Tyre wear - mileages

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iandriver
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Re: Tyre wear - mileages

Postby iandriver » 9 Nov 2019, 9:55pm

Ok, are all things equal? Same tyres, different sizes? Different sized tyres created equally, same thickness rubber?
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MikeF
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Re: Tyre wear - mileages

Postby MikeF » 9 Nov 2019, 10:33pm

Braking can play a big part in rear tyre wear. Braking transfers weight to the front wheel. The result is that the rear wheel lifts and and when the back brake is used the rear tyre tends to slide even if there isn't skidding, causing wear. If you use your back brake more on the Moulton than the Mercian, then there will be more wear on the rear tyre
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mig
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Re: Tyre wear - mileages

Postby mig » 9 Nov 2019, 10:44pm

i feel that a smaller wheel accelerates more easily for a given effort and would scrub more with that change in speed.

pure observation only also makes me think that riders have a 'choppier' action on small wheeled bicycles. they seem to move up and down more and i equate that movement with more flex, more rub, more aggro for the tyre.

i'd guess that you've ridden far far more miles on the mercian? you've had it longer reading other posts. so you're used to it's feel, how the frame rides and your responses are more in tune with it.

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The utility cyclist
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Re: Tyre wear - mileages

Postby The utility cyclist » 9 Nov 2019, 11:58pm

Tigerbiten wrote:What kills a tyre is the amount of slippage against the road.
The lower gears on the Brompton encourage this type micro/macro slippage going uphill
.
As you live where it's hilly, the rear tyre suffers.
The rear wheel on my bent trike also suffers from this type of wear due to the lack of weight on it.
I've worn a new tyre out in under 1,000 mile due to a lot of hill climbing on damp roads.
This is the reason I use a Big Apple tyre on my bent trike, it has more rubber to wear off before reaching the carcass.

Luck ...... :D

Will it? I can't say that I agree with this, how much slippage occurs on any given ride/tyre type and in differing weather conditions, tiny, tiny amounts IMO, micro slippage as you admit, for that to reduce the tread thickness to the point of complete wear in such a relatively short space of distance compared to another tyre would suggest its not micro at all but significant slippage all the time if that is the case, slippage that the OP would notice a lot.
Slippage/sliding can have an effect on wear but I really can't see how it would have anything like the massive affect in the distances given and the OP not coming out with something like that upfront.

What wears tyres faster and is constant over all tyres is weight and load, more weight and load of the all up weight on the rear is going to end up with more wear.

I bought some Jack Brown blue tyres and the square patch pattern has worn fairly quickly but the tyre itself isn't worn, I don't expect to get high mileage out of it as it's not a tyre designed for such, that said I have better wearing tyres (Specialized Borough Pro CX) that feel just as fast rolling in exactly the same width.
Sadly that particular tyre is no longer made but I have two left and one on the rear of the commuter that has done very nicely, more s than the previous as it's had a lot less load on the back both in terms of rider weight and luggage. One buys what you feel best fits your own use with regards to performance. wear + puncture protection and sometimes that can be hit and miss, I've found Giant PSL2s to be an excellent tyre, for me they outperform or at least match Conti 4Seasons in every single facet, I ended up selling on the 4 seasons after a very short period of use, the Giants immediately felt better and they've worn brilliantly.

I just think tyres can be so hit and miss and when we don't get what we want we should move onto another tyre.
EDIT, re the acceleration aspect mentioned by mig above, that also adds to the mix but wouldn't think it's adding a significant amount more wear

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RickH
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Re: Tyre wear - mileages

Postby RickH » 10 Nov 2019, 1:16am

Even if everything else was equal you would expect to get roughly 2/3 of the mileage from tyres on the Moulton as the wheels are rotating approximately 50% more frequently for a given distance.

Brucey
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Re: Tyre wear - mileages

Postby Brucey » 10 Nov 2019, 1:22am

MikeF wrote:Braking can play a big part in rear tyre wear. Braking transfers weight to the front wheel. The result is that the rear wheel lifts and and when the back brake is used the rear tyre tends to slide even if there isn't skidding, causing wear. If you use your back brake more on the Moulton than the Mercian, then there will be more wear on the rear tyre


I agree. I think I've mentioned before now that I think it is quite possible that a moulton rear wheel may be hopping and skipping on steep, bumpy descents, and that this will wear tyres abnormally fast if there is any braking effort whatsoever being applied at the same time. Will this be worse than on a 'normal' bike? Probably, yes.

