pros and cons of different tyre sizes?

nedmoran

I'm quite new to road cycling and have a giant defy 3. It came with 700 25c tyres and i was wondering what the pros and cons were between 25c and 23c. Also can i fit 23's to my wheels without any bother?

danlikesbikes

Should have no issue with either set on your wheels.

25's tend to be heavier due to the larger size, give better grip due to wider footprint in contact with the road, slower to get up to speed due to the increased weight/increased friction

23's basically the above in reverse

I know people are going to jump in and correct me but am assuming the tyres are like for like etc

ellj22

Some argue that friction is reduced with a 25mm as the contact patch is wider but shorter. I doubt anybody really notices a difference. A 25mm has a greater volume and therefore can be ran at a lower pressure with less risk of pinch flat, this offers more comfort and traction. 23mm will run better on narrower rims ~20mm or less as the tyre is less likely to roll and squirm whereas on the new style of wide rim 25mm may fit better. Some pro's have moved to wider tyres to suit wider wheels which supposedly are affected less in side winds whilst still remaining aero, in this case a narrower tyre creates an unwanted gap between tyre and rim so their tyre size has increased.

Bare in mind that differences are minimal as we are only talking about 2mm here and some brands 23mm tyres will measure up the same as anothers 25mm.

25mm will probably suit the 'comfort' character of the defy a bit better but the bike can probably take anywhere from an 18-27mm tyre with compromises.

Lycra-Byka

I have a defy 3 and changed to 23mm's after many miles. Personally, I found no difference.

cyclingfury

25mm tyres are not necessarily heavier than 23mm tyres. Michelin Pro Race 4 25mm and 23mm are both advertised as 200g.
Go figure!

Monty Dog

Weight difference is marginal for the same tyre model between 23 and 25mm, in the region of 10-20g.
There is no evidence to show a narrow tyre is faster - in fact the reverse for the same tyre construction. For the wider tyre rolling resistance is less and you'll likely suffer less from impact punctures because of the higher carcass volume. Aerodynamics are negligible. What I like about wider section tyres is the rounder profile means that handling on corners is far more progressive - on skinnier tyres you can feel a harsh transition as you heel over, and therefore more likely to loose grip.

nedmoran

Thanks for the replies all. I've been looking at getting a set of mitchelin pro4 service course tyres and would've liked them with red walls to add a bit of colour to my bike(it's all white with black), but can only find the 25c ones at a decent price in black.

Wirral_paul

Go for the black ones then - probably for the best as apparently the coloured tyres are generally slightly less grippy.

Maybe its just me but i dont like coloured tyres anyway - dont look right to me. Am i alone? :?:

bernithebiker

A tyre's rolling resistance is not so much the friction against the road but the constant deformation of the contact patch.

You are effectively squeezing the rubber of a new piece of tyre all the time. Thhis warms the tyre and is wasted energy.

A 23c has a smaller volume than a 21 so there is less deformation going on, and also you tend to run higher pressures in a thinner tyre ( but this means less comfort).

This is why eco cars like the green Golfs and Prius's use the thinnest tyres they can get away with.

Historically, thinner was always considered faster, but current thinking seems to be suggsting the opposite, not sure why......

hipshot

You could argue 23s are faster, but the difference is vanishingly small. The increase in comfort and cornering stability using 25s seems very real to me however - could be placebo admittedly.

bernithebiker

I use 21 up front and 23 back. I can see the argument for going to a 23 front for Alpine descents, but 25 seems like overkill to me.

But your weight and road surface are factors - if you're a bit heavier and surface is poor, then 25s may be useful.

Monty Dog

Historically, thinner was always considered faster, but current thinking seems to be suggsting the opposite, not sure why......

