apex doesn't mean much if you're not pointed at the exit. Almost everyone has to roll off to get the bike turned on the last left, and then roll on again.
 
khill said:
How about "exit direction".....

Ken
Click to expand...

Listen to Ken's "free" advice carefully. Normally, it costs about $700.

He's saying "get the bike pointed before picking up the throttle/ bike". Basics...
If you add throttle and aren't pointed towards the exit, you have to add lean angle too...

Yes, even experienced racers add lean angle and throttle without dropping their body lower/ more inside at times...and then highside. It's just that we know we're probably tempting fate...
 
Holeshot said:
Listen to Ken's "free" advice carefully. Normally, it costs about $700.

He's saying "get the bike pointed before picking up the throttle/ bike". Basics...
If you add throttle and aren't pointed towards the exit, you have to add lean angle too...

Yes, even experienced racers add lean angle and throttle without dropping their body lower/ more inside at times...and then highside. It's just that we know we're probably tempting fate...
Click to expand...

Thanks for the expanding on my somewhat criptic posts..I wanted the OP to think a bit about his riding instead of putting the issue elsewhere. Riders like the OP we want to keep in the sport and not have silly tipovers! His crash was totally explainable and is an easy fix..

When can you safely accelerate off a corner? When you can see your exit and take away lean angle...

We have such an amazing sport, let's grow it and enjoy it!

Ken
 
Last edited:
Missing the apex is irrelevant to the crash, WOT on a 69hp motorcycle through that turn should not have put you down. :)
Would be interesting to see a vid from the rear :teeth

Holeshot said:
Listen to Ken's "free" advice carefully. Normally, it costs about $700.
Click to expand...


:thumbup
 
Last edited:
khill said:
Thanks for the expanding on my somewhat criptic posts..I wanted the OP to think a bit about his riding instead of putting the issue elsewhere. Riders like the OP we want to keep in the sport and not have silly tipovers! His crash was totally explainable and is an easy fix..

When can you safely accelerate off a corner? When you can see your exit and take away lean angle...

We have such an amazing sport, let's grow it and enjoy it!

Ken
Click to expand...

I definitely have been thinking about it as I continue to dismantle my machine and heal my foot, and appreciate the advice, cryptic or not. I wouldn't have posted here if I wasn't looking for help.

The way I think of turns is basically a traction "budget". Lean angle, tightness of turn, speed and acceleration (or brake on entry) all reduce allowable traction and need to be managed in concert. This is definitely not an original idea. In my estimation, the exit of T10, at full throttle, a moderate lean, a relatively straight turn and decent speed did not subtract all of my traction budget. But I was wrong. Lowering of any of these variables would have prevented it, though some are better to reduce than others.

Ken, could I have maintained full throttle if I had straightened the corner out by hitting the apex and therefore lowered my lean angle?

And thanks by the way. I do love this sport.
 
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