MTB Tire Direction

[nochain]

There must be a way to test all this !! (in the real world )

 

I would volenteer but my medical aid is bit "gatvol" of me!!

 

[Ox_Wagon]

 Like all things in cycling there is no simple answer. If the knobblies are symmetrical there is no difference and if they not, I ?think? we agreed in the ?truce?, that most of us will not be able to notice the difference.<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

MTB tire design is a trade off study in traction, low rolling resistance and life span. The next question you also need to ask your self is what was the manufactures main focus when the specifying the rotational direction.  Were they sacrificing a bit of traction for better live span or rolling resistance etc? My opinion is that it is the case with all of the ?one sided ramped knobby? tires (SB8, Nevegal, Monorail, Crossmark, TT).  

 

I personal want the following in MTB tires:

 

Front: A fast rolling tire with excellent sideways traction (90deg to rolling direction) so it will not wash out on turns. So I looking for the following:

 

Rear: Fast rolling tire with excellent traction. So I looking for the following, although I will run it the ?wrong? way around:

 

 

Classic examples of this are the WTB Velocity Raptors and long before them the Panaracer Smoke and Dart. 

 

 

 

That said, my last 3 sets of tires (WTB Primal raptors, Conti Mountainking and SB8) where all not front/rear specific. I did however find the SB8 was not up to the job as a front tire.

 

Here is a nice experiment you can do in your/friends kids sandbox.  Take a shaped block and push it through the sand and work out for you self which direction (A/B) will give you the most traction/least rolling resistance/longest tire life. Have fun. 

Ox_Wagon2008-10-02 03:16:29

[Wyatt Earp]

  

Firstly' date=' the avatar is Brad, Headshok mascot. Lefty is a Headshok product.

Cannondale Headshok suspension is based around a square tube sliding in a round hole.

There are two product ranges; Fatty and Lefty. got it?

 

[/quote']

Thanks for the lesson, I did not know that, I have never seen the inside of one

For the Lefty they shove the SI designation under his chin, maybe I am just being anal, it won't be the first time.

It's actually a round tube with four sides that have been machined with a flat surface per side, each one of the four flat surfaces hosts a metal slider then a set of needle bearings with another metal slider sandwiching the needle bearings, these get held together by a retainer clip.

Pretty much the same way the Egyptians used to transport those massive blocks of stone by using logs.

Let's see how big a fan you are, I have a question.

Which well known road cyclist used to race for Cannondale and made it to his  first olympics as a mountainbiker in the first olympic MTB race ?

Secondly you must have a beeeeeeg scale

Thirdly, weight is a big factor in keeping things stable, ever tried to fly a radio control plane with the nose hanging down or one wing heavier than the other, yes it's balance and if the balance is not equal we have stability issues.

The word stability or stable can be found in any old dictionary nowadays

Your adhesion theory also does not apply, try again.

 

Si is a concept of which Lefty, Fatty, BB30, Hollowgram I& IISL, and Headshok Headtube all form part. It is nomenclature given to a family of technologies that makes a Cannondale unique. At least I know you have lifted the boot of the lefty to see whats underneath and therefore demystified it for yourself. Have you looked inside the DLR2, or FoX Inertia Lefty's yet? Have you tuned the Shim stacks in either or changed the negative springs to accomodate a rdiers weight on a size of bike that was not tuned to accomodate that weight?

 

Cadel Evans

 

No I use two bathroom scales. those german scales are pretty accurate. One under each wheel is sufficient.

 

Balance in a model aircraft has nothing to do with balance on a bicycle. Please use relevant examples.

MAss balance in an model aircraft is  exaggerated due to it's light weight and the big influence of the aerodynamics.

Balance discrepansies can be trim out by tweaking the wings, ailerons or by fitting trim tabs on the stabilators.

Stability is merely the ability to maintain balance. How does a tyres tread affect this?? please explain because as far as I can see the tyres tread is not pulling both my arms and my toes equally to keep me upright on the bike. Or is this one of those sinister third forces...?

 

On a bicycle the riders weight provide sufficient balance because it rests over the centre line of the bike while riding in a straight line. While cornering the weight is on the inside of the arc prescribed by the path the contact patch follows. The contact patch deforms because now the load is made up of vertical as well as side forces. The tread merely serves as an anchor to resist the side load therefore the deeper the tread can penetrate the more the side forces can be resisted. the friction forces remain the same. It makes stuff al difference what the shape of that tread is.

