tyre width question

[oldnick]

I'm looking at buying some Michelin Pro4 Endurance tyres to mount on Shimano Ultegra wheels on my alloy Giant TCR (one bike that has to do it all, mainly 2 hour training rides to support my mountain biking).

Question is what difference do people find in the real world between 23mm and 25mm width? I'm currently on the original 23mm Michelin Dynamic sport tyres, and wouldn't mind a little more insulation from the road surface.

Also do people alter the pressures for that 2mm? I currently run 95/105psi F/R.

Cheers, Nick

[coolboarder]

I ride Pro 4 Endurance in 23 mm and find them fine run at 95 psi (I weigh 65kg), Michelin already come up with a slightly bigger air-pocket than most other brands so they are ostensibly nearer 24. 25mm will give a bit more comfort but with a quality tyre like this the better carcase quality gives a good ride. I've always used 23 mm tyres as a compromise between 19 for reduced air resistance at speed and 25 for lower rolling resistance/comfort. I would stick to 23 personally.

[Mike the bike]

I am a simple soul who always struggled with physics and I find it counter-intuitive that a wider tyre could have a lower rolling resistance. But, faced with an avalanche of evidence, I have surrendered.

In the real world of lumpy and bumpy road surfaces, away from laboratory conditions, wider tyres can and do offer lower resistance than narrow varieties. So your 23 mm Michelin could make you pedal harder than the next size up.

At what size this advantage becomes minimal or disappears altogether I have no idea but my latest order for new tyres was for the 25mm version. I am running them at the same pressure as the 23s and they feel fine, but as the weather improves I may experiment a little. And, as cb says, I am enjoying the comfort advantage too.

[oldnick]

Thank you both .

Given that I am <ahem> a little heavier than the svelte CB and will never again get close to the time-trialling whippet that I was in my formative years, plus having bought the most bone-shaking bike known to man I'll try 25mm this time.

I might even go mad and do some back to back 'free-wheeling down a hill and seeing how far along the flat I get' testing, once the torn knee ligaments and calf muscles cheer up a bit

[nickdodo]

Interesting... I have signed up for a couple of rides with cobbles (Tour of Flanders and Paris Roubaix) and was advised that some 25mm would help. Any thoughts?

[Mike the bike]

Didn't I read somewhere that teams are gearing up to use massive 28mm tyres in the P - R? Makes sense to me but this approach could mean some radical re-designing of their bikes. I'll be interested to see if the idea becomes reality.

[nickdodo]

Didn't I read somewhere that teams are gearing up to use massive 28mm tyres in the P - R?
.

Not sure anything much bigger than 25mm would fit in my frame!

[Nobby Giles]

It's a little off the original topic, but how'd you find the Ultegra wheels? I've seen them receive good reviews and they look like a decent potential upgrade.

[oldnick]

Not got them yet but 2 separate roadie friends like them and they seem to get good reviews.

The big question though, grey or black? Which is faster?

[Nobby Giles]

Must be black, surely?