23mm 100psi faster on short climbs?

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silentC
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23mm 100psi faster on short climbs?

Postby silentC » Mon Nov 05, 2018 9:59 am

So the received wisdom these days is wider tyres at lower pressure. And indeed I currently run 25mm Continental GP4000S tyres at 90 psi on my main bike. However a couple of recent experiences have got me wondering about this.

A week ago I found a crack in my rim where a spoke head has pulled through. Because I don't have a spare wheel for the bike, I am currently riding my 1993 Giant Allegre. This bike runs 23mm Continental GP4000S, same tyre as the other bike but smaller. What I found was that I got up punchy little climbs a fair bit quicker than I do on the Merida. This seemed counter intuitive to me because not only am I running smaller tyres, but the bike is a couple of kg heavier, being steel. In fact a couple of the guys I ride with commented on how well I went up the climbs on it.

I realise there may be more going on here, but I have had three rides on it now and it definitely feels as though I am getting up the climbs faster. It all falls apart on longer climbs because the weight of the bike and lack of lower gears becomes more of a factor. But certainly for punchy short climbs it feels as though it is quicker.

One of the other guys was on 25mm for awhile but he has gone back to 23mm much for the same reason. He reckons he climbs better on the 23mm tyres. In that case you're talking about different tyres on the same bike. It is still anecdotal and hard to quantify, just wondering what other people have found?
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Re: 23mm 100psi faster on short climbs?

Postby Derny Driver » Mon Nov 05, 2018 11:11 am

For hillclimb championships, I used to replace my front 23mm wheel/tyre with a special light aluminium wheel with a 19mm tyre pumped to 120psi. I cant comment on the science of it but it worked for me.

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Re: 23mm 100psi faster on short climbs?

Postby redsonic » Mon Nov 05, 2018 11:43 am

I wonder if it has anything to do with a quicker movement from centre to side of the tyre? Punching up hills, you tend to rock the bike side to side, even if you are seated. A wider tyre would have a little more resistance to rolling over to its edge.

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Re: 23mm 100psi faster on short climbs?

Postby uart » Mon Nov 05, 2018 12:07 pm

silentC wrote:So the received wisdom these days is wider tyres at lower pressure.

It really depends on the surface. Narrow tyres at higher pressure are still very efficient if the surface is smooth enough. Depending on the surface, there is no reason why 23c @100psi couldn't be more efficient than 25c @90.

The difference is likely to be pretty small though, a couple of Watts or so at best.

By "punchy little climbs" I assume you mean short enough duration really to hit them and keep up speed with a good short burst of power. No idea of exactly what sort of power levels that is for you personally, but say for example a 430W burst with 82kg (bike plus rider). A 2kg increase in bike weight would set you back about 8.5W on a 6% climb. I honestly doubt that the differences in tyres you mention would account for this.

So I suspect other factors at play. How energetic you feel varies a bit from day to day. Quite minor differences in wind and air density, even when it's a light wind that's not really very apparent, these can have an effect of more than couple of Watts. Also your fit and positioning on the bike will effect the efficiency that you transfer to power to the pedals. You might be getting power to the pedals slightly more efficiently on the alternate bike.
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Re: 23mm 100psi faster on short climbs?

Postby g-boaf » Mon Nov 05, 2018 12:45 pm

What are these short climbs? 200m, 2000m 10,000m?

I think there are other factors at play, if the tyres are similar weight. What will give benefits is very light wheels. I have a set of extremely light carbon wheels, they are amazing up hill - but equally terrible for braking going downhill.

silentC wrote:One of the other guys was on 25mm for awhile but he has gone back to 23mm much for the same reason. He reckons he climbs better on the 23mm tyres. In that case you're talking about different tyres on the same bike. It is still anecdotal and hard to quantify, just wondering what other people have found?


I reckon the better gains would be achieved by training more to gain power and drop weight.

I don't ride much hills here in Australia, but I do go overseas and do some massive rides in the mountains and I go okay, so the 26mm tyres I run can't be too much of a problem. Hills are all about the right training.

The short hills might just be you having more momentum ahead of it.
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Re: 23mm 100psi faster on short climbs?

Postby NASHIE » Mon Nov 05, 2018 1:25 pm

uart wrote: Also your fit and positioning on the bike will effect the efficiency that you transfer to power to the pedals. You might be getting power to the pedals slightly more efficiently on the alternate bike.


More this i think. Currently riding a Vitus 979 Frame with modern running gear, 23 front 25 rear. It’s lighter than my Clamont SLX steel frame with exactly same running gear, but Clamont frame just climbs so much better. Over a big climb not much in it, but stiffer Clamont frame wins when on the gas.
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Re: 23mm 100psi faster on short climbs?