Energy losses are due to tyre deformation called hysteresis - you're correct that less deformation provides decreased rolling resistance. However, it's the wider tyre that deforms less as skinnier tyres have a longer, thinner contact patch.

http://www.schwalbetires.com/tech_info/ ... resistance

Comparison to car tyres is meaningless as their rolling resistance is about 20x higher and the contact pressure significantly less.

muzzan

Last night I swapped over the stock mavic yksion 23's tyres from my mavic krysiums for some conti 4 seasons 25's. Weighed them & diff was 20 g per tyre, & this is for a winter tyre v a summer tyre, so difference really is small. If there is a comfort gain to be had then I'm happy to sacrifice the 40g.

wavefront

There's a good article in the new issue of Cyclist magazine (may 2013 issue) that has quotes/interview with the product managers and development guys of Schwalbe and Continental. They both agree that that the 25 tyres are 'faster' than the 23's (25 conti gp4000s are apparently 7% faster than the 23's), but 25's are possibly heavier than 23's so you lose some of that gain through more effort to get up to speed (inertia etc). That said you may find one manufacturers 23's could still be heavier than another's 25's.

They sum up saying wider tyre is better, but there is a trade off, and they thing 24's are the best compromise!!!

I'm sticking with my gp4000s 25's!

bernithebiker

Monty Dog wrote:

Historically, thinner was always considered faster, but current thinking seems to be suggsting the opposite, not sure why......

Energy losses are due to tyre deformation called hysteresis - you're correct that less deformation provides decreased rolling resistance. However, it's the wider tyre that deforms less as skinnier tyres have a longer, thinner contact patch.

http://www.schwalbetires.com/tech_info/ ... resistance

Comparison to car tyres is meaningless as their rolling resistance is about 20x higher and the contact pressure significantly less.

Seems not everyone agrees with what Schwalbe says; Zipp for example says that wider tyres are more aerodynamic, in direct contradiction to Schwalbe. Also I'm not sure why a long thin contact patch is worse than a short, fat one?

cheaterkiller

This is actually quite pathetic.

wellbeloved747

quite simply the wider the slower but more grip, the thinner the faster and less grip.

Bordersroadie

cheaterkiller wrote:

This is actually quite pathetic.

cheaterkiller wrote:

No need to talk like a prick.

Yes, quite.

Bordersroadie

Back on topic. . .

For the same pressure a 23c contact patch is long and narrow and a 25c patch is short and wide (the area of the contact is the same in each case), so it is quite logical that on a similar surface the 25c has lower rolling resistance. Research quoted above verifies this.

On the rough roads round here the 25c is without any doubt the faster tyre and also definitely the more comfortable.

The other advantage of 25c (especially perhaps if you ride long distances) is that, because they can be run at lower pressure, they are far easier to get back to operating pressure in the event of a puncture, with a mini-pump.

pollys_bott

Bordersroadie wrote:

On the rough roads round here the 25c is without any doubt the faster tyre and also definitely the more comfortable.

The other advantage of 25c (especially perhaps if you ride long distances) is that, because they can be run at lower pressure, they are far easier to get back to operating pressure in the event of a puncture, with a mini-pump.

I'm curious about this as I do a lot of my riding on rural lanes which aren't in the best condition, so I've just put 25mm Rubino Pros on my winter trainer / commuter thinking that I can get a bit more of a comfortable ride. However - I see that the min pressure for both 23mm and 25mm Rubinos is 100psi, so how is there going to be a difference whether I'm running 23mm or 25mm? 100 psi is 100 psi isn't it? (I suspect not, but don't know why...!)

On a slightly different note, do people go below pressure recommendations and notice much difference in ride comfort / grip / visits from the pf? For example, would there be any benefit to riding the 25mm Rubinos at 80/90 psi? (Yes, I know there's a reason why a manufacturer states a recommended min pressure). Clearly at some point you reach a trade-off point between more comfort and risk of pinch-flats, I'm just curious as to whether anyone has played around with pressures and what the results were. I'm 70kg and looking for any and every little way of making my monthly metric ton that bit more comfortable

Monty Dog

The biggest advantage of wider, higher volume tyres is to run less pressure - taking the 'bounce' out the tyre smooths out the rough roads. I was riding 30mm tyres at 80psi on A23 rims at the weekend, it was incredibly comfortable and was still able to maintain speeds well in excess of 40kph when needed.

smoggysteve

bernithebiker wrote:

Monty Dog wrote:

Historically, thinner was always considered faster, but current thinking seems to be suggsting the opposite, not sure why......

