tyre pressures

[duncan]

[Gerry H]

Maybe I am getting confused here but for sprints surely you'd get better grip with lower pressures and they would warm up quicker with lower pressures -hence why heavy cars need more pressure and light cars need less pressure?

That's the thinking

A sprint is a lot different to thundering round a tarmac race circuit.

Come on Duncan at least you'd then know what we're on about and you can then speak from experience

[Andy916]

Maybe I am getting confused here but for sprints surely you'd get better grip with lower pressures and they would warm up quicker with lower pressures -hence why heavy cars need more pressure and light cars need less pressure?

Short answer is 'it depends'.

Single-lap sprint is so short that you need a compound that grips without pre-heating. Ideal sprint compound would be unlikely to last a 20min track session. How low you can go on pressure depends on the sidewall stiffness - put 24psi in most tyres and they'll flex too much and feel awful, at best. Only when you've got a lap or two warmup time can you make use of a lower pressure to increase flex to make it warm up quicker (and reach much the same optimal hot pressure).

Dunc - does anyone use tyre warmers in the gucci sprint? Are they allowed? And Gerry - are they allowed in modified sprint class?

[Gerry H]

I think this thread has taken the usual sprint meanderings. :roll:

The OP asked about tyre pressures, Stuart quoted Alan Meaker who was speaking specifically about 888s

Without knowing what tyres Graham is running, what track type (concrete probably, or tarmac) track temp on the day, and of course whether Elvingdon is to be treated to a SSO style downpour it's all rhetoric.

I'd set off with 30 all round regardless and see how it performs.

[duncan]

Why call it gucci sprint?

No-one runs tyre warmers - not worth it as we have plenty enough track time to be able to warm them up normally. Biggest problem is keeping them cool

[Gerry H]

Gerry - are they allowed in modified sprint class?

Don't know and I couldn't afford them anyway plus they'd be stone cold by the time the green light came on

[Andy916]

Why call it gucci sprint?

Just quoting the tongue-in-cheek moniker that appeared on 22b a while ago; tis unjustified of course, as chasing a target using an engine, race or non-race, four wheels or two, is always expensive.

[Andy916]

Gerry - are they allowed in modified sprint class?

Don't know and I couldn't afford them anyway plus they'd be stone cold by the time the green light came on

Yup. Perennial argument in bike club racing where warmers have become almost universal in the last decade, is how much heat is retained whilst waiting for the start. The one-lap warmup makes more of a difference to carcass temperature, but warmers warm the rim and internal air too which helps with overall retention. Different scenario really, one in which the main object is to dive into the first corner first.

Andy

[Gerry H]

Sprinting and Time Attack are very much alike in that it isn't racing.

[Pike]

Don't open that hornets nest Mr H