Corsa Pro vs GP5000 STR - tread width

[mikehhhhhhh]

I've long wondered whether the apparent limited tread width on a cotton cased tyre like a Vittoria could be detrimental to grip at extreme lean angles compared to say a GP5000 which appears to have good rubber all the way to the sidewall.

I always assumed it was nonsense, they would make it wider if it needed to be.

Until tonight pulling out some Corsa Pros I crashed on during the summer, I notice scuffs on the sidewalls - starting high up, continuing radially until it scuffs all the way down the sidewall.

I descend hard and this was no exception. I was descending 600m in switchbacks until one I just slid out on, past the braking and turn-in phase, approaching mid-corner - no warning and both tyres seemed to give way at the same time. At the time I put it down to just overcooking it.

These marks have me wondering whether I managed to bank onto the cotton sidewall, where there was just no grip.

Is that a thing? Does anyone *know* any better about the subject?

[Hexsense]

Yeah,
that's why Specialized tires were slow comparatively even with similar construction on Turbo Cotton to Vittoria cotton tires.
They refuse to make tread narrow. Their road tires tread coverage are 45-50%. Turbo Cotton 28mm tread coverage is 50%.
Not around 41% like Vittoria Corsa Pro, or 36% like Vittoria Corsa Speed. Or worse yet, Michelin Power Cup TLR 28 has only 35% tread coverage despite not being a proper TT tire.


PS1. you don't have to roll 100% on the sidewall part to slide. If the tread part protude more than sidewall then you lean. The less rubber in contact with the road could be enough to just let you lost grip.

PS2.
Mountain bike tires doesn't have this issue. They have big knobs on the side. The more you lean, the better they bite.
Motorcycle, despite having slick tire, is not comparable too. Motorcycle is heavier than the rider, not other way around. So bike leaning dynamic is different and rider suppose to lean more than the bike (while on road bike and mountain bike, you have to lean bike more than the rider). A brand that just transfer motorcycle knowledge to bicycle usually fail short here. They'd make the tread too narrow.

Road bike is much lighter than the rider. So you suppose to lean the bike more than the rider. Yet, we don't have knobs to help bite into soft ground like mtb. So we just need wider tread coverage comparatively.

[mikehhhhhhh]

So you're saying that manufacturers reduce tread width, potentially at the expense of cornering grip because it reduces rolling resistance?

[Hexsense]

That's correct.
Vittoria have many tires.

Corsa Speed have narrowest tread.
Corsa Pro have narrow tread.
Corsa Pro Control have moderate tread width.

The faster one also have the narrowest tread and slowest one have widest tread.
Usually, across most brands. TT tires have narrowest tread. Then all out race tire. Then normal tire.
There are some exception like Michelin and Goodyear non TT tires also have narrow tread. And Specialized don't make tires with narrow tread at any level.
But generally, tire that have narrow tread like TT tires should not be corner hard on.

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Yeah,
that's why Specialized tires were slow comparatively even with similar construction on Turbo Cotton to Vittoria cotton tires.
They refuse to make tread narrow. Their road tires tread coverage are 45-50%. Turbo Cotton 28mm tread coverage is 50%.
Not around 41% like Vittoria Corsa Pro, or 36% like Vittoria Corsa Speed. Or worse yet, Michelin Power Cup TLR 28 has only 35% tread coverage despite not being a proper TT tire.


PS1. you don't have to roll 100% on the sidewall part to slide. If the tread part protude more than sidewall then you lean. The less rubber in contact with the road could be enough to just let you lost grip.

PS2.
Mountain bike tires doesn't have this issue. They have big knobs on the side. The more you lean, the better they bite.
Motorcycle, despite having slick tire, is not comparable too. Motorcycle is heavier than the rider, not other way around. So bike leaning dynamic is different and rider suppose to lean more than the bike (while on road bike and mountain bike, you have to lean bike more than the rider). A brand that just transfer motorcycle knowledge to bicycle usually fail short here. They'd make the tread too narrow.

Road bike is much lighter than the rider. So you suppose to lean the bike more than the rider. Yet, we don't have knobs to help bite into soft ground like mtb. So we just need wider tread coverage comparatively.