Energy losses are due to tyre deformation called hysteresis - you're correct that less deformation provides decreased rolling resistance. However, it's the wider tyre that deforms less as skinnier tyres have a longer, thinner contact patch.

http://www.schwalbetires.com/tech_info/ ... resistance

Comparison to car tyres is meaningless as their rolling resistance is about 20x higher and the contact pressure significantly less.

Seems not everyone agrees with what Schwalbe says; Zipp for example says that wider tyres are more aerodynamic, in direct contradiction to Schwalbe. Also I'm not sure why a long thin contact patch is worse than a short, fat one?

Zipp make wheels - Schwalbe make tyres and tubes. Why would you listen to a wheel manufacturer over a tyre manufacturere when it comes to the dynamics of tyres. Think I would listen to the people who make and design the things over the guys who just stick them to their product.

sungod

bernithebiker wrote:

<...>Seems not everyone agrees with what Schwalbe says; Zipp for example says that wider tyres are more aerodynamic, in direct contradiction to Schwalbe. <...>

zipp is talking about this in the context of zipp's current rim profiles, much wider than traditional rims, they need to be used with the correct width tyre to get lowest drag, so at the system level zipp is correct

schwalbe would be correct for a skinny tyre on a traditional skinny rim vs. a fat tyre on a traditional skinny rim (but i'm sure zipp's wide tyre/rim system will have lower drag than either)

keef66

Pollys Bott wrote:

Bordersroadie wrote:

On the rough roads round here the 25c is without any doubt the faster tyre and also definitely the more comfortable.

The other advantage of 25c (especially perhaps if you ride long distances) is that, because they can be run at lower pressure, they are far easier to get back to operating pressure in the event of a puncture, with a mini-pump.

I'm curious about this as I do a lot of my riding on rural lanes which aren't in the best condition, so I've just put 25mm Rubino Pros on my winter trainer / commuter thinking that I can get a bit more of a comfortable ride. However - I see that the min pressure for both 23mm and 25mm Rubinos is 100psi, so how is there going to be a difference whether I'm running 23mm or 25mm? 100 psi is 100 psi isn't it? (I suspect not, but don't know why...!)

On a slightly different note, do people go below pressure recommendations and notice much difference in ride comfort / grip / visits from the pf? For example, would there be any benefit to riding the 25mm Rubinos at 80/90 psi? (Yes, I know there's a reason why a manufacturer states a recommended min pressure). Clearly at some point you reach a trade-off point between more comfort and risk of pinch-flats, I'm just curious as to whether anyone has played around with pressures and what the results were. I'm 70kg and looking for any and every little way of making my monthly metric ton that bit more comfortable

I never checked for a minimum inflation pressure on my 25mm GP 4 Seasons. Trial and error has led me to the conclusion that 70 psi front and 80 psi rear gives a comfortable ride and decent handling.

deswahriff

...I've always run my Michelin 25mms at 90 psi, I'm about 67kg and I think this is also close to the minimum pressure on the tyre....there's a chart on the USA website, can't seem to find it elsewhere, which charts the rider weight. pressure, tyre size thing:http://www.michelinbicycletire.com/michelinbicycle/index.cfm?event=airpressure.view

...you would think every manufacturer would do one, wouldn't you?

pollys_bott

Keef66 / deswahriff - thanks for your replies, I'm out for a ride tomorrow on the non-billiard table-esque roads of West Yorkshire so will drop the pressures down a bit and see how it goes.

On the Continental website they recommend 95 psi with a max of 110 for 25mm GP4s, but they don't openly state a minimum...

cheaterkiller

F1 car tyres are fat as fuckin hell. The cars go like hell too. If narrow tyres were faster then F1 cars would use em.

smoggysteve

cheaterkiller wrote:

F1 car tyres are fat as fuckin hell. The cars go like hell too. If narrow tyres were faster then F1 cars would use em.

Bit of a difference between 1 x human power and 700+ BHP. F1 cars have the benefit of downforce to add grip. what extra grip and speed can a human eek out of a few more extra mm of rubber?

thiscocks

cheaterkiller wrote:

F1 car tyres are fat as fuckin hell. The cars go like hell too. If narrow tyres were faster then F1 cars would use em.

There is a difference between rolling resistance and grip. F1 car designers dont give a toss about rolling resistance.