PLEASE READ THIS POST, I THINK YOU WILL FIND IT INTERESTING.
After being called out by some members for lacking detailed knowledge about the tire situation in MotoGP I went on a 3 day research binge. Work is slow so I've had time to pour over RRW, Moody blog, Mamola blog, Ryder blog, Krpotkin, Noyes, etc. I've also consulted some racers and I even sent an email to Bridgestone (no reply)
<span style="font-size:18pt;line-height:100%Intro
Before I start, here is the over simplification that allows discussion:
1. Tire compound - the rubber that touches the road
2. Tire construction/carcass - the inner tire structure
3. Tire flex - change in carcass shape that leads to a more efficient contact patch
4. Tire deformation - change in carcass shape that lead to an inefficient contact patch
The 800s have changed everything. We already knew that but a lot of the changes in tires actually started with TC and fuel restrictions. TC means racers have a predictable exit so the generally try to find speed by pushing the corner entrance. During the 500cc era unleashing the raw power of the engine was of utmost importance. During the 500cc era compound grip improved drastically but the tire carcasses developed slowly. Towards the end of the 990 era when TC and fuel restriction meant racers had to push in the corners, racers actually started buckling/deforming the tire carcass. When they added 3kg and reduced fuel again for the 800cc class, manufacturers went out to build bikes that were still faster in the corners. It was impossible to go faster at many tracks without better carcass design
Bridgestone/Ducati probably realized this phenomenon early on because Ducati was one of the first companies to roll out its 800. I imagine Ducati and Bridgestone were probably testing 800 tires for several years before the competition began.
The 2007 Bridgestones probably had a revolutionary design in terms of the materials used, or the manufacturing technique. They were probably also relatively expensive. Harder carcass tires are not an absolute advantage b/c some corners are too slow to make a really hard carcass tire flex. Racers need a bit of flex to get a good contact patch, but too much flex causes deformation of the carcass and causes the contact patch to become large and inefficient. Heat builds up as a result and the compound is compromised.
For several years now tire carcasses have been paramount to tire performance. In fact, when the announcers relay tire choices the information they give often reflects the nature of the tire carcass and not the compound rubber. Apparently, both manufacturers are capable of making rubber that is sticky and can go the race distance, but the way they build carcasses is very different.
<span style="font-size:18pt;line-height:100%Qatar
Fast forward to Qatar 2008. Casey shows up with the 2007 spec Bridgestones and Rossi shows up with the old 990 spec Bridgestones. Casey waited at the back for his tires to come up to temperature. Once the hard construction was up to temp, he set off on a tear. He was pulling huge cornerspeed in Qatar's fast turns. The 2007s were built to handle extreme cornering loads.
Rossi went for an old 990 setup soft front hard rear (remember those are carcass ratings). I thought it had to do with the tires being like 990 tires, but it didn't. Rossi was hoping the Bridgestones would be strong enough to allow him to ride his old 990 style. Soft front hard rear is a BRAKING setup. When you hammer on the brakes the front tire goes flat like an automobile tire. You can break deeper and later, then fling the bike on its side loading the hard carcass in the rear. This setup is not good for cornerspeed because cornerspeed requires a tighter line with a lot of lateral force on the front tire; braking puts more compression force on the carcass and air pressure can help it hold it's shape.
Rossi's tires have been melting since 2006. He is simply too hard on his Michelin tires in the cornerspeed era. He must ride hard to compensate for his lack of top end. When the carcass deforms excess friction results and the tires melt.
