What is all this move from 23 to 25 tyres all about?

rolf_f

meanredspider wrote:

When I tested the whole width thing over a very consistent ride (it's a commute but forget all ideas of traffic, junctions, lights etc) I found 25C were 1mph average faster than 23C

Lol - you must really have wanted the 25s!

meanredspider

Rolf F wrote:

meanredspider wrote:

When I tested the whole width thing over a very consistent ride (it's a commute but forget all ideas of traffic, junctions, lights etc) I found 25C were 1mph average faster than 23C

Lol - you must really have wanted the 25s!

I just pedalled with one leg on the 23s

Miles253

littledove44 wrote:

Miles253 wrote:

Can anyone recommend any good 25's ? I've got Conti 23, so might stick with Conti, but are there any better?

I have done 3000 miles on my Cont GP 4000's 25mm. Not a single puncture. And they were highly rated in that test on the previous page. Stop dithering and buy some.

Having jinxed that I am off now to get a puncture.

Good advice! No punctures for you!

ai_1

One thing not mentioned so far that I can see is that a bigger tyre at lower pressure will have better grip. Grip is dependent on the contact area and a lower pressure means a bigger contact area.

ai_1

MattC59 wrote:

vespario wrote:

...the air density is lowered in latex tubes which creates a floating effect and actually lowers rolling resistance.

I'm not biting, I call shenanigans ! Nobody is that stupid !

+1 on shenanigans!
-1 on "Nobody is that stupid" - trust me they are.

g00se

Ai_1 wrote:

One thing not mentioned so far that I can see is that a bigger tyre at lower pressure will have better grip. Grip is dependent on the contact area and a lower pressure means a bigger contact area.

AS I understand it - if you go too low though (as well as risking snakebite puncture), there is a risk of the tyre rolling away when cornering (I don't mean rolling off of the wheel, but having the rims deflecting across the tyre sidewalls). This will make cornering squirmy. Wider profile rims will allow you to go lower before this happens.

ai_1

g00se wrote:

Ai_1 wrote:

One thing not mentioned so far that I can see is that a bigger tyre at lower pressure will have better grip. Grip is dependent on the contact area and a lower pressure means a bigger contact area.

AS I understand it - if you go too low though (as well as risking snakebite puncture), there is a risk of the tyre rolling away when cornering (I don't mean rolling off of the wheel, but having the rims deflecting across the tyre sidewalls). This will make cornering squirmy. Wider profile rims will allow you to go lower before this happens.

When I say lower pressure I mean dropping say 10% to 15% which will give a corresponding increase in the contact area.
So for example if you normally have your back tyre at 120psi with 23mm tyres you might drop to 105psi on 25mm tyres.
Reducing pressure significantly without changing the tyre size will of course increase the risk of pinch punctures but that's not the case if the tyre size is increased, that's the whole point. As for tyres coming off, I don't see that being a risk at what are perfectly normal tyre pressures.

I weight ~85kg, used to be a few kg more, and I routinely ride 25mm Continental 4 seasons with around 85-95psi at the front and 95-115psi at the back. I like the softer end of the range for long rides on bad roads and the harder end for better roads and when I plan to spend some time climbing out of the saddle or sprinting. The front does start to feel a bit mushy when sprinting or climbing out of the saddle if I drop the front tyre pressure towards 70psi which I have tried. It's not a problem as such, i just prefer it to feel more solid. I've never had a pinch puncture in 1.5 years of riding 25mm tyres.

sloppyschleckonds

Another thing to consider is that the 25mm tyres will weigh more than the 23mm.

marcusjb

SloppySchleckonds wrote:

Another thing to consider is that the 25mm tyres will weigh more than the 23mm.

20g extra for Conti 4000S II (23 to 25mm - 205g to 225g)

Not much for a big gain in comfort and possibly speed.

I ride on 28s and can't wait to get hold of 4000S II in 28mm.

ai_1

SloppySchleckonds wrote:

Another thing to consider is that the 25mm tyres will weigh more than the 23mm.

Yes and 20mm tyres will weigh less..... The difference is small and IMO not worth worrying about.

slowbike

Ai_1 wrote:

I've never had a pinch puncture in 1.5 years of riding 25mm tyres.

