Re: importance of tyre aero vs rolling resistance data [pyf] [ In reply to ]

Mar 20, 12 13:35

Post #26 of 106 (11121 views)

pyf wrote:

Chris,

Thanks a lot for sharing !
Don't know if you could do that but it would be awsome if you could make a graph with the curves of both the Pro Race 3 700x23 and Corsa CX 23 700x23 on the same wheel at the different angles. You would really be the first company to show this information on same wheel and I think even though it's only two tires that's exactly what everybody wants to see here !!!

Hopefully you can make this information available (and even add it on your website to show how important tire choice is), thanks in advance !!! ;-)

The information is certainly interesting but it can be misleading as well. You have to take into account that there are more things that contribute to tire selection than aerodynamic performance. Let me try to explain...

We chose the two tires you listed above because they are both good all around tires. For example, they have similar rolling resistances (fairly low actually), they both corner well, they are both pretty lightweight etc etc etc.

If we were to test additional tires then those tires may have rolling resistance values that counter any aero benefit you may gain, OR perhaps the tires lack grip in corners or in wet conditions. If a tire doesn't corner well and the rider on the bike knows that, they will be hesitant going into corners. In a race like a crit where you can have dozens of corners, holding back on every corner will cost you far more time than a 50gram aero benefit.

I guess the point I'm trying to make is that we don't want people to get overly hung up on having the "the most aero tire". As I said above... the tire may be super aero but if it isn't worth riding, who cares? I re-read this post and specifically this point and I hope I didn't come across as harsh. Tire selection is definitely an interesting topic and something we are going to spend more time investigating in the future. It's also something athletes should be interested in. When we do investigate additional tires we will be sure to use tires that are worth riding.

So my apologies if I was harsh... I was just trying to make the point that some people trip over the dollars trying to pick up the pennies.

All in all, the vittoria was up to 50 grams slower. You can basically just move the curves we have put together up 50 grams to give yourself a pretty good idea of where the vittoria tires would be.

I hope that makes sense. Please let me know if you have any additional questions.

Chris Thornham
Co-Founder And Previous Owner Of FLO Cycling

Re: importance of tyre aero vs rolling resistance data [Canadian] [ In reply to ]

Mar 20, 12 13:57

Post #27 of 106 (11107 views)

No worries Chris and really no need for apologies.
I understood the point you were trying to make but was actully going to answer exactly what you said in your second answer --> of course we are not talking about riding the tires with super high rolling resistance just because it's more aero, not talking about riding a tire that will drive us off road in the first corner (though Corsa CX 320 tpi which is a tire I love on dry roads does pretty much that on wet roads !!!). But what I was talking about was an aero comparison between tires with low rolling resistance, good grip and good puncture resistance.
On that topic Josh answer is of great help. We got to talk with Josh at Taipei show a few days ago (always good to see you Josh :-) !!!) and I told him I have Attack 22, GP4000S 23 and GP TT 23 that I keep switching on my 808, 404 and 303 firecrest and we got to talk about what tire is more aero VS which one has lower rolling resistance.

It seems out of the 3 (they all have good cornering grip so I don't take this into consideration here) :
GP TT : lightest, fastest RR, worse aero, less puncture resistance. So I thought GP TT would be my tire of choice for all important even but maybe it shouldn't be...oops.
GP4000S : heaviest, RR slower than TT / close to Attack, best aero, best puncture resistance.
GP Attach : middle weight, RR slower than TT / close to GP4000S, best aero at low angles (on Josh graph) but shifts earlier than GP4000S, good puncture resistance.

I also have Corsa CX TT 320 tpi, Bontrager R4, Schwalbe Ultremo ZX, Hutchinson Atom and some Michelin Pro 4 700x20... all interesting tires but I'm really into Conti + latex tubes these days.

Oh and just to be clear, this seems to matter more for clinchers than tubulars, since all tubulars are round except for Zipp Tangente as opposed to clinchers which all have different shapes (much more interesting aero wise ;-) ).

Re: importance of tyre aero vs rolling resistance data [pyf] [ In reply to ]

Mar 20, 12 14:53

Post #28 of 106 (11086 views)

Actually the Attack has a lower RR than 4000S IIRC. But I dont have the Tour Sept 2011 on hand...

Re: importance of tyre aero vs rolling resistance data [pyf] [ In reply to ]

Mar 20, 12 14:59

Post #29 of 106 (11077 views)

Impressive collections of clincers. Have you considered the SuperSonic in 20 mm? Low Crr and probably pretty good at low yaw because of the width. Don't know how it fares at higher yaw, though.

