# Tread..............needed?



## Panter (4 Oct 2007)

As title really.

My new SCR3 has tyres which are basically slicks. There's a kind of token tread pattern at the edge of the tyre but nothing at all in the centre.

As an MTB'r I'm used to seeing a couple of inches of lumps and bumps snagging the asphalt, this smooth rubber is a bit disconcerting to say the least.

IIRC, the tread on car tyres is designed to channel the water from the road and kind of clear a path for itself through the water. Is it the case that roadie tyres are so thin they cut through the surface film anway?


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## Tim Bennet. (4 Oct 2007)

If the surface you are riding on is soft enough for any tyre knobbles to make an impression, (off road / tow paths / etc) then grip will help. But on tarmac, grip is dependent on the contact patch size and the 'grippiness' of the tyre compound. Any tread on the tyre effectively reduces the amount of tyre that's actually in contact. So a big chunky mtb tyre may actually have less rubber in contact with the road than a 23c slick. And the knobbles can be very unstable when cornering at speed as well.

You are right about the water clearance. A bike tyre is narrow enough to displace the water without any channels. Apparently aquaplaning is not an issue with a bike until about 180mph.


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## Elmer Fudd (4 Oct 2007)

I'd go with the cut through theory Panter, I mean a car tyre has a lot more surface contact point so needs to shift the water out of the way , whereas a cycle tyre is like a hot knife through butter and will just displace the water.

Don't know what happens when you're doing 70mph+ tho' !!


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## Panter (4 Oct 2007)

Thanks for the replies, appreciated 


I've no worries about aquaplaning then , none at all!!


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## Smokin Joe (4 Oct 2007)

The tread on a bike tyre is for show only and serves no purpose, other than to reassure car drivers who associate tread with wet weather grip. As Elmer and Tim say, a bike tyre is narrow enough to shift the water on it's own.


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## Top Cat (4 Oct 2007)

So what tryes should I use on my bike when travelling in excess of 180mph to avoid aquaplaning???????

TC


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## Panter (4 Oct 2007)

Bloody good ones


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## John the Monkey (4 Oct 2007)

Sheldon Brown has a great article on this topic here.


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## Panter (4 Oct 2007)

Superb link, thans for that John


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## cyclebum (4 Oct 2007)

I have to say panter, this is not the first thread that you have started that i have wanted to ask myself. Many thanks for this and previous ones as they have saved the pressure to my fingrnails, as all I have to do is read and move on to the next


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## Elmer Fudd (5 Oct 2007)

cyclebum said:


> ( I have to say panter, this is not the first thread that you have started that i have wanted to ask myself. Many thanks for this and previous ones as they have saved the pressure to my fingrnails, as all I have to do is read and move on to the next  )


And stops bonj digging at you ?


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## cyclebum (5 Oct 2007)

so true


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## Panter (5 Oct 2007)

cyclebum said:


> I have to say panter, this is not the first thread that you have started that i have wanted to ask myself. Many thanks for this and previous ones as they have saved the pressure to my fingrnails, as all I have to do is read and move on to the next



Its a pleasure 


Believe me, there's plenty more, I just haven't encountered them yet


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## mickle (5 Oct 2007)

I remember Mike Burrows waffling-on on this very subject years ago, he pointed out that if a bike has 100psi in its tyres then the contact point with the road is exactly 100psi. Water doesnt stand a chance in such an environment. There may be a reduction in grip due to water lubricating the contact point but no aquaplaning. Car tyres run at lower pressures, have a much wider contact area and run at much greater speeds.


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## bonj2 (5 Oct 2007)

mickle said:


> I remember Mike Burrows waffling-on on this very subject years ago, he pointed out that if a bike has 100psi in its tyres then the contact point with the road is exactly 100psi.



How can the contact point by anything psi. The contact point is a measure of area not pressure.


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## frog (5 Oct 2007)

> How can the contact point by anything psi. The contact point is a measure of area not pressure.



'ere we go again. Someone get the kettle on, the big one'll do. I've got the Hobnobs and some sponge cake.

All sitting comfortably? Great!

OK bonj, we're all sitting here waiting for you to make a prat of yourself again.


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## Smokin Joe (5 Oct 2007)

Bonj is right.


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## domtyler (5 Oct 2007)

What the wise one says is true. I believe that what Mickle means is that the pressure between the tyre and the road would be 100 PSI and that would be enough to squeeze the water out. Personally I would have thought that that measurement would be a function of the combined weight of bike and rider but there you go.