 

Also, it is impossible to corner a bike within weight on thefront wheel. Without weight, there is no grip. grip is what turns you. A body will remain in a state and direction of motion unless acted upon by a force. So contrary to popular belief you do need weight on the front wheel and the close it is too 50/50 the better the balance of the bike and the better it will turn. On a descent, a rider will move their weight slightly rearward to counter the weight transfer due to the gradient, to maintain the weight distribution.

 

Therefore, your front tyre is the most important tyre on your bike. It absorbs the braking energy & turning  forces. It's grip is a function purely of the friction properties of the rubber and to a much smaller extent, the depth of the tread blocks. the shape and direction of hose tread blocks means nothing in science but clearly is a gold mine to a marketer.

 

 

Yes Cadel, good googling there.

Si/ system intergration .

As for lefty's and headshocks there is not a single shock I have not opened from Cannondale

Perhaps Terry could explain this to you.

I hate lifting the boot.

As you find my model aircraft example irrelevant ,I find your examples quite confusing as well.

You keep referring to science,am going to say it again, the tire compamies have given us facts, they have spent money on R&D, they pay for patents.

If you can give me better explanations than just some laymans opinion, I would gladly support your THEORY.

Oh by the way, if you have been around the Cannondales long enough you would have understood my inside joke.

It's your avatar, not mine

[Canaris]

Ox you should coat the block in honey before you start and "Roll it" on the kitchen floor to symulate hard back.  (Check the wife face......)

[dirtrider]

And stay outta the catbox ! MY block got stuck !

[intern]

 

Ox you should coat the block in honey before you start and "Roll it" on the kitchen floor to symulate hard back.  (Check the wife face......)

 

Syntax, syntax, syntax. Coat the wife in honey and roll her on the kitchen floor and check the look on her face.

 

Not sure where the tyre fits in. Oh my, what an unfortunate bit of syntax that is.

 

[Johan Bornman]

There must be a way to test all this !! (in the real world )

 

Yes there is. You'd want to test two things which are core to what we are discussing here:

 

1) Slip-out angle. It is measured as a simple angle with a given downforce.

2) Co-efficient of friction in a straight line. (It's been called grip and traction here, all the same thing measured the same way. There is no unit for the coefficient of friction, it is merely a coefficient. But that's not English in your book.

 

Forget about doing a riding test, that's just too messy. You'll have to do the tests statically.

 

For the co-efficient of friction, I suggest you cut a piece out of your mate's directional tyre. A length of about 100mm should do the trick.

 

Flatten it and nail it to a wooden board. Load the wooden board with a couple of bricks and attach a string to each end of the board. Now pull the board on a uniform surface with one of those fishing scales and get a reading. Pull it from the other side and get another reading. Do that several times, throw away the extreme results at either end and average the bunched results. See if it differs significantly from left to right.

 

For the slip-out angle it'll be a bit more difficult. You'll have to get two tyres where the surface area and depth of the two sets of knobblies differ in looks but are exactly the same otherwise.

 

Then you'll have to apply a known force to each wheel and slowly tip it (on your preferred surface) until it slips out. Measure that angle and compare the two after you've taken away the "noise" in the experiment as described above.

 

This would be a real world test. I've never seen any tyre manufacuter perform and publish the results of this test.

 

 

[dirtrider]

Ok the first test I am sure I can do but the second one I am not to sure I have the right equipment for that !

[Ysterman]

... found this on Michelin's website ... if I am allowed to copy:

 

"Why have a fitting direction?
The tyre's fitting direction will enable mountain bikers to optimize their tyres' performance in terms of braking and traction.
In the most frequent types of usage, the front tyre has to contribute to braking, while the rear tyre has to provide maximum traction, as it transmits to the ground the force applied by the cyclist on the pedal."

 

"Should everyone ride with the same fitting direction?
Depending on their style of riding, each individual may seek different types of performance, so everyone can adapt the fitting direction to their riding style."

 

Ysterman2008-10-02 03:39:20

[Johan Bornman]

 Like all things in cycling there is no simple answer. If the knobblies are symmetrical there is no difference and if they not' date=' I ?think? we agreed in the ?truce?, that most of us will not be able to notice the difference.<?: prefix = o ns = "urn:schemas-microsoft-com:office:office" />

cut cut cut cut

[/quote']

 

Hey Ox, welcome to the debate. Where have you been?

