25 are faster than 23s - discuss
El Selb
Posts: 137
as suggested elsewhere on this board, is this true??
in the middle of a tyre change and would appreciate advice!
in the middle of a tyre change and would appreciate advice!
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Comments
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Depends how fast you're going. At some point the aero benefits of 23s will outweigh the rolling resistance benefit of 25s. No idea where the crossover is though.0
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My understanding was a narrower tyre will deform less, thus giving lower rolling resistance.
Am i wrong?0 -
At a given tyre pressure and all else even, wider tyres have lower rolling resistance (RR) than narrower, because the casing deforms less, and losses are concentrated in casing flexion.
However, narrower tyres can be inflated to higher pressure, and as inflation pressure is increased, RR drops.
However again, in real use, too high inflation pressure slows you down, because the tyre loses its ability to insulate the bike from road chatter, which is exhausting for the rider – and may actually impair progress because of the interruption of forward motion (I've never seen experimental evidence for this, though many claim it nonetheless. I'll wait for data).
In general, wider tyres tend to be more heavily constructed for durability, which may entirely negate these points. Most of this may be academic so far, with little consequence between similar tyres. Grip, however, is a real concern– and wider tyres at slightly lower pressure will maintain road contact on uneven surfaces dramatically better than narrow tyres inflated bullet-hard. That has significant real-world effect, hence why I choose 25mm tyres (I'd go wider if my frame would let me), which are grippier and more comfortable than narrower versions of the same.
Edit: here are some RR test graphs, to give you an idea of the margins at hand:
http://www.terrymorse.com/bike/imgs/rolres2.gif
http://www.terrymorse.com/bike/imgs/rolres.gif0 -
outcastjack wrote:My understanding was a narrower tyre will deform less, thus giving lower rolling resistance.
Am i wrong?
yep !constantly reavalueating the situation and altering the perceived parameters accordingly0 -
my friends at continental rekon 23`s are optimum . though personally being a heavier rider , i like to have more psi. so use a 20 on the front ,which also helps with the aero dynamicsconstantly reavalueating the situation and altering the perceived parameters accordingly0
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i personally dont like 23s at all, i find them way too harsh for my liking and absolute hell on poor roads. i used to use gatorskin 23s but for the last 2 yrs ive stuck with gatorskin 25s, which i find much more forgiving and they smoothen things out very nicely for me. it all boils down to personal preference.0
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I dont really notice much difference between 23 and 25 in terms of comfort and relative speed. With 25 i have to loosen my brakes (open them more than what the lever thingy can do) when changing a wheel so that can be a pain in the arse trying to get them aligned just as i like them again0
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thats quite interesting.
cheers for the links0 -
ddraver wrote:I was half thinking of putting a 23 on the back for lower RR and a 25 on the front for a bit of comfort when I next change tyres....done similar things on the MTB to good effect
On a road bike, most of the weight is on the rear - so a 23 up front (for aero) and a 25 rear (for compliance) would make more sense.
On a separate note, the optimum tyre for the individual may depend on their weight (8st vs 16 stone rider) combined with the quality of the roads they travel on.
...just my 4 penneth.Cycling weakly0 -
On a road bike, most of the weight is on the rear - so a 23 up front (for aero) and a 25 rear (for compliance) would make more sense.
I run that and it's great, I'm on Conti UltraSports. Was a bit of an accident as I was sent the wrong rear tyre and didn't notice until I'd fitted it.
Bought some used wheels for my tourer and they came with 23mm Vittorio Rubino tyres. Ride is dreadful, horribly harsh. Can't wait to get them off.http://www.strathspey.co.uk - Quality Binoculars at a Sensible Price.
Specialized Roubaix SL3 Expert 2012, Cannondale CAAD5,
Marin Mount Vision (1997), Edinburgh Country tourer, 3 cats!0 -
It's an old testers myth that narrow super-high pressure tyres are fastest (assuming they aren't TTing on a track). For most people a 25 does make more sense than a 23 as you get the comfort and no real drawback, for a tester then speed and wheels will come into as the aero benefit (especially if the tyre width smooths out airflow across the rim) is much more pronounced, even then though narrowest isn't always best (and certainly super high pressures aren't)0
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As far as speed is concerned, sidewall construction is the key.
