Wednesday, 12 November 2014

Should Mercedes Have Pitted Hamilton on Lap 27? (Brazil 2014)

This is an analysis about whether Lewis Hamilton would have overtaken Nico Rosberg had he pitted on lap 27 (in the second round of pitstops). Hamilton unfortunately spun on lap 28 which jeopardised his race chances. Many sources are suggesting Hamilton had enough time in-hand to jump Rosberg, Mercedes deny this allegation. We jump in to find the truth behind the matter!

The best method for analysing this is to use the first pitstop round as the initial basis as we know the result of the first pit-stops.


First Pit-stop Sequence

End of Lap 7 – Rosberg pits 
At the end of lap 7 Nico pitted (adding 5.2 seconds to his time - see end of article for back-up). He was measured as being 3.921 seconds behind Hamilton.

Source: FORIX

Lap 8 
Hamilton crushes in a 1:20.715 in-lap (including a 5.2 second penalty for pitting, which is an equivalent 1:15.5 second lap, 6 tenths faster than his previous lap adjusted). Rosberg’s outlap is a 1:34.087.

Lap 9 – the run down 
Hamilton has a 2.8 second stop and comes out near Rosberg. Rosberg’s first sector may have been hindered losing time behind Grosjean.

The gap must be around 0.3 seconds at this point.

Reading the above doesn't really tell us anything as it’s very difficult to get any sense of comparison between what is a good out-lap and a good in-lap. However using the above as the basis can allow us to see what was different in the second pitstop window, which is crucial.

Second Pit-stop Sequence

End of Lap 26 – Rosberg pits 
At the end of lap 26 Rosberg pits, this time he’s calculated as 4.377 seconds behind Hamilton. Hamilton is therefore 0.456 seconds closer than last time. This puts him net ahead, remember the gap was 0.3 seconds after the first pit-stop sequence.
Source: FORIX

Lap 27 
Hamilton pushes very hard on lap 27 and sets a 1:14.303 (which for the purpose is the article is calculated as an in-lap of 1:14.303 plus 5.2 seconds = 1:19.503). A 1:19.503 is 1.212 seconds faster than in the first pit-stop window, which must put Hamilton in a commanding position.

Meanwhile Rosberg, aided by a potentially faster pitstop, does an out-lap of 1:32.326 – 1.761 seconds faster than in the first pit-stop. That therefore means he’s gained more time relative to Hamilton (second versus first pit-stop sequences).

Lap 28 – the run down and pitstop 
The very tight battle has been affected by Mercedes delivered a 3.7 second stop to Hamilton, which cost him 0.9 seconds relative to the first pitstop window. It's impossible really to know how much quicker/slower Hamilton was out of the pits on lap 28 compared to lap 9 (versus Rosberg's first sector) but it must have been marginal.

The Calculation


Update: When comparing Rosberg's first sector on lap 9 vs. lap 28 the difference is 0.156 seconds (18.9 versus an 18.744). Hamilton's first sector out of the pits on lap 9 vs. lap 28 was a 36.639 versus a 37.439, bear in mind the 0.9 seconds lost in the pit and Hamilton went 0.1 seconds faster out of the pits the second time. Also note that Hamilton may not have been pushing as hard after his chance to take the lead had evaporated. The difference is therefore pretty negilible again although pushes it more towards 0.45 seconds difference without the bad pit-stop.

Substantiating the 5.2 seconds pit penalty rule

Hamilton was 1.099 seconds behind on lap 25 but 4.377 seconds ahead on lap 26 (a 5.4s swing). On lap 49 Hamilton was 2.040 seconds behind but 2.997 seconds ahead on lap 50 (a swing of over 5.0s). A similar pattern was seen throughout the field, betwen 5.0 and 5.4 seconds so the mid-point was used. This is obviously distorted by the lap in-between but this pattern was remarkably similar throughout the field.


Rosberg probably did enough to stave off being passed had Mercedes pitted Hamilton. Hamilton needed a 2.3 or 2.4 second stop to make it extremely close which was unrealistic. Then there's the matter of actually making the pass pay off, which is anyone's guess.

Ultimately what cost Hamilton was the spin as he clearly had better pace and likely would have won due to tyre issues had he pressurised Nico for the whole of the marginal last stint. The strategy change and the slow pit-stop were Mercedes' issue. There were benefits to pushing mightily for one lap or making the tyres last slightly longer to give Hamilton fresher rubber in the final stint. It seems the team put him at risk by telling him to push very hard and then leaving him out. 


  1. Great article! Can't wait for Abu Dhabi

    1. Thanks Brian! I can't wait either. I'm personally looking forward to another strong showing from the Williams drivers and a classic title showdown (with no reliability issues).