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## papercorn2000 (5 Oct 2007)

It would be. The force on the road is a function of the weight of rider and bike divided by the area of rubber in contact with the road. Divided front and back according to weight distribution on the bike.

Bonj is roght
Bonj es right
Binj i srught

Sorry, I can't bring myself to say it.


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## frog (5 Oct 2007)

Bugger! Bugger! Bugger! Well, I suppose in 1,900 posts he'd have to get at least one right 

Anyway, not much chance of the tea getting cold, biscuits getting soft, or the cake stale before he's off on one again.

Over to you Mr Starter!


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## Panter (5 Oct 2007)

> Over to you Mr Starter!



Oh, Ok 

Tread is NOT required on a road tyre then, as discussed above. Its simply a marketing ploy to make the tyre look more attractive to newbs such as myself (as read from a link above)


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## Cycling Naturalist (5 Oct 2007)

papercorn2000 said:


> It would be. The force on the road is a function of the weight of rider and bike divided by the area of rubber in contact with the road. Divided front and back according to weight distribution on the bike.
> 
> Bonj is roght
> Bonj es right
> ...



Or, to put it more simply, the very high pressure of the bike tyre means that only a tiny part is in contact with the road surface and this displaces the water as the curved part of the tyre flattens as it makes contact with the road.


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## mickle (5 Oct 2007)

bonj said:


> How can the contact point by anything psi. The contact point is a measure of area not pressure.



POUNDS (as in WEIGHT) PER SQUARE INCH (as in AREA).

Bonj aint right, the question is; can I be arsed to put him right?

Er. No.


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## Smokin Joe (5 Oct 2007)

Bonj is still right.


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## Panter (5 Oct 2007)

mickle said:



> POUNDS (as in WEIGHT) PER SQUARE INCH (as in AREA).
> 
> Bonj aint right, the question is; can I be arsed to put him right?
> 
> Er. No.



ah, but he is right.


PSI is a measure of the pressure of the gas within the tyre, ie at 100psi, every sq inch of tyre is subject to 100lbs of force.

The contact area of the tyre on the road will be a measurement as a square area ie 20 sq millimetres for example.

The psi of the tyre is irrelevant, except of course in that the higher the psi of the tyre, the more resistant to compression under load it will be and therefore able to mantain a smaller contact area.


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## Panter (5 Oct 2007)

Doh.....beaten to it


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## Smokin Joe (5 Oct 2007)

Yeah, that avitar is cruelly misleading. We think we are replying to a well fit young babe and it turns out to be some old git whose own mother made him wear a paper bag over his head.

Get rid of it.


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## mickle (5 Oct 2007)

Panter said:


> ah, but he is right.
> 
> 
> PSI is a measure of the pressure of the gas within the tyre, ie at 100psi, every sq inch of tyre is subject to 100lbs of force.
> ...




You are _so_ close, all the information you need is in you own post.





(Ps. Bonj versus Mike Burrows, chosen subject 'Bicycle Science'. I know where my money is going. And its not Bonj)


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## Panter (5 Oct 2007)

Please enlighten me then 




> Yeah, that avitar is cruelly misleading. We think we are replying to a well fit young babe and it turns out to be some old git whose own mother made him wear a paper bag over his head.
> 
> Get rid of it.


 Sorry, I've got rather attached to it


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## Tynan (5 Oct 2007)

go on then

Physics and Maths A levels here and a Mechanical Engineering Degree

Painter's post and indeed Bonj's look right to me

I read the Sheldon and it was an eye opener to me but the tyre either opens a perfect contact to the road or it doesn't, and if it doesn't then tread does help

I find it hard to believe that all those bike shops are in on the lie and don't tell the truth to people that ask them about tyres

I was talked into some 2" City Slicker Fat Boys on an early MTB for commuting when they were the must buy bike and they ran fine but skated around something horrid in the wet, not skidded, waltzed


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## mickle (5 Oct 2007)

Tynan said:


> go on then
> 
> Physics and Maths A levels here and a Mechanical Engineering Degree
> 
> ...



How does tread help? All tread does is reduce the contact area.

You give cycle shop workers too much credit. 

Wet conditions do reduce grip whether you are riding slicks or treaded tyres or knobblies or bleedin tungsten studded ice tyres but a slick bicycle tyre cannot aquaplane.


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## Smokin Joe (5 Oct 2007)

The tread pattern on a car tyre will disperse water from beneath the tyre and aid grip. It cannot do that on a cycle tyre because the tread cut is not deep enough. You can see this by riding over a damp patch and then looking at the line left by the tyre on the dry road, no impression of the tread will be visible because the whole of the tyre has been in contact with the road and the water has not been channeled away.

