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Pirelli changes tyres for Bahrain - In depth look at how the race will pan out

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Pirelli changes tyres for Bahrain - In depth look at how the race will pan out
Apr 17, 2013, 10:12 AM

This weekend's Bahrain promises to be another tense race and is likely to be decided on race strategy, if last weekend's Chinese Grand Prix and las...

This weekend's Bahrain promises to be another tense race and is likely to be decided on race strategy, if last weekend's Chinese Grand Prix and last year's Bahrain Grand Prix are anything to go by.

And one important detail to note is that Pirelli has changed the tyre specification for this weekend from the soft compound tyres which proved short-lived in China, to mediums, which have been used in every race so far. Alongside this tyre is the hard compound, which was used in Malaysia. Due to lead times and logistics, this decision will have been made before the Chinese weekend, but when Pirelli announced the tyres for the first four races of the season, the soft and hard were the nominated tyres.

This will help the Red Bull and Mercedes teams, which have had more problems with the softer compounds and will work against Lotus, which has a more gentle action on the tyres. Nevertheless Kimi Raikkonen could have won in Bahrain last year and is one of the favourites this year.

So how will this weekend play out? As usual we can show you all the detailed considerations the teams will go through when planning their race.

With very high temperatures, lots of corners following each other and a heavy car at the start of the race, Bahrain it is one of the toughest circuits of the year on brakes, with four major stops per lap from over 300km/h.

The late April date means that the temperatures are likely to be very high, as they were last year, which leads to increased tyre wear.

The track, being in a desert, is also at risk of being coated in fine sand and this can compromise grip levels. There is usually significant track improvement as the weekend goes on.

Sakhir Circuit; 5.41 kilometres. Race distance: 57 laps = 308.23 kilometres, 15 corners in total, mostly medium speed, with three long straights

Aerodynamic setup – Medium downforce. Top speed 322km/h (with Drag Reduction System on rear wing) - 310km/h without.

Full throttle – 64% of the lap. Total fuel needed for race distance: 150.8 kilos.

Time spent braking: 16% of the lap. 7 braking zones. Brake wear: High.

Loss time for a Pit stop = 18.6 seconds

Total time needed for pit stop: 22.6 seconds.

Fuel effect (cost in lap time per 10kg of fuel carried): 0.38 seconds (average/high). Fuel consumption: 2.6 kg/lap

Form Guide

The Bahrain Grand Prix is the fourth round of the 2013 FIA F1 World Championship.

No team and driver has shown any significant advantage to date, with the top four teams quite closely matched on performance. Tyre management continues to be as important to results as any other factor.

Lotus could have won in Bahrain last year with Kimi Raikkonen; they came very close to beating Sebastian Vettel’s Red Bull, so Lotus will be worth keeping an eye on this year, especially with their superior tyre management.

As far as drivers’ form is concerned at Bahrain, Fernando Alonso has won the race three times, Felipe Massa twice while Jenson Button and Sebastian Vettel have both won it once. Lewis Hamilton has never won in Bahrain. As far as teams are concerned, Ferrari has four wins from the seven races held at the venue since the 2004 inauguration.

Weather Forecast

The end of April is quite late for a Bahrain Grand Prix, and last year we saw the temperatures rise throughout the month and it is forecast to be very hot again, around 34 degrees or more over the race weekend, as it was last year. With very dark asphalt the track temperature tends to be significantly higher, well into the 40 degree range with such ambient temperatures.

Likely tyre performance and other considerations

Pirelli tyre choice for Bahrain: Medium and Hard.

This is the second time this combination of 2013 Pirelli tyre compounds has been seen, after Malaysia. Last season for Bahrain Pirelli brought the soft and medium tyres.

The original plan announced by Pirelli in February was for soft and hard tyres at this race. But that has been changed.

Tyre degradation was very high last year, especially due to the heat. Degradation is a measure of the decline in lap time performance, whereas wear is the consumption of the tyre. Degradation on the soft tyre was very extreme in China, with tyres lasting no more than seven laps in the race and drivers reluctant to use them in Q3 for fear of compromising strategy by starting the race on a used set and making an early first stop.

