I had the same issue
wheelie king
I had the same issue
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Hardcore Biker
How come we have brilliant suspension backup and support at the track but no tyre retailers around that can help us out?
There must be a fortune spent on tyres each round.
Harrasing towbars since 2007
I'm no expert but I believe its completely suspension that is causing the issues here....even the suspension gurus would agree I'm sure. Besides, if there were tire distributors about what use would they be?Originally Posted by johan
Hardcore Biker
I don't know either what is causing some bikes chewing tyres and others not.
It's obviously an interaction between tyres and suspension, and many other variables causing wear.
I'd imagine tyre companies have a lot of data how to use their tyres, what compound, pressure and operating temperature that would work best for a given environment. It sure would be handy to have someone to ask that about.
How do I compensate my tyre pressure from summer 25 C ambient to winter 10 C ambient temperature? Am I required to collect data and take photos under a season to get my head around their product?
I've asked a tyre importer about any numbers or data they could share, but basically got the answer it's very technical so here, try this random number as cold pressure. I'm doing software engineering and have no problem digging into numbers or theories, please bring it on.
So far I've received more tyre tips from a suspension tech than from a tyre tech.
I'm happy to pay for any consultancy, because it will save me money in the end.
They still charge us full price, some say for old tyres. We're struggling to get their products to work, yet we buy them again and again for each round.
I'm just thinking it would benefit everyone to get some help to the problem.
Anyone agree?
Pretengineer
Not necessarily. Tyres, I imagine, are designed to run within a temperature range. Like all things it's about compromise. XYZ tyre manufacture may have decided that they can ultimate grip out of their tyres, but only if the track temp is over 20 degrees and under 50 (example). Above or below those ranges and they wont work. But that is the compromise the tyre manufacture decided to make in order to achieve the results they want.
Many other factors that exist are riders, each rider rides differently and some styles might make cold shredding more susceptible. Also, a worn linkage/swingarm unit, that'll also have an effect as to how much control the shock will have over the wheel on the ground.
Tyre age is probably a big one, as is tyre compound. I dare say that it would be very unlikely that a tyre manufacture would design a full blown race tyre to run on track temps as low as what we were running on at round 2.
I wonder if a Road tyre would be more suited, as they would be designed to handle the colder temps?
I don't have a informed opinion on it, but those are ideas floating around in my head.
Old Man
Well hes an idea I have concerning this.
You put your tyre warmers on and soak the tyres so the whole carcass is up to temp. When the tyres hot the "rubber" is alot softer and elastic and less likely to tear. Then your called up to race and in the process of waiting on the dummy grid and doing a moderate lap the outside surface of the tyre cools off considerably and is more likely to tear. Because the "rubber" underneath is still hot and elastic when the tyre is placed under load the top surface of the tyre gets small tears in it from the track surface. Once started these cracks get bigger and you end up with the wear pattern that most call cold shear.
As argued at length on other threads I've seen it happen on the best setup bikes suspension wise and bikes with crap suspension.
There are ways to stop it happening but I'm no tyre or suspension expert so aren't qualified to give advice on these matters even if I know what worked for me.
Harrasing towbars since 2007
What tires are you running Johan? I've found Andrew at Forbes and Davies to be really helpfull in answering questions on the METZELER tires. I do think however that a lot of the technology is not shared with the distributors and most of the knowledge base that the likes of F&D have is based on other peoples/users feedback. They have the basic information to get you going but issues like sketchy has highlighted (rider style etc) is a bit 'trial and error.'
Glen Williams
My experience is that you can still "sheer" tyres in summertime - but it is almost always a suspension set up issue or a track surface specific issue (i e Teratonga type surfaces) & can be solved. In winter however the track temp tends to make the rubber run below its optimum temperature range (see sketchy post) & therefore the window for setting up your suspension to keep the tyre within range becomes very small indeed. The window can also change from session to session. Even very small changes in tyre pressure can have quite dramatic effect.
Evidence of this is that it is not that uncommon to have identicle bikes with identicle rubber fitted exhibiting completley different types of front or rear tyre "sheer".
Sometime the quicker riders suffer less from sheer, - because their speed adds heat into the tyres & sometimes the oposite applies !
It is a genuine conundrum that keeps the tyre suppliers and the suspension guys working hard to solve on any given day.
Good managment of and the quality of your tyre warmers also can have an effect on sheer.
Road compound tyres - do often sheer a little less - but in my experience have less grip overall even-so.
GlenW
Hardcore Biker
At some really cold meetings (esp pre-tyre warmer days) it seems like you have to scare yourself through to get / keep the tyres working. Weird. There is more sidewall movement before they're up to temp/ pressure. At cold track days & races without tyre warmers I use more pressure because of this.
Forum whore
Hi Deano,
As you will recall we stated that the shock needs revalving to a firmer internal damping spec that we have developed and is working really well. Springs sometimes sort the issue but its also about controlling the rate of change of position, that is taken care of by the damping.
Forum whore
Maybe they dont want to work for free!
Forum whore
No and yes.
As per my first post in this thread that particular long track throws up some major setup compromises and tyre wear issues, it gets a whole lot worse in the ridiculously cold temps we race in.
Some very valid points have been raised by Glen, Glen and GSVR etc. Here are a few more;
1) Many of the new tyres we purchase are not new at all! They are often up to 3 years old and as Shaun has eluded to may have been subject to unacceptably wide temperature fluctuations in storage. Unacceptable but then consumers price demands may in effect be driving part of that .
2) For consistent and acceptable tyre performance they should be no older than 1 year old.
3) NZ is a very price concious market and I would imagine that some of the tyre distributors may purchase ''specials'' from the manufacturers. The specials relating to price specials. You get good batches of home baking and not so good batches. The baking also has a storage lifespan. Ditto for tyres.
4) If you are using hand me downs then likely the tyres are well past their best and will exhibit issues more readily
5) There is a temperature operating window for tyres and compounds, that ''window'' has got a lot narrower even over the last couple of years.
6) Soft compound tyres on cold tracks are a recipe for disaster, much sooner
7) SUSPENSION SETUP is indeed a huge factor. Yes you can screw tyres if the setup with your top shelf suspension is off. Point of fact the springing / preload etc has to often be firmer in the winter months to help build heat into the tyres. But with aftermarket suspension there are readily available spring options and the ability to revalve quickly using a setting bank of alternative damping curves / characteristics. Try that with a stock shock and also allow much much more time for revalve.
And I have to say it spring supply and exchange for Ohlins springs is in NZ VERY LIBERAL. In all other markets that I know of you have to purchase and own your own spring options. This makes a mockery of those that chastise my operation of being in it entirely for the money.
8) Tyre warmers should heat to no more than 75 degrees celsius. Tyres are like cakes. You can overcook them and ruin them. And how many heat cycles had many of the tyres used at the weekend been through?
And so on.....MISHY WHERE ARE YOU? You will be able to describe the technicalities of tyres much better than me.
Forum whore
Further to this the SV650 has a particularly ''non racing friendly'' rear linkage as the bike was never ever intended as a racebike. Shock internal spec has to account for that and its surprising how aggressive the low speed shimming and bypass into the reservoir has to be.
#3
Thanks again for your help at the weekend. I will get the shock to you soon for that revalve.
Thanks also Glenn et al - there are obviously a lot of factors to consider and I've learnt quite a bit.
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Forum whore
Dont ever be afraid to ask Deano, and anyone else having problems. If we can help we do. And its not all about money.
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