Winter, wet weather tyres

[maximus meridius]

I've been aware that the main (or only?) point of tread on car tyres is to clear water away, to prevent hydroplaning.

But given that the shape of bike tyres and contact area of bicycle tyres is so different, is there a reason why road bike tyres have any tread at all? If tread is just for mud and similar. Couldn't they all be slicks?

I've got Continental Contact Plus 700x37 by the way.

[Nearholmer]

^^^
Astonishingly good general purpose tyres, and they even cope well with a surprising range of off-road surfaces/conditions. If I hadn’t “gone tubeless”, I’d still be using them.

Sheldon Brown gives a well-argued explanation as to why tread is unnecessary on bike tyres used only on the road (you have to read down a fair way). https://www.sheldonbrown.com/tires.html#google_vignette

Personally, despite being an engineer, and supposedly a rational, evidence-led sort of chap, I still struggle slightly with this at an instinctive level, and still “feel itchy” when I see very slick road bike tyres, so it’s probably a good job that I ride a fair bit off-road, because that legitimises me having some tread!

[pwa]

Some of the most grippy road tyres (in the wet) that I have used have had very little tread. Not exactly slicks, but not far off. Especially with fairly narrow tyres, the contact patch is quite small, so the downward pressure is concentrated and therefore effective. The crucial thing is the "rubber", with some tyres having grippier rubber than other tyres. Traditionally (don't know if it still holds true) grippier rubber wears down quicker.

[Nearholmer]

It’s interesting that SB, very fairly, includes a note that one informed commentator advocates a very fine tread to aid grip when cornering, and that at least half makes sense to me.

Forget hydroplaning, because, as he says, bike tyres aren’t subject to the conditions that initiate that, and think simply about the lubrication provided by a film of surface water, especially if contaminated with fine silt etc.

When riding in a straight line the contact patch created, the direction of the forces at play, which are in line with the axis of the bike, and the mass of the rider forcing the tyre down through the water film into solid contact, are such that grip should be fine without tread, the micro-interlocking within the contact patch does the job.

Start to corner significantly at significant speed, and the position of the contact patch changes, it probably also changes shape slightly especially if the tyre is not ideally circular in cross section, more so the smaller the diameter of the wheel, and, more significantly IMO, an additional force comes into play, at right angles to the axis of the bike.

Now, there may be so much “excess grip” available within the contact patch of a slick tyre, more than is needed to deal with the along-the-axis forces, that the across-the-axis force can easily be accommodated, but I do wonder, and I wonder whether adding a very fine tread, some bits of rubber to deform and resist sideways sliding, might help. It might not though, because what tread patterns actually do is create areas that aren’t in contact with the surface, they reduce the area of the contact patch within which micro-interlocking occurs.

Maybe the optimal solution even for cornering is a slick tyre made from very soft, grippy material. Or, maybe one should run at slightly reduced pressure in wet weather, to increase the size of the contact patch, but not so low as to reduce the downward force per unit area so low that micro-interlocking is compromised.

Is there a bike tyre technologist in the house who can give us the full and proper detail?

[Mike Sales]

I read a leaflet from Continental which said that bike tyres could aquaplane, but only at 120mph and faster.

I have found a Continental site on the subject.

Bicycles are not susceptible to aquaplaning. Whereas car tyres create a square road contact -- and have a straight leading edge with the road that makes it easier for a car to trap water under the tyre as it rolls -- bike tyres have a rounded contact with the road which pushes the water to either side of the tyre more efficiently. That's because they're designed to lean into corners.

Another key difference is that bike tyres are narrow and inflated to a relatively high air pressure. This means less water is in contact the leading edge of the tyre, and the high tyre pressure is more efficient at pushing water out from under the tyre. By comparison, car tyres are wide and inflated to a lower air pressure; this can make it difficult for water to escape from the middle of the car tyre.

Finally, there is the question of speed. A car travels much faster. Depending on the depth of water, this speed leaves less time for water to be dispersed. It's highly unlikely that a bicycle will ever travel fast enough to begin aquaplaning, no matter how furiously you pedal.

https://www.continental-tyres.co.uk/b2c ... -bicycles/

[Nearholmer]

Yes, that’s the sort of thing SB says: only at effectively unachievable speeds.