 

If I were that way inclined, I'd spank you for the use of "fast rolling". Lets stick to low Rolling Resistance, at least that has units of measurement.

 

Looking at your first picture where you circled the "Sideways traction", you omitted to mention that aggressive side knobblies "walk" on hardpack/tar when cornering and drift quite noticeably. It is a problem - they grip on soft stuff but drift on harder stuff.

 

For those of you who don't see what I mean, do this:

 

Mimick a man walking with two fingers on your right hand. Now with your left hand, push the walking man sideways. See how your simulated knobblies flex sideways and now don't put one foot in front of the other, but to the side.

 

I think you were too subtle when you said you'd run your tyres wrong way around. Your catbox experiment is nice and illustrates what you mean. The wrong way around means you'll drag the block to the B direction even though the manufacuters say you should drag it in the A direction.

 

 

 

[Johan Bornman]

... found this on Michelin's website ... if I am allowed to copy:

 

"Why have a fitting direction?
The tyre's fitting direction will enable mountain bikers to optimize their tyres' performance in terms of braking and traction.
In the most frequent types of usage' date=' the front tyre has to contribute to braking, while the rear tyre has to provide maximum traction, as it transmits to the ground the force applied by the cyclist on the pedal."

 

"Should everyone ride with the same fitting direction?
Depending on their style of riding, each individual may seek different types of performance, so everyone can adapt the fitting direction to their riding style."

 

[/quote']

 

Michelin has used some fancy words and pictures to say that it doesn't matter. That piece of text is also flawed. Maximum traction is required on the front wheel and for when you brake. Propulsion requires very little traction. Our engines are very weak.  No-one I know can spin a rear wheel (even a slick) whilst apply full downforce (i.e in the sitting position) on their bike. I'm not talking about riding on ice rinks.

 

 

 

 

Johan Bornman2008-10-02 03:48:07

[Tumbleweed]

DR - ek probeer vir jou help my ou' date=' die ou se dit maak nie saak hoe om jy die tyre opsit nie jy gaan nog steeds stadig wees ......[/quote']

 

HR why you struggling see above ........

 

wie bitte, ich ich verstehen nicht

 

Du alte flaume, bisst due deppert oder wass?

 

entschuldigung?

Aber bitte mit Sahne!

 

nein, mit milch

[intern]

These Germans are crazy. Don't mention the war!

[dirtrider]

So you have seen the idian dude doing a burnout on his bicycle ?

[GoLefty!!]

  

Firstly' date=' the avatar is Brad, Headshok mascot. Lefty is a Headshok product.

Cannondale Headshok suspension is based around a square tube sliding in a round hole.

There are two product ranges; Fatty and Lefty. got it?

 

[/quote']

Thanks for the lesson, I did not know that, I have never seen the inside of one

For the Lefty they shove the SI designation under his chin, maybe I am just being anal, it won't be the first time.

It's actually a round tube with four sides that have been machined with a flat surface per side, each one of the four flat surfaces hosts a metal slider then a set of needle bearings with another metal slider sandwiching the needle bearings, these get held together by a retainer clip.

Pretty much the same way the Egyptians used to transport those massive blocks of stone by using logs.

Let's see how big a fan you are, I have a question.

Which well known road cyclist used to race for Cannondale and made it to his  first olympics as a mountainbiker in the first olympic MTB race ?

Secondly you must have a beeeeeeg scale

Thirdly, weight is a big factor in keeping things stable, ever tried to fly a radio control plane with the nose hanging down or one wing heavier than the other, yes it's balance and if the balance is not equal we have stability issues.

The word stability or stable can be found in any old dictionary nowadays

Your adhesion theory also does not apply, try again.

 

Si is a concept of which Lefty, Fatty, BB30, Hollowgram I& IISL, and Headshok Headtube all form part. It is nomenclature given to a family of technologies that makes a Cannondale unique. At least I know you have lifted the boot of the lefty to see whats underneath and therefore demystified it for yourself. Have you looked inside the DLR2, or FoX Inertia Lefty's yet? Have you tuned the Shim stacks in either or changed the negative springs to accomodate a rdiers weight on a size of bike that was not tuned to accomodate that weight?

