Thanks to safety rules and cost cutting F1 is far from being the unfettered pursuit of raw speed it used to be.

But it never fails to impress me how cunning designers keep coming up with ways to wriggle free from the constraints of the rule book and build F1 cars which are just a little bit quicker than the governing body wants them to be.

There are some significant changes to the F1 rules this year, but not as drastic as those we saw in 2009. So how much more speed can the designers conjure out of the cars – and how will it affect race strategy?

How 2010 rules changes will affect lap times

Last year’s rules changes were mainly intended to allow the cars to follow each other more closely but they also had the effect of slowing the cars down, or at least keeping them roughly at their 2008 level of performance. This year the aerodynamic rules are largely unchanged apart from minor details such as the banning of the wheel ‘spinners’.

More significant is the reduced width of the front wheels explained in the diagram (right). Front tyres will be 245mm wide in 2010, 25mm less than last year. The cars will lose almost 10% of their front tyre contact patch which will obviously cut their cornering speeds.

It’s down to the designers to claw back that lost time – and more – by refining the cars’ aerodynamics and weight distribution as best they can. It’ll get harder for them in 2011 if the mooted ban on double-diffusers comes to pass.

I suspect we will ultimately see the 2010 F1 cars lapping quicker than their predecessors on a single low-fuel qualifying run. But the banning of refuelling will make it a very different story when it comes to race lap times.

Race lap times

With drivers no longer allowed to refuel during the race, cars will have much larger fuel tanks. This will have one obvious effect – as well as others that might not be immediately apparent.

Cars will now be much slower at the start of races than at the end of them. In the example above from last year, Lewis Hamilton began his 24-lap middle stint in the Hungarian Grand Prix lapping two seconds per lap slower than at the end of it. Multiply that across a full race distance and we could see lap times differing by six seconds, though this will vary with different circuits and conditions.

It will also have an interested effect on strategy. Previously after a car pitted the driver would leave the pits with more fuel on board and lap more slowly than he had immediately before his stop. Now, as the drivers’ fuel load will not increase during a pit stop, they will be faster immediately after it, thanks to their fresher tyres.

This may tempt a driver who is stuck behind a rival into pitting early in an attempt to get ahead. But they could run into trouble later in the race when their tyres are more worn than their competitors’ are.

Stint lengths are likely to change too. Instead of splitting the race up into roughly equal portions, as in the example above, tyres will now suffer greater punishment at the beginning of a race compared to the end.

Using rough numbers we can see that if a car carries 200kg of fuel to last a 60-lap Grand Prix its average weight over the first half of the race will be 151kg compared to 51kg for the second half.

Drivers are still required to use each of Bridgestone’s two compounds at least once per race. In our example, they could start the race on the harder tyre then switch to the softer. But the exact moment when they should change is no longer dictated by how much fuel’s in the tank – it’s down to the driver to decide if and when he needs new tyres.

Faster laps, slower races?

The upshot of all this is that even though we may well see faster individual laps in 2010 compared to 2009, race distances will take longer to complete. If we get a safety car period at Singapore – as we have the last two years – we might not even see the race distance completed within the two hour time limit.

We’ll get out first impression of how quick the 2010 F1 cars are when testing begins at Valencia on February 1st. Here’s a reminder of what the quickest times were last year in testing at the three tracks where the teams are returning this year:

Jerez – 1’17.494 (Kazuki Nakajima, Williams-Toyota)

Circuit de Catalunya – 1’18.926 (Rubens Barrichello, Brawn

Valencia – No group test in 2009

2010 F1 cars

Image (C) Red Bull/Getty images