<span style="font-size:18pt;line-height:100%Jerez
The second round at Jerez was a much different race than Qatar. Everyone was on the same tires bar Kawasaki who still run the 2007s and Pedrosa was running a hard carcass rear. Right from the get go I noticed the tires looked a bit squishy, but when the qualifiers came out, records started falling. During the race nearly everyone was on the same medium medium setups. So even though the compounds they were running might have varied slightly, nearly everyone on the grid had the same flex and rigidity in the carcass. Pedrosa was the only one recommended to run a hard rear carcass. Look at the splits from the race. Pedrosa, Hayden, Vale, and Lorenzo were all about equal in the first 3 sectors, but Pedrosa was faster by about .2 every lap in the fourth sector. What is the fourth sector? Fast right handers that put maximum load on the rear tire. So while the burger munchers behind him struggled with tire deformity, Mr. Pedrosa sailed through the high speed turns to the final hairpin. Burger-munching Hayden was especially slow because he's heavy and he's on a bike with a greater rearward weight bias than the Yamaha.
Does anyone find it strange that Michelin would tell the 50kg Pedrosa to run a hard rear while they told the 70kg Hayden to run a medium?
<span style="font-size:18pt;line-height:100%Anyway, this business with the carcasses explains a lot of things in MotoGP:
1. The Ducati is only fast when you ride it hard. That was true when it had the 2007 tires. The only way to get those things to flex was to ride like you were insane. The harder you ride the better chance you will get them to flex. Now on the 2008s, if you ride it too hard you crash. Just like the LCR Honda in 2006.
2. Part of Stoner's crashing episodes this year is definitely related to the loss of the 2007 technology. 5-10 laps in the 2007s tires were coming into their own and Stoner could push as hard as he wanted. The "newer" tires can't sustain the cornering loads he generates (the front in particular) and he has dropped the bike when the front buckled under heavy cornering force.
3. Michelins fall apart at resurfaced tracks. But more importantly the resurfaced tracks on the calendar are fast flowing tracks (Laguna, Brno). Resurfaced venues have slightly lower grip so you have to run a softer compound, but Laguna and Brno require a hard carcass to sustain the cornering abuse. Michelin riders had to push extra hard to keep up with the Bridgestone runners. Because Michelin carcasses aren't as rigid the tires would deform. The excess friction caused the tires to melt, the sharp surface caused them to shred. The only solution was extremely hard compounds.
4. Pedrosa is almost always faster than Nicky and his tires never fall apart. Pedro is 20kg lighter than Hayden and Michelin can make tires to support his weight. Unfortunately, for him Bridgestone made better tires for Stoner and Vale is a better rider. Hayden was hopeless. He is 20kg heavier than his teammate on a brand that has tire deformity problems. Hayden really needed the ultra stiff construction of the 2007 Bridgestone tires.
5. Michelin said they needed harder compounds. As I said at the beginning, tire tech has changed so much since the 500s that "compound" is now synonymous with the carcass specifications. When Weber was talking about compounds he meant Michelin needed to find a more rigid carcass spec.
I said it sounded like he was full of it, but he wasn't. Michelin do need harder carcasses to compete at many venues.
6. Kawasaki went well at Brno. Brno is mainly all fast turns and it's resurfaced. The 2007 spec are perfect for that track. Considering Stoner's result I think it's safe to say he didn't have them.
I have no idea what this means going forward. If the carcass controls the amount of lateral acceleration it seems like everyone will be at a disadvantage to lighter riders at high cornering speed tracks. This control tire is going to take an incredible feat of engineering to be able to support the larger riders and the different weight distributions of the bikes. They just need to add more fuel so people can ride point and shoot.
I think Ducati might be up a creek if motogp adopts a control tire. It also seems like they'll be doomed if they move to Michelin. They built a bike that rips through high speed corners, now they are going to have to create something a bit more nimble. I suppose their top speed may compensate but that advantage is slowly evaporating. Hayden may not have trouble adapting to a softer control tire, if the technical council actually go through with it. Stoner has shown he can't ride tires that he can't thrash. It could be ugly for him.
I'm also curious about PI. PI is a fast flowing track like Donny. Stoner will certainly be pushing the bike for a huge win. I think there is a good chance he might chuck it if the 2007s don't make a reappearance. I think Ezy owes him the 2007s. Now that Vale has clinched, why wouldn't they make an appearance for Stoner's home race?
