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BennyG

tyre choice for Port Mac Ironman Australia

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Hi guys

First time in years I am racing on clinchers instead of tubbies at Port Mac and I am interested to see which tyres (brand and widths) you'll be using up there and Why?

I was looking to jump on some S works turbo cotton 24's but they seem rarer than hens teeth at the moment.

Looking forward to hearing your thoughts!

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Preface: I'm a BOPer and carry spares as I don't want my day ruined by a flat.

 

I run Conti 4 Season. Not the lightest, but pretty tough for puncture protection. Good in all weather (obviously).

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I have been using cont grand prix tt on recommendation from the LBS, they roll really nice and have had no puncture issues. They are slicks no tread. Handling seems no different to the GP4000 but maybe roll a little better, I cant really tell but I know i like em.

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Hi guys

First time in years I am racing on clinchers instead of tubbies at Port Mac and I am interested to see which tyres (brand and widths) you'll be using up there and Why?

I was looking to jump on some S works turbo cotton 24's but they seem rarer than hens teeth at the moment.

Looking forward to hearing your thoughts!

 

Turbo Cotton are absolutly the fastest clincher out there. The normal S-Works 24c is a fairly good tyre too. I would *highly* recommend using a latex tube that allows you to run sealant for either of those.

 

25c clinchers are where it's at otherwise. 25c turns out to be a sweet spot for rolling resistance and comfort - you dont quite need to go as high a pressure, the added volume makes the tyre ride better, testing is showing 25c is a few watts less rolling resistance.

 

I use a few different tyre brands, but everything other than the S-Works Turbos are 25c. With the wider rim wheels I have, I am trying out Turbo 26c. I alos have Bontrager R4 25c which is a very nice tyre that I'm trying.

 

Basically, I think you need to try a few tyres out to really get something you like, some people will recommend certain brands, I dont. But absolutly go 25c for a clincher - that's the way pro teams are going.

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Basically, I think you need to try a few tyres out to really get something you like, some people will recommend certain brands, I dont. But absolutly go 25c for a clincher - that's the way pro teams are going.

 

But don't do what I did: order some new 25c Conti GP 4000s, fit them on your wheels, pump them up, and then discover that your rear wheel won't turn because there's not enough clearance from the frame on your TT bike!

Oops.

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Yes, a 25mm wide tyre is not only wider when pumped up, it is also taller. I found this out recently when my Cervelo S5 with a new 25mm front tyre caught on the down tube and stopped completely while I was walking it in the garage. Had to change it back to a 23.

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Lots of good data online but seems overly focused on crr rather than also the aero affects.

 

Anyone got a good study looking at both, which is obviously the real world impact rather than roller crr tests

Edited by Esoteric

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Lots of good data online but seems overly focused on crr rather than also the aero affects.

 

Anyone got a good study looking at both, which is obviously the real world impact rather than roller crr tests

 

I cant quote the study I saw immediatly but 25c *combined* with a wider rim is what you are after for best aero. The tyre by itself is a marginal improvement at best. The newer range of 23mm rims go hand in hand with 25c and present a smoother air path so that the air stays attached to the tyre / rim and flows smoothly - A 19mm rim with a wider tyre may give you an air flow that breaks away from the tyre / rim and becomes turbulent.

 

Now while 25c does roll better and wiht the right rim presents a better air flow profile, the other advantage is that - especially with a wider rim - present to the road like a tubular and thence handle better.

 

Given of course as pointed out, as long as your bike allows for wider wheels and tyres. 25c by itself is enough of a benefit to justify going to, with a wider rim you are legit talking about some tyres like the S-Works Cotton being as good or better than tubbies.

 

(For the record, my present go to tyre for day to day is a Specialized Turbo Pro 25c. I find them a really nice and reliable tyre that works with my wider rims and is great to ride on. They are def not the best 25c out there but they are a good tyre)

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Yes, a 25mm wide tyre is not only wider when pumped up, it is also taller. I found this out recently when my Cervelo S5 with a new 25mm front tyre caught on the down tube and stopped completely while I was walking it in the garage. Had to change it back to a 23.

 

Atrap for young players LOL

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I have typically used 23c vittoria corsa cx with vittoria laxtex tubes on my race wheels and conti GP4000s 23c for everyday use. Having now moved to Port and riding a good section of the course a few times a week. I have found that 25c GP4000s with laxtex gives the nicest ride at around 95 psi (I weigh around 72kg).

