Alex Rins explains Sepang Test top speed: “Rear tyre was in the air!”

Alex Rins finished the Sepang MotoGP test 15th on the timesheets with his new Monster Yamaha, 1.2s behind Francesco Bagnaia’s all-time circuit record and 0.354s from team-mate Fabio Quartararo (11th)

But Rins was only 22nd on the top speed charts, despite team and riders believing the new M1 engine ‘has enough power’.

While Quartararo had been quickest of any rider through the speed trap on day two (338.5km/h) and joint ninth (335.4km/h) on day three, Rins was ahead of only Ducati test rider Michele Pirro on a 333.3km/h.

His top five average of 332.7km/h also compared with an average of 334.9km/h for Quartararo.

Rins admitted the difference between the M1 top speeds also caught his eye.

After digging deeper, Rins revealed that problems in braking were causing the appearance of a poor top speed and, in reality, he was reaching the same ‘Vmax’ as Quartararo.

“I'm quite happy because we are doing good testing [work] but it's true that we are missing a little bit of setup,” Rins said.

“I was struggling a little bit to stop the bike. The rear tyre was up in the air! So we are losing a little bit of time in that area.”

That forced Rins to brake earlier than Quartararo, causing his official top speed to shrink.

“I thought a lot about this and I looked at a lot of data,” Rins said of the poor official top speed.

“It was because the [circuit] top speed sensor is just at the [turn 1] braking point. 

"On the data, we can see that Fabio is braking some 5-7 metres further than me and [the speed difference] was for this.

“On [our] data, on the speed channel, it was the same.”

Sepang top speeds also gauge braking ability

Rins’ explanation that the Sepang speed chart reveals as much about stopping power as engine power also highlights that Gresini’s Marc Marquez and rookie Pedro Acosta are braking very strongly on their new machines.

Marquez set the second-highest average speed of 336.4km/h on his GP23, better than even the new GP24 machines, which have more engine power this year. GASGAS rider Acosta had the third best average speed with 336.0.

The highest top speed (338.5km/h) and average (338.0) on day three was by KTM’s Brad Binder. The South African didn’t want to speculate if it was down to braking, engine or aero.

“Not too sure,” Binder said. “I saw my fastest speed was on my first lap this morning when the grip was mint, it was nice and cold.

“I didn’t have a look at the top speed after that = but we’ve got a bit of speed.”

Meanwhile, Quartararo spent much of the Sepang tests trying to tame the power delivery of the new M1 engine and make it less aggressive, to try and reduce wheel spin.

“I feel the same,” Rins explained. “Not [as strongly] as him because I'm coming from another bike and especially with the Honda last year we were struggling a lot on that [rear grip] phase.

“So for me this bike is a little bit better on acceleration [than the Honda], in terms of how the rear grip arrives.

“But it's true that if we want to push for one fast lap or for a race pace, we are struggling compared to the others.

“For example, exiting from corner 14, or corner 5 where you need to carry speed. It looks like we are losing a little bit the rear.

“But anyway, I'm quite happy with the work done. We are creating a good group of work. So let's see if we can continue like this and keep improving.”

Rins was also revived to suffer only minor issues from last year’s leg fractures.

“The Shakedown test was fine but the first day of the [official] test I had a bit of pain. But then the second and third days were perfect. So on the bike I was able to ride in my way.”

The final pre-season test, before Rins makes his Yamaha race debut, will take place in Qatar from February 19-20.