Austria MotoGP Subscriber Notes, Part 2: Tire Pressures, Jack Miller's Woes, Quartararo & Marquez, And Pecco Bagnaia's Secret New Part

Jul 04, 2023

Dorna and the FIM announced at the end of the summer break that from Silverstone onward, they woulds start to enforce the minimum tire pressures mandated by Michelin. That enforcement would be delayed at the first round after the summer, the British Grand Prix, as both the sprint race on Saturday and the Sunday grand prix were classed as wet races. The sprint race started on a wet track, the grand prix started as a dry race, but the rain flag was shown, making it formally wet.

The agreement with Michelin was that minimum tire pressures would not be enforced in case of rain, as the conditions changed the stress on the tires and the load put into them considerably. So tire pressures were not checked at Silverstone.

Last weekend's Austrian Grand Prix was a different kettle of fish. Spielberg was caught in the heatwave which has gripped southern Europe, and the weekend was dry bar a few Alpine storms, which thankfully left the races pretty much untouched. The Red Bull Ring is also one of the tracks which most stresses the front tire, with a lot of exceptionally heavy braking, a lot of it uphill.

Punishment coming?

Would we finally find out which of the teams or factories had been, shall we say, interpreting the minimum tire pressure requirements rather broadly?

The answer to that question is no, as it happens. For a couple of reasons. First and foremost, because Spielberg is an unusual track in a number of ways. The track is 677 meters above sea level, so air pressure is already below normal: if air pressure is 1 atmosphere (1 bar) at sea level, then it is 0.92 bar at the elevation of the Red Bull Ring.

The pressure was not the 1.88 bar in the front and 1.7 bar in the rear which is the baseline everywhere else. "They changed it for this race," Luca Marini, perhaps the smartest rider on the grid, told the media. "It depends on the pressure of the atmosphere and humidity and things like that. Every GP they take the decision on Thursday, I think. It depends on the situation."

That makes sense, of course. TPMS systems in modern vehicles have this same compensation built in – the system automatically corrects pressure shown to allow for temperature, humidity, and other factors – and given that the load on the tire carcass is related to both the internal and external pressures (the atmosphere pushes back on the carcass of the tire), 1.88 bar is not the same at 677 meters as it is at sea level.

The other major reason we heard very little about tire pressures was that the sprint race provides such great data to prepare the grand prix on Sunday. There is no substitute for data gained in race conditions, where bikes are packed together, and riding a large number of consecutive laps at full speed. Even though the sprint race is only half the distance of the Sunday race, it provides a superb basis on which to figure out your tire pressures for the grand prix.

"The good point of the sprint is that you can prepare the long race," Aleix Espargaro explained. The Saturday race had been very useful for the Aprilia rider. After seeing tire pressures soar in the sprint race, Espargaro's team knew to start with very low pressure. "Yesterday we were one of the riders who rode with the highest pressures, and today we started very very low. Like a flat tire. It was unbelievable, you can't imagine how low we start." Even then, pressures still went up a long way.

Starting with a front tire that is pretty much flat poses its own challenges, of course. The bike doesn't really want to turn until the front tire heats up and the air expands. "It's super super heavy. But with how we start now in MotoGP, in two laps it's OK. The first lap you brake very very hard. The first lap you don't really push like hell, because you can't because there is traffic, you have a full fuel tank. So on lap 2 it starts to be normal, lap 4 is already normal."

That meant taking a little extra care at the start, Espargaro explained. "You brake earlier. To start lower, you have to brake a little bit earlier." It had advantages as well, however. "But to stop it, actually it's sometimes even better, you have more contact patch."

YMMV

Though no one was under the minimum – to verify this, a random selection of bikes were pushed into scrutineering, where pressures were measured manually and compared with the data from the sensors, to show that the official sensors are correctly calibrated – the experience of the new tire pressure rules varied widely.

There were those for whom it was not a problem. "No effect," was Fabio Quartararo's verdict on the new rules. Alex Marquez felt the same way. "No, we were quite on the pace, a little bit high on the rear, but not a problem."

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….sorted to his liking. We have yet to see his best on the KTM but I’m sure that it’ coming!

In reply to I hope that Jack’s settings are….. by Rusty Trumpet

You can always hope but the race was a typical Miller race with him dropping down because of him not being able to take care of his rear tire, I’m surprised Dave wasted that many words on a problem that has been going on since his Pramac days.

In reply to You can always hope but the… by Dieterly

Miller is usually competitive in the first half of the race and has often led them early, often to the detriment of his late race pace. In Austria and Silverstone he never looked fast in the races after his (and KTM's) usual good qualifying and launch placed him in podium positions early. David's explanation fits and adds information and clarity.