 

Just as important is that you need to really concentrate on riding in the wheel tracks of the cars on the long straight out to Lake Cathie and out past Bonny Hills. These tracks are starting to get very worn which may for a much smoother and faster ride.

 

I also run my tyres with sealant as an extra strategy net.

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As said above if you have the newer wider rim style Eg firecrest then 25c are the bees knees in aero , ride and speed

If you want a good fast and very reliable go the conti GP 4000s , 25c seem to be getting harder to find

 

If you like changing punctures then go a vittoria (espually on ports roads )

 

For what it's worth I rode a set of zipp firecrest 303s with gp4000s to a 4-51hr ride at IM frankston a couple of weeks back at under 200watts avg

So they must roll ok

 

Good luck with your choice

Cheers

Ivp

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For what it's worth I rode a set of zipp firecrest 303s with gp4000s to a 4-51hr ride at IM frankston a couple of weeks back at under 200watts avg

So they must roll ok

That's fantastic Ivp - nice to see a great time without monster power numbers.

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From what the data shows over on Slowtwits, Conti Gp4000s with a latex inner seems to be the best choice. Some chose to run a sealant of somesort which adds weight but gives you that extra peace of mind.

 

FWIW, i run gp4000s in Wagga and at Bathurst on pretty bad chipseal and only 1 puncture in 4 years. Obviously i change tyres when they wear out but they're a solid choice

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I managed to find a set of Turbo Cottons today (I feel like I found a unicorn!) and I'm installing /racing on them Monday. I *very* interested to see if the facts match the hype.

 

Previous race setup - S-Works Turbo 24c, ChallengeIT latex tubes, sealant, 105psi.

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As said above if you have the newer wider rim style Eg firecrest then 25c are the bees knees in aero , ride and speed

If you want a good fast and very reliable go the conti GP 4000s , 25c seem to be getting harder to find

 

If you like changing punctures then go a vittoria (espually on ports roads )

 

For what it's worth I rode a set of zipp firecrest 303s with gp4000s to a 4-51hr ride at IM frankston a couple of weeks back at under 200watts avg

So they must roll ok

 

Good luck with your choice

Cheers

Ivp

Ip just wondering how you decided to run that setup when a lot of the guys around you would have been runnung a disk or at least a 90mm rear?

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rbr

that's my bike a built for UM and it came with the 303s

 

I was gunna run my disk?404 tub as its built for IM franga but I went to put it on and it was too much mucking around with he older thinner disk/404 adjusting the aero brakes on my tmr 01 (aero road bike set up as a complete TT rig)

 

as I only really did the IM as training run for UM and didn't expect to do any good I wasn't that worried about it

 

as it worked out my possie on the tmr is super aero and the whole set up seems to work ok with each other

 

cheers

IVP

Edited by ironpo

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Ok cool, yes I figured you must be very aero with the low power figure and great ride time. Don't suppose you have a picture of your position?

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I am yet to choose between GP4000II's in 23mm and GP All Seasons in 25mm.

 

Just how rough are these roads? That will likely be the deciding factor.

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Ok cool, yes I figured you must be very aero with the low power figure and great ride time. Don't suppose you have a picture of your position?

Nope sorry

PM me your mob number and I'll text you something

It doesn't look that radical or much diff to what I've done in the past bit it does ss em to work pretty good

 

The biggest thing is that I can ride pretty much the whole time with my head down and out of the wind , you can do this very easierly at Im franga due to the amazing road

 

Plus I draft all the time LOL

 

Cheers

Ivp

Edited by ironpo

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I am yet to choose between GP4000II's in 23mm and GP All Seasons in 25mm.

 

Just how rough are these roads? That will likely be the deciding factor.

The 4000s are up to the task

Cheers

Ivp

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Just out of interest here is some data regarding tyre width and aero performance (first graph) and performance of the Specialised Cotton 24c vs Conti 4000S (second graph).

 

Graph 1 - Zipp wind tunnel testing of a Firecrest 303 with different width tyres.

 

Zipp%20Tyre%20Width_zpscsmvhjci.jpg

 

 

Graph 2 - total of rolling resistance + aero drag for Specalised SWorks 24c cotton tyre vs Continental 4000S 23c @ 40km/hr

 

This info is from - http://bikeblather.blogspot.com.au/2014/07/theres-new-sheriff-in-town.html

 

It looks like the lower rolling resistance of the Spec cotton tyre (4 watts at zero yaw) trumps the aero advantage of the 4000S up to 10 degree yaw

Spec%20Cotton_zps8yo12hbs.jpg

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Just out of interest here is some data regarding tyre width and aero performance (first graph) and performance of the Specialised Cotton 24c vs Conti 4000S (second graph).