I've never had a pinch puncture running 23mm Conti brand tyres .... just means I haven't ridden over a sharp enough pothole with enough force to matter ...

drlodge

Slowbike wrote:

Ai_1 wrote:

I've never had a pinch puncture in 1.5 years of riding 25mm tyres.

I've never had a pinch puncture running 23mm Conti brand tyres .... just means I haven't ridden over a sharp enough pothole with enough force to matter ...

I've had pinch flats on both bikes, mix of 23 and 25, just unluckly to hit a pot hole or stone (or going too fast to see them! :shock: )

darkhairedlord

last pinch flat was more than thirty years ago on my old '79 raleigh gentleman.
I don't believe in the PUNCTURE FAIRIES!

ai_1

drlodge wrote:

Slowbike wrote:

Ai_1 wrote:

I've never had a pinch puncture in 1.5 years of riding 25mm tyres.

I've never had a pinch puncture running 23mm Conti brand tyres .... just means I haven't ridden over a sharp enough pothole with enough force to matter ...

I've had pinch flats on both bikes, mix of 23 and 25, just unluckly to hit a pot hole or stone (or going too fast to see them! :shock: )

The point being - consideration of pinch punctures is not a good reason to choose one tyre size over the other!

term1te

How does the trend towards slightly wider rims impact this? Claims of larger internal volume and contact area are made. If I ran a 23mm tyre on a wider rim, would I get the perceived benefits of a 25mm tyre without the extra 20g?Although, I guess the rim would weight more. Other than specific tubeless tyres, are we likely to see regular clinchers specifically designed for wider rims?

In the good old days I ran some 19mm tyres for extra speed. I don't remember them feelilng particulalry harsh, although with the standards 36 spoke wheels and lower spoke tensions a bit of hose pipe would have felt OK. I do remember them not being very good at going around corners though.

slowbike

Ai_1 wrote:

drlodge wrote:

Slowbike wrote:

Ai_1 wrote:

I've never had a pinch puncture in 1.5 years of riding 25mm tyres.

I've never had a pinch puncture running 23mm Conti brand tyres .... just means I haven't ridden over a sharp enough pothole with enough force to matter ...

I've had pinch flats on both bikes, mix of 23 and 25, just unluckly to hit a pot hole or stone (or going too fast to see them! :shock: )

The point being - consideration of pinch punctures is not a good reason to choose one tyre size over the other!

sounds reasonable ....

that and drlodge needs to look where he's going!

darkhairedlord

the wider tyres and rims are just to get us used to the form factor before the next big thing. My moneys on radials riding on 720c rims, cycling is always at least 30 years behind everything else.

drlodge

Slowbike wrote:

that and drlodge needs to look where he's going!

Hey, I'm getting older but fitter so my eye sight can't keep up with my increasing speed!

slowbike

drlodge wrote:

Slowbike wrote:

that and drlodge needs to look where he's going!

Hey, I'm getting older and fatter so my eye sight can't keep up with my increasing downhill speed!

FTFY

ai_1

Term1te wrote:

How does the trend towards slightly wider rims impact this? Claims of larger internal volume and contact area are made. If I ran a 23mm tyre on a wider rim, would I get the perceived benefits of a 25mm tyre without the extra 20g?Although, I guess the rim would weight more. Other than specific tubeless tyres, are we likely to see regular clinchers specifically designed for wider rims?

In the good old days I ran some 19mm tyres for extra speed. I don't remember them feelilng particulalry harsh, although with the standards 36 spoke wheels and lower spoke tensions a bit of hose pipe would have felt OK. I do remember them not being very good at going around corners though.

You'd have to have a look at the dimensions of the different tyre and rim options and see how it works out in terms of total enclosed cross section. Without seeing REAL dimensions I don't know how a wider rim and "23mm" tyre would compare to a typical rim and "25mm" tyre in terms of volume. I also wouldn't take anything the marketing people have to say at face value and to some extent professional reviewers are now part of that marketing group :?
As you say, you really need to consider the rim/tyre combo both in terms of both tube volume, tyre shape and combined tyre/rim weight.

As far as wider rims giving bigger contact area is concerned - that's simply misinformation unless there's also discussion of tyre pressure. Contact area is a function of pressure. For a very supple tyre, i would assume the pressure applied to the ground will be fairly constant across the contact patch. In that case the area of the contact patch at rest is simply = Mg/P
where Mg = weight (Mass x gravitational acceleration) and P = pressure.
For accelerating, braking or cornering the Mg term gets a little more complex but the area is still a function of load on the wheel and tyre pressure. The dimensions of the tyre don't come into it. The shape of the contact patch may be effected but the area should not.

