Valentino Rossi and the curse of the cold tyre

Valentino Rossi’s championship ending crash during practice for last weekend’s Italian MotoGP race once again put the issue of big high-side crashes on cold tyres into sharp focus. 

High-side crashes on cold tyres have become an increasing hazard of the job in MotoGP, with practically every rider on the grid caught out by pushing too hard before a tyre has reached optimum working temperature. 

Rossi is undoubtedly the highest profile victim, the Italian suffering a vicious high-side during practice for his home race. The outcome was a broken right leg that leaves Rossi currently lying in a Florence hospital bed pondering his return later in the season but with his 2010 title dreams shattered.

There is no question that Bridgestone offer phenomenal levels of grip and you’d be hard pushed to find any rider in the paddock who is not mesmerised by the consistency of performance over a race distance.

Rossi himself has spoken at how the rapid development in tyre performance has helped see lap records continue to tumble at most tracks, even though there is no longer any competition between tyre brands in MotoGP. Records have already been broken at two races in 2010 in Jerez and Mugello, both times by Dani Pedrosa’s supposedly wayward factory Honda RC212V.

But crucially the Bridgestone tyres can take as long as two or three laps to generate optimum temperature, depending on track surface and weather conditions.

Most big crashes seen so far in 2010 have come in Saturday morning’s second free practice session.

Now the MotoGP field completes just one hour of track time on a Friday, usually in hot and humid conditions. Friday morning practice was abolished at the start of 2009 as part of a range of cost-cutting measures to counter the impact of the global financial meltdown.

The extra track temperature on Friday though contributes to significantly faster tyre warm-up, and as a result less high-side crashes.

But temperatures and track conditions come Saturday morning can be completely transformed, sometimes with as much as 20 degrees less on the ground.

That means tyres take longer to hit working temperature and several riders have been caught out. Ben Spies, Alvaro Bautista and Mika Kallio all crashed on the same lap in Le Mans on Saturday morning.

All blamed a cold rear tyre. Track temperature on Friday afternoon in Le Mans was 44 degrees, yet on Saturday morning it had dropped by nearly 15 degrees.

In Mugello last weekend, track temperature for Friday’s opening practice peaked at 50 degrees.

When Rossi crashed on Saturday morning it was nearly 50 per cent cooler at 28 degrees. This would have been a factor, but Rossi unfortunately contributed to his own demise. His own reluctance to show rookie Hector Barbera the secrets to a fast lap round the spectacular Mugello track cost him dearly.

Rossi had slowed by nine seconds in the third section to avoid towing Barbera, but in doing so he’d let crucial temperature drop out of the left side of his rear Bridgestone tyre and he high-sided at over 100mph when he decided to revert back to his full flying pace.

A cold tyre caught out Texan Spies on Saturday morning in Le Mans and he is still suffering the impact of a badly sprained left ankle.

He told MCN: “When the tyres are on they really work incredible. But warming them up when the tyre is new is very tricky and we’ve seen some people have some really big crashes.

“It’s one of those fine lines. You don’t blame the company but some of the crashes come when the riders are trying to be easy but it catches you out. Not taking anything away from my crash and Valentino’s but sometimes it is like you hit the deck and you think ‘I was going slow enough.’”

Fiat Yamaha team-mate Jorge Lorenzo is well aware of how good Bridgestone’s rubber is, but he’s also experienced the cold tyre curse.

The Spaniard said: “Bridgestone is an excellent tyre but every time I crash in MotoGP I crashed on cold tyre. It is a big problem when you don’t wait for the tyre to heat up and you don’t expect it to be so cold.

“But the tyre is still so cold and if you wait for some riders to go away then it has the possibility to be very dangerous, I want to speak with Bridgestone and maybe we find some solution for this. Maybe we need a tyre that has better performance in the first two laps but it is not easy.”

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