Grip in the wet
pangolin
Posts: 6,666
From article on the frontpage:
http://www.bikeradar.com/news/article/michelin-rolls-out-three-new-pro4-tires-36376/
Wut. I get pressure increases as area decreases. But I thought more tyre on floor would = more grip. Pressure would decrease of course, but I assumed the extra area more than made up for that.
Hmm. Perhaps they are referring to an ideal world with no road debris. Whereas, with a few little stones around, a lower pressure tyre would be ok (mould around the grit / stone whatever, and still touch the ground) but a really high pressure would hit it, be in contact with only the obstacle, and slide out.
Thoughts?
http://www.bikeradar.com/news/article/michelin-rolls-out-three-new-pro4-tires-36376/
The Michelin Pro4 Grip clincher
The Pro4 Grip has a few features designed to keep you rolling in the wet. Sipes are cut into the tread, not to clear water as many might think, but to increase pressure and therefore grip by reducing the contact patch of the tire. Margadonna gave the analogy of a football player with a size 14 shoe and a little girl with a high heel; "the girl's heel is putting more pressure on the ground because the contact patch is much smaller," Margadonna said.
Of course a soft rubber would squish and negate some of that benefit, so a higher-durometer rubber is used.
Grip in the wet, Michelin claims, is 15 percent better than the regular Pro4.
Wut. I get pressure increases as area decreases. But I thought more tyre on floor would = more grip. Pressure would decrease of course, but I assumed the extra area more than made up for that.
Hmm. Perhaps they are referring to an ideal world with no road debris. Whereas, with a few little stones around, a lower pressure tyre would be ok (mould around the grit / stone whatever, and still touch the ground) but a really high pressure would hit it, be in contact with only the obstacle, and slide out.
Thoughts?
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Comments
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Michelin claims blah blah blah sales speal blah blah
I picked up the new Pro4 'endurance' when they came out, they proved anything but.0 -
Yes - it's very complicated because the "simple" rules of friction don't apply when you add a fluid "lubricant". The simple rules don't really apply to tyres anyway but that's a whole other story...ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0
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Vorspruntecnik (I think that's how you spell his name) usually has the correct and absolute answer to these types of things....Food Chain number = 4
A true scalp is not only overtaking someone but leaving them stopped at a set of lights. As you, who have clearly beaten the lights, pummels nothing but the open air ahead. ~ 'DondaddyD'. Player of the Unspoken Game0 -
I'm with Pangolin. My understanding is that knobbly mountain bike tyres are not so good on a wet road as there is less rubber in contact with the tarmac. A narrow road bike tyre has to be doing an unachievable speed before aquaplaning is a risk. Therefore that sounds like a triumph of marketing over reality.
The above may of course be nonsense.0 -
Well in the snow in cars you are much better off with a narrow tyre than a wide low profile one, the higher pressure / narrower contact point presumably gets to contact, rather than skate on a film of water / snow.
that said, its very difficult to play fooball in high heels.
Is Margadonna a football playing chararcter from the argentine version of the Simpsons?Bianchi Infinito CV
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Front half of a Viking Saratoga Tandem0 -
Friction is indepenadant of surface area as GCSE physisc tells you....
Sipes work by creating an edge that grips against protrusions from the surface, winter tyres have lots of sipes to do this, but overheat in summer as the extra tread block moevement heats the tyre up.
Using a high durometer rubber seems to offset the benefits of the sipes leaving you back where you started from.
Most Michelin tyres seem rubbish in the wet (car, M/C and bike!)Currently riding a Whyte T130C, X0 drivetrain, Magura Trail brakes converted to mixed wheel size (homebuilt wheels) with 140mm Fox 34 Rhythm and RP23 suspension. 12.2Kg.0 -
pangolin wrote:From article on the frontpage:
http://www.bikeradar.com/news/article/michelin-rolls-out-three-new-pro4-tires-36376/The Michelin Pro4 Grip clincher
The Pro4 Grip has a few features designed to keep you rolling in the wet. Sipes are cut into the tread, not to clear water as many might think, but to increase pressure and therefore grip by reducing the contact patch of the tire. Margadonna gave the analogy of a football player with a size 14 shoe and a little girl with a high heel; "the girl's heel is putting more pressure on the ground because the contact patch is much smaller," Margadonna said.
Of course a soft rubber would squish and negate some of that benefit, so a higher-durometer rubber is used.
Grip in the wet, Michelin claims, is 15 percent better than the regular Pro4.
Wut. I get pressure increases as area decreases. But I thought more tyre on floor would = more grip. Pressure would decrease of course, but I assumed the extra area more than made up for that.
Hmm. Perhaps they are referring to an ideal world with no road debris. Whereas, with a few little stones around, a lower pressure tyre would be ok (mould around the grit / stone whatever, and still touch the ground) but a really high pressure would hit it, be in contact with only the obstacle, and slide out.
Thoughts?
I think what they are trying to say is as the bike & rider weight remains the same by reducing the contact area of the tyre the downward force increases onto the road therefore increasing the grip. Which is correct if the tyre compounds were similar or harder on the smaller contact patch version to compensate for the extra downward force.
However I would think that the compound of rubber itself would be more important along with the design of the tyre to aid water dispersion.
IMHO the jury is still out.Pain hurts much less if its topped off with beating your mates to top of a climb.0 -
The Beginner wrote:Most Michelin tyres seem rubbish in the wet (car, M/C and bike!)
Their (car) winter tyres are superb in snow, however. I've run them on several RWD Mercs and I couldn't be happier.
Sipes also work by shedding snow.
Shouldn't get too hung up on GCSE physics either because it doesn't really work for tyres.ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0 -
Their Pilot Road 3 M/C tyres are very good in the wet, they have the sipes, so I suspect they've went sipe-happy!Disc Trucker
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Planet X London Road0 -
I think the main thing to note is that static friction - as mentioned above - does not rely on contact area. Kinetic friction, however, does show a dependency on contact area. When a tyre rolls, it could be said that it operates in the static friction regime. This isn't entirely correct as it will operate in the kinetic regime to a certain extent; especially when the tyre loses grip and slides. I can only assume that this is what they are talking about, especially in the wet when you tend to slide a bit more. So when this happens, area can make a difference... (As above, let's not even think about lubrication because of the rain)
But on the question of "are we listening to Michelin hype?"; all I know is that companies want you to spend your hard earned readies with them... If only you could try before you buy
Shand Skinnymalinky
Argon 18 Radon0 -
A hard compound tyre with snipes? plenty about, most if any do not get rave reviews about their wet weather grip...
Color me Skeptical!0
