25mm tyres

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

Randonneurs are not really 28mm.

What????

Counter intuitive, but he's right. A really hard tyre will get more punctures than a reasonnably inflated one.

I cant think of anything worse than running my tyres at 80psi.
I can think of a few.

London roads being what they are, I'd say get a few more mm, you'll care less about potholes and won't be any slower.

Randonneurs are not really 28mm.

i know, they are 25mm wide by 28mm high

Dude, by all means! But graduate off your 23mm at 140psi and try 25mm tyres at 90psi for a week and I'll eat my hat if you don't go wow, that was a revalation ;-)

I notice the drop in speed/increase in perceived effort when my tyre pressure drops from 120-100psi from a few days of riding on shitty London roads, the difference is huge, which is why I top my tyres up every other day, lower pressures increase tyre wear as well since you are increasing drag and the tyres footprint on the road, I can't even begin to think how shit it would feel at 80-90.....no thankyou!

For the record I currently run 23C tyres front and back, but I think my 28C's I had way back earlier this year, were faster at the same pressure, from my experience I think 28's are probably the optimum size for speed/comfort through the streets of London.
Having tried every extreme either side of this size, I can honestly say that 28'c felt best, and thats what I will be going back to shortly.

80-90 psi IS a puncture!

I tell you what though Duncan, by the same toke, I wouldn't like to be cornering hard on bumpy roads with a 19C tyre up front, I prefer slightly wider because you can throw the bike around a bit more and still have bags of grip, but then again being as big as I am I guess I need a bit more grip lol, I also prefer the extra protection a slightly wider tyre gives the rim from pothole scuffs etc.

Your problem is that you are running conti ultra sports, the shittest tyre from the shittest manufacturer on the market.

http://www.londonfgss.com/thread3195.html

@CrazyJames - Tyre width and pressure go hand in hand. Yes, 80-90 psi on a 23mm is bad/flat/slow/puncture prone. I don't recommend anyone do this!!! 80-90 on a 25mm is correctly inflated. If you're running wider 28mm, you could go even lower. If you're on the heavy side, go a little harder.

@Donut! - like most things in life, don't knock it till you've tried it :-)

I tell you what though Duncan, by the same toke, I wouldn't like to be cornering hard on bumpy roads with a 19C tyre up front, I prefer slightly wider because you can throw the bike around a bit more and still have bags of grip, but then again being as big as I am I guess I need a bit more grip lol, I also prefer the extra protection a slightly wider tyre gives the rim from pothole scuffs etc.

I get the impression we have different definitions of 'throwing the bike around' ;)

But I ride pretty damn hard on my veloflex's (20mm front) and they've never let me down. I think its partly down the the oval profile of the tyre, which seems to put more rubber down when cornering.

I feel I've got to wade in with a non-fact based point.

Everyone says pump your tyres up to the max to avoid punctures... so I do. I very rarely get punctures now.

Also puncture proof tyres help.

I agree and I agree with what others said about this.
From experience, and my ingenuis brain of mine.

The more solid the less likely something is going to impale in to it.
If it's a soft tire, you may aswell have playdough wheels.

I get the impression we have different definitions of 'throwing the bike around' ;)

But I ride pretty damn hard on my veloflex's (20mm front) and they've never let me down. I think its partly down the the oval profile of the tyre, which seems to put more rubber down when cornering.

Ah well ordinarily you would be right, but these days i'm not on a trick bike for getting around anymore, just a Cotic Roadrat.
On my trick bike I had flippin huge tyres, 38c marathon plus up front and a 35c Bontrager touring tyre at the back :)

The more solid the less likely something is going to impale in to it. If it's a soft tire, you may aswell have playdough wheels.

No! The casing is the bit that's soft and it doesn't change it's softness with pressure!!!!

Here's an instructive Blue Peter style home experiment...

Take some kitchen foil, blutack, drawing board pins, and a bag of flour.

Construct a shitty pieve of road by blutacking the pins point up. Drag the sheet of foil over the pins. Sprinkle a little flour on top of the foil. Drag. Sprinkle. Drag. Sprinkle. Drag. How much flour does it take to puncture the foil? None? A lot? Little?

