25mm tyres

Last week i had 3 punctures on my fairly new but crappy off the peg Conti Ultra Race tryes that came with the bike (Genesis Flyer). They were all in different places so my ropey mechanics cannot be blammed.

The existing ones are 23mm but i was wondering if 25mm would help - especially with the crappy pot-holed London road or is it just a case of getting something with better puncture resistance.

What do all you guys and gels ride on?

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http://www.londonfgss.com/thread8603.html

Use the search for specifics, but to answer your general question, yes 25mm tyres help with puncture resistance... and ride comfort... and grip... and rolling resistance. The only marginal downsides are weight and aerodynamics, but this only matters if you're racing. IMO more people would be happier/better off using 25mm tyres!

aerodynamics

of tyres!?!?! 25mm infact increases rolling resistance as larger area in contact with the road, but not really a problem unless your lance. oh and utfs please

25mm infact increases rolling resistance

Untrue.

less contact with the road = less rolling resistance

http://www.schwalbetires.com/tech_info/rolling_resistance

UTFS is only actually useful if there is an existing debate! Lot's of what tyre threads, but no real comment on 23 vs 25 that I could see!

Rolling resistance isn't to do with rubber in contact with the road, it's to do with casing deformation. Which is linked to contact patch size and pressure, in that a bigger contact patch (more rubber) actually leads to lower rolling resistance given the same pressure. In practice, the same tyre in 25mm will roll quicker than it's 23mm counterpart at an appropriate pressure. That's for a perfectly smooth road. If the road's rougher, then it swings more in favour of the 25mm.

Aerodynamics, for sure! But clearly only a meaningful effect at higher speeds. Point is, for us mortals, the aero disadvantage of a 25mm compared to 23mm is not worth worrying about.

20mm tyres.

Less contact with road = less chance of hitting something sharp.

(as for aerodynamics. I read that 23mm tyres give optimal aero dynamics, as they offer the best balance of cutting through the air and pushing the air away from the wheels.)

i run a 23 front and 28 rear. best of both worlds :)

less contact with the road = less rolling resistance

It's more about the tyre pressure though, surely.

For real aerodynamics the tyre plus rim would need to be 4 times deeper than it is wide so depth of rim would need to be factored in for anyone really worried about it.

As if most fixie skidders need to worry about aerodynamics as they ponce around London! *

*with the exception of LaLeLiLoLu of course.

You also have to consider the different rubbers, layers/structure, weave etc,.etc,. so bit of a minefield.

As if most fixie skidders need to worry about aerodynamics as they ponce around London! *

*with the exception of LaLeLiLoLu of course.

That surprises me. Thought that is why the love of deep Vs :-)

The love of deep Vs stems from all the pretty colours they come in.

For real aerodynamics the tyre plus rim would need to be 4 times deeper than it is wide so depth of rim would need to be factored in for anyone really worried about it.

Not strictly true. Even a brick has aerodynamic properties and you can improve these properties in small and meaningful ways.

Back to tyres... you can virtually disregard the rim for most rim (e.g. non-aero) rim sections. The main aerodynamic effect is then that of a bluff body, being the tyre. Make the tyre wider, you increase the drag, simple as that.

i run a 23 front and 28 rear. best of both worlds :)

Me TOO! Do we win a prize?

20mm tyres.

Less contact with road = less chance of hitting something sharp.

Imagine walking across a room of broken glass barefoot vs tiptoe. If you're lucky, barefoot you might not get any splinters. If you're unlucky, tiptoes, and you hit a piece of glass you can guarantee you'll get a splinter! Same deal, the higher pressure your tyre runs, the greater your chance of punctures.

(as for aerodynamics. I read that 23mm tyres give optimal aero dynamics, as they offer the best balance of cutting through the air and pushing the air away from the wheels.)

The pushing/cutting analogy is misleading. The optimal tradeoff with 23mm tyres is simply between weight, rolling resistance, and aerodynamics, for typical racing use.

The main aerodynamic effect is then that of a bluff body, being the tyre. Make the tyre wider, you increase the drag, simple as that.

But the wheel does horrible things to the passing air. This is why Zipp rims actually increase in diameter before narrowing to the spokes. Its to push some of the passing air away from the spokes. 25mm tyre would do this very well with being too wide. 20mm tyres are lighter. The best balance (for racing) it seems is 23mm.*

(*all just stuff I read on teh interwebs somewhere)

Regarding the OP.

I would argue that narrower tyres would be less pu*c%ur& prone than wider ones. The higher pressures and narrower profile would mean that stuff should'nt stick into them so much.

Imagine walking across a room of broken glass barefoot vs tiptoe. If you're lucky, barefoot you might not get any splinters. If you're unlucky, tiptoes, and you hit a piece of glass you can guarantee you'll get a splinter! Same deal, the higher pressure your tyre runs, the greater your chance of punctures.

What????

The pushing/cutting analogy is misleading. The optimal tradeoff with 23mm tyres is simply between weight, rolling resistance, and aerodynamics, for typical racing use.

Too slow.
But this is what I was trying to say.

For the record I run 22mm rear 20mm front on my fixie skidder. Both tyres are coming to the end of their lives yet have only experianced one pu#ct¤re each.*

(*I neither commute or ride in Londons spikey London on this bike)

So there you have it. SF has cleared it up. If you don't want punctures in London, don't ride in London.

Thanks SF.
Thread closed! ;)

So there you have it. SF has cleared it up. If you don't want punctures in London, don't ride in London.

Thanks SF.
Thread closed! ;)

I hear its dirty there too.