 

Cadel Evans

 

No I use two bathroom scales. those german scales are pretty accurate. One under each wheel is sufficient.

 

Balance in a model aircraft has nothing to do with balance on a bicycle. Please use relevant examples.

MAss balance in an model aircraft is  exaggerated due to it's light weight and the big influence of the aerodynamics.

Balance discrepansies can be trim out by tweaking the wings, ailerons or by fitting trim tabs on the stabilators.

Stability is merely the ability to maintain balance. How does a tyres tread affect this?? please explain because as far as I can see the tyres tread is not pulling both my arms and my toes equally to keep me upright on the bike. Or is this one of those sinister third forces...?

 

On a bicycle the riders weight provide sufficient balance because it rests over the centre line of the bike while riding in a straight line. While cornering the weight is on the inside of the arc prescribed by the path the contact patch follows. The contact patch deforms because now the load is made up of vertical as well as side forces. The tread merely serves as an anchor to resist the side load therefore the deeper the tread can penetrate the more the side forces can be resisted. the friction forces remain the same. It makes stuff al difference what the shape of that tread is.

 

Also, it is impossible to corner a bike within weight on thefront wheel. Without weight, there is no grip. grip is what turns you. A body will remain in a state and direction of motion unless acted upon by a force. So contrary to popular belief you do need weight on the front wheel and the close it is too 50/50 the better the balance of the bike and the better it will turn. On a descent, a rider will move their weight slightly rearward to counter the weight transfer due to the gradient, to maintain the weight distribution.

 

Therefore, your front tyre is the most important tyre on your bike. It absorbs the braking energy & turning  forces. It's grip is a function purely of the friction properties of the rubber and to a much smaller extent, the depth of the tread blocks. the shape and direction of hose tread blocks means nothing in science but clearly is a gold mine to a marketer.

 

 

Yes Cadel, good googling there.

Si/ system intergration .

As for lefty's and headshocks there is not a single shock I have not opened from Cannondale

Perhaps Terry could explain this to you.

I hate lifting the boot.

As you find my model aircraft example irrelevant ,I find your examples quite confusing as well.

You keep referring to science,am going to say it again, the tire compamies have given us facts, they have spent money on R&D, they pay for patents.

If you can give me better explanations than just some laymans opinion, I would gladly support your THEORY.

Oh by the way, if you have been around the Cannondales long enough you would have understood my inside joke.

It's your avatar, not mine

 

 

Joke? youmade a joke? really? where? please show me.

 

So you don't have an arguement and now resort to the buddy club and length of service. Well if this has to be a dick swinging exercise then so be it.

 

In your mind the tyre marker is a god who cannot be challenged. Well heres a secret; Marketers lie [try to contain your horror at this revelation.]

 

mine is not a theory, it's fact. Science fact, engineering fact.

 

Patents:

the only patents that are valid revolve around the compound formulation and noise reduction around the shape of the tread. it can be argued that noise is energy loss and therefore if you reduce it you infact save ex[end less energy. This applies on a tar road. On a gravel road, where MTB tyres are most use, it makes no difference because the substrate is compliant. So if you ride on slick rock or tar all the time then perhaps direction is important to minimise energy loss through noise. Here, in SA we ride on gravel road or sandy trail.

what benefit does a patent have in tread design? Marketing. It provides the customer with a "reason to believe" in the product. Its something the buyer can see and touch and they will believe everythng it says on the box. I'm sure if someone invented coffee scented tyres everyone would belive that the tyres will your coffee for you.

 

Motocross bike tyres have to cope with much higher acceleration, great weight per cm^2 and therefore the tread design here plays a bigger roll. On a bicycle it makes no difference as long as there is a paddle to provide the trust through soft soils. the surface area and depth are the biggest contributors.

 

read up on this, there is plenty of information on the WWW to support these facts.

[Ox_Wagon]

Ox you should coat the block in honey before you start and "Roll it" on the kitchen floor to symulate hard back.  (Check the wife face......)

Syntax' date=' syntax, syntax. Coat the wife in honey and roll her on the kitchen floor and check the look on her face.

Not sure where the tyre fits in. Oh my, what an unfortunate bit of syntax that is.
[/quote']

 

This sounds like a very promising experiment!