As a random PS: one tyre type that I really do not like is the sort that has fine or no tread in the centre, then a marked transition to side knobs/lugs. I find them alarming on the road, because feedback (and by implication grip) suddenly change at just the moment you don’t want it to, during hard cornering. A tyre with either a consistent surface all round, or a very gentle transition, vmcertainly feels more reassuring.

[Brucey]

FWIW I agree

[maximus meridius]

Thanks for the replies.

I'm working my way up to 120 mph. When I get there I'll get more knobby tyres.

In the meantime it looks like tread doesn't matter much, for me. 98% of my cycling is on road or occasionally crushed gravel, with the rest a small... oh, wait, I've just remembered a very short section on a regular ride that is sometimes a bit muddy, if it's been raining. Anyway, when it's time for new tyres I'll ignore tread, and as my very-short-sometimes-muddy section is away from traffic and up hill, with very high banks to catch me on each side, I'll take the risk and see what happens.

[Nearholmer]

I can tell you what happens when the mud gets just right: wheelspin, sometimes immediately followed by falling off, into the mud.

It was having episode after episode of wheelspin on mud, wet grass etc which made me swap from those Continental contact plus to tubeless tyres with little knobbles. They aren’t as good on hard surfaces, but better on soft or loose.

[maximus meridius]

I can tell you what happens when the mud gets just right: wheelspin, sometimes immediately followed by falling off, into the mud.

It was having episode after episode of wheelspin on mud, wet grass etc which made me swap from those Continental contact plus to tubeless tyres with little knobbles. They aren’t as good on hard surfaces, but better on soft or loose.

The uphill-that-is-sometimes-muddy is one of the very few sections where I need to use my inner chain ring (on a triple). So yes, I fully anticipate wheel spin and falling off. But it's a very narrow path, with very high banks (taller than me, even on a bike) so about as good a place to come off as imaginable. If/when I do I'll walk the rest. It's only a few yards.

Also I've just remembered a section (of a few feet) where I sometimes go on grass (though I don't have to, and usually avoid it if it's wet).

But my mileage is low. I'm happy with the Continental Contact Pluses at the moment, so it'll be a long time before they need replacing. At that point I may have expanded my bike collection to include "road only" and "rough stuff".

[rareposter]

Contact Plus are good tyres.

The tread thing is interesting - most customers simply won't buy tyres without tread, they can't get their heads around the whole slick thing so tyre manufacturers put some basic sipes / pattern on their road tyres for marketing purposes. 99% of the time, it makes no difference whatsoever.

The compound used is the main factor and a lot of manufacturers use a harder compound in the tyre centre for durability and a softer one on the edges for better grip in corners.

Good winter tyres should be slightly softer for better grip in cold / wet conditions but also have a better puncture belt underneath the tread due to the increased likelihood of debris on the roads - water acts as a lubricant for debris to penetrate the tyre so it needs a thicker tread / puncture belt.

I really rate the Schwalbe Durano tyres too in winter although they've been renamed and updated now, they're called the Schwalbe One (not to be confused with the Pro One which is a racing tyre).

[SimonCelsa]

I recently bought a pair of second hand Continental Grand Prix 4 Season 700 x 28 so I would hope they prove to be good, winter, wet weather tyres. The reviews seem to indicate they're pretty good.

[JohnR]

I'm surprised that no one has mentioned leaf mush which takes months to decompose and afflicts many of my lesser local roads. Normal traffic moves it to the sides but then something very big, or two vehicles trying to pass, spreads it back onto the road again. How do slick, or near-slick, tyres cope with that muck? Sand and fine gravel washed onto roads by heavy rain is another potential hazard.

My current preferred winter tyres are the Schwalbe G-One Allround which, I feel, can try to get some grip on whatever they encounter (other than deep mud or ice) while running fine on clean tarmac.

[maximus meridius]

I'm surprised that no one has mentioned leaf mush...

Ha! Yes indeed. A couple of the streets round me have that. But the worst leaf mush is on my drive. I actually skidded into the front of my own house the other day!! So I suppose I've nobody to blame by myself.

[Brucey]

My current preferred winter tyres are the Schwalbe G-One Allround which, I feel, can try to get some grip on whatever they encounter (other than deep mud or ice) while running fine on clean tarmac.

https://www.sjscycles.co.uk/tyres-large ... nch-57584/

good tyres but small stones will [almost inevitably] tend to get stuck in the tread and this might drive you nuts. Is there a cheaper alternative I wonder?