Monty Dog

On a related topic, got involved in some silly commuter racing on the way back from work - this guy passes me on his shiny new Giant road bike - head down, legs pumping furiously but the flappy, fluoro nylon jacket was a bit of a nodders give-away. I quickly got in his draft and in my top gear was easily able to hold 20mph+ on the flat - after half a mile I got on the front as he was flagging and he was soon well behind - the moral of the story is that it's not the tyres, but the engine as my tyres are 3 inches wide and inflated to a whopping 10psi!

Moonbiker

Why were you riding that monster tyre bike?

Just to piss people off when you pass then? :twisted:

Monty Dog

Moonbiker wrote:

Why were you riding that monster tyre bike?

Just to wee-wee people off when you pass then? :twisted:

My most direct commute takes me offroad across the Aldershot ranges and I have to ride a short piece of road to reach them - inevitably I have to share this short stretch of tarmac with other bikes. Hard to sneak-up on riders with tyres that sound like buzz-saws! Tyres weigh a kilo each so do take a bit of effort to wind-up to speed but once there, the really roll.

mpatts

I bumped into a chap yesterday at stockport station with a new Scott roadbike shod in 25's. I chatted to him about them - he said he's been riding them for years "I even rode on them in the 2000 olympics".

cycleclinic

Conti have been doing 28mm 4 seasons for a decade. wide tyres are nothing new touring cyclist and audax riders have used them for years it just that the roadie crowd have realised that the these much maligned cyclists knew something they didn't all along.

marcusjb

thecycleclinic wrote:

Conti have been doing 28mm 4 seasons for a decade. wide tyres are nothing new touring cyclist and audax riders have used them for years it just that the roadie crowd have realised that the these much maligned cyclists knew something they didn't all along.

Quite!

I feel very ahead of the curve.

Most long distance cyclists run fat tyres - they are fast and comfortable. It becomes hard to ride 200+ miles for several days in a row if you've been beaten up by skinny tyres on day one.

I am very much looking forward to a really fast fat tyre shipping (4000S II in 28mm). I like 4 Seasons, but in summer a bit of extra speed never goes amiss.

I think it is all good and will hopefully lead to more bikes with larger clearances.

The roads are not going to get better, so bigger really is better

t4tomo

Monty Dog wrote:

On a related topic, got involved in some silly commuter racing on the way back from work - this guy passes me on his shiny new Giant road bike - head down, legs pumping furiously but the flappy, fluoro nylon jacket was a bit of a nodders give-away. I quickly got in his draft and in my top gear was easily able to hold 20mph+ on the flat - after half a mile I got on the front as he was flagging and he was soon well behind - the moral of the story is that it's not the tyres, but the engine as my tyres are 3 inches wide and inflated to a whopping 10psi!

Ouch my eyes my eyes.

MODs can you put a warning on threads if things like this are going to be posted.
PS what the heck is it?

cycleclinic

There is even wider than the GP4000s in 28mm the Challange strada at 30mm (never tried them but I want to and the Grand Bios Extra Leger at 32mm and it is very light too - again never tried them but I'd like too. Supple casings in these should let them roll with low resistance.

samsbike

thecycleclinic wrote:

There is even wider than the GP4000s in 28mm the Challange strada at 30mm (never tried them but I want to and the Grand Bios Extra Leger at 32mm and it is very light too - again never tried them but I'd like too. Supple casings in these should let them roll with low resistance.

The problem becomes that unless you then go to cyclocross bikes, these dont fit other road/ audax bikes. Most audax type bikes seem to go to 28 with mudguards (and I really like mudguards), so unless manufacturers take notice, you are going to have to change the bike.

Also with bikes like the Trek Domane - do you really need/ want wider tires? (genuine question btw)

bikes`n`guns

I rode 25`s on my Domane up until I went tubeless and dropped back to 23`s.
The 25mm were super comfy on the road, and I reckon even quicker than what I had been using. The whole feel was brilliant.
I like the tubless and they run great on the road, not convinced they feel as good as the tubed 25`s though