2023 Motul Grand Prix of Japan

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We might see some long lap penalties during the sprint and during the race on Sunday. They have put the track limits sensor right on the edge of the grass for Turn 1 and it's catching a few of the riders out because they are avoiding the grass more than the tiny patch of artificial turf. It caused Bagnaia's lap to be canceled during practice, and I think Marquez' as well.

The racing isn't that close, but maybe we will see some mistakes at Turn 1.
 
Curious . . . and obviously, haven't been keeping count, but how many CF failures have there been in MotoGp over the years? Mayhaps, I'm just not paying attention. Last one I remember, was around 1984 when Freddie Spenser, a few laps away from winning on the HRC NSR, crashed out of the Daytona 200 at 180 miles per hour when the rear CF wheel just disintegrated.
 
Keshav said:
Curious . . . and obviously, haven't been keeping count, but how many CF failures have there been in MotoGp over the years? Mayhaps, I'm just not paying attention. Last one I remember, was around 1984 when Freddie Spenser, a few laps away from winning on the HRC NSR, crashed out of the Daytona 200 at 180 miles per hour when the rear CF wheel just disintegrated.
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I doubt very many but cf has a quality about it similar to safety glass in a car windshield. It can structurally shatter and still be in tack. It loses it's integrity like a bell with a crack in it. Its hard to explain but it becomes what we call "dead."
 
MdubSTYLIE said:
You can make cf more flexible with shape absolutely, but the cost is integrity. A wing has a fairly constant amount of force compared to a motogp bike. Same with a bicycle. A wing has lift force and the flex is there to make it smoother. A bicycle has force on the bottom bracket and laterally. One big hit on a carbonfiber mtb or road bike and it becomes "dead." The integrety shatters like glass and it loses all of its stiffness and becomes nothing more than a paperweight. The amount of side, forward, and back torque on a motogp because of breaking, accelerating, and cornering is a lot more severe and complicate. You wouldn't use cf in an attempt to recreate the qualities of steel. It would be chosen because of the qualities it possesses. A lot about cf has been learned since Ducati tried this. As Michael mentioned KTM has a lot more resources including those from F1. I have no doubt they have made advancements and may have found an excellent design. I'm not sure if Binder is running it or not but his times where very good today. If he is they may have truly found something.
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I am no CF expert.
Yes it is more fragile if hit hard wouldn't however say one big hit and it is dead. It depends where and how hard plus the surface area of the force applied to it.
I have 10s of thousands of ks on CF road bikes and have had a few big off's. Haven't killed one yet. They are mass produced though and plenty have failed.
I have killed a few aluminium frames and steel at the weld. Aluminium has a definite fatigue limit. If you build one too light it ain't going to last. Cannondale had the nickname of cracknfail amongst some back when they made mainly aluminium frames.

I expect KTM are using CF to give the rider more feel. Shape, thickness and layup can be changed to introduce more or less stiffness and I assume that will allow the rider to "feel" the traction of the bike more.
Anyway Brad used one to go pretty fast yesterday and break the lap record. It seems to be working. Interested to hear more about it. Will see how it goes. It ain't making the bikes cheaper though I don't expect.
 
warthog1 said:
I am no CF expert.
Yes it is more fragile if hit hard wouldn't however say one big hit and it is dead. It depends where and how hard plus the surface area of the force applied to it.
I have 10s of thousands of ks on CF road bikes and have had a few big off's. Haven't killed one yet. They are mass produced though and plenty have failed.
I have killed a few aluminium frames and steel at the weld. Aluminium has a definite fatigue limit. If you build one too light it ain't going to last. Cannondale had the nickname of cracknfail amongst some back when they made mainly aluminium frames.

I expect KTM are using CF to give the rider more feel. Shape, thickness and layup can be changed to introduce more or less stiffness and I assume that will allow the rider to "feel" the traction of the bike more.
Anyway Brad used one to go pretty fast yesterday and break the lap record. It seems to be working. Interested to hear more about it. Will see how it goes. It ain't making the bikes cheaper though I don't expect.
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Ahh... the bicycle angle makes it easier to understand what you both are talking about. I confess, it went right past me when Dub referenced his experience, 'cause I too easily discounted the gap between competition bikes and motorcycles when he first mentioned it. But between the two of you, it becomes clearer. Never did competitive stuff on bicycles, but I rode bicycles just everywhere, all across the 5 boroughs of New York for more than 30 years and went through a LOT of frames. Always wanted one of those $4,000.00 CF framed bikes, but heard horror stories about stress fractures, not shattered like a store window, but still, essentially rendering the frame useless, or on the verge of failure. Not a thing you want between yer legs when you hit a New York pot hole at 35-40 miles an hour coming off the Williamsburg Bridge in rush hour.
 