If you've read this entire thing, you are a brave soul.
This entire post isn't 100% technically sound and a lot of the info is being taken from reliable but not 100% correct sources, but I think it still explains quite a bit.
After being called out by some members for lacking detailed knowledge about the tire situation in MotoGP I went on a 3 day research binge. Work is slow so I've had time to pour over RRW, Moody blog, Mamola blog, Ryder blog, Krpotkin, Noyes, etc. I've also consulted some racers and I even sent an email to Bridgestone (no reply)
<span style="font-size:18pt;line-height:100%Intro
Before I start, here is the over simplification that allows discussion:
1. Tire compound - the rubber that touches the road
2. Tire construction/carcass - the inner tire structure
3. Tire flex - change in carcass shape that leads to a more efficient contact patch
4. Tire deformation - change in carcass shape that lead to an inefficient contact patch
The 800s have changed everything. We already knew that but a lot of the changes in tires actually started with TC and fuel restrictions. TC means racers have a predictable exit so the generally try to find speed by pushing the corner entrance. During the 500cc era unleashing the raw power of the engine was of utmost importance. During the 500cc era compound grip improved drastically but the tire carcasses developed slowly. Towards the end of the 990 era when TC and fuel restriction meant racers had to push in the corners, racers actually started buckling/deforming the tire carcass. When they added 3kg and reduced fuel again for the 800cc class, manufacturers went out to build bikes that were still faster in the corners. It was impossible to go faster at many tracks without better carcass design
Bridgestone/Ducati probably realized this phenomenon early on because Ducati was one of the first companies to roll out its 800. I imagine Ducati and Bridgestone were probably testing 800 tires for several years before the competition began.
The 2007 Bridgestones probably had a revolutionary design in terms of the materials used, or the manufacturing technique. They were probably also relatively expensive. Harder carcass tires are not an absolute advantage b/c some corners are too slow to make a really hard carcass tire flex. Racers need a bit of flex to get a good contact patch, but too much flex causes deformation of the carcass and causes the contact patch to become large and inefficient. Heat builds up as a result and the compound is compromised.
For several years now tire carcasses have been paramount to tire performance. In fact, when the announcers relay tire choices the information they give often reflects the nature of the tire carcass and not the compound rubber. Apparently, both manufacturers are capable of making rubber that is sticky and can go the race distance, but the way they build carcasses is very different.
<span style="font-size:18pt;line-height:100%Qatar
Fast forward to Qatar 2008. Casey shows up with the 2007 spec Bridgestones and Rossi shows up with the old 990 spec Bridgestones. Casey waited at the back for his tires to come up to temperature. Once the hard construction was up to temp, he set off on a tear. He was pulling huge cornerspeed in Qatar's fast turns. The 2007s were built to handle extreme cornering loads.
Rossi went for an old 990 setup soft front hard rear (remember those are carcass ratings). I thought it had to do with the tires being like 990 tires, but it didn't. Rossi was hoping the Bridgestones would be strong enough to allow him to ride his old 990 style. Soft front hard rear is a BRAKING setup. When you hammer on the brakes the front tire goes flat like an automobile tire. You can break deeper and later, then fling the bike on its side loading the hard carcass in the rear. This setup is not good for cornerspeed because cornerspeed requires a tighter line with a lot of lateral force on the front tire; braking puts more compression force on the carcass and air pressure can help it hold it's shape.
Rossi's tires have been melting since 2006. He is simply too hard on his Michelin tires in the cornerspeed era. He must ride hard to compensate for his lack of top end. When the carcass deforms excess friction results and the tires melt.