There is more weight transfer on a moulton because the front suspension compresses and the rear extends, moving your CoG further forwards than it would be on a rigid bike (of the same wheelbase). The rear suspension is then oversprung and overdamped vs the loads which it is seeing, making hopping and skipping more likely.

Almost certainly Mick will not be able to feel if this happening; the variation in load passing through the rear suspension won't be much different from normal, so what you feel with your backside won't be abnormal in any way. However that the tyres wear unevenly is strongly suggestive that this is happening.

A similar argument applies to climbing, except that the suspension is then undersprung and underdamped vs the loads seen, and gross slippage is less likely to occur in the same way. It doesn't stop the tyres from squirming as they deform though, and this can be almost as harmful as gross slippage.

On the latter point if you squash a (softish) tyre against a (wet) piece of glass, and observe carefully through the glass, you will see that the tyre can't squash flat against the glass without some slippage within the contact patch. Tyre width for tyre width, pressure for pressure, these deformations are almost invariably worse with smaller wheels.

cheers
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RickH
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Re: Tyre wear - mileages

Postby RickH » 10 Nov 2019, 3:16am

Another thought... :o

Is the Moulton laterally stiffer than the Mercian? The frame probably is & the smaller wheels probably too.

In which case, is more of the sideways force as you pedal that causes the BB to bend sideways, & possibly some flex of the wheels, that will be happening with Mercian being transmitted to the rear resulting in the rear tyre scrubbing from side to side to a greater extent with the Moulton?

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Mick F
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Re: Tyre wear - mileages

Postby Mick F » 10 Nov 2019, 8:23am

^^^^
That sounds like it's the reason.

Moulton has a VERY stiff frame. As the wheels are small, they too are stiff. The only movement therefore, is the tyre.
Mercian is 531c and as such is very forgiving. Movement will be distributed throughout.
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Cyril Haearn
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Re: Tyre wear - mileages

Postby Cyril Haearn » 10 Nov 2019, 8:36am

Whatabout front tyres?
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Mick F
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Re: Tyre wear - mileages

Postby Mick F » 10 Nov 2019, 10:38am

Front on Moulton?
The front one I changed only a month ago had lasted 6,800miles.



Just thinking about the frame and wheel stiffness Idea ..............
If it's the reason for the premature rear tyre wearing, it must be the same for all bikes with very stiff frames.
Aren't some CF bikes very stiff?
Do they suffer in the same way?
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Cyril Haearn
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Re: Tyre wear - mileages

Postby Cyril Haearn » 10 Nov 2019, 10:54am

The tyre and wheel on a Moulton take more strain, but suspension prevents the strain being passed on to the rider?
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Mick F
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Re: Tyre wear - mileages

Postby Mick F » 10 Nov 2019, 11:07am

Yes but no.

The bike "bobs" so you take the strain in extra effort.
No problem riding gently in a flat area, or in a town. Nice and comfortable and easy to ride. A delight!
The strain comes when you want to get a move on and encounter hills as well. Not such a delight then.

I still love riding it though. :D
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axel_knutt
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Re: Tyre wear - mileages

Postby axel_knutt » 10 Nov 2019, 12:03pm

I've got three HS368 Marathons. One has done 13,000m, one has done 15,000m, and the other 3,200m. None of them are worn out.
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Tigerbiten
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Re: Tyre wear - mileages

Postby Tigerbiten » 10 Nov 2019, 2:49pm

On tour I can do 1,000 of miles with a similar wear pattern front/back as long as it's flat.
But once I'm in the hills, especially +20% hills, them my rear wears a lot faster than the front.
The only reason I can think is ...........

Low gears not only increase torque on the back wheel but also increase the variations in the amount of torque.
On a hill this variation in the right condition could cause a very localized small slippage of the rubber against the road.
The steeper the hill, the more likely this is to happen.
It's small enough not to be noticed, but if it happens every few pedals strokes on silly steep hills then it adds up.
Over time this accelerates the wear on the back tyre.

YMMV ........... :D

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Re: Tyre wear - mileages

Postby MikeF » 11 Nov 2019, 5:29pm

axel_knutt wrote:I've got three HS368 Marathons. One has done 13,000m, one has done 15,000m, and the other 3,200m. None of them are worn out.

What size wheels and front or back? I have a 700x32 Vittoria Hyper that has travelled 11,000 miles on the front. Tyre wear on the rear is more, even though the back brake has minimal use.
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