Postby silentC » Mon Nov 05, 2018 2:28 pm

Yeah short little climbs, like one in particular that is 8% for 350m and then 4% for another 650m (distance not elevation!). Hills you can sprint up in a big gear and then roll over. The surface is mostly course chip bitumen. Princes Highway.

It's a bit hard to be objective, I suppose I might have just been a bit fresher those last couple of rides, but I certainly didn't feel it. I got on those little climbs and just felt like I could go that bit harder than usual. I got dropped on the straight though :(

Maybe nothing in the tyres, I was just trying to work out how I felt better on the old bike even though it weighs a tonne :)

Another thing is the Giant is race geometry whereas the Merida is an 'endurance' frame.
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Re: 23mm 100psi faster on short climbs?

Postby Duck! » Mon Nov 05, 2018 9:15 pm

It could be the tyre construction and tread compound as much as anything. What the "wider, softer, faster" brigade often forget to mention is that it's only relevant when comparing tyres of the same or similar construction. Lightweight, supple racing tyres will roll and grip better than tough, heavy training or commuting tyres regardless of width, and often to the point of the narrow, high-pressure tyre will still be faster than the wider, tougher, lower-pressure tyre.
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Re: 23mm 100psi faster on short climbs?

Postby silentC » Tue Nov 06, 2018 9:16 am

In my case it's the same tyre, I run Conti GP4000S II on both bikes. But I see what you mean.

Anyway I didn't feel particularly fresh this morning and Strava agreed :(
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Re: 23mm 100psi faster on short climbs?

Postby macca33 » Tue Nov 06, 2018 10:35 am

I've ridden 23, 24 & 25mm tyres at varying times, with pressure reduced as the widths went upwards, respectively, and really have not found a great deal of difference b/w them all as far as speed, or Watts required to roll at speed, are concerned.

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Re: 23mm 100psi faster on short climbs?

Postby Jmuzz » Tue Nov 06, 2018 11:02 am

Do you have a powermeter? It's kind of impossible to judge your own effort accurately.
The tyre/rim differences will be single digit watts, which is just the smallest extra subconscious effort or tapering training a bit.

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Re: 23mm 100psi faster on short climbs?

Postby silentC » Tue Nov 06, 2018 11:23 am

Nah don't have one. Just going off how it felt in terms of where I'm sitting with the other guys and how I feel at the top. I'm pretty sure I go up short climbs better on it for whatever reason. Could be psychological. When I get the other bike back on the road I'll see if it is really noticeable.
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Re: 23mm 100psi faster on short climbs?

Postby rodneycc » Tue Nov 06, 2018 11:35 am

Yeah I'm with you on this one Silent. Narrower harder tyres on climbs. Even worst are 28c on the front at 80psi. Did this on a 40deg day up in the hills and it defeated me. Just seemed to sink into the tarmac and really wasn't rolling freely.

Not sure why the back doesn't bother me but the wider front tyre does??
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Re: 23mm 100psi faster on short climbs?

Postby madmacca » Wed Nov 07, 2018 3:24 pm

rodneycc wrote:Yeah I'm with you on this one Silent. Narrower harder tyres on climbs. Even worst are 28c on the front at 80psi. Did this on a 40deg day up in the hills and it defeated me. Just seemed to sink into the tarmac and really wasn't rolling freely.

Not sure why the back doesn't bother me but the wider front tyre does??


Ya know, I think it might just be the 40 deg day that defeated you, not the tyres. And depending on the mix, it might just be that you were sinking into the tarmac. :shock:

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Re: 23mm 100psi faster on short climbs?

Postby silentC » Wed Nov 07, 2018 3:58 pm

Yes this has been known to happen :)
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Re: 23mm 100psi faster on short climbs?

Postby rodneycc » Wed Nov 07, 2018 4:45 pm

madmacca wrote:
rodneycc wrote:Yeah I'm with you on this one Silent. Narrower harder tyres on climbs. Even worst are 28c on the front at 80psi. Did this on a 40deg day up in the hills and it defeated me. Just seemed to sink into the tarmac and really wasn't rolling freely.

Not sure why the back doesn't bother me but the wider front tyre does??


Ya know, I think it might just be the 40 deg day that defeated you, not the tyres. And depending on the mix, it might just be that you were sinking into the tarmac. :shock:


yeah I still keep to that story of the tyres rather than the engine :wink: The indignity of walking the bike up a hill should just never happen :-)
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Re: 23mm 100psi faster on short climbs?

Postby foo on patrol » Fri Nov 09, 2018 10:22 am

Still yet to find a wider tyre being betterer than a narrow one. :?

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Re: 23mm 100psi faster on short climbs?

Postby g-boaf » Fri Nov 09, 2018 10:56 am

foo on patrol wrote:Still yet to find a wider tyre being betterer than a narrow one. :?

Foo


I think I can find you some examples. I'm using 26mm tyres (the S-Works equivalent to 25mm) and they are vastly better than the narrower 23mm Continental tyres I used to use. Cornering grip is way better and they are so much nicer over bumpy roads, especially bumpy high speed descents. They also roll a lot better too.

