What causes this then/solution?
 

After my first TD at Silverstone on the SP yesterday...the tyre seemed to mark-up a lot more than the old 748 I had, which I guess is to be expected (85-90 HP vs 125-130 HP)...but I was suprised to see this down the middle of the tyre, all the way around.

Never seen it before, and looking around the padock there were some very fast boys whose tryes didn't look anyway near as shagged as mine on bikes like Gixer 1000's etc. So whats the cause/answer. I'm assuming its something to do with my rear compression/rebound damping settings.

When you see this kind of thing on a rear tyre, is it generally because things are too stiff or too soft?

Any ideas?

Its normally because the tyre is working harder than it needs to, this can be because the suspension is too soft or hard!!!

How does the bike feel? Try tweaking the suspension harder or softer as you feel it needs and see if it improves.

Tim

Tricky one...being the first time out on it 'in anger' it felt OK.

I did make a couple of changes during lunch, ensuring that both the rebound and compression damping were set at the middle of the range, which they were pretty much anyway.

So I'm now wandering which way to go next...harder or softer?

Harv
What tyre pressures were you running??? Under inflation can give the wear pattern you have.
Glyn

I reckon you should go softer first - in theory if the suspension is too hard, it'll work harder than if its too soft? Depends upon how soft or hard it is now I suppose.

Maybe you should look at getting one of the expert suspension guys to take a look, either at the track or at any of the major Ducati players?

I know that 100% have a fella who'll work with you all day and tweak as you go along.

Or try a search on how some of the Performance Bikes / Superbike magazines have set their Dukes up. But do make a note of your settings first - then you can always go back. That might tell you whether your settings are on the hard or soft side.

Tim

Yeh, I agree Glyn, that looks more like low pressure than anything else.
Any tyre will wear like that if its working hard, and as far as I know, wear in the middle always means the pressure is too low.

I was running 32 in the rear...which I think is OK for a slow/inters pace I was running.

WHAT !
You should be on more like 36 front and 42 rear I think !

32 is only any good for classic-style tyres.

(or 2.5bar front and 3bar rear for youngsters :saint:)

[Edited on 31-5-2005 by phil_h]

And how accurate was the pressure gauge, never seen that in all my years of racing (started same time as Glyn) with a correctly inflated tyre.
If it was on the edge I would suspect to much compression damping.

We ran Chippy's 749 at 32psi rear at Llandow on Friday without any problems, if he had been going 5 secs a lap quicker we would have dropped it a bit futher. I usuallu run 30psi in the rear for my race pace.

Not true Phil, on a hot day many of us run 012ss's (as I believe these are) at 32f / 30r ... 36f / 42r is way too hard as when the rear heats it'll be like a solid tyre.

On a coolish day in novice / inters I'd personally run 33f / 36r

I only ever run on 012ss's and these settings work well for me in Inters / Fast .....

Yeah...I was under the impression that 32 is fine for the track...even had some recommend a little lower still.

I know manufacturers often say 42 in the rear, but I've never run with more than 36 in a rear, and thats when I ride on the road...then just lower a little for the track!

...and as for the accuracy of the guage...well not sure...one of those pencil jobbies which I have always found to be pretty good.

I have two here (as I'm always losing them) so I'll check again...they can't both be wrong by the same amount!!!

And...yes I did check the tyres when cold prior to going out in the first session.

Maybe its a riderer weight issue :lol:

Maybe it was bottoming out the suspension over a bump and over working the rear tyre.

BAR guys, BAR... translate in BAR....
Just kidding..:lol::lol::lol:

Track pressures should be around 30 each end in this weather, Supercorsas run 30/29 front /rear.
That looks like pick up to me, I sometimes get a similar thing on my front tyre and an Ohlins man I spoke to about it said it was pick up, where you collect rubber on the tyre when it's hot and you are slowing down (like the in lap)
Not an exhaustive answer though I hasten to add! ;)

Here you are Fabio http://www.projects.ex.ac.uk/trol/scol/ccpress.htm
now you can have it any way you want it 32psi = 2.21Bar

Well...it was the day after the WSB boys had been there all weekend...on the same circuit...so there certainly was plenty of rubber on the track. But again...I can't remember seeing it on any other bikes I looked at and I wasn't going particularly slow on the in lap any way apart from the last couple of corners before the pits?:cool:

As for rider weight Kev...are you suggesting I could do with putting some on? How kind:pig:

So what did you think of her now you've been on track together Harv-Cameron used to track her quite often when he lived in Spain where he got her. He used to live just down the road from Jerez at the American base there.

John

Sweeeeet!

It just kept making me giggle coming out of the slower (at my pace anyhow!) corners and just holding on as it attempts to hoick the front wheel at every opportunity!

The way the power just kicks in at 7500 rpm and just keeps going to 11500, it just has to be ridden to be believed...

Having the extra rev range was a real benifit at a couple of points on the circuit, allowing me to pull one gear just that little bit longer, and therefore being able to concentrate on the riding and my lines etc rather than changing gear at a difficult point on the track.

And the bike didn't miss a beat all day...

I'm doing the GP circuit next Tuesday evening...Ohhhhhh yes!

[Edited on 31-5-2005 by Harv748]

It does look a bit like pick-up, but I'm sure it wouldn't make such a tidy strip like that.

I had a very similar pattern on my rear at rocky last year... with the help of mr spalding I softened the rebound 3 clicks and changed the pressures to 30f/32r and next session out it was gone.
Don't know if it was the rebound or the pressures that cured it tho!

If it was pick-up would I be able to pick bits off with a bit of effort? I mean it wasn't hot enough to melt the rubber and bond it together surely...so if it is pick-up, I should be able to pick bits off I would imagine.

And I agree Nick...I can't imagine it would make such a tidy strip around the tyre if it was this.

What does a blistered tyre look like...never seen one first hand. Could it somehow be this?

Yep harv, you can peel the bits of other peoples tyres off quite easy, i've been doing just that this morning.

Don't know what a blistered tyre looks like either! But whether it's blisterd or 'ruffled up' then i'd be sure it's either pressures or suspenders. 30/32 should be at least OK for the pressures, so set up your sag properly before your next trackie, then find someone in the know to help with the suspension between sessions... but just change one thing at a time. Try'n get a feel for what the bikes doing while you're out - is it 'wallowing' around the turns (like mine was)? is it chattering?? is it drifting???

p.s. d'you know what causes this?:

Uhm..a heavy right hand and balls of steel?

As for 'my problem' I think it is pick-up.

Just been out there again to take another look, and with a bit of effort, was able to scrape it off with a metal edge. It wasn't easy and it really was goey...but underneath appeared to be quite fresh and flat original tyre.

I'll be taking it out for a spin soon on the road...so I assume most of it will go within a few miles.

I guess all of that rubber from the WSB boys was still fresh!

None of the above Harve - just losse some weight ya fat b*stard! :lol::lol:

This was my tyre, same day same track....

Yep...looks familiar...I see you have a similar thing down the middle of yours to!

i think thats the yellow streak!!

Pic looks odd. Have you you checked your front and rear wheel alignment?

harv,

The pic looks very much like pick up to me.

I have spent long enough cleaning up slicks to know that it is hard work to clean off when cold.

Ray

I know what you guys mean,

Heres mine after Donnington, this is an abrasive track of right handers and tends to do this if your 'on-it'.

My bike was setup by a suspension techy as it was much worse before that!! He actually softened the suspension off? but that is a UJM bike and my Duke is setup very-very hard.

Andy;)

ps. Must try using the middle more...

[Edited on 6-6-2005 by andys 900ss]