Teams like Lotus and Force India also found that there was a significant benefit last year to saving a set of new tyres for the race compared to used sets from qualifying. So it could well be another disjointed qualifying session.

Based on last year’s figures, a new set of tyres compared to a used set is worth around 8 seconds over the course of a stint.

This race is likely to produce the highest track temperatures of the season so far. The high temperature creates more movement in the tyre compound and this accelerates the tyre degradation.

The stable weather conditions in Bahrain are likely to mean that the practice sessions will give strong indications for race strategy.

Number and likely timing of pit stops

Last year the race was a fairly clear three stopper for most of the front runners. This year the choice of the hard compound tyre as well as the medium should lead to better durability, but three stops is likely to be the order of the day. It’s how the teams break those stints down and which combination and order of tyres they use, which will be the key. Spacing the stops evenly and bringing a car out into gaps in the traffic are first order priorities. This requires careful planning, good data from Friday practice running and a strong grid position.

However Force India showed last year that there is another way; the team took the decision for Paul Di Resta not to do a lap in the final part of qualifying, but instead to save the tyres for the race, knowing that he was going to try to do a two-stop race. This gave him two new sets of soft tyres and one new set of mediums for the race.

The ideal two stop race was to stop on laps 19 and 38, but even though he had new soft tyres at the start, he couldn’t get further than lap 14 before the degradation became too great, relative to the three stoppers, and he had to pit. He was the last of the top ten to do so. This left him exposed on worn tyres at the end of the race, but he still got a sixth place finish.

For a car that is gentle on its tyres, this is a strategy worth thinking about for this year, depending on expected life for the soft.

Once again, it will be the degradation in tyre performance, especially the medium, which will decide the pit stop strategy and this is likely to be dictated by the high track temperature and by the way the teams get their cars set up to cope with it. The rear tyres will go off first due to the number of traction events out of corners.

The front runners, who must start the race on their qualifying tyres, will be likely to start on used medium tyres as it is clearly the faster tyre for a qualifying lap.

Chance of a safety car

The chance of a safety car at the Sakhir circuit is low, due to the vast expanse of run off areas around the circuit. There was a safety car in the 2007 race to clear away on track debris, but otherwise the races have been fairly clear.

Recent start performance of drivers

Getting a good start can make a huge difference to the way the strategy is managed and the final result, while a poor start compromises a race and makes it harder for the strategy engineers. As far as 2013 start performance is concerned drivers have gained (+) or lost (-) places off the start line this season as follows:

Gained

+7 Van der Garde



+5 Gutierrez

+4 Perez


+4 Button


+4 Alonso


+4 Sutil


+2 Pic


+2 Maldonado


+2 Hulkenberg**


+1 Chilton

Held position


Vettel

Bianchi

Massa

Lost

-1 Bottas

-1 Di Resta


-2 Hamilton

-2 Rosberg

-3 Webber*

-4 Raikkonen

-4 Ricciardo


-5 Grosjean

-7 Vergne

*Webber dropped from second to seventh after a clutch problem in Australia
** Hulkenberg did not start in Australia

Pit Stop League Table


Of course good strategy planning also requires good pit stop execution by the mechanics and we have seen tyre stops carried out in less than two and a half seconds by F1 teams, including Red Bull’s fastest stop in the recent Malaysian GP at 2.05 seconds.

The league table below shows the order of the pit crews based on their fastest time in the recent Chinese Grand Prix, from the car entering the pit lane to leaving it.

Interestingly the field has really closed up here, with just 1.4seconds separating the fastest and slowest teams. Williams has dropped to the bottom of the league table.

1. Red Bull 19.323s 


2. Ferrari 19.449s


3. Mercedes 19.600s

4. Force India 19.831s 



5. McLaren 19.862s


6. Lotus 20.083s

7. Toro Rosso 20.235s


8. Sauber 20.327s

9. Marussia 20.625s

10. Caterham 20.743s


11. Williams – 20.794s

The UBS Race Strategy Briefing is written by James Allen with input and data from several F1 team strategists and from Pirelli

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