Despite that, if the engine isn't working, no tyres are going to save you. Call me old fashioned.

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Re: 23mm 100psi faster on short climbs?

Postby rodneycc » Fri Nov 09, 2018 1:08 pm

g-boaf wrote:I think I can find you some examples. I'm using 26mm tyres (the S-Works equivalent to 25mm) and they are vastly better than the narrower 23mm Continental tyres I used to use. Cornering grip is way better and they are so much nicer over bumpy roads, especially bumpy high speed descents. They also roll a lot better too.

Despite that, if the engine isn't working, no tyres are going to save you. Call me old fashioned.


I remembered your post last time on these tyres so I had a closer look (well I didn't actually get my hands on one) at these Turbo's and got a bit confused with the Cotton ones vs the Non Cotton ones. The Non Cotton ones reviews weren't great so I chased some cotton Turbo's down on Bike Exchange (because I couldn't find them anywhere else - maybe I should of tried my LBS) but they wanted like $100 for one so I've gone F...Forget that... And just bought the Pirelli Velo's instead for a try (which really aren't much diff to the GP4000SII). Anyway will wait a few months for the GP5000 to test out.
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Re: 23mm 100psi faster on short climbs?

Postby foo on patrol » Fri Nov 09, 2018 3:34 pm

g-boaf wrote:
foo on patrol wrote:Still yet to find a wider tyre being betterer than a narrow one. :?

Foo


I think I can find you some examples. I'm using 26mm tyres (the S-Works equivalent to 25mm) and they are vastly better than the narrower 23mm Continental tyres I used to use. Cornering grip is way better and they are so much nicer over bumpy roads, especially bumpy high speed descents. They also roll a lot better too.

Despite that, if the engine isn't working, no tyres are going to save you. Call me old fashioned.


I'm using Robino Pro's and they corner better than GP4000s and were only $23 each. :wink: Never been a fan of wide tyres, even when I was in the State Squad for the Track as a young bloke. :P Train on heavy, race on light. :idea:

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Re: 23mm 100psi faster on short climbs?

Postby g-boaf » Fri Nov 09, 2018 8:17 pm

foo on patrol wrote:
g-boaf wrote:
foo on patrol wrote:Still yet to find a wider tyre being betterer than a narrow one. :?

Foo


I think I can find you some examples. I'm using 26mm tyres (the S-Works equivalent to 25mm) and they are vastly better than the narrower 23mm Continental tyres I used to use. Cornering grip is way better and they are so much nicer over bumpy roads, especially bumpy high speed descents. They also roll a lot better too.

Despite that, if the engine isn't working, no tyres are going to save you. Call me old fashioned.


I'm using Robino Pro's and they corner better than GP4000s and were only $23 each. :wink:



I used to like GP4000s, not any more. ;) When I'm going down a treacherous bumpy descent - I'll take the wider tyres. They don't slow me down any, and I ride fairly big hills. ;) I wouldn't go any wider though - unless I were going to ride on cobbled roads, which I might do next year, nothing set in concrete yet.

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Re: 23mm 100psi faster on short climbs?

Postby singlespeedscott » Sun Nov 11, 2018 6:49 am

I’ll never go back to narrow tyres. My 30mm tyres are in another realm of comfort and grip compared to the 23mm bone shakers that I used in the past. My fastest climb times have been on wider tyres and my descent speed is in another realm.

A good quality wide tyre does not roll any slower, or faster, than a narrower tyre on smooth surface. Factor in a coarse road surface though and the narrower is slower.
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Re: 23mm 100psi faster on short climbs?

Postby Alex Simmons/RST » Sun Nov 11, 2018 3:50 pm

Show me the data.

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Re: 23mm 100psi faster on short climbs?

Postby g-boaf » Sun Nov 11, 2018 8:13 pm

singlespeedscott wrote:I’ll never go back to narrow tyres. My 30mm tyres are in another realm of comfort and grip compared to the 23mm bone shakers that I used in the past. My fastest climb times have been on wider tyres and my descent speed is in another realm.

A good quality wide tyre does not roll any slower, or faster, than a narrower tyre on smooth surface. Factor in a coarse road surface though and the narrower is slower.


Might have to bring Foo over to France next year, I reckon Col de Sarenne would be fun on 23mm tyres, what do you think? That was one of the worst condition 'road' surfaces I've ever seen. There were some nasty waves across it at various points and also some massive holes, you dare not hit those - it'd be game over. Cool to ride along there though. :)

I did that climb from Barage du Chambon, 13km at 7.5% average, maximum around 13%, then heading down the very rough bit before getting to Alpe d'Huez - that's just crazy fun. Going the other way you climb the worst section and descend on the better surfaced but more technical bit.

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