A good 25 will be faster than a poor quality 23. But a good 23 will be faster than a good 25. How much faster is argueable, would the average rider notice the difference ?0 -
I can't tell the difference, I run 25's on my commuter, 23's on my "sunday best" and 21F 23R on my TT machine.0
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^ I'm still surprised that people still get this wrong, but if you took two tyres of the same construction, inflated to the same pressure e.g. a 23 and a 25, the 25 would be faster, grip better, be more comfortable and less likely to puncture. The impact on aerodynamics of the slightly wider tyre is beneficial e.g. the latest trend for aero wheels to go for wider rim shapes. The other factor that no-one's mentioned so far is tyre pressure and road surface - because whilst you can pump up the tyre harder, beyond about 7 bar it's pointless because you have no influence on the surface of the road. Most tyre data is from using a tyre on a smooth steel drum in a laboratory - hardly the same as a road.Make mine an Italian, with Campagnolo on the side..0
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I've used 19s and 23s and not really noticed a difference. I loved the 19s as they looked super skinny and very cool. Non cyclists would often comment that they were amazed that I didn't fall off all the time because they were so thin... I only switched to 23s because 19s are quite hard to get hold of...Do not write below this line. Office use only.0
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There's a bit in Fignons Autobiography "When we were young and carefree" about his team switching from 20c to 23c.
The better handling was so marked he reckoned that it won them a few races before everyone else started using 23c as well0 -
well some where the advantages of wider tyres must be out weighed by the disadvantages. Also, a common mistake in comparing things is :
20c and 23c are similar in performacne but 23c more comfortable so use 23c
then later:
23c and 25c are similar in performance but 25c more comfortable so use 25c
etc
soon we'll all be riding 2inch slick MTB style tyres on our road bike. But if you compared
23c and 2inch slicks you will probably notice the weight difference and areodynamics would be different.0 -
balthazar wrote:At a given tyre pressure and all else even, wider tyres have lower rolling resistance (RR) than narrower, because the casing deforms less, and losses are concentrated in casing flexion.
However, narrower tyres can be inflated to higher pressure, and as inflation pressure is increased, RR drops.
However again, in real use, too high inflation pressure slows you down, because the tyre loses its ability to insulate the bike from road chatter, which is exhausting for the rider – and may actually impair progress because of the interruption of forward motion (I've never seen experimental evidence for this, though many claim it nonetheless. I'll wait for data).
In general, wider tyres tend to be more heavily constructed for durability, which may entirely negate these points. Most of this may be academic so far, with little consequence between similar tyres. Grip, however, is a real concern– and wider tyres at slightly lower pressure will maintain road contact on uneven surfaces dramatically better than narrow tyres inflated bullet-hard. That has significant real-world effect, hence why I choose 25mm tyres (I'd go wider if my frame would let me), which are grippier and more comfortable than narrower versions of the same.
Edit: here are some RR test graphs, to give you an idea of the margins at hand:
http://www.terrymorse.com/bike/imgs/rolres2.gif
http://www.terrymorse.com/bike/imgs/rolres.gif
This seems like a pretty good explanation of the factors affecting tyre width choice...Do not write below this line. Office use only.0 -
kieranb wrote:well some where the advantages of wider tyres must be out weighed by the disadvantages. Also, a common mistake in comparing things is :
20c and 23c are similar in performacne but 23c more comfortable so use 23c
then later:
23c and 25c are similar in performance but 25c more comfortable so use 25c
etc
soon we'll all be riding 2inch slick MTB style tyres on our road bike. But if you compared
23c and 2inch slicks you will probably notice the weight difference and areodynamics would be different.
No.
1) Slick road tyres in fast compounds that are larger than 28c are very rare. Even in 25c there is much less choice of tyre.
2) Most racing frames struggle with anything over 28c. Recently I had GP4 Seasons 28mm (actually 26.5mm) on my Orbea. They were ok but there was no room for any more tyre. Also the normal drop brakes meant that the tyre had to be deflated to get it in and out
3) Racing wheels are the optimal width for fitting 20 to 25c tyres
It's not just a question of fitting some new rubber and trying it out. Going above 25c is difficult0 -
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vorsprung wrote:kieranb wrote:well some where the advantages of wider tyres must be out weighed by the disadvantages. Also, a common mistake in comparing things is :
20c and 23c are similar in performacne but 23c more comfortable so use 23c
then later:
23c and 25c are similar in performance but 25c more comfortable so use 25c
etc
soon we'll all be riding 2inch slick MTB style tyres on our road bike. But if you compared
23c and 2inch slicks you will probably notice the weight difference and areodynamics would be different.
