Tyres for the wet

Commuting, Day rides, Audax, Incidents, etc.
thekelticfringe
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Tyres for the wet

Postby thekelticfringe » 31 Oct 2009, 2:15pm

I got a new fast commuter this summer, which came with Bontrager Select K 700x25 tyres. These were fine across dry weather but now that autumn is here I have had a number of pretty scary slides, both on the road and on Sustrans type surfaces. I'm running the tyres at their recommended pressure (about 100psi) and am reasonably experienced rider on road and MTB.

Thing is; I can't decide if it is the tyres, the new bike, simply that I'm being too much of a hoodlum, or whether I've just had a spell of bad luck.

Has anyone else been taken by surprise in the wet using these tyres? What do people prefer to use for fast commuting. (I do about 15 miles each way on road and hard trails).

Thanks
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sungod
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Re: Tyres for the wet

Postby sungod » 31 Oct 2009, 6:17pm

if you're having the problem on surface that's rough but not loose, that's easily done with a slick at 100psi, the contact patch is small and the tyre can bounce from bump to bump with no traction in between, you'd need to go for a wider tyre at lower pressure to get more grip, you could try running at lower pressure but pinch flats are more likely if you go too far

if it is happening on good smooth road, what speed are you cornering at? is it front or back that is sliding? and sorry to ask, but you're not, er, braking as you corner are you?

i use conti gp4000s 700x23, aside from metal drain covers etc. they stay grippy in the wet (c. £23 online, but some places charge over a tenner more, so shop around)

gilesjuk
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Re: Tyres for the wet

Postby gilesjuk » 31 Oct 2009, 6:38pm

It's the problem with two wheels, if you slide you're on the floor.

Diesel, oil and other things get onto the road and with a small racing tyre there's nothing to soak up the bumps so your tyre bounces around (unless the forks/frame can absorb the movement).

Watch any pro bike race in the wet and people slide off at the corners.

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Swizz69
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Re: Tyres for the wet

Postby Swizz69 » 31 Oct 2009, 8:16pm

Got Vittoria Zaffiro tyres on my roadbike - 700x23. I've had the back slide out now & again if pedalling hard coming out of a corner when the road is wet, although not enough to lose control of the bike.

The bike is short compared to an audax bike or tourer & its easy to lock the back wheel when stopping in a hurry, so i'd put my experience in part down to the characteristics of the bike being light on the back end - the front tyre (where a lot of the weight is when hunched over the bars) has always remained firmly planted.

Don't forget, if you're talking about rain after a decent dry spell. Thats usually when tarmac is at its greasiest - after all the diesel/oil/scrubbed tyres has just been lifted off the surface by the rain. A good time to take it easy then, which is easier said than done when your on a mission on zippy tyres :twisted: :twisted: :twisted:

gilesjuk
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Re: Tyres for the wet

Postby gilesjuk » 31 Oct 2009, 8:28pm

Vittoria Pro Tech have are a racing tyre designed for wetter conditions.

Always avoid slippery things like drain covers and painted lines in the wet.

thekelticfringe
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Re: Tyres for the wet

Postby thekelticfringe » 31 Oct 2009, 10:48pm

Cheers - I have lost the back when climbing, accelerating or braking, and also had it slide/tramline quite badly along road imperfections. This hasn't been enough to result in a fall, but is unnerving particularly in traffic. I've also had an 'off' when the front just seemed to let go entirely, on pavement/footpath rather than road and at about 6 or 8 miles an hour.

I've ridden many bikes/tyres over a number of years and I'm really surprised at how touchy this one is in the wet (it's fine in the dry). I've been trying consciously to weight up the front wheel in corners, but get small slides even then.

So its a sort of head game now - basically I don't trust the tyres any longer which makes my riding stiffer. Think I'll take a look at some of the tyres recommended here and hope for some improvement.

Thanks for the advice
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reohn2
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Re: Tyres for the wet

Postby reohn2 » 1 Nov 2009, 9:49am

Have you tried running your present tyres with a little less air in,in damp and wet conditions, say 90psi ?
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Gearoidmuar
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Re: Tyres for the wet

Postby Gearoidmuar » 2 Nov 2009, 6:27am

Cycle more carefully in the wet. You will not get the same traction in the wet as in the dry. e.g climbing a steep hill in the wet, stay sittin. As others said, avoid painted lines and any metal shore-covers etc. The tread has nothing to do with it. Slicks are just as good in the wet. I've ridden mostly slicks for 20 years.

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mark_w
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Re: Tyres for the wet

Postby mark_w » 2 Nov 2009, 6:37am

I've done quite a few runs now on my nice Conti UltraGator's and they grip fantastically well - even yesterday morning's 20 mile run with the torrential rain where I got told off by MrsW for flooding the kitchen on my return from the water off my legs!

