Has anyone run different tyre profile front & rear?

[Jayfish]

Kind of thinking out-loud here, what with winter and reduced grip and increased braking times...
Would there be any benefit to running say a 700c23 rear and say a 25c front?
A 23 contact patch should be enough for drive but will a 25 (or larger) help prevent front wash on slipperry surfaces due to bigger contact patch?
In this hovering around zero (& having a right brown trouser moment the other day) I'm more concious and concerned about grip than before, much like driving the +2 to -5 is the slipperiest.

[yellowjack]

There are already tyre sets available with specific (different) widths for front and rear. These, for example:

http://www.wiggle.co.uk/continental-grand-prix-att...

although they may not be your best bet for grip and protection over the winter months. It may be worth a look at the leading tyre manufacturer's websites to see if any of them have 'done the science' behind fitting different profile widths on front and rear tyres, and which way round they should go to get the best balance of handling and grip.

[Rolls]

I have, but in the alps on the Mtb, so of no use I'm afraid.

[aka_kerrly]

On the MTB I almost always used to run a 2.3 rear and a 2.1 front in the belief that I needed a wider tyre for impact absorption (HT bike) and that a narrower front would help cut through mud and aid the steering.

More recently when I swapped from Tioga FDHs to Continentals the shop assistant (Noahs Ark in Stroud) suggested I opted for a narrower on the rear and a fatter on the front as this would make my drive to the rear wheel more effective and the wider front tyre would generate better grip which would improve steering and braking on the front.

To my surprise it seems to work rather well....

[Accelebrate]

I ran a 700x28 rear and 700x35 studded front for a few days last year, mainly because at the time I only had a spare front wheel for speedy weather dependant tyre changes. Worked fine, and in a way still being able to lose traction at the back is quite a good way of reminding you not to get too cocky.

That said, I've got a complete set of wheels and studded tyres built up and ready to pop on this year.

[Jayfish]

Cheers Yellowjack for the link but their guide lists those one as pro-tour quality, I'll need a lifetime and a time machine to reach that standard

A lot of comments elsewhere seem to suggest lowering pressures, but I don't want to increase puncture risk especially in the cold. Maybe I should just put larger sections on both ends and live with the extra rolling resistance?

[yellowjack]

Jayfish said:

A lot of comments elsewhere seem to suggest lowering pressures, but I don't want to increase puncture risk especially in the cold. Maybe I should just put larger sections on both ends and live with the extra rolling resistance?

There was a piece in the Summer 2012 edition of Cycling Plus magazine, written by their Senior Technical Editor, entitled "Want to go faster? Go fatter..."

It was a one page item, exploring a trend among Pro Tour teams to race on larger section tyres. Apparently this is partly due to the increasing rim widths of the latest high end aero wheels, as this stretches and flattens the profile of 23mm tyres too much. GreenEdge, Rabobank and Sky have been racing 25mm tyres, and Schwalbe have done studies that show smaller diameter tyres have higher rolling resistance than larger tyres for the same pressure. It's to do with deflection/deformation of the tyre under load, where the area of the contact patch of a 23mm tyre spends more time being 'less round' than a 25mm tyre, because of the increased volume of air within the larger tyres.

There is a caveat in the editorial that states that there is no real advantage to be gained in going up several sizes in the same sort of tyre, as all the advantage gained by reducing energy loss through tyre flex will be countered by the increase in effort needed to rotate a tyre with a larger mass. The advantages are still there though, among them a more uniform contact patch on the road, and an increase in rider comfort. This would mean that you could run a larger tyre at the same pressure as your current tyres and see an increase in comfort without a greater risk of 'pinch-flats'.

Be aware that much of this 'science' and research is aimed at racers, so we're not talking sections of 28mm - 35mm here, rather a more conservative increase in section from a 'standard' 23mm tyre to a 'fat' 25mm tyre. Warren Rossiter's last sentence from the article:

"If your also looking for comfort then 25s are the way to go - go for a quality lightweight tyre and you'll also get a boost in pace too."

From the tone of the piece, it sounds like there is much to gain, and little to loose, in trying a wider tyre, especially over the winter months. I know that we're talking about tiny measurements when it comes to the size of a bicycle tyre contact patch, but any measurable increase sounds a lot more if you think of it in terms of percentage increases. It sounds like it would be worth a try, no?

[Jayfish]

yellowjack said:

Jayfish said:

A lot of comments elsewhere seem to suggest lowering pressures, but I don't want to increase puncture risk especially in the cold. Maybe I should just put larger sections on both ends and live with the extra rolling resistance?

There was a piece in the Summer 2012 edition of Cycling Plus magazine, written by their Senior Technical Editor, entitled "Want to go faster? Go fatter..."

It was a one page item, exploring a trend among Pro Tour teams to race on larger section tyres. Apparently this is partly due to the increasing rim widths of the latest high end aero wheels, as this stretches and flattens the profile of 23mm tyres too much. GreenEdge, Rabobank and Sky have been racing 25mm tyres, and Schwalbe have done studies that show smaller diameter tyres have higher rolling resistance than larger tyres for the same pressure. It's to do with deflection/deformation of the tyre under load, where the area of the contact patch of a 23mm tyre spends more time being 'less round' than a 25mm tyre, because of the increased volume of air within the larger tyres.

There is a caveat in the editorial that states that there is no real advantage to be gained in going up several sizes in the same sort of tyre, as all the advantage gained by reducing energy loss through tyre flex will be countered by the increase in effort needed to rotate a tyre with a larger mass. The advantages are still there though, among them a more uniform contact patch on the road, and an increase in rider comfort. This would mean that you could run a larger tyre at the same pressure as your current tyres and see an increase in comfort without a greater risk of 'pinch-flats'.

Be aware that much of this 'science' and research is aimed at racers, so we're not talking sections of 28mm - 35mm here, rather a more conservative increase in section from a 'standard' 23mm tyre to a 'fat' 25mm tyre. Warren Rossiter's last sentence from the article:

"If your also looking for comfort then 25s are the way to go - go for a quality lightweight tyre and you'll also get a boost in pace too."

From the tone of the piece, it sounds like there is much to gain, and little to loose, in trying a wider tyre, especially over the winter months. I know that we're talking about tiny measurements when it comes to the size of a bicycle tyre contact patch, but any measurable increase sounds a lot more if you think of it in terms of percentage increases. It sounds like it would be worth a try, no?

That's really quite interesting, especially the "same pressure" part; common 'wisdom' seems to be 25's can be run circa 10 psi lower than the 23 equivalents (which would ofc increase both the resistance and the contact patch) and was what i was considering originally.

Hmmm... think I might have to get some 25's and try the higher pressure to start with and see if it gives me a little more grip confidence, then maybe reduce the pressure if needed.

TBH the bike is still shod in the bontrager slicks it came with and they're probably a £12 tyre at best so anything i do will be an improvment