In reply to Not Typical, slow earlier by rick650

It’s a very typical Miller behavior, it happened numerous times when he was riding the Ducati. Like I wrote elsewhere, just like Colin Edwards he’s great for the sport but he will never win a MotoGP championship.

In reply to I hope that Jack’s settings are….. by Rusty Trumpet

Agreed for sure, but I'm starting to think Miller might not have that last something required for a factory team. He was quite good at Marc VDS and Pramac. He just doesn't quite have the consistency most factory teams expect of their riders. Whatever happens I just want him to stay in MotoGP, he's still insanely skilled and one of the best personalities to boot!

funny.

Michelin say's it's not safe below 1.88 bar. but to achieve this, riders start "ridiculously low, like a flat tyre" according to AE. I'm guessing that'll be somewhere arround 1.2 bar. But it IS safe according to the rules and Michelin to start with a tyre inflated to only 2/3'rds of it minimum safe pressure. what a joke.

In reply to funny.Michelin say's it's… by janbros

You’re getting caught up with numbers, rather than looking at the situation.

Low pressures allow the tyre to flex, which heats the carcass, just like repeatedly bending/straightening a plastic ruler.

It’s fairly obvious a low pressure for a couple of initial laps is very little stress on the carcass, while low pressure for an entire race is many levels of magnitude worse.

It’s not a joke, it’s just the practical reality.

In reply to Reality check by Seven4nineR

While you may be right there is a difference between a couple of laps and the entire race the fact remains that there have been no front tire failures while not enforcing the standard. Michelin don't want a Bridgestone moment and are being overly cautious. That's their prerogative but it certainly isn't the prerogative of many fans. Maybe a true critical front tire failure would force the team's hands on this front tire test we keep hearing no one wants to do.

In reply to While you may be right there… by Joshua Melanson

Imagine how low the pressure would need to be at the start to run the entire race below the limit.

Here's a different view of it. Less work = less heat. You could use this rule to make big downforce prohibitive.

In reply to Imagine how low the pressure… by WaveyD1974

That’s exactly what I’m thinking: coming down hard on tyre pressures is making the manufacturers and teams feel the pain of the aero they want.

Fair enough too, why should Michelin risk the public pain of a tyre failure when teams have obviously been flouting the pressure guidelines?

I actually hope the racing gets worse, to really force the issue, and aero is consigned to the skip like dustbin fairings. I’d rather spend my coin supporting a local club meet than watching Motogp at the moment.

In reply to Pain before pleasure? by Seven4nineR

Racing bad -> look for solution -> F1 makes lots of money and racing is bad -> vomit

Why do they continue to use a clutch lever and a thumb operated rear brake, rather than using a thumb operated clutch mechanism and use the left hand lever for the rear brake. Surely they could design an effective thumb operated system for the hydraulic clutch, and having the lever to brake would provide the rider with more rear braking sensitivity and control.

In reply to Thumb operated clutch? by Morgs

If you think about the position they are on the bike at full right lean, operating the lever is actually quite hard. A thumb lever is easier to reach. Someone (I forget who for the moment) told us they could barely reach the left clipon at full right lean.

In reply to If you think about the… by David Emmett

Very good point David. There is many photos of Lorenzo with just the tips of his left hand fingers barely touching the bars...

In reply to Very good point David… by le racer

Look at that beautiful bike, unmolested by the aero scourge.... how I miss thee.

In reply to Look at that beautiful bike,… by lotsofchops

And it doesn't look like a diseased hyena exiting corners!

In reply to And it doesn't look like a… by Dtorg

Good description.

In reply to Look at that beautiful bike,… by lotsofchops

So true! A thing of beauty.

In reply to If you think about the… by David Emmett

Thanks for explaining.

The consideration of the riders weight is well documented, with total weight in the junior classes already existing. However, how a riders height and where that body mass is distributed around and above the bike's chassis will be different for each rider. Miller's crew had tried to change his setup to get it closer to the other KTM riders. This may not be the best decision. Not only because his body dimensions and distribution are somewhat different from his cohorts, but his riding style is also unique.

Yamaha showing with the new fairing and running around top 10, they don't need concessions.

In reply to Yamaha showing don't need concessions by slfish

Will be interesting to see how they get on over the next few races. Austria was a good race for Yamaha last year with Fabio in 2nd and Pecco saying that one more lap and it would have been a win. Catalunya is also, normally, a good track for Yamaha.

Hold on.

1.88 bar at 650m elevation IS the same as 1.88 bar at sea level.