Which reminds me... (off to post new thread...)
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thekelticfringe
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Re: Tyres for the wet

Postby thekelticfringe » 2 Nov 2009, 8:38am

Well - interesting - spent the weekend riding the mountain bike through sodden, rooty woodland and marshy saturated trails in the pouring rain. Very alert to handling characteristics and had a fine time.

This am on the ride to work I really tried to ride well - not on the bike-handling autopilot that I often have to engage when dealing with wayward traffic, suicidal pedestrians, random door openers etc. Paid off I think - felt a lot better, apart from a downhill stretch of wet leafy cobbles (I know, I know!).

Think the roads are cleaning up too - at least up here they have been pretty much underwater for about 48 hours.

So maybe it's that old thing about workmen and their tools - I'll try to keep focussed!
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ronyrash
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Re: Tyres for the wet

Postby ronyrash » 10 Nov 2009, 3:55pm

its the tyres.fault in the design of the tread. smooth down sharp corners with a knife, or possibly a grinder will do a better job. and there will be a big improovment in traction.i was in a similar situation myself and i know how fraustrating it can be.because you do alot of mileage,like myself,your body becomes very sensitive to the bike and when something is seriously amiss it sends warnings and when you cannot rationalise these messages (as in the dangerouse tread syndrom)it brings on acute anxiety.i had 2 wonderfull years with marathon Slicks,allowing for their almost smooth surface,but a wrongly designed tread (such as marathon plus) is far more trecherous.a "Snake in the grass"

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[XAP]Bob
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Re: Tyres for the wet

Postby [XAP]Bob » 10 Nov 2009, 8:03pm

Just to note ronyrash's hatred of M+ tryes, and various people responses in the following thread: viewtopic.php?f=16&t=24329

However, back OT:
Tread on tryes always lowers the area for contact and therefore the grip afforded by the tyre on any given surface (assuming surface and tyre aren't designed for each other as in a belt drive system)
This is why F1 cars use slicks - maximum mechanical grip.

The problem with slicks is that they can easily aquaplane. The ONLY thing tread can do to provide grip is to pump water out of the way. On thin, high pressure bike tyres the tread is unlikely to flex enough to act as a pump (on a road car there is enough weight to set up a pumping action in the tread), so it will act as a channel only - on the other hand roads are generally fairly well drained, so there is rarely alot of water to displace, and bike tyres should be able to cut their way through it to the road below.

I'd expect slicks to deal quite well on wet roads, although anything that increases the contact area will improve traction - basically that means lower pressure & wider tyres.
The other thing is to try to minimise the work they have to do - slow down before, rather than during, corners etc...

Bob

PS - Those two postage stamp sized sections of tyre are the only thing you can use to speed up, slow down, turn a corner and stay upright!
PPS - When my brother was doing his mech eng they were told that a (car) tyre in the wet is ~1/3 as efficient as a tyre in the dry - I presume that isn't a million miles off for bikes.
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niggle
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Re: Tyres for the wet

Postby niggle » 11 Nov 2009, 1:20am

[XAP]Bob wrote:The problem with slicks is that they can easily aquaplane. The ONLY thing tread can do to provide grip is to pump water out of the way. On thin, high pressure bike tyres the tread is unlikely to flex enough to act as a pump (on a road car there is enough weight to set up a pumping action in the tread), so it will act as a channel only - on the other hand roads are generally fairly well drained, so there is rarely alot of water to displace, and bike tyres should be able to cut their way through it to the road below.


No way are skinny bicycle tyres going to aquaplane at cycling speeds, could only happen at several times such speeds, whereas wide car tyres are much more prone to it at speeds which cars are quite capable of. There are other factors which can come in to play such as the tyre compound which may not grip as well when it is cold, or the width of the tyre and size of the contact patch.

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Si
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Re: Tyres for the wet

Postby Si » 11 Nov 2009, 9:29am

Yeah, tread on road tyres is pretty pointless. And cutting it away to reduce the surface contact will only lead to less grip - not to mention voiding the warranty on your tyres and potentially weakening them.

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[XAP]Bob
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Re: Tyres for the wet

Postby [XAP]Bob » 11 Nov 2009, 9:42am

niggle wrote:
[XAP]Bob wrote:...bike tyres should be able to cut their way through it to the road below.

No way are skinny bicycle tyres going to aquaplane at cycling speeds, could only happen at several times such speeds, whereas wide car tyres are much more prone to it at speeds which cars are quite capable of.

Thought that's what I said.

Should have been more explicit - wide slicks are prone to aquaplaning ;)
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.