Is that leaning philosophy 100% right? I know on a motorcycle you place your weight on the inside of the bike and physically lean into the corner to keep the bike as upright as possible, which enables the biggest contact patch possible and the highest speed possible for that corner. If you don't do this and try and corner at the same speed you'll either run out of ground clearance or ride off the edge of the tyre. It also helps you get on the throttle earlier exiting the corner = the sooner you get the bike upright the harder you can get on the gas and avoid high sides.

I assumed the same can be said for road bikes but obviously not as extreme (no knees or elbows down in the tour as yet). Therefore whenever I corner I try to lean my upper body into the curve to keep the bike as upright as possible and my speed as high as possible.

Aside from the differences of a motorcycle and bicycle, isn't the effect of gravity and cornering forces essentially the same?

You weight the outside peg of a motorcycle in a corner same as you do on a bicycle. You don't just do that on a bicycle to avoid pedal strikes in the corner, it's to apply outside pressure to the bike to keep it as stable and upright as possible.

Tom Pidcock seems to employ a motorcycle-like method of cornering on descents, and he seems to descend better than most

[warthog101]

Motorcycle, despite having slick tire, is not comparable too. Motorcycle is heavier than the rider, not other way around. So bike leaning dynamic is different and rider suppose to lean more than the bike (while on road bike and mountain bike, you have to lean bike more than the rider). A brand that just transfer motorcycle knowledge to bicycle usually fail short here. They'd make the tread too narrow.

Road bike is much lighter than the rider. So you suppose to lean the bike more than the rider. Yet, we don't have knobs to help bite into soft ground like mtb. So we just need wider tread coverage comparatively.

Sort of.
Yeah not really comparable to bicycle cornering despite them having two wheels.
Much larger braking forces and in the case of motoGP about 300hp on corner exit.
The rider holds their weighf off the bike to hold the bike more upright and have a wider contact patch as those forces are applied. Also more grip through the corners.
There is a throttle to control slides and the best riders will use their body to hold up all that weight when front traction is gone.
Nobody better at that than this fella

[Hexsense]

Is that leaning philosophy 100% right?

I can't confirm if it's correct but here is what I think.

Motorcycle is inherantly very stable. Long trail value and the motor bike have low CG and is very heavy (Thus, CG can't get very far off center no matter where rider is). You as a rider have to get inside to persuade the motorcycle to lean and corner.

Bicycle is different. Lower trail value and is very light compare to the rider. If you put your body too far on the inside, you'll just wash out. The force vector from cg is highly offcenter and will push bike tire laterally out of the corner.
Instead, you lean the bike to make it corner. But you keep the body (which dictate where CG is) as inline over the top of the contact patch as possible so that the tire don't wash out. To make that possible, you have to separate bike lean vs body position. Bike lean as sharp as corner dictate. Lower body may have to follow the bike due to how things are attached. Upper Body stay as on top of the tire as feasible, not lean way inward like you glue on top of the tilted seat.
On Mtb, dropper post helps a lot here on cornering descend. Since it put seat lower and out of the way so that you can stay more on top of the tire.

Tom Pidcock seems to employ a motorcycle-like method of cornering on descents, and he seems to descend better than most

Look again carefully where his bum is vs the seat. The bike lean more than his body. The seat line up with his right bum when cornering right. Pidcock tried to stay as on top of the tire as he can given the limitation of tall saddle which gets in the way.

[warthog101]

Foot pegs on a motorcycle dont move as you don't need to pedal them.
Much smaller footprint from the narrow tyres as great big wide tyres = drag.
You can't hang off as much and don't need to as the high lean angles that necessitate it on a motorcycle are not achievable on a bicycle.
And again no throttle and far less braking force.
Not remotely comparable imo.
Both fun though

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Is that leaning philosophy 100% right?

I can't confirm if it's correct but here is what I think.

Motorcycle is inherantly very stable. Long trail value and the motor bike have low CG and is very heavy (Thus, CG can't get very far off center no matter where rider is). You as a rider have to get inside to persuade the motorcycle to lean and corner.

