23's or 25's

slowbike

thecycleclinic wrote:

I personally would ride tyres as wide as you can

Hmm ... I'm on 32mm slicks on the CX at the moment ... I could go wider - probably around 45mm ? Don't think I will though as it's blummin hard work on the 32mm and much prefer the 23mm GP4Seasons that are on there for the summer.

smidsy

Rolf F wrote:

No need for the sarcastic smiley.

Touchy today are we?

Rolf F wrote:

Do you seriously believe that rolling resistance has no impact on speed?

You know I am not saying that.
A tyre is a component and therefor has no inherant speed. Yes it is true that some tyres will assist the rider in maintaining their speed, but it is the rider that achieves speed, not the tyre.

The tyre may or may not help the rider, but it in no way generates or maintains speed, merley affects the riders ability to do so to a greater or lesser extent depending.

Anyway even I am bored now so that is the end of my contribution to this discussion.

chrisw12

Buckles wrote:

At racing speeds rolling resistance becomes insignificant compared to air resistance or gravity

Yeah I've got a mate who believes this, keeps riding his armadillos and keeps getting dropped when we free wheel going downhill.

Keep posting it though, the more people who believe it the better chance I'll have in races. 8)

rolf_f

smidsy wrote:

The tyre may or may not help the rider, but it in no way generates or maintains speed, merley affects the riders ability to do so to a greater or lesser extent depending.

Oh, I see - you were just being unnecessarily pedantic!

smidsy wrote:

Rolf F wrote:

No need for the sarcastic smiley.

Touchy today are we?

No, not really. It's just that that smiley is unhelpful. It antagonises people and usually shows the user of it in a rather poor light.

buckles

chrisw12 wrote:

Buckles wrote:

At racing speeds rolling resistance becomes insignificant compared to air resistance or gravity

Yeah I've got a mate who believes this, keeps riding his armadillos and keeps getting dropped when we free wheel going downhill.

Keep posting it though, the more people who believe it the better chance I'll have in races. 8)

Probably 'cause you're fatter than him, or he's less aero.

Seriously - how can you possibly know it's the tyres slowing him down?

chrisw12

^ Are you seriously suggesting that rolling resistance is insignificant?

buckles

chrisw12 wrote:

^ Are you seriously suggesting that rolling resistance is insignificant?

No, try again, I said

At racing speeds rolling resistance becomes insignificant compared to air resistance or gravity

Maybe a more accurate statement would have been "far, far less significant", I don't know.

It only takes a few watts to overcome a tyre's rolling resistance at 27mph. Try looking at how much power is required to overcome gravity when doing 27mph up a fairly steep hill, or on a flat road with double your frontal area (you may have to start eating more food to achieve this) and you'll understand what I mean.

bendertherobot

I think what often gets overlooked in the width debate is the bike they're fitted to. 23's are the domain of the racer and 32's the domain of the commuter. That's a generalisation but it's fairly true.

Those bikes will themselves be unequal. But then you add other stuff into the mix like wheels, weight, sitting position, mudguards and panniers and it all becomes rather insignificant to talk about rolling resistance.

What you really want is a tyre that's comfy and works for the job in hand. For the average sportive rider 25 or 28 are probably a good choice.

bigflangesmallsprocket

Tires all have their own properties, which could be accumulative marginal gains when combining what you find desirable. I'm very light, I find pumped up 23's to be a very hard ride and do notice the difference at 25c comfort-wise, but not speed-wise + or -, other than the extra comfort aids my ability to apply myself without distraction or loss of energy through vibration fatigue (orginal config on my early stiff OCR killed my legs after a just a 35 miler, compared to riding same distances on diff equipped steel s/s..accumulated marginal losses rather than gains!). When younger I had a hack bike with 28's fitted at one point, noticeably slower, noticeably more comfy.

I've found that appropriate pressure for your body-weight also makes a difference. I'm very light and don't need much pressure at all in my tires, personal experience finding about 85-90 max being the sweet-spot, I'm sure that would have some folks rolling around thinking they'd got a puncture! It doesn't sound much but Michelins recommended pressures puts me in the same ball-park. Just cos your tire can take 120 doesn't mean that you should.

Some makers tell fibs about their tyre sizes, or just round them up or down. You COULD switch from a nominal generous 23c to a different brand nominal skimpy 25 and find you've not actually changed, or (possibly) even gone down a little.

I don't think there's much of a weight jump from 23 to 25, but it'd more significant going up to 28, and I think there'd be less choice regarding finding folding versions, so a bit more weight penalty there too.

Then theres grip and compliance. A more grippy compound would give you more push compared to something a little harder. Some tires have better TPI factors so will also aid grip as well as comfort.

Even if you stick all that together, unless you're going from one extreme to the other you may not notice much difference. But if a tire feels better for you personally, that may be enough for you to put in a better ride, whatever.

ugo.santalucia

I had a good session at Richmond Park this morning... managed to drop a few people with my 32 mm touring tyres. It's bizarre how some 6'4" guys with big thighs have so little power...

maltloaf_df

I've always ridden 23's apart from a brief stint on 21's a few years ago. At the start of this winter I went for some 25's because of all this talk of them rolling better than 23 and they felt horrid to me. Wooly feeling and like I was riding through porridge. Went back to 23's within about 300 miles.