Tyre Tread Direction

[RodTi]

And there we have it... 

Thanks Johan!

 

But will this remain the final say, or can we expect some of the more technically minded Hubbers to wade in?....

Especially given the long debates on this forum about "this tyre works better than that tyre"....

 

Have popcorn.

Will eat it

 

 

[ps - Johan, have yet to go and test the "beer = shim" formula... Will drop you a line when I do...]

 

[MintSauce]

You'll notice that grip doesn't come in anywhere. All patterns have to roll over random terrain and therefore there is no optimum pattern. A pattern is a pattern in terms of grip and grip is largely (95% plus' date=' in my estimate) determined by the type of rubber. 

[/quote']

 

 

 

*cough-bullsh*t-cough*

 

 

 

 

[Johan Bornman]

You'll notice that grip doesn't come in anywhere. All patterns have to roll over random terrain and therefore there is no optimum pattern. A pattern is a pattern in terms of grip and grip is largely (95% plus' date=' in my estimate) determined by the type of rubber. 

[/quote']

 

  

*cough-bullsh*t-cough*

 

  

 

Please offer your reasons for shooting down that explanations. It'll help the debate much more than a cough or two.

[#Pete#]

 

You'll notice that grip doesn't come in anywhere. All patterns have to roll over random terrain and therefore there is no optimum pattern. A pattern is a pattern in terms of grip and grip is largely (95% plus' date=' in my estimate) determined by the type of rubber. 

[/quote']

 

  

*cough-bullsh*t-cough*

 

  

 

Please offer your reasons for shooting down that explanations. It'll help the debate much more than a cough or two.

 

Terrain is not truelly random - there is certainly a 'dominant' terrain - whether this is dry hardpack or loose rocks or mud - and IMO tread therefore plays a huge role.I guess as you say 'pattern' may be less important than rubber type or size/spread of the nobs.

 

Nevertheless IMO it is easy to detect differences in tread direction in many tyres (front and rear) (sorry - anecdote again, not science).

 

[MintSauce]

You'll notice that grip doesn't come in anywhere. All patterns have to roll over random terrain and therefore there is no optimum pattern. A pattern is a pattern in terms of grip and grip is largely (95% plus' date=' in my estimate) determined by the type of rubber. 

[/quote']

 

  

*cough-bullsh*t-cough*

 

  

 

Please offer your reasons for shooting down that explanations. It'll help the debate much more than a cough or two.

 

 

Because when I switch between a Bontrager Jones 2.3 and a Kenda Nevegal 2.1 the Kenda, even though it's a smaller diameter, has superior cornering grip and traction.

 

No scietific tests....it's all based on a couple of years of barreling down technical singletrack as fast as my little legs can carry me.

 

It's how it feels to me, how I perceive it. But, based on other discussion on this forum, you don't seem to think 'feel' has any baring on bikeriding so we're just going to have to agree to disagree.

 

 

 

[#Pete#]

http://www.schwalbetires.com/images/new_img/e_img_1160_2.jpg

 

Neverteless, this sort of tyre doesn't always work better when run as indicated....why the hell not? I guess it depends on what one want form a tyre - one person wants the best grip possible, the other the fastest rolling.

 

[Johan Bornman]

cut cut cut.....

 

Nevertheless IMO it is easy to detect differences in tread direction in many tyres (front and rear) (sorry - anecdote again' date=' not science).
[/quote']

 

OK Pete, here's the deal. You and I and as many Hubber witnesses as care to attend do the following.

 

YOu bring the bike with directional tread tyres on that you are familiar with. I put a pilot instrument rating training helmet on your head. This will allow you to look forward only, not down. I then give you a bike, allow you to ride as much as you like and you tell me which direction the treads point. Now remember, you have a 50% chance of being right, therefore we'll do the best out of ten.

 

Deal?