Bicycle is different. Lower trail value and is very light compare to the rider. If you put your body too far on the inside, you'll just wash out. The force vector from cg is highly offcenter and will push bike tire laterally out of the corner.
Instead, you lean the bike to make it corner. But you keep the body (which dictate where CG is) as inline over the top of the contact patch as possible so that the tire don't wash out. To make that possible, you have to separate bike lean vs body position. Bike lean as sharp as corner dictate. Lower body may have to follow the bike due to how things are attached. Upper Body stay as on top of the tire as feasible, not lean way inward like you glue on top of the tilted seat.
On Mtb, dropper post helps a lot here on cornering descend. Since it put seat lower and out of the way so that you can stay more on top of the tire.

Tom Pidcock seems to employ a motorcycle-like method of cornering on descents, and he seems to descend better than most

Look again carefully where his bum is vs the seat. The bike lean more than his body. The seat line up with his right bum when cornering right. Pidcock tried to stay as on top of the tire as he can given the limitation of tall saddle which gets in the way.

you steer a motorcycle by countersteering. you tip a bike into a turn by countersterring into it (same as any two wheeled transport above about 10mph i think). you put your weight to the inside of a motorcycle to keep it as upright as possible for the aforementioned reasons.

you've got a point in that image to be fair. notice how they all stick a knee out into the corner though? this isn't to use it as a lean angle gauge like a motorcycle, it's to put weight as far inside the corner as possible. on the majority of decents they're riding it for the first time in that race so as well as seeing through the corner, they also need to be aware of gravel/debris/poor road surface. i would say that's why on a lot of corners they keep their heads so central or even outside the centre line — so they can see through the apex. you'll notice road-race motorcyclists (isle of man etc) hang off less than GP riders for similar reasons.

we've all seen the following video 100 times, and could probably watch it 100 times more. adam blythe mentions seeing through the corner at around 3 minutes. if Tom had his head and upper body on the inside of his centre line and as low as possible, he wouldn't be able to see through the corner...



when taking switchbacks and corners with good visibility cyclists (Tom in this instance) seem to do this less. i'm assuming this is to enable a more upright bike which equals more contact patch which equals speed.

here's another image that i think shows good body position technique — weight as low and as far inside the corner as is safe to do so for that moment...

would genuinely like to hear what the serious racers on this board make of this discussion and I wonder if anyone's asked Tom himself?

[TobinHatesYou]

I drop my knee for many reasons.

1) It's stabilizes my lower body, puts it under a bit of tension.
2) It gets my knee out from under my chest, which I'm trying get as low as possible.
3) It helps me point my hips/chest in the direction I want to go, which affects my control of the bike at perhaps a subconsious level. It's a basic tenet of MTB cornering.
4) Maybe dropping the knee does help weight distribution a little.
5) It might provide a little bit of an air brake effect too.

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100%.

rotating your hips and upper body into the corner is exactly the same for motorcycle riding too. it's the initial body position set up to hanging your upper body off and into the turn. again, the air brake effect is the same for motorcycles. so much so they dangle a whole leg now, but there was debate around that last time i checked in to motorcycle racing

sorry for derailing your thread, Mike. guess it's relevant though!

[warthog101]

This appears to be a conversation comparing motorcycle cornering to bicycle cornering by people who don't ride motorcycles
Weight, throttle, tyre surface area, ability to position the body, need to position the body, footpegs that dont move, braking ability, suspension, lower centre of gravity etc etc.
Apart from them having two wheels there aint much in common with respect to cornering them fast.

[TobinHatesYou]

I'm not comparing bicycle handling to motorcycle handling at all. I'm stating what I do in order to consistently get me through a corner on a bicycle as fast as possible.

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not sure if i'm included in that but FWIW i do ride motorycles, track and road so i do have personal experience of this.

each to his own but when i corner on a bicycle i employ the movement of my upper body to the inside of the corner same as i do a motorcycle. this enables me to keep the bike more upright through a corner at a given speed. feels safer to me at least

[Romb1k]

According to this videos both points are accurate in some way: you put your weight insinde on the handlebar and outside on the pedal. Your bum is slightly up from the saddle and outside.