I wonder if Binder can split Bez and Martin from Pecco. Say Bez P1 then Martin P2 then Binder then Pecco. That would sure make it interesting
 
Keshav said:
Ahh... the bicycle angle makes it easier to understand what you both are talking about. I confess, it went right past me when Dub referenced his experience, 'cause I too easily discounted the gap between competition bikes and motorcycles when he first mentioned it. But between the two of you, it becomes clearer. Never did competitive stuff on bicycles, but I rode bicycles just everywhere, all across the 5 boroughs of New York for more than 30 years and went through a LOT of frames. Always wanted one of those $4,000.00 CF framed bikes, but heard horror stories about stress fractures, not shattered like a store window, but still, essentially rendering the frame useless, or on the verge of failure. Not a thing you want between yer legs when you hit a New York pot hole at 35-40 miles an hour coming off the Williamsburg Bridge in rush hour.
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I've doing r & d and testing on different types of steel, aluminum, and carbon since the mid 90's. The first carbon project I was involved with was for GT bikes in 1995. They used a carbon aluminum fusion. The headtube, bottom bracket, and rear drop outs were made of aluminum the rest of the bike was carbon. It was over $10,000 a frame long before bikes had that kind of price tag. It never made it to production but it was the beginning of the future.
 
MdubSTYLIE said:
You cannot make thin cf on a motorcycle chassis and you cannot add flex points. If you are using cf it is because you are looking for a stiff light material. Adding flex points is a very bad idea for cf because it has very little fatigue before failure. Steel breaks like a mailable substance where cf shatters the moment it is over stressed. Besides adding flex points is not the same as using a more flexible material. Steel flexes evenly like a curve. Adding flex points will give it a point a, point b, point c flex making it very unnatural and also inconsistent.

Yes you can wrap carbon fiber around other materials but then you dont have a true carbon fiber chassis. You have a hybrid chassis. A true carbon fiber chassis is a monocoque design. It is important to have the load evenly distributed with cf to reduce the chance of failure. It is very unlikely that a team would use a hybrid cf chassis as there would be no benefit. You aren't going to get the qualities of cf just a little weight reduction.
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It's its ability to be used to flex in a desired direction and the amount of flex that makes CF a good material. To add to Warthog's response about push bikes the rear stays of the carbon push bike are designed to flex sidewise is a certain way to transfer the riders legs power efficiently to the rear wheel without loosing energy, if the rear of the pushbike frame was totally stiff the rear wheel would skip robbing valuable energy.
michaelm said:
I know nothing about all this and am in no doubt you know much, but the problem tor me and pretty much what you seem to be saying now when Ducati tried it in the Stoner years was that you either have a carbon fiber chassis or you don't, and you are stuck with what you bring for a race weekend or longer. The old Ducati steel trellis frame was reputedly pretty much infinitely adjustable by cutting/welding etc, but Ducati Corse which was pretty much an artisanal concern then couldn't even produce 2 bikes the same for their lead rider with the trellis frame chassis. That was nearly 15 years ago though, and doubtless technology has advanced as well as KTM being a very sophisticated and much bigger and better resourced concern than Ducati was then. Sounds like they have come to the same point as Ducati that their traditional trellis frame thing doesn't match a space frame chassis. I actually wouldn't mind them succeeding with a carbon fiber approach, much more philosophically appealing to me/more my idea of innovative technology in the premier class than aero and ride height devices.
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The old Ducati had a frame that attached to engine using the engine as a stressed member. In that situation I doubt that it would of mattered what material the frame was made of

Back to the race Rins has withdrawn, replaced by Bradl. They are expecting Rins to race in Indonesia in 2 weeks time
 
mikesbytes said:
It's its ability to be used to flex in a desired direction and the amount of flex that makes CF a good material. To add to Warthog's response about push bikes the rear stays of the carbon push bike are designed to flex sidewise is a certain way to transfer the riders legs power efficiently to the rear wheel without loosing energy, if the rear of the pushbike frame was totally stiff the rear wheel would skip robbing valuable energy.
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Correct this is adding flex points. This is entirely different than the quality of steel which flexes uniformly as a whole. And also snaps back equally. Thats all I was pointing out is the difference in materials and how they work. You are not going to add flex points to a motogp bike chassis for a magnitude of reasons. Thats the suspensions job first of all. Flex points do not share the same trates as steel what so ever.

When they are added to bike frames it is for riders feel at the cost of efficiency. Very few frames add flex at the chainstays and they do so vertically not horizontally. Thats in order to dampen the chatter the rider feels. But it has a cost. Cannondale does this. Specialized does it but differently.
 