No.
1) Slick road tyres in fast compounds that are larger than 28c are very rare. Even in 25c there is much less choice of tyre.
2) Most racing frames struggle with anything over 28c. Recently I had GP4 Seasons 28mm (actually 26.5mm) on my Orbea. They were ok but there was no room for any more tyre. Also the normal drop brakes meant that the tyre had to be deflated to get it in and out
3) Racing wheels are the optimal width for fitting 20 to 25c tyres
It's not just a question of fitting some new rubber and trying it out. Going above 25c is difficult
But that's just a question of availability and frame design, it doesn't explain whether 28c is better than 19c or whatever....Do not write below this line. Office use only.0 -
Look at what the pro's use on courses most similar to the conditions you ride in - that will be the fastest.0
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dawebbo wrote:Look at what the pro's use on courses most similar to the conditions you ride in - that will be the fastest.
Pros don't ride at under 30kph around the West Country so unfortunately aren't there to provide an example for me0 -
Headhuunter wrote:
But that's just a question of availability and frame design, it doesn't explain whether 28c is better than 19c or whatever....
kieranb was talking about a risky shift to larger and larger tyres
I was addressing this specific issue. It is unlikely that this would happen because of the other problems of using larger tyres
Other posters have discussed the plusses and minuses of various tyre size effects, quite comprehensively I feel0 -
@ kieranb;
I came from an mtb with 2" slicks to a road bike with 25mm Conti 4 seasons, and I'm sure the 25s are faster! Aero benefits probably don't apply to my stately pace, so it's likely down to weight / carcass flexibility
Beyond that I can't really comment cos I've never ridden 23s; I do know that if I inflate the 25s to the 100-110psi I frequently see people quoting for 23s, they are tooth-rattlingly hard and grip is poorer.
I suspect for me / my riding style / my bike / these crappy roads, that the optimum tyre size will be 25 or 28. If these 25s ever wear out I'll try 28s next.0 -
So if 25s or even 28s are better, where's the cut off point? As Kieran asked, should manufacturers be producing 2" slick, high thread count etc MTB tyres for your average road rider? Should frame producers be producing frames to take these?Do not write below this line. Office use only.0
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Headhuunter wrote:So if 25s or even 28s are better, where's the cut off point? As Kieran asked, should manufacturers be producing 2" slick, high thread count etc MTB tyres for your average road rider? Should frame producers be producing frames to take these?
Jan Heine seems to believe that bicycle design is basically wrong and that we should be riding 650c x 32c tyres. He has put his money where his mouth is and is running a business selling parts to do this. He is interested in long distance racing and touring.
See his blog here http://janheine.wordpress.com/
Frame producers are making frames that will take huge tyres, the 29er. These are basically overgrown MTB
But no one is suggesting that large tyres are fabulous for going fast on a road in the manner of a racing bike.
23c is a popular choice for a reason. For light people on short fast rides on good roads it seems to be ideal. If you are heavy/going further/on poor roads then a slightly wider tyre might be good.
23c is a compromise based on years of experience. If you look at old photos of bikes in races in the 1930s they often seem to have tyres of 28mm or 32mm or more. This was because they were on poor roads doing longer races.0 -
23mm for the pros,
25mm, 28mm for the rest of us.0 -
Right then, I have a pair of GT4000s on their way to me for about £65 in 23s. I spent so long thinking about brand/type I didnt even think about size....but I've since started thinking that 25s are the way to go as 1) a touch more comfortable, 2) a touch more puncture resistant & 3) potentially even a touch faster, perversely. So I've also got some gatorskins in 25s on route, £20 cheaper at £45.
Since I'm clearly a bit indecisive, and a bit of a novice - what would everyone put on if they had a trek 1.2 2009...
gatorskin 25s
or
gp4000 23s
?0