Pretty cool respsonse from Josh, by the way. Love the graph he posted.

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 20, 12 17:22

Post #30 of 106 (11048 views)

joshatzipp wrote:

Tire size generally changes the drag curve, a shift up or down is generally a change in tire size, a change in tire shape can dramatically change the drag curve.
Here's some tunnel data comparing a few different tires on the 303 FC carbon clincher (internally coded x45FC). you see that the GP4000 23 and 25mm are similar curve shapes, only shifted in magnitude, while the Attack despite being narrower has a different curve shape due to the different tire shape...the Michelin PR3 measures over 24mm wide despite the 23mm printed on the casing, but the shape of the tire has changed everything, especially when you consider that the GP4000 25mm is still 1mm wider.
I've thrown a V shaped wheel in for good measure, you see that tires can have nearly as much affect on aero as rim shape. Ultimately, the most aero tires are all pretty close together for a given width, maybe running 10-15 grams different between them, while the less aero tires can really spoil the party. The PR4 performs better than the PR3 here, so I'm not trying to call out Michelin, this is just a good example of the effect of tire choice. Also, the Michelin 20mm measures more like 22.3mm, and performs between the Conti 23 and 25 curves below, so I'm purely using this to illustrate a point.

Kraig Willet has a great piece about this on his site, he even has data comparing Tangentes, Bontrager wing tires, Veloflex and some others... I recommend it. he also talks about comparing rolling resistance between the tires and offsetting the data relative to the aero charts...good stuff. http://www.biketechreview.com
Josh

Cool stuff (as usual) Josh.

So...what do you think it is about the 4000S vs. the Attack that makes the difference above 12.5 deg of yaw? The side tread pattern?

I only ask because it seems as if the casing and treads are fairly similar between those 2.

Oh yeah, is it important to note that the chart above is for the 303FC, which as I understand it performs best with 23mm width tires? Those same tire widths on a 404FC or 808FC may not perform as well as a narrower tire choice right?

What do you think of the Supersonics, BTW? :-)

http://bikeblather.blogspot.com/

Re: importance of tyre aero vs rolling resistance data [Canadian] [ In reply to ]

Mar 20, 12 17:29

Post #31 of 106 (11043 views)

Canadian wrote:

If we were to test additional tires then those tires may have rolling resistance values that counter any aero benefit you may gain, OR perhaps the tires lack grip in corners or in wet conditions. If a tire doesn't corner well and the rider on the bike knows that, they will be hesitant going into corners. In a race like a crit where you can have dozens of corners, holding back on every corner will cost you far more time than a 50gram aero benefit.

Baah...tire width (i.e. NEED to be wider for handling) is over-rated IMHO, even for fast crits. For example, just a few weeks ago a rode a TT on a Sunday with a 20C Supersonic on the front Jet 90 and a 21C Specialized S-Works Mondo Open on the rear Jet 90 (both narrow rims). I had a crit to race the following Saturday, and being lazy I decided the only mod to the wheels was to remove the cover. I never felt that my tire choice held me back in the crit :-)

If one chooses wisely, it IS possible to get low Crr AND good handling properties in a narrow tire (or, at least what is considered now-a-days to be narrow...heck, it wasn't long ago that everyone raced RRs and crits on 18C and 19C tires!)

http://bikeblather.blogspot.com/

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 20, 12 19:28

Post #32 of 106 (11005 views)

joshatzipp wrote:

Tire size generally changes the drag curve, a shift up or down is generally a change in tire size, a change in tire shape can dramatically change the drag curve.
Here's some tunnel data comparing a few different tires on the 303 FC carbon clincher (internally coded x45FC). you see that the GP4000 23 and 25mm are similar curve shapes, only shifted in magnitude, while the Attack despite being narrower has a different curve shape due to the different tire shape...the Michelin PR3 measures over 24mm wide despite the 23mm printed on the casing, but the shape of the tire has changed everything, especially when you consider that the GP4000 25mm is still 1mm wider.
I've thrown a V shaped wheel in for good measure, you see that tires can have nearly as much affect on aero as rim shape. Ultimately, the most aero tires are all pretty close together for a given width, maybe running 10-15 grams different between them, while the less aero tires can really spoil the party. The PR4 performs better than the PR3 here, so I'm not trying to call out Michelin, this is just a good example of the effect of tire choice. Also, the Michelin 20mm measures more like 22.3mm, and performs between the Conti 23 and 25 curves below, so I'm purely using this to illustrate a point.