<span style="font-size:18pt;line-height:100%Jerez
The second round at Jerez was a much different race than Qatar. Everyone was on the same tires bar Kawasaki who still run the 2007s and Pedrosa was running a hard carcass rear. Right from the get go I noticed the tires looked a bit squishy, but when the qualifiers came out, records started falling. During the race nearly everyone was on the same medium medium setups. So even though the compounds they were running might have varied slightly, nearly everyone on the grid had the same flex and rigidity in the carcass. Pedrosa was the only one recommended to run a hard rear carcass. Look at the splits from the race. Pedrosa, Hayden, Vale, and Lorenzo were all about equal in the first 3 sectors, but Pedrosa was faster by about .2 every lap in the fourth sector. What is the fourth sector? Fast right handers that put maximum load on the rear tire. So while the burger munchers behind him struggled with tire deformity, Mr. Pedrosa sailed through the high speed turns to the final hairpin. Burger-munching Hayden was especially slow because he's heavy and he's on a bike with a greater rearward weight bias than the Yamaha.
Does anyone find it strange that Michelin would tell the 50kg Pedrosa to run a hard rear while they told the 70kg Hayden to run a medium?
<span style="font-size:18pt;line-height:100%Anyway, this business with the carcasses explains a lot of things in MotoGP:
1. The Ducati is only fast when you ride it hard. That was true when it had the 2007 tires. The only way to get those things to flex was to ride like you were insane. The harder you ride the better chance you will get them to flex. Now on the 2008s, if you ride it too hard you crash. Just like the LCR Honda in 2006.
2. Part of Stoner's crashing episodes this year is definitely related to the loss of the 2007 technology. 5-10 laps in the 2007s tires were coming into their own and Stoner could push as hard as he wanted. The "newer" tires can't sustain the cornering loads he generates (the front in particular) and he has dropped the bike when the front buckled under heavy cornering force.
3. Michelins fall apart at resurfaced tracks. But more importantly the resurfaced tracks on the calendar are fast flowing tracks (Laguna, Brno). Resurfaced venues have slightly lower grip so you have to run a softer compound, but Laguna and Brno require a hard carcass to sustain the cornering abuse. Michelin riders had to push extra hard to keep up with the Bridgestone runners. Because Michelin carcasses aren't as rigid the tires would deform. The excess friction caused the tires to melt, the sharp surface caused them to shred. The only solution was extremely hard compounds.
4. Pedrosa is almost always faster than Nicky and his tires never fall apart. Pedro is 20kg lighter than Hayden and Michelin can make tires to support his weight. Unfortunately, for him Bridgestone made better tires for Stoner and Vale is a better rider. Hayden was hopeless. He is 20kg heavier than his teammate on a brand that has tire deformity problems. Hayden really needed the ultra stiff construction of the 2007 Bridgestone tires.
5. Michelin said they needed harder compounds. As I said at the beginning, tire tech has changed so much since the 500s that "compound" is now synonymous with the carcass specifications. When Weber was talking about compounds he meant Michelin needed to find a more rigid carcass spec.
6. Kawasaki went well at Brno. Brno is mainly all fast turns and it's resurfaced. The 2007 spec are perfect for that track. Considering Stoner's result I think it's safe to say he didn't have them.
I have no idea what this means going forward. If the carcass controls the amount of lateral acceleration it seems like everyone will be at a disadvantage to lighter riders at high cornering speed tracks. This control tire is going to take an incredible feat of engineering to be able to support the larger riders and the different weight distributions of the bikes. They just need to add more fuel so people can ride point and shoot.
I think Ducati might be up a creek if motogp adopts a control tire. It also seems like they'll be doomed if they move to Michelin. They built a bike that rips through high speed corners, now they are going to have to create something a bit more nimble. I suppose their top speed may compensate but that advantage is slowly evaporating. Hayden may not have trouble adapting to a softer control tire, if the technical council actually go through with it. Stoner has shown he can't ride tires that he can't thrash. It could be ugly for him.
I'm also curious about PI. PI is a fast flowing track like Donny. Stoner will certainly be pushing the bike for a huge win. I think there is a good chance he might chuck it if the 2007s don't make a reappearance. I think Ezy owes him the 2007s. Now that Vale has clinched, why wouldn't they make an appearance for Stoner's home race?
If you've read this entire thing, you are a brave soul.
