Crashed on a drying track

[MarkJ]

Hi, I did a trackday at Silverstone yesterday, which was my first time there. I've done about 25 trackdays total and am normally mid to top fast group.

I've been pretty lucky with weather the past few years and normally either end up on a dry trackday or it rains the last session and I leave early.

It hammered it down yesterday morning. I went out on the sighting laps on my Supercorsas which were suitably unhappy, but giving plenty of warning of slides and good feedback. Came back in after the sighting laps and swapped straight to my second hand Dunlop race wets, which were block pattern front and rear. I Went out after it stopped raining on a sopping wet track and all was hunky dory. Eventually the sun came out and the track started drying pretty fast. Most of the group were going round on full wets, but half the track was dry and half wet, but I'd had no slides so all was going OK. I was going to change back to Supercorsas after this session

I went through the shallow left hander at Maggots, and as I was coming out the bike just fell away.

This part of the track had dry and wet spots. All day I'd been going through the shallow left hander and then the right on a neutral throttle, so I don't think I was ham fisted through it. I didn't hear the engine revs rise as it slid away from me either.

There were no warning signs up to that point it was going to let go, so I'm a bit stumped at what happened. The marshall said it just slid away from me, the trackday people that picked me up said it was probably a wet patch that did it?

Anyone any ideas what happened? Did I overheat the tyres? Or maybe trying to ride wets like supercorsas and wasn't careful enough? I want to learn something from this but not sure what happened


TLDR: Crashed on wets on a half wet/dry track. No feedback suggesting grip was about to go. Want to know what I did wrong.

[garth]

Are you sure you were on a neutral/positive throttle and not a closed throttle?

You haven't said if the front or rear broke traction 1st, but it sounds like it could've been an off the throttle-back-end-overtakes-the-front-so-slide-on-arse moment.

[MarkJ]

It went down so quick I thought I was still on the bike whilst I was actually sliding down the track

Looking back, it felt like both tyres went at the same time (although, as above, it happened very quick so could have been an individual tyre first).

I went down super softly, no bruises rashes or anything. I didn't go face first like a front end tuck, but nor did I slide off the back like I'd spun the rear up either. I just sort of slid next to the bike when I was on the ground.

With the throttle, I thought I was neutral. Had been neutral at that point all day, and wasn't passing anyone so the line was the usual one I'd been taking rather than off line.

Without vid evidence, though, can't say for certain.

[ws4936]

Diesel patch, bro? Joke
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If everything seems under control, you're just not going fast enough.

[Red Devil]

Sounds like the back let go, similar to my crash at Mallory in the snow at the opening round (https://youtu.be/G9s_4ugaRC0 skip to around 2.30 for the crash). That was about -1 though and it was actually snowing during that video!

Does sound like Garth said, closed throttle and the back tyre gave up. Those wets you described are the really old ones I think, what year are they? Probably didn't help!
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Thundersport Pre-National Sport 600 2014 #92
EMRA Roadstock 600 2013 - 3rd
www.facebook.com/MattJohnstonRacing

[MarkJ]

That crash looks just like what happened to me, so does look like the rear let go Did you get any warning signs with that crash of yours or did it just go?

Not sure what year, they look fine but think I'll change them, they're a slightly different profile anyway.

Tempted to actually buy brand new wets considering I don't get through them very fast. Any recommendations? Pirelli website says they don't do 180 55 17 rear rain tyres but that can't be right surely!

[G]

How does the tyre look?

When I lost the front at a race practice (getting on the power, too), looking at the front, it was obvious that it was pretty knackered - other people were caught out that day and as usual had been paying more attention to the rear.

Remember ideally you should be on a slightly open throttle while cornering.

Consider your body position and how that affects the weight distribution too.

A bit late now, but it'd have definitely been worth feeling your tyre directly after.

When I crashed on supercorsas in the wet on a track day in February I think - as was obvious - the tyre was freezing cold.
Might have had an idea if it was actually too hot.

[MarkJ]

[Red Devil]

No warning, just slid out on me.

Apparently dunlop wets are good, haven't tried them myself though. How far into the session was it?
____________________
Thundersport Pre-National Sport 600 2014 #92
EMRA Roadstock 600 2013 - 3rd
www.facebook.com/MattJohnstonRacing

[MarkJ]

Been out a while, it was 3rd or 4th lap. So been out ages since Silverstone is like a billion miles long

For reference, I came off roughly where the camera is here: https://goo.gl/maps/DC61Y and the bike finished up just past that car in front.

[Red Devil]

Odd place to crash, can remember it being a very quick corner when I went.
____________________
Thundersport Pre-National Sport 600 2014 #92
EMRA Roadstock 600 2013 - 3rd
www.facebook.com/MattJohnstonRacing

[G]

Was it bumpy at all?

The corner before that used to be terrible, I remember; presumably all the F1 cars with their downforce kicking in, using 900hp to tear the tarmac up.

[MarkJ]

Ah! It was actually, on the sighting lap around that part there was a lump that really seemed to unsettle the bike. I'd totally forgotten about that. Could it be that? Marshall said a few people had been off on that corner before me

Bollocks, can't believe I'd forgotten about the lump until now.

[G]

In variable conditions, bumps can certainly make much more of a difference.

Especially if you're pushing the tyre a bit because it's too hot or two cold.

Remember that the more the bike is leant over, the less the suspension can do anything useful.