Kraig Willet has a great piece about this on his site, he even has data comparing Tangentes, Bontrager wing tires, Veloflex and some others... I recommend it. he also talks about comparing rolling resistance between the tires and offsetting the data relative to the aero charts...good stuff. http://www.biketechreview.com
Josh

Josh I have the 404FC and the 808FC sets. I run 4000S on the 404's for my road bike and use the 808FC for TT's and tri with a Bonty R4 aero up front. Can you give me an idea of how well the R4 aero performs on the FC shape? I also have a 21 Tangente and I have heard you say the the FC shape performs better with narrower tires so I'm curious whether I'm giving anything up with the current tire choice. Thanks for your input it's great to have someone like you chiming in.

Last edited by: valdlaw: Mar 20, 12 19:29

Re: importance of tyre aero vs rolling resistance data [Tom A.] [ In reply to ]

Mar 20, 12 19:35

Post #33 of 106 (10996 views)

Tom A. wrote:

Canadian wrote:

If we were to test additional tires then those tires may have rolling resistance values that counter any aero benefit you may gain, OR perhaps the tires lack grip in corners or in wet conditions. If a tire doesn't corner well and the rider on the bike knows that, they will be hesitant going into corners. In a race like a crit where you can have dozens of corners, holding back on every corner will cost you far more time than a 50gram aero benefit.

Baah...tire width (i.e. NEED to be wider for handling) is over-rated IMHO, even for fast crits. For example, just a few weeks ago a rode a TT on a Sunday with a 20C Supersonic on the front Jet 90 and a 21C Specialized S-Works Mondo Open on the rear Jet 90 (both narrow rims). I had a crit to race the following Saturday, and being lazy I decided the only mod to the wheels was to remove the cover. I never felt that my tire choice held me back in the crit :-)

If one chooses wisely, it IS possible to get low Crr AND good handling properties in a narrow tire (or, at least what is considered now-a-days to be narrow...heck, it wasn't long ago that everyone raced RRs and crits on 18C and 19C tires!)

Interesting tire choice Tom. I can still get my hand on the open tubular 21 but the 23 is gone. I know Al had roller data on the 23 but is there anything on e 21 that you know of? I think if the crr is similar the 21 would probably be faster than the 23 on the FC 808 which is still apparently relatively faster with a narrow tire. Thoughts? BTW are you pleased with what you've seen from the supersonic on the front? Do you think it would be a good choice for the FC as well or would you stick with the R4 Aero?

Last edited by: valdlaw: Mar 20, 12 19:37

Re: importance of tyre aero vs rolling resistance data [valdlaw] [ In reply to ]

Mar 20, 12 19:45

Post #34 of 106 (10985 views)

valdlaw wrote:

Tom A. wrote:

Canadian wrote:

If we were to test additional tires then those tires may have rolling resistance values that counter any aero benefit you may gain, OR perhaps the tires lack grip in corners or in wet conditions. If a tire doesn't corner well and the rider on the bike knows that, they will be hesitant going into corners. In a race like a crit where you can have dozens of corners, holding back on every corner will cost you far more time than a 50gram aero benefit.

Baah...tire width (i.e. NEED to be wider for handling) is over-rated IMHO, even for fast crits. For example, just a few weeks ago a rode a TT on a Sunday with a 20C Supersonic on the front Jet 90 and a 21C Specialized S-Works Mondo Open on the rear Jet 90 (both narrow rims). I had a crit to race the following Saturday, and being lazy I decided the only mod to the wheels was to remove the cover. I never felt that my tire choice held me back in the crit :-)

If one chooses wisely, it IS possible to get low Crr AND good handling properties in a narrow tire (or, at least what is considered now-a-days to be narrow...heck, it wasn't long ago that everyone raced RRs and crits on 18C and 19C tires!)

Interesting tire choice Tom. I can still get my hand on the open tubular 21 but the 23 is gone. I know Al had roller data on the 23 but is there anything on e 21 that you know of? I think if the crr is similar the 21 would probably be faster than the 23 on the FC 808 which is still apparently relatively faster with a narrow tire. Thoughts? BTW are you pleased with what you've seen from the supersonic on the front? Do you think it would be a good choice for the FC as well or would you stick with the R4 Aero?

I guess you missed this: http://forum.slowtwitch.com/...ring=roller;#3819430 ;-)

Due to the shape of the tread (i.e. Specialized's "dual radius" thing...the center of the tread is flattened out) I probably wouldn't run an S-Works Mondo Open on a front application.

