Cycling UK Forum

I cannot repeat it too often: just try the Conti Topcontact WInter II (preferably the 26 inch size): you will be on a different planet. I don't know if it is mostly the rubber compound or the tread pattern, but I don't care: the result is spectacular.
Willem

Brucey wrote:Mud, road slime, smoother surfaces, wider tyres, lower tyre pressures etc will all provoke (and/or help to maintain) what is effectively a 'viscous aquaplane' condition (see wikipedia) more easily and here tyre tread will make a difference.

Never heard the term 'viscous aquaplane' before. Followed your link, and I note that it appears to be related specifically to aircraft landings. I dont want to build too much upon that but also I dont find it a helpful concept in trying to understand cycle tyre issues, especially those related to mud, slime, moss etc. That's because this sort of material can cause problems even when speed is entirely removed from the situation. Ever failed to get moving on a muddy uphill because of wheel spin?
For my money, thinking about lubrication is more helpful.

Could just be the other side of a coin though

DaveP wrote: Could just be the other side of a coin though

...or different shades of the same colour.

I don't expect people to immediately understand the intricacies of the fluid dynamics at the interface, but obviously the tyre can't grip if it isn't touching the road, and the main things that determine this are the viscosity of whatever 'fluid' is in the way, the speed, and the tyre contact pressure. Mud and slime are viscous, and tyre tread patterns both increase contact pressure and give somewhere for the displaced fluid to go to. This all happens less well at higher speeds. 'Good lubricants' usually have high viscosities (that may vary with pressure) and high film strengths.

It doesn't matter if the tyre is attached to an aircraft or a bicycle; the right combination of speed, pressure and viscosity will cause the same thing to happen in each case.

That 'something complicated' can happen at the contact patch is self-evident; for fun, mix up cornflour and water into a 'fluid', and poke it with a stick. Weird huh? Ask yourself if any tyre would push through this sort of stuff and make contact with the road. This is an extreme case of course but real-world mud and slime can -in detail- have equally peculiar properties.

cheers

willem jongman wrote:I cannot repeat it too often: just try the Conti Topcontact WInter II (preferably the 26 inch size): you will be on a different planet. I don't know if it is mostly the rubber compound or the tread pattern, but I don't care: the result is spectacular.
Willem

It's the rubber compound. Tread pattern won't make much if any difference on ice but the cold weather "grippiness" of the rubber compound will, but as you say it don't matter as long as it works.

I think the OP might find the 700C size preferable.