[Minion]

 

4) This leaves us with tread pattern. a) on a road bike' date=' the tread pattern is there for cosmetic purposes only since it cannot sype water and the tyre's boat shape disperses all the water that you can throw at it, at the speed you go. Bicycle, motorbike and aeroplane tyres don't sype, thanks to their shape and any patterns in there are purely cosmetic. Airoplane tyre customers don't care about cosmetics and go completely slick. Motoribike tyre customers have a somewhat misconception about syping and go semi-slick, but in effect, if you look at highperformance motorbike tyres, they're effectively sans tread. Bike tyre buyers also suffer a bit from the syping syndrome they get from watching too much TV and insist on a pattern - slick tyres just don't sell, so manufacturers put a costmetic criss-cross on there for their peace of mind. They're drinking sugar pills.[/quote']

 

I have never come across sype before, but after a bit of reading, I presume you mean disperse water to the side through tread that runs laterally (eg v-grooves)?. The reasoning behind doing this on cars tyres being to reduce hydroplaning risk?

 

Most large aircraft do not run on slicks - they have tread grooves that run around the circumference of the tyre. I presume that they don't have lateral tread as the individual tread blocks would wear much quicker than the single, solid hoop.

Hydroplaning is a real problem for aircraft and a fair amount of research has been carried out on it. Their tests have shown that the minimum hydoplaning speed (Vp) for slicks can be predicted by:

 

Vp [mph] = 8.6 x sqrt (Tyre PSI),

 

Due to shape similarities, this can give a rough estimate of the performance of motorbike and bicycle tyres e.g. for tyres at 120 PSI you need to get to 150 km/h before hydroplaning starts.

 

This illustrates why you really don't need tread on a road bike tyre, but why you would need it on a motorbike - note that Moto GP bikes do use grooved wet tyres. It's not all a marketing gimmick.

 

[Johan Bornman]

I have never come across sype before' date=' but after a bit of reading, I presume you mean disperse water to the side through tread that runs laterally (eg v-grooves)?. The reasoning behind doing this on cars tyres being to reduce hydroplaning risk?

[/quote']

 

Yup, sype is the term for dispersing water out from underneat the contact patch. Yes, on car tyres, due to their shape they aquaplane easier than boat-shaped contact patches and it increases the speed at which it starts to aquaplane.

Most large aircraft do not run on slicks - they have tread grooves that run around the circumference of the tyre. I presume that they don't have lateral tread as the individual tread blocks would wear much quicker than the single' date=' solid hoop.
Hydroplaning is a real problem for aircraft and a fair amount of research has been carried out on it. Their tests have shown that the minimum hydoplaning speed (Vp) for slicks can be predicted by:

Vp [mph'] = 8.6 x sqrt (Tyre PSI),

 

Yes, you'll see that the 8.6 constant takes care of the boat shape of that particular tyre. It'll be a smaller constant for a car tyre.

 

However, I suspect that the lateral grooves are there not to sype but to do something else, perhaps as a tread wear indicator? To sype, the water has to be squeezed out laterally, fore/aft just puts more water in the tyre's path.

 

QUOTE=Edman]

Due to shape similarities, this can give a rough estimate of the performance of motorbike and bicycle tyres e.g. for tyres at 120 PSI you need to get to 150 km/h before hydroplaning starts.

Now you've fuelled the fire! Hubbers will tell you they need the tread pattern because they go that fast.

 

QUOTE=Edman]

This illustrates why you really don't need tread on a road bike tyre, but why you would need it on a motorbike - note that Moto GP bikes do use grooved wet tyres. It's not all a marketing gimmick.

 

Yes you are right, they do use wet tyres with grooves.  But from the cursory looks I've given most superbikes, I think their tread is essentially slicks with costmetic patterns that double up as tread wear indicators. Where does tread begin and slicks start? Let me have a look at some bike tyres and I'll see if I can post some pics here.

 

 

[dirtrider]

Hu . u okes trying to confuse us ??

 

 

 

There is a huge difference in traction when turning a tyre like the TT around and I will take that blindfold test any day .

 

 

 

And I has similar experience as Minty .

[IanJ]

 

However' date=' I suspect that the lateral grooves are there not to sype but to do something else, perhaps as a tread wear indicator? To sype, the water has to be squeezed out laterally, fore/aft just puts more water in the tyre's path.

 

 

[/quote']

 

The grooves are probably there for heat dissipation. Aircraft tyres get very hot.