Keshav said:
Curious . . . and obviously, haven't been keeping count, but how many CF failures have there been in MotoGp over the years? Mayhaps, I'm just not paying attention. Last one I remember, was around 1984 when Freddie Spenser, a few laps away from winning on the HRC NSR, crashed out of the Daytona 200 at 180 miles per hour when the rear CF wheel just disintegrated.
Click to expand...
You have a great memory, the Honda wheels is the only one I can think of, I think a Honda broke a CF wheel on a 500 in South Africa about the same time as the Daytona one. The use of CF has greatly improved since then but I still wouldn't like to see it used in MotoGP wheels. I recall that someone did a CF frame in 250cc but I don't recall any failures, perhaps Google would remember.

For F1 they xray the components to check for problems, probably the same is or will be happening in MotoGP

Oh and for the lighter side of CF, I crashed my CF push bike earlier this year after it broke, but it wasn't the CF frame that broke it was the alloy stem (between the CF forks and the alloy handlebars). I took off from the lights I firm pedal stroke sending me over the handlebars and then the broken stem stabbed me in the leg requiring me to be taken to hospital to be stitched up and I've got to scar to prove it. Worst accident I've had at 3kph LOL
 
mikesbytes said:
It's its ability to be used to flex in a desired direction and the amount of flex that makes CF a good material. To add to Warthog's response about push bikes the rear stays of the carbon push bike are designed to flex sidewise is a certain way to transfer the riders legs power efficiently to the rear wheel without loosing energy, if the rear of the pushbike frame was totally stiff the rear wheel would skip robbing valuable energy.

The old Ducati had a frame that attached to engine using the engine as a stressed member. In that situation I doubt that it would of mattered what material the frame was made of

Back to the race Rins has withdrawn, replaced by Bradl. They are expecting Rins to race in Indonesia in 2 weeks time
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Yes, and iirc (which I may not, it is a while ago) this was problematic for the cf thing when the limitation on the number of engines which could be used over a season came in.

My theory at the time was that the first CF chassis bike they gave Casey felt really good on the track he tried it on , but didn’t suit every track and as has been discussed couldn’t be changed every race week to suit different tracks. The tire was also changed from the one for which the bike was designed as has also been said.

We will get to see fairly soon whether Miller can get his tires to last even sprint race distance with the CF chassis, but it is interesting that he has regained his one lap pace, which had been absent for quite a few races, on the CF bike. I really thought he was finished and just couldn’t ride the current tires. Perhaps as a new design the new CF bike has been designed to better suit tthose tires
 
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Boring sprint, only the duel between the old Ducati teammates spiced the race a little bit. Martín untouchable, Bezz must be affected by his crash in quali because he didn't have the same speed he showed in practice, Miller did well given his recent stinkers, Marc best of the Japanese bikes by far. Tomorrow will be more interesting, Pecco may need to take some risks to protect that lead.
 
Keshav said:
Ahh... the bicycle angle makes it easier to understand what you both are talking about. I confess, it went right past me when Dub referenced his experience, 'cause I too easily discounted the gap between competition bikes and motorcycles when he first mentioned it. But between the two of you, it becomes clearer. Never did competitive stuff on bicycles, but I rode bicycles just everywhere, all across the 5 boroughs of New York for more than 30 years and went through a LOT of frames. Always wanted one of those $4,000.00 CF framed bikes, but heard horror stories about stress fractures, not shattered like a store window, but still, essentially rendering the frame useless, or on the verge of failure. Not a thing you want between yer legs when you hit a New York pot hole at 35-40 miles an hour coming off the Williamsburg Bridge in rush hour.
Click to expand...
Traditionalists bang on a out CF failing suddenly. It is possible but it is likely to be a manufacturing fault where there is a void in the wall of the tube.
I have long since stopped worrying about sudden failure.
10s of thousands of ks on carbon framed bicycles. I do knock them around but they aren't treated with kid gloves either.
A very strong, light and reliable frame material ime.

This bloke makes a living out of testing and repairing them. Uses ultrasound to test for voids.
 
The sprint continues to show that Martin is a real threat to Bagnaia for the championship.

Miller much improved, only lost one place. Still behind his teammate.

Bezzecchi had a good scrap with M Marquez

Well done Di Giannantonio in getting into the sprint points, is that the first time? Di Giannantonio is getting better but too late to save his seat for next year, unless Gresini doesn't get you know who.
 
The ktm's looked really good. I was waiting from lap two on for Miller to fade like he always does. This is a point and shoot track so it favored the tendencies of their bike. Binder and Martin are going to make tomorrows race boring as .....
 

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