The SS works nicely on front...both in TTs AND in crits ;-) I'd be interested to see how it tests out on an FC404 or FC808...

http://bikeblather.blogspot.com/

Re: importance of tyre aero vs rolling resistance data [Tom A.] [ In reply to ]

Mar 20, 12 19:55

Post #35 of 106 (10973 views)

Tom A. wrote:

valdlaw wrote:

Tom A. wrote:

Canadian wrote:

If we were to test additional tires then those tires may have rolling resistance values that counter any aero benefit you may gain, OR perhaps the tires lack grip in corners or in wet conditions. If a tire doesn't corner well and the rider on the bike knows that, they will be hesitant going into corners. In a race like a crit where you can have dozens of corners, holding back on every corner will cost you far more time than a 50gram aero benefit.

Baah...tire width (i.e. NEED to be wider for handling) is over-rated IMHO, even for fast crits. For example, just a few weeks ago a rode a TT on a Sunday with a 20C Supersonic on the front Jet 90 and a 21C Specialized S-Works Mondo Open on the rear Jet 90 (both narrow rims). I had a crit to race the following Saturday, and being lazy I decided the only mod to the wheels was to remove the cover. I never felt that my tire choice held me back in the crit :-)

If one chooses wisely, it IS possible to get low Crr AND good handling properties in a narrow tire (or, at least what is considered now-a-days to be narrow...heck, it wasn't long ago that everyone raced RRs and crits on 18C and 19C tires!)

Interesting tire choice Tom. I can still get my hand on the open tubular 21 but the 23 is gone. I know Al had roller data on the 23 but is there anything on e 21 that you know of? I think if the crr is similar the 21 would probably be faster than the 23 on the FC 808 which is still apparently relatively faster with a narrow tire. Thoughts? BTW are you pleased with what you've seen from the supersonic on the front? Do you think it would be a good choice for the FC as well or would you stick with the R4 Aero?

I guess you missed this: http://forum.slowtwitch.com/...ring=roller;#3819430 ;-)

Due to the shape of the tread (i.e. Specialized's "dual radius" thing...the center of the tread is flattened out) I probably wouldn't run an S-Works Mondo Open on a front application.

The SS works nicely on front...both in TTs AND in crits ;-) I'd be interested to see how it tests out on an FC404 or FC808...

Yes I missed that thanks Tom. If I used the 21 Mondo I was thinking perhaps as a rear tire because my experience has been that they are fairly robust. I'm also trying to decide between the SS and R4 Aero for the front. Maybe Josh could chime in with some "insider" data or educated speculation ;)

Re: importance of tyre aero vs rolling resistance data [pyf] [ In reply to ]

Mar 20, 12 20:13

Post #36 of 106 (10963 views)

Where did you get the info regarding the GP TT being worse aerowise?

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Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 20, 12 20:50

Post #37 of 106 (10940 views)

Josh does a 23mm tire that interfaces better with the rim make it so much more aero that it beats out having a 19mm tire that has less rolling resistance but is less aero? Sure the 23mm might perform better in a wind tunnel but how anout on the road?

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Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 1:34

Post #38 of 106 (10897 views)

Conti's from what I've heard also test the best on Hed wheels, clincher and tubs, and possible Envy wheels as well. This makes me think that the Conti casing shape suits the wider rim deigns better than the rest.

hoppersportsperformance.com

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 1:46

Post #39 of 106 (10892 views)

Josh: where on the biketech website do you find this info?
I cant seem to find it...

Re: importance of tyre aero vs rolling resistance data [Bmanners] [ In reply to ]

Mar 21, 12 4:28

Post #40 of 106 (10856 views)

Bmanners wrote:

Josh does a 23mm tire that interfaces better with the rim make it so much more aero that it beats out having a 19mm tire that has less rolling resistance but is less aero? Sure the 23mm might perform better in a wind tunnel but how anout on the road?

you have a zipp 303 and a 19mm tire that has better crr than 23mm options?

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Re: importance of tyre aero vs rolling resistance data [jackmott] [ In reply to ]

Mar 21, 12 4:40

Post #41 of 106 (10854 views)

Hypothetical question Jack.