 

 

[Minion]

 

However' date=' I suspect that the lateral grooves are there not to sype but to do something else, perhaps as a tread wear indicator? To sype, the water has to be squeezed out laterally, fore/aft just puts more water in the tyre's path.[/quote']

 

I've just found a Dunlop article which mentions that the grooves are there to help remove water. The wear indication is a useful side effect of this.

 

It makes sense if you look at the contact patch. Instead of being one large contact it is now several smaller ones where the water is squeezed out into the grooves. From the grooves, it can be squeezed out to the rear, rather than piling up at the front.

 

Dunlop

When to change the tyre on your 727

 

Now you've fuelled the fire! Hubbers will tell you they need the tread pattern because they go that fast.

...or they're running MTB slicks with much lower pressures

 

But from the cursory looks I've given most superbikes' date=' I think their tread is essentially slicks with costmetic patterns that double up as tread wear indicators. Where does tread begin and slicks start? Let me have a look at some bike tyres and I'll see if I can post some pics here.[/quote']

I work with a couple of bikers. I'll also go out and have a squiz at the bikes in the parking lot tomorrow.

 

[The Saint]

Johan to give my ignorant opinion.

 

I really cannot see the logic behind offering a motogp bike a wet weather tyre with tread as opposed to a slick if the wet weather tyre did not "actually" work. Frankly I have seen more Motogp riders fall off in the wet with slick tyres than with treaded tyres.

 

There is a vast difference between a semi slick which I presume you talk of above "where does tread begin and slicks start". In Motogp and F1 teams slicks are often converted into treaded tyres by literally taking a slick tyre and cutting grooves into it (semi slick), however a true wet weather tyre is manufactured to top secrect specifications. F1 is a good example of this in that a Bridgestone wet tyre out performs a Michellin wet tyre and the tread patterns on those tyres are definately not the same and neither is the rubber compound. Motogp teams are also famous for cutting tread into a slick tyre for semi wet weather conditions. Here I agree with you there is probably no science to the tread pattern however with your true wet weather tyre there is definately a science to it. A smooth rock will skip on the water however a rock with edges will not.

 

The same principle would apply to a bicycle tyre it's all reletive to weight and speed.

[Minion]

I found an article (and like an idiot forgot to bookmark it) that said that the tyre tread pattern only has a positive effect on traction when it leaves an imprint on the surface over which it travels - in other words, when it digs in. This applies to soft surfaces such as sand and mud.

 

It can be illustrated by the extreme case of an ice tyre (one of those crazy things with metal studs embedded in them).

Without the studs you're not going anywhere. Put them on and you've got something that will embed itself in the ice to give you traction.

Same idea for something like rubgy boots vs. takkies.

 

Of course this says nothing about the shape of the pattern - merely the necessity of having a pattern.

 

[Ox_Wagon]

A Brigstone racing slick<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

 

A Brigstone wet racing tire, please note the grooves

 

 

 

A Brigstone Dot racing tire, street legal race tire

 

 

 

Sport bike rider are the roadies of the bike world, image is everything. They like to have there bike looking like the MotoGP bikes and that means as slick as possible tires.  Most of these bikes are mainly used/only usable in good weather.  The liter class bikes are not really usable in real world condition anymore.  Some manufactures has gone so far to give the rider three power setting (remapping the fuel injection) so that you can set it on the lowest power output when riding in wet weather.

 

I have had my front (120mm) tire of my VFR750 start to hydroplane in a freak storm, not fun.  In short the groves are important.

Ox_Wagon2007-11-22 04:38:46

[Ox_Wagon]

Next up Road Bicycle Tires:<?:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

It is something I read here on the hub that makes a lot off sense.  The size of the contact patch is so small that groves are irrelevant for water dissipation.   The important factor is how well the softer tire molds to the harder road surface.  So the softer the compound the better the grip, but like all thing in live, the shorter the life of the tire will be and the more prone to cut s it will be.  Some manufactures try to juggle this by using a harder compound in the centre, high wearing area, and softer compounds on the shoulder of the tire where you would like more grip.