Tyre wear pattern.

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awkwardbydesign
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Tyre wear pattern.

Post by awkwardbydesign » Nov 1st, '17, 11:09

At Mallory on 6th October, I had this wear pattern on my rear tyre. The weather was sunny but cool, and I ran the rear at 29lbs, 1lb lower than usual due to the cooler temperature. My reasoning being to warm the tyre up quicker in the lower temperature. Now I may have got that wrong, of course, and this is how the tyre looked on the left side. The right side is more normal. At Mallory there is only one significant left, the Devil's Elbow on to the front straight, where I short shift from 2nd up to 5th still leant over, then to 6th when upright.
Has the tyre overheated due to underinflation, is there a pulsing wear pattern due to incorrect suspension setting, or what? Any ideas from our more experience track riders? I have high and low speed compression damping on my Nitron shock, which I had set (at Anglesey) by Peter Clifford a while ago.
Any advice welcome.
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Re: Tyre wear pattern.

Post by billinom8s » Nov 1st, '17, 12:04

I run 26 hot on my rear tyre, seems to get a nice even wear pattern.
With tearing like that I would take the pressure down to about 27.
Thing is Anglesey setup is different to the setup for, Mallory is a lot harder on the tyres. You may want to soften the rear shock a mil or two on the preload.
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Scotty
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Re: Tyre wear pattern.

Post by Scotty » Nov 1st, '17, 13:05

... and the left side of the tyre will be comparatively cold as well. You're taking the Devil's Elbow in 5th?? :shock: That must take some doing, managing a triple short-shift coming out of the bus stop, or have you secretly fitted a seamless gearbox? We need to know.... :-?
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awkwardbydesign
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Re: Tyre wear pattern.

Post by awkwardbydesign » Nov 1st, '17, 14:07

Thanks for the replies.
Simon; it doesn't look like tearing to me, and in fact the reason I dropped the pressure was because I had obvious tearing previously (although the tear pattern was ambiguous; I wasn't sure if it was hot or cold tearing!). This looks to me like melting. I have used the same rear setting everywhere, as I'm not usually that hard on tyres. Maybe I'm getting faster as I get older? =))
Scotty; I wondered if the tyre could be cold on the left, but I thought that looked like overheating! As for gears, well obviously I am a track god. Or maybe just slow. I hit 3rd as I exit the Bus Stop, 4th as I hook it left, and then 5th as the bike drifts right before I straighten, then 6th after I hit the grid markings (I think). A dab of the brake passing the pit exit and 5th all the way to Edwina's, 3rd for that, up to 5th before the hairpin, and 2nd until after the Bus Stop. Unless I miss a gear, which is not unknown. My SV is one of the slowest bikes on track, so I generally get passed on the straights, but often get them back on the brakes, or round Gerrards. Bearing in mind I am now back in the novice group, as my reactions and strength drop.

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Re: Tyre wear pattern.

Post by DynaMight » Nov 1st, '17, 16:55

Please dont take this the wrong way, I dont know your riding! but I've seen this a few times on the wifes bike when she wasnt going all that fast. We shared the same bike a few times, when she would come in the tyre would look exactly like that but would clean up when I used it. It's just rubber off the track thats been picked up by the tyre.
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Re: Tyre wear pattern.

Post by Devon jeff » Nov 1st, '17, 17:25

tyre prssure is too high,

I would be aiming for 26/27 psi hot rear 31/32 psi hot front, if you have tyre warmers its easy to set, if not you will need to go 2-3 psi lower than your desired psi, a soft tyre will generate heat quickly and in turn pressure. ( but may feel a bit funny at the rear for a lap) check pressures as soon as you can after a session and adjust accordingly, i wouldnt mess around with suspension settings until you get the correct prssures, Also refer to the manufactures website for hot pressures, manufacturers specify different hot pressures depending on side wall constructions.

most important suspension setting is the rider sag front and rear,

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Re: Tyre wear pattern.

Post by awkwardbydesign » Nov 2nd, '17, 09:51

DynaMight wrote:Please dont take this the wrong way, I dont know your riding! but I've seen this a few times on the wifes bike when she wasnt going all that fast. We shared the same bike a few times, when she would come in the tyre would look exactly like that but would clean up when I used it. It's just rubber off the track thats been picked up by the tyre.
I don't claim to be fast, but have done enough trackdays (30+) to know the difference between wear and pick-up!
PS. I was overtaking people through Devil's Elbow.

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Re: Tyre wear pattern.

Post by awkwardbydesign » Nov 2nd, '17, 09:56

Thanks to all who have suggested a particular pressure, but bear in mind my SV runs 33 front and 36 rear for the road. I guess I will have to do a bit more research on this, as I was suspecting under inflation, leading to overheating and surface melting. Unfortunately I can't do trakdays often enough to do much experimenting. And this is the first time I have seen this happen.

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