When we measure tire pressure we typically measure gauge pressure, which is the pressure relative to the ambient pressure. So if I measure 1.88 bar at sea level the pressure in the tire is 1.88 bar greater than the ambient pressure. If I then take that tire up to 650m and measure it again I will find that the pressure has increased, but only because the ambient pressure has decreased.

But the teams will all be filling the tires at track, at 650m of elevation, so 1.88 bar at in the pit will be right about the same wherever you are on track. More or less, and the pit area at Austria is near enough the bottom of the hill anyway, so it's not like they need to add extra pressure to compensate for riding downhill. Are they going to get an allowance for riding downhill from the pits at the Sachsenring?

However, they will have slightly less mass of air in the tires if they are filled at 650m vs sea level since the air at that elevation is less dense. This might make a difference to the rate at which the pressure varies due to temperature, but I doubt it'll be that great.

I reckon Dorna looked at the weather forecast, and looked at the braking area for T3 and thought, "temperature (and pressure) is going to rocket into there, we'll cut the teams some slack." Either that, or Gigi decided he could use bullshit to baffle brains and asked Dorna for an allowance based on spurious reasoning due to elevation above sea level. Michelin obviously could have called Gigi on it, but just couldn't be arsed!

In reply to Absolute Pressure != Gauge Pressure by nickridiculous

Right. I presume they set pressures using the TPMS sensor because that's what they're judged by. That would be zero referenced to ambiemt pressure and I can't imagine they would retain a standard atmosphere reference for the hell of it...or maybe they do. Whatever the tpms reference is, it must be the same for all and as precisely as possible. The sensors could all be given a reference of ambient pressure measured at one time by a master instrument at the start of each event. Or, to save messing around, they could just set different limits for tyre pressure on Thursday as Marini mentions. I don't know much about tpms but at a guess they don't have free access to ambient pressure being on the inside of the tyre/wheel. I think they rely on being referenced. Maybe for security the reference cannot be changed and is set at the time of calibration to some standard atmosphere or mean sea level whatever number.

In reply to Right. I presume they set… by WaveyD1974

Yeah if the TPMS don't measure with respect to ambient pressure then I suppose what ever they say would vary as the elevation varried. Good point.

In reply to Didn't think of that. by nickridiculous

I think you're right in what you say Nick. Tyre pressure is absolute minus ambient as the difference is responsible for the stress in the tyre. So 1.88 on the tip top of mount everest is the same as 1.88 at sea level. It's the zero reference which changes.

I still think the key to managing tyre pressures is modulating heat, not pressure.

Heating elements in the rim “to control tyre temperature, your honour”…..which would inherently keep pressure stable, thereby not falling foul of:

“The use of any device on the wheel to adjust the tyre pressure whilst on track is prohibited.”

You can’t say pressure has been adjusted if the pressure remains the same.

A front mudguard constructed of a material that absorbs heat and sprouts cooling fins. Or the steampunk version cooled by a radiator piggyback style. Just to continue with appendages and devices that have little to no application on road-going bikes.

In reply to A front mudguard constructed… by spongedaddy

....but it must have neon ?

In reply to ....but it must have neon ? by WaveyD1974

And moving parts that glitter in the sunlight to enhance Motogp's slow-mo video clips.

If everyone ran a bleed off valve on the tyres to maintain constant pressures Danny couldn't sack everyone out of the race.

In reply to If everyone ran a bleed off… by Grahamuk-oz

Even better, if everyone ignores the rules and gets the same penalties then it’s a wash and the race results are not affected

Marquez’ crashes into other riders and all the blows he’s taken in his own crashes, have left me thinking about the double vision problems he’s had. Does anyone wonder if perhaps the problem has returned? Or if his depth perception is off? Just something that crossed my mind.

In reply to Marquez’ crashes into other… by Faitbien

I thought some of his riding in Austria was classic Marquez. Nothing pointing the way it should be and yet fast. He obviously knows that with this bike there isn't really a chance of a win, it would take some very strange circumstances. So in the races, he just gets miles in. I think he's grown up a bit. A sniff of the podium and he's mad again.

In reply to Marquez’ crashes into other… by Faitbien

I think that is has a big part to play in his "follow-the-fast-guy" way of pulling out a fast lap. He said many times that following another rider makes the bike easier to turn while every one else says that they lose the stability and downforce to accelerate and brake properly. To me it sounds like a weak excuse to cover an issue he'd rather not discuss, the one you mentionned.

In reply to I think that is has a big… by le racer

In Austria his fastest laps were alone. I think what he says is that he and the Honda have less trouble following than others seem to have. That may point to Honda not losing something they don't have.