UKC

Never really thought the tyres on my road bike were a major issue or weakness in any way.

However last week I badly cut one of the tyres (not poss to repair) and thought I might as well replace both. They were otherwise in good condition - but maybe 5 years old or so. I bought some Continental Grand Prix 4000 on the advice of an acquaintance. I went for 25mm - was previously 23mm (which I am sure has an effect as well as the change) .

It is like I have a new bike - I am so shocked - it has transformed the comfort and handling and general "feel" and I cant believe I went so long on the old tyres. I guess it is probably completely obvious to those in the know but I thought I might as well encourage anyone who is thinking they have plenty of life in their tyres to have a good think.

Not cheap mind....... But probably pound for pound by far the best cash I have spent possibly including my new/old (ebay) Ksyrium SL wheels a few years ago.

In reply to djellworth:

5 years? They must have been in tatters.

I've heard several things about 25mm being thought better than 23 - faster, cornery-er and comfortabler. I can understand the latter two, but I don't understand how they can be faster. Some physics magic, I suppose

In reply to djellworth:

Same with you car. Doesn't matter how much you can accelerate, how good your brakes are, if you've got rubbish tyres as they are the only bit that touch the road (seriously think about the way people skrimp and save on car tyres - and what it does to their and others safety some cheap tyres are terrifying in the wet)

In reply to nufkin:

There's certainly arguments that low pressure can be faster (lower rolling resistance) than high on not perfectly flat surfaces as it absorbs the imperfections in the surface. At a guess 25v23 allows lower pressure for same resistance

In reply to balmybaldwin:

>" There's certainly arguments that low pressure can be faster (lower rolling resistance) than high on not perfectly flat surfaces"

I certainly find this on my commuter bike riding on crap roads. With hard tyres you skip and bounce over bumps and struggle to put the power down. With softer ~80 psi 25 mm tyres you can power through everything, although I struggle on cattle grids.

In reply to djellworth:

Try some l latex tubes also..... mmmmmmmm

In reply to djellworth:

The wheel/tyre combination makes the biggest impact on how a bike handles.

The thing about wider tyres is partly due to the different profile a wider tyre makes when sat on the rim (more circular) and partly due to the shape of the contact point on the ground - shorter and wider - which is why they can be faster. The point about lower pressure seems counter-intuitive but if you went the other way you'd end up with a solid tyre! Obviously there's a point at which handling becomes affected by lower pressure so you need to find that balance between speed and handling which will also be affected by your weight and riding style.

In general the larger the volume of a tyre the lower the pressure - Boyle's Law - so a 25mm tyre can run at a slightly lower pressure than a 23mm tyre. I'd run a 23mm at about 100psi but a 25mm at 90psi for example. On my commuter which has 28mm tyres then between 75-85psi. My mountain bike has a 2.35" tyre on the front at 25psi and a 2.2" tyre on the back at 28psi but that's also partly due to them doing subtly different jobs.

In reply to djellworth:


I am in the same camp as you. Changed the rear cassette and chain last weekend and like you am now peddling a new bike. I also need new tires so I look forward to riding my new Ferrari next week when that job is done!

In reply to djellworth:

Conti tyres are the only logical choice for me, any of them are good, the 25mm Gatorskins are awesome as an all round tyre.

NOTE: They actually come up pretty big so some race geometry frames may be a little tight

In reply to djellworth:

I had the same shock when I put Conti GP4000s on my bike 3 1/2 years ago and am now on my second set of them. I have never had a puncture with them despite fishing quite a few glass shards out of them. Best cash I have spent on my bike too!