Tyres - 23mm v 25mm - interesting article

ajb72

http://janheine.wordpress.com/2012/06/1 ... -of-tires/

Interesting commentary (℅ Michael Barry on Twitter!) on the merits of different tyres / tyre width. Confirms the theory I seen expressed on here that 23mm isn't necessarily faster than 25mm etc.

Wily-Quixote

Interesting but it does not account for increased weight for the larger tyre... Although I presume this would only be 50g or thereabouts in most cases... I'm thinking of hills not the flat.

ajb72

Indeed this focuses on rolling resistance. However, unless you are doing a hill climb TT I guess you'll also be descending roughly about the same amount as you will climb, so the difference should even out?

Herbsman

Does a heavier tyre make you descend faster?

Monty Dog

For a race-weight tyre, difference between a 23 and 25mm is something like 20g - a swig from your water-bottle.

It's also not just rolling resistance, but heel a 25mm tyre over and it'll put a far bigger 'footprint' on the road and the rounder carcass makes handling far more predictable, particularly in the wet.

stickman

So all the people who have been suffering 18mm tyres have done it for no benefit!

yeachan153

I think 25mm's grip better as well because rubber touches the road; and also because it's run at lower pressures!

Monty Dog

18mm tyres was a 'fad' on the misconception that they were faster - you needed to pump them up rock hard to avoid pinch flats and the handling on anything but a straight line was truly awful. As said, a bigger carcass means you can run wider tyres at lower pressures which improves comfort and grip too for virtually no loss in performance.

springtide9

The only slight 'flaw' to the linked test is that they appeared to use the same bit of road.

I personally think it also depends on the road surface - thinner tires will roll better than wider tires on a smooth road, where was a thinner tire on a rough road seems to scrub off more speed than a wider tire.

I usually ride Conti GP 24mm but swapped over to Conti 23mm GP Attack / Force last summer; the Attack / Force were noticeably quicker on smoother roads - but the opposite on rougher roads.

Bordersroadie

Interesting subject. My two penneth worth from my "real world testing" and taking a poor road surface into account:

I have a rainy day bike, 11kg with 25c, summer bike 9kg, 23c.

I train on the same routes with each bike (hilly (100ft per mile), often poor roads, from 20 to 90 mile routes) and whilst theory says that the lighter bike should give significantly quicker times, this is not the case. I wonder if the tyre effect is at play here?

I guess a test would be to put 25c on the lighter bike, but this is not so easy as the OLN of the rear hub is 130 vs 126 so I can't just swap wheels.

rick_chasey

25mms are less aero.

Tom Dean

Rick Chasey wrote:

25mms are less aero.

Not necessarily - it depends what rims you are using.

notlongnow

When I got my bike it came with 25mm tyres but when I bought a spare wheelset they came with 23mm ones so I thought I give them a try and couldnt tell the difference,however after a month I thought id put my other wheels back on with the 25's and yes there is a difference much smoother ride and roll just as good imo.

asprilla

I've got 25mm tyres on 19mm rims on the commuter and 24mm tyres on 23mm rims on the weekender along with 23mm tyres on 19mm rims on my medium section carbon rims.

In real world usage there is very little difference in my pace with any of them. If anything the increased comfort and grip makes it easier to maintain smooth pedalling and quicker cornering.

HED, Zipp and Reynolds are all now using 23mm wide rims which gives a wider tyre profile which is apparently more aerodynamic as well as the other benefits.