A Blue Peter badge for the first correct answer :-)

when i used to watch blue peter, we had solid tyres

Was it in Black and White too?

yup, you cheeky little (huh?) whipersnapper

I tell you what though Duncan, by the same toke, I wouldn't like to be cornering hard on bumpy roads with a 19C tyre up front, I prefer slightly wider because you can throw the bike around a bit more and still have bags of grip, but then again being as big as I am I guess I need a bit more grip lol, I also prefer the extra protection a slightly wider tyre gives the rim from pothole scuffs etc.

I wouldn't like to either, thats why I run a 23c Stelvio Plus on the front, nice and grippy, and a Stelvio 28c on the rear, loads of life for fixie skidding. :)

No! The casing is the bit that's soft and it doesn't change it's softness with pressure!!!!

Here's an instructive Blue Peter style home experiment...

Take some kitchen foil, blutack, drawing board pins, and a bag of flour.

Construct a shitty pieve of road by blutacking the pins point up. Drag the sheet of foil over the pins. Sprinkle a little flour on top of the foil. Drag. Sprinkle. Drag. Sprinkle. Drag. How much flour does it take to puncture the foil? None? A lot? Little?

A Blue Peter badge for the first correct answer :-)

Interesting.

I still say a solid tire is less prone to a puncture. =)

So what's the answer Mr. Smartie Pants? :P

I wouldn't like to either, thats why I run a 23c Stelvio Plus on the front, nice and grippy, and a Stelvio 28c on the rear, loads of life for fixie skidding. :)

Tyre choice fail on my part there, lack of sleep is stopping my brain from functioning properly today.
Stelvios/Duranos are what I plan on getting front and back next in 28C me thinks, thinking its nice to have the extra traction up front as well for my silly powerful hope disc brake ;) Heard nothing but good things about those tyres.

I've ridden Stelvios for ages and love them. I think there are two kinds you can get tho, one with a puncture proof strip and one without. Get the better ones, a few more quid, but the puncture protection works really well.
Rear is slick but still grippy (not so much in the wet) and the Stelvio Plus has a nice bit of tread on the sides so great for cornering.

so much bullshit in this thread about aerodynamics and shit.

PSI affects rolling resistance, because PSI decreases casing deformation. Narrow tires (say like 19 mm clinchers that my friends swears by) are run at a higher PSI because they have to be, and so they are associated with a lower rolling resistance.

Higher PSI will lead to less pinch flats and, in theory, more puncture flats. I side with higher PSI because i like lower rolling resistance and assume that glass will cut into tires at almost any ridable PSI. I also like the way a very hard tire feels on a bike.

Shitty tires will get more puncture flats than good city tires. This is the biggest variable. Get good city tires (to prevent flats) and run them at the maximum PSI (to make for a fast ride).

I ride Contis 23mm Ultra Race on my geared bike, and 25mm Ultra Gatorskins on my fixed bike. There is a logic to this. They are the same fucking tire, except that (3 layers of casing at 60 TPI), but the Gatorskins have some "duraskin" shit. I don't know what it is, but it works well. The Ultra Race are fast fucking tires when run at 125PSI, and work for my geard bike because it never sees the city. I always ride it out in the hills and there's nothing on the streets except dead rodents and bird shit. The Gatorskins are indestructible. Run them at 125 PSI and they are still pretty fast. They are relied on for preventing flats when i'm riding around downtown.

Narrow tires (say like 19 mm clinchers that my friends swears by) are run at a higher PSI because they have to be, and so they are associated with a lower rolling resistance.

Which is incorrect.

so much bullshit in this thread.....

....The Gatorskins are indestructible.

enough said

Which is incorrect.

that'll be the 'so much bullshit' he was referring to :-)

Hahahaha ^

Which is incorrect.

oh?

you try running 19 mm tires at 120 psi.

i just find it funny you are calling me out for something that is completely CORRECT, and yet on page one there is some crap about pushing air away from spokes. If you push air away from spokes, what takes it's place? A vacuum? Water? Celestial Ether?

Smaller tires must run a higher PSI. FACT.

enough said

elaborate.