If you look at the gaps between the tread cuts on a car tyre they are wider than the entire contact patch of a cycle tyre and that is enough to disperse the water to either side. Pro teams who ride on slicks do not change tyres when it rains and they have no trouble matching the performance of teams with treaded tyres.


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## Alcdrew (5 Oct 2007)

What about in snow? will slicks be better then something with a bit of tread to it? 

Just asking as I bike to work year round, and this year is my first on 700 x 32slicks, Iam a little worried.


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## asterix (6 Oct 2007)

Although I agree that in most conditions tread is irrelevant on a road bike tyre, I think Tynan may have a point. 

Should the road be coated with slimy substance denser, less displaceable than water than water, e.g. a film of mud or rotting leaves, a bit of tread may prevent the slippery substance lubricating the contact between tyre and road by cutting through it.

Certainly in normal years Autumn is a very dodgy time of year due to the over-confidence built up by months of dry summer roads.


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## mickle (6 Oct 2007)

asterix said:


> Should the road be coated with slimy substance denser, less displaceable than water than water, e.g. a film of mud or rotting leaves, a bit of tread may prevent the slippery substance lubricating the contact between tyre and road by cutting through it.



How?


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## mickle (6 Oct 2007)

Ah the power of public service broadcasting. The grooves on car tyres are designed to displace water. If the water isnt displaced fast enough from the contact point the water will build up under the leading edge with nowhere else to go but under the tyre. At this point the tyre loses contact with the road. Its called aquaplaning. Slick tyres, those with little tread and wide tyres are most susceptable. Vehicle speed, vehicle weight and volume of water are also a factor. A light enough motor vehicle with wide enough tyres can drive on water if its going fast enough.
Cars can aquaplane at speeds as low as 30 mph, motorbikes at speeds as low as 60mph, given enough water. 
Cycle tyres cannot aquaplane. They can lose grip if conditions are slippery, but slipping is not the same as aquaplaning. What keeps your bike lycra side up is grip. That grip is a function of the durometer or stickiness of the rubber, the area of rubber in contact with the road, the pressure exerted by the tyre over the contact area and the ability of the tyre to conform to the changing shape of the road surface (carcass flexibility).
All other things being equal, a treaded tyre will lose grip before a slick tyre.

Please dont start me off on the dynamics of off road treads, Ill be here all night.


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## andy_wrx (6 Oct 2007)

<pedant on>
What we're talking about is _tread pattern_.

All tyres have _tread_. Tread is the sticky rubber on the outside of the radial/crossply carcass of the tyre.
<pedant off>

Murray Walker could never get it...


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## Smokin Joe (6 Oct 2007)

andy_wrx said:


> <pedant on>
> What we're talking about is _tread pattern_.
> 
> All tyres have _tread_. Tread is the sticky rubber on the outside of the radial/crossply carcass of the tyre.
> ...


There's always a smartarse.


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## Panter (6 Oct 2007)

Thanks peeps. This has evolved into an interesting read, IMO anyway 



What I'll take from this:

I don't have to worry about the lack of tread in wet conditions, but I still need to take it easy as the road will be slippery anyway.

I would _guess_ that some sort of tread _may_ help on a muddy surface by creating localised ridges with more weight on them which may push through the mud. Although they would also ultimately have a smaller contact patch so would lose out on grip the rest of the time.

I have renewed faith in my slicks and when they wear out, they'll be replaced with more slicks 



> Please dont start me off on the dynamics of off road treads, Ill be here all night.



I did have some MTB tyre questions, guess they can wait.................................................

Thanks again,


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## Panter (6 Oct 2007)

Ok, _Tread pattern_, sorry


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## mickle (6 Oct 2007)

andy_wrx said:


> <pedant on>
> What we're talking about is _tread pattern_.
> 
> All tyres have _tread_. Tread is the sticky rubber on the outside of the radial/crossply carcass of the tyre.
> ...



Yup. I stand corrected. 

Ill get my coat.


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## Tynan (6 Oct 2007)

can't say I've found any of the arguments against tread convincing

either the water on the road interferes with grip or it doesn't, I'm hearing that it does

but the tread makes no difference whatsoever?

and the entire cycle industry is carrying on the lie?


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## alfablue (7 Oct 2007)

Tynan said:


> but the tread makes no difference whatsoever?



Well it will, in that if the tread pattern is at all significant it will reduced grip as the contact area is reduced, and nobblies used on the road will induce squirm, further impairing grip and handling.