 

Graph 1 - Zipp wind tunnel testing of a Firecrest 303 with different width tyres.

 

Zipp%20Tyre%20Width_zpscsmvhjci.jpg

 

 

Graph 2 - total of rolling resistance + aero drag for Specalised SWorks 24c cotton tyre vs Continental 4000S 23c @ 40km/hr

 

This info is from - http://bikeblather.blogspot.com.au/2014/07/theres-new-sheriff-in-town.html

 

It looks like the lower rolling resistance of the Spec cotton tyre (4 watts at zero yaw) trumps the aero advantage of the 4000S up to 10 degree yaw

Spec%20Cotton_zps8yo12hbs.jpg

What about 25c GP 4000s

These seem to be the go now?

Cheers

Ivp

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What about 25c GP 4000s

These seem to be the go now?

Cheers

Ivp

Now that's a good question.

I reckon there are too many variables and not enough data publicly available to answer it. But I'm going to have a go :)

 

From the Zipp windtunnel tests 23c vs 25c (GP4000S)

 

0 yaw = 23c is 1 watt better

5 yaw = 23c is 1 watt better

10 yaw = 23c is 1.5 watts better

12.5 yaw = 23c is 2.8 watts better

15 yaw = 23c is 7 watts better

 

From Tour Magazine tests on rolling resistance

http://www.conti-tyres.co.uk/conticycle/road_tyres/GP4000sII/WideRaceTyreTest_TOUR_Magazine_2014.pdf

 

23c vs 25c = 25c is 1.4 watts better

 

So all up (combining rolling resistance and aero drag) there is probably not much difference at low yaw angles if you look at the tyre and wheel in isolation. Goodness knows about the interaction with the bike frame.

 

I guess if the net of aero and rolling resistance is neutral (except at high yaw angles) then the comfort of the 25c might win the day for the GP4000s 25c vs 23c

 

But on data alone the Spec cotton tyre looks the best.

Edited by Bill D B

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Now that's a good question.

I reckon there are too many variables and not enough data publicly available to answer it. But I'm going to have a go :)

 

From the Zipp windtunnel tests 23c vs 25c (GP4000S)

 

0 yaw = 23c is 1 watt better

5 yaw = 23c is 1 watt better

10 yaw = 23c is 1.5 watts better

12.5 yaw = 23c is 2.8 watts better

15 yaw = 23c is 7 watts better

 

From Tour Magazine tests on rolling resistance

http://www.conti-tyres.co.uk/conticycle/road_tyres/GP4000sII/WideRaceTyreTest_TOUR_Magazine_2014.pdf

 

23c vs 25c = 25c is 1.4 watts better

 

So all up (combining rolling resistance and aero drag) there is probably not much difference at low yaw angles if you look at the tyre and wheel in isolation. Goodness knows about the interaction with the bike frame.

 

I guess if the net of aero and rolling resistance is neutral (except at high yaw angles) then the comfort of the 25c might win the day for the GP4000s 25c vs 23c

 

But on data alone the Spec cotton tyre looks the best.

Geeez bill you know your stuff

Thanks for posting

Cheers

Ivp

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After the initial race on Turbo Cottons, I can only join in the praise. Awesome tyres!

I hate saying things without numbers to back it up but the gut feel is that Cottons really are a genuine alternative to the fastest tubulars. Highly impressed.

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After the initial race on Turbo Cottons, I can only join in the praise. Awesome tyres!

I hate saying things without numbers to back it up but the gut feel is that Cottons really are a genuine alternative to the fastest tubulars. Highly impressed.

That's good

But how are they for puncture resistance ?

 

No good being .234765142 of a watt faster if you spend 10 mins on the side of the road fixing a flat in the first 10 k and then at 112k

Cheers

Ivp

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That's good

But how are they for puncture resistance ?

 

No good being .234765142 of a watt faster if you spend 10 mins on the side of the road fixing a flat in the first 10 k and then at 112k

Cheers

Ivp

 

About the same as other S-Works tyres, it has the same puncture protection as normal compund S-Works Turbos.

 

I'm setting them up with latex tubes and 60ml of Cafe Latex sealant, there should be very little that will force a tube change stop.

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