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Re: importance of tyre aero vs rolling resistance data [Bmanners] [ In reply to ]

Mar 21, 12 4:50

Post #42 of 106 (10845 views)

Bmanners wrote:

Hypothetical question Jack.

then yes hypothetically there will be CRR differences large enough that a tire with worse aero will be faster than one with better aero =)

in practice though, generally, this will not be true, if comparing similar types of tires (ones mean to be kinda fast)

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Aeroweenie.com -Compendium of Aero Data and Knowledge
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Re: importance of tyre aero vs rolling resistance data [valdlaw] [ In reply to ]

Mar 21, 12 5:51

Post #43 of 106 (10816 views)

Holy crap, am I reading that chart right? The 23mm Pro Race 3 was over 100 grams worse than a 23mm GP4000 at 12+ degrees yaw? And it was better to have a non aero rim + GP4000 than to have Zipp 303 + PR3?

Wow.

Last edited by: matto: Mar 21, 12 5:52

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 6:07

Post #44 of 106 (10802 views)

interesting things about that chart:

No Tangente tires on there? Does it beat all of those?
Why is the PR3 so bad in your chart but so good on the Flo wheels test I wonder? Or perhaps the vittoria is even worse?

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 6:18

Post #45 of 106 (10790 views)

Josh, nice comments on Lennard Zinn's website about tradeoffs between rolling resistance and aerodynamic drag.

http://velonews.competitor.com/...s-roll-faster_209888

Re: importance of tyre aero vs rolling resistance data [jackmott] [ In reply to ]

Mar 21, 12 7:05

Post #46 of 106 (10751 views)

Since nobody ever believes manufacturers data showing their own product to be fastest, I didn't include the Tangente data (though I did push people to the Biketechreview site to get tangente data...). Ultimately, the Tangente is a near wash with the GP4000 in terms of aero, it beats other tires with aero 'features' on them, and in my opinion is a darn fine tire combining exceptional aero and road feel with good puncture protection and good Crr. Ultimately, all of this tire talk really comes down to the relative risk that the rider is willing to take on. The tires with the Best Crr, generally have no puncture belting and worse aero (thinner treads mean less shaping). while more aero tires will have slightly higher Crr, and adding puncture belting increases this further. For my math, a Tangente or GP4000 type tire is hard to beat for tri, good Crr (but not as good as tires without puncture belting), great aero (withouth sacrificing major Crr for better aero), and good handling/road feel. As with anything, there are options that may be better in one aspect or another, but making a good decision is about understanding the relative risks and benefits of the total package.

Lastly (and I'm working on getting a major magazine to independently test this), wear is an absolute killer when it comes to tire aero. We have created an amazing data set over the last 5 years using worn tires from our athletes (data that I won't even show you because you'll just accuse me of wanting to sell more tires) showing tire wear to be very detrimental to aero performance. Just look at the difference in drag resulting from tire shape, and then think about what happens to the tire as it wears...it is not good. this is so big that we instruct our pro athletes to only race key events on new or nearly new rubber...as a GP4000 with 500km becomes no better than the PR3 in that graph.

New rubber along with new chain, is some of the most effective race day money you can spend when looking for those last few watts.

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Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 7:11

Post #47 of 106 (10741 views)

joshatzipp wrote:

New rubber along with new chain, is some of the most effective race day money you can spend when looking for those last few watts.

Noted. Thanks for the contribution Josh!

One question. This discussion surrounds tires on the front wheel, right? How important is aero on a rear tire within a well fared rear such as any of the latest tri bikes?

"One Line Robert"

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 7:22

Post #48 of 106 (10731 views)

Josh, thanks for the info!!!

Regarding the Tangente, do you have any insight into choosing between the 21mm vs 23mm? Do the drag and Crr tradeoffs produce a clear winner? Or is it more of a wash, so you should pick based on road conditions?

Last edited by: matto: Mar 21, 12 7:22

Re: importance of tyre aero vs rolling resistance data [joshatzipp] [ In reply to ]

Mar 21, 12 7:24

Post #49 of 106 (10726 views)

Josh, I think you mean the 4000S and not the GP 4000. Those are 2 different tires.

You may wanna edit your reply because people who read your reply out of context (because they come from some search engine maybe) may mistakenly think you're talking about the GP 4000.

Re: importance of tyre aero vs rolling resistance data [matto] [ In reply to ]

Mar 21, 12 7:25

Post #50 of 106 (10725 views)

zipps website indicates 21 for the 404 and 808, 23 for the 303

matto wrote:

Josh, thanks for the info!!!

Regarding the Tangente, do you have any insight into choosing between the 21mm vs 23mm? Do the drag and Crr tradeoffs produce a clear winner? Or is it more of a wash, so you should pick based on road conditions?

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

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