> and the entire cycle industry is carrying on the lie?


 Yes...though "lie" may be a bit harsh. Many in the industry may be under the misapprehension that tread pattern is necessary, whilst the tyre manufacturers are probably not, but are probably just responding to what the market wants, however ill-informed.

Schwalbe are very good on "telling the truth" they say


> Even in wet conditions, on a normal, smooth road, a slick tire actually provides better grip than a tire with a tread, because the contact area is larger.



They have a very comprehensive technical document (on all aspects of bike tyres) here


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## John the Monkey (7 Oct 2007)

Panter said:


> I would _guess_ that some sort of tread _may_ help on a muddy surface by creating localised ridges with more weight on them which may push through the mud. Although they would also ultimately have a smaller contact patch so would lose out on grip the rest of the time.



Not quite the same situation, but I rode a piece of road between two farm tracks that was covered in sand, when I was in France. (It led to a lot of the little routes I was doing, so I went over it a lot). I had both my road bike, and the gite's knobbly tyred MTB to use - on the MTB, the grip was far more assured on this particular bit of road (on the slick tyred road bike, I could feel the back wheel losing grip on this part of the road).


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## DustBowlRefugee (7 Oct 2007)

I was going to go out on my road bike (with slick tyres) this morning but seeing all the wet fallen leaves I took the MTB instead (with knobbly tyres). Would I have been better off on the roadie?

Thanks
Mark


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## alfablue (7 Oct 2007)

With anything covering the road, like leaves or sand, the contact patch is compromised and it will be slippy. I can see knobblies working better in sand (as the blocks will cut throiugh it), but with leaves the tyre loses contact with the road and it may not make much difference what you use.


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## Panter (8 Oct 2007)

Cool link, Alfablue, thanks


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## DustBowlRefugee (8 Oct 2007)

Panter,

This is one of the most useful threads I've read on here, not least because I was just about to invest in a set of "winter tyres" for my road bike. Having read the various links involved I won't bother now.

Having once been a motorcycle racer I'd like to know if anyone could comment on different compounds used on the tread. Can I pay a bit more for a "comp" type tread which forgoes longevity? On my RG500 I didn't care about tyre life - only grip hence A1 Demons were the order of the day. Can I buy a bicycle tyre which does the same? I seem to cycle a lot faster (especially downhiill) when I am convinced that the Japlops won't spit me off.

Seems you're not too far from me - Where do you get out to?

Cheers
Mark


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## Panter (8 Oct 2007)

Just locally at the moment, very much a newb you see.


Mmmmmmmm, RG500, I always wanted one of those 
My last bike was an R1 but I'm "between bikes" can't afford to run one at the moment 


Hope someone can help with your question, I take it you reas the Shwalbe link ,some good info on compounds there


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## mickle (9 Oct 2007)

Lots of tyres are available with dual compound trad; hard on the centre line for durability and soft on the edges for grip. 

Extra soft racing tyres are available for off road racing, I used a pair of Tioga SL dirt tyres for a while, they were so sticky that seemed to pick up every bit of grit that they contacted and throw it at the down tube. You could almost watch them wearing out as you rode along but they were awesome in corners, especially on the road funnily enough.


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## BentMikey (9 Oct 2007)

DustBowlRefugee said:


> I was going to go out on my road bike (with slick tyres) this morning but seeing all the wet fallen leaves I took the MTB instead (with knobbly tyres). Would I have been better off on the roadie?
> 
> Thanks
> Mark




On the other hand, the MTB tyres may lose grip more predictably than the roadie, so you might have less overall grip, but be more easily able to control the bike.


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## John the Monkey (9 Oct 2007)

So, would this be any good then?


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## Tim Bennet. (9 Oct 2007)

> Our display bike, shown above, tips the scales at 37 pounds.


OMG!

But, if you want to ride on a surface where you need to float (sand or snow) then it's going to be better than sinking idown up to your hubs.

But in this country, we frequently have mud that is too thin to float on, so the perceived wisdom is to use a narrow tyre that cuts down to a solid base and gives more clearance to cope with all the encrusted crud on the tyre. So mtb 'mud' tyres tend to be only 1.5 inches wide with very widely spaced pronounced knobbles.

However I have a real problem with riding trails in these conditions as it does 'cut them up' badly (like horses do). I know some people live in areas where this is their only option, but luckily up here we can restrict our riding to rocky trails when it's really wet.


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## andy_wrx (9 Oct 2007)

John the Monkey said:


> So, would this be any good then?



I think it comes from the country which brought us the HummVee...


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