Tyre directionalness

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cycle tramp
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Joined: 5 Aug 2009, 7:22pm

Re: Tyre directionalness

Post by cycle tramp »

LancsGirl wrote: 11 Aug 2022, 5:54pm Ok, I know "directionalness" isn't a word. At least not yet.

I've got Marathons. The "ordinary" ones ("Greenguard"?)

I've just noticed that my front one is mounted the wrong way round, according to the arrow. This bike has disc brakes, so I can't just turn the wheel around. It's been like that for about 1500 miles.

Does it matter?
...in real life? Not if we're taking bicycle tyres..
(Yes for motorcycles and definitely yes for sports motorcycles)
If it matters to you and you find yourself worrying about it then you might want to have a mental health/reality check :-D
It's time to go :-)
MikeF
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Re: Tyre directionalness

Post by MikeF »

cycle tramp wrote: 13 Aug 2022, 10:52am
LancsGirl wrote: 11 Aug 2022, 5:54pm Ok, I know "directionalness" isn't a word. At least not yet.

I've got Marathons. The "ordinary" ones ("Greenguard"?)

I've just noticed that my front one is mounted the wrong way round, according to the arrow. This bike has disc brakes, so I can't just turn the wheel around. It's been like that for about 1500 miles.

Does it matter?
...in real life? Not if we're taking bicycle tyres..
(Yes for motorcycles and definitely yes for sports motorcycles)
If it matters to you and you find yourself worrying about it then you might want to have a mental health/reality check :-D
:shock:
If it matters to you, take the tyre off and mount it as indicated. It doesn't look as though Marathon Greenguard have a tread pattern with much directionality from what I can see though so as others have indicated it probably won't matter. My Vittoria Hypers have very distinct chevrons although much of the centre part has worn away - not good in the wet if ever we get any?!
"It takes a genius to spot the obvious" - my old physics master.
I don't peddle bikes.
wirral_cyclist
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Location: Wirral Merseyside

Re: Tyre directionalness

Post by wirral_cyclist »

MikeF wrote: 13 Aug 2022, 7:27pm My Vittoria Hypers have very distinct chevrons although much of the centre part has worn away - not good in the wet if ever we get any?!
The curved profile of a bicycle tyre is enough to clear water, grooves etc are only needed on flat tyres that might trap water underneath.
MikeF
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Re: Tyre directionalness

Post by MikeF »

wirral_cyclist wrote: 13 Aug 2022, 10:13pm
MikeF wrote: 13 Aug 2022, 7:27pm My Vittoria Hypers have very distinct chevrons although much of the centre part has worn away - not good in the wet if ever we get any?!
The curved profile of a bicycle tyre is enough to clear water, grooves etc are only needed on flat tyres that might trap water underneath.
Indeed. I think you will find your cycle tyres deform at the bottom with each revolution.
"It takes a genius to spot the obvious" - my old physics master.
I don't peddle bikes.
KM2
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Joined: 23 Oct 2008, 5:38pm

Re: Tyre directionalness

Post by KM2 »

If using chevron tread tyres, the chevrons point backwards to direction of rotation on the rear and with rotation on the front.
Difference between driving forces and driven(front)
Barrowman
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Joined: 8 Jan 2022, 6:35pm

Re: Tyre directionalness

Post by Barrowman »

Think what KM2 says is on the Money. Can recall doing some work on a friends bike, noted the tyres had directionality markers mounded in that suggested they were fitted one way round on the back, the opposite way round on the front.
KM2
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Re: Tyre directionalness

Post by KM2 »

It’s too present the largest face of the rectangular chevron to the direction of force.
On the back in a corner, the rear is being driven by pedalling but at the front the larger side helps prevent slide in a corner.
MikeF
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Re: Tyre directionalness

Post by MikeF »

KM2 wrote: 15 Aug 2022, 8:26am If using chevron tread tyres, the chevrons point backwards to direction of rotation on the rear and with rotation on the front.
Difference between driving forces and driven(front)
Nothing to do with driving forces and being driven. It's the direction of rotation that matters.
"It takes a genius to spot the obvious" - my old physics master.
I don't peddle bikes.
KM2
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Re: Tyre directionalness

Post by KM2 »

Mike , I would disagree. Front slides forward and out. Rear drive doesn’t need that as much.
MikeF
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Re: Tyre directionalness

Post by MikeF »

The purpose of the chevron(s) and, more importantly the grooves alongside them, is to shed water etc to the outside, so that the centre rubber is in contact with the surface underneath, thereby providing maximum grip. If you put them on the other way round then water etc is trapped under the centre of the tyre, which is what you don't want for maximum grip. It probably doesn't make a great deal of difference with a bicycle tyre on roads, and also if the tyres (chevrons) are worn it probably makes little difference which way the tyres face.

How would your logic apply to a bicycle with a motorised front hub?
"It takes a genius to spot the obvious" - my old physics master.
I don't peddle bikes.
KM2
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Re: Tyre directionalness

Post by KM2 »

Wouldn’t that be a driven wheel which is less likely to slide due to the higher mass of the wheel.
Bmblbzzz
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Re: Tyre directionalness

Post by Bmblbzzz »

Where tyre directionality does matter it's due to differences in carcass construction more than tread, and is more likely to apply with high loads (weights and speeds) so really only motor vehicles. I think.
MikeF
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Re: Tyre directionalness

Post by MikeF »

Bmblbzzz wrote: 16 Aug 2022, 9:00am Where tyre directionality does matter it's due to differences in carcass construction more than tread, and is more likely to apply with high loads (weights and speeds) so really only motor vehicles. I think.
Any motor vehicle tyre with an asymmetric tread either around the circumference or laterally is unidirectional.
"It takes a genius to spot the obvious" - my old physics master.
I don't peddle bikes.
cycle tramp
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Joined: 5 Aug 2009, 7:22pm

Re: Tyre directionalness

Post by cycle tramp »

I don't know..
I've ridden on 25 mm slicks, 28 mm and 32 mm road tyres 26 3/8 world tours, all manner of 559 tyres, and 16 x 1 3/8 brompton tyres. I can't remember any of them having chevron pattern. Whilst i've gone sideways many times (wet drain covers, gravel on a down hill left hander, gravel on a down hill right hander, into a patch of stinging nettles along a towpath)..I've never wiped out simply by riding into a puddle without any chevrons on my tyre.
It's time to go :-)
timearl
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Joined: 12 Aug 2022, 8:32am

Re: Tyre directionalness

Post by timearl »

Th
MikeF wrote: 16 Aug 2022, 7:54pm
Bmblbzzz wrote: 16 Aug 2022, 9:00am
Any motor vehicle tyre with an asymmetric tread either around the circumference or laterally is unidirectional.
The tread on my tyre is the same in both directions (no chevrons), and it still has a direction of rotation arrow.
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