Tubular Tires, Wheels and Aerodynamics

Everything about building wheels, glueing tubs, etc.
Mep
Posts: 491
Joined: Fri May 28, 2004 4:11 pm

by Mep

sungod wrote:
Mep wrote:
Fri Jan 11, 2019 9:32 pm
I've been running tubular tires for a long time and have come to terms with the fact that I will run into more rolling resistance with the benefit of lighter weight and ride quality.
why?

simply because it's become fashionable for people to parrot that clinchers have lower crr than tubs does not mean any given clincher has better (or worse) crr than any given tub

if you use the bicycle rolling resistance website data as a reference, the two lowest crr results are clinchers running tubeless, then it's a tub, if the clinchers were run with a normal inner tube i believe the tub would have lowest crr

data (for running tubeless) from brr site...

Vittoria Corsa Speed (open TLR) 7.7 W
Continental Grand Prix 5000 TL 8.3 W
Vittoria Corsa Speed (tubular) 9.1 W

note: these 'wattages' need understanding in the context of brr's methodology as explained on their site, safest is to regard them as relative values, not real world figures

looking deeper, the conti is 27mm wide and quoted loss is at 120psi, the tub is 23mm wise, same pressure

you might run a 23mm tub at 120psi, will you really run a 27mm clincher at that pressure? at 100psi the clincher loses 8.9w, at 80psi it's 9.9w, oh dear, and that's still without an inner tube, so which is 'faster' in the real world?

the brr methodology may or may not translate to equivalent results on the road, but taking the headline numbers to say x is 'better' than y clearly is unsafe

reality is that there are many variables and trying to test them all would be uneconomic - for instance do the results stand irrespective of rim width? road surface? temperature? pressure? rider weight? what about non-linear effects?

at road speeds, i'd think the crr losses have the potential to be dwarfed by aerodynamic impact of tyre/rim matching, especially on the front
I'm certainly not saying that all clinchers have lower crr than all tubulars period. In my case I usually run Veloflex Carbons (crr around 0.0049), which I have accepted as being worse than many top end clincher tires out there (e.g. GP4000s II). My point was that it's not actually all that much worse, and I can live with the drawbacks given the benefits.

The bigger question is whether I'm being penalized significantly more on the aerodynamics of the tire tread and tire/rim interface compared to running clinchers, which I think is the same question you're raising.

by Weenie


Hexsense
Posts: 864
Joined: Wed Dec 30, 2015 12:41 am

by Hexsense

sungod wrote:
Fri Jan 11, 2019 10:07 pm

if you use the bicycle rolling resistance website data as a reference, the two lowest crr results are clinchers running tubeless, then it's a tub, if the clinchers were run with a normal inner tube i believe the tub would have lowest crr

data (for running tubeless) from brr site...

Vittoria Corsa Speed (open TLR) 7.7 W
Continental Grand Prix 5000 TL 8.3 W
Vittoria Corsa Speed (tubular) 9.1 W
Corsa Speed open TLR design as tubeless.
Running it with tube is handicapping it.
Compare Vittoria Corsa G+ (non speed) between clincher version and tubular version is a more direct comparison.

RyanH wrote:
Sat Jan 12, 2019 1:39 am
Maybe I'm misinterpreting, but I think Hambini's test suggest that the rule of 105% might not be an actual rule.
I agree that it is just an observation from some Zipp/HED/Bontrager wheelsets. They were traditional U-shape. Widest far below brake track. Somehow, their brake track are roughly 5-7% narrower than max width of the rim too. Coincident or not, that actually imply same brake track width to tire width. Who knows if they make observation on a rim that is widest at the brake track itself, would there be a 100% rule rather than a 105? Or different rim shape doesn't follow the same aerodynamic implication at all? Who knows.

sungod
Posts: 1701
Joined: Fri Dec 24, 2010 9:37 pm

by sungod

Hexsense wrote:
Sat Jan 12, 2019 6:10 am
Corsa Speed open TLR design as tubeless.
Running it with tube is handicapping it.
so you agree with what i said
Hexsense wrote:
Sat Jan 12, 2019 6:10 am
Compare Vittoria Corsa G+ (non speed) between clincher version and tubular version is a more direct comparison.
you really are missing the point, which is that 'cinchers are faster than tubs', as widely stated without any qualification, is provably untrue

what counts is specific tyres under specific conditions, changing conditions will change performance and potentially swap which of any given pair is 'faster', and that's before factoring in aerodynamics

RyanH
Moderator
Posts: 2565
Joined: Tue Jan 17, 2012 4:01 pm
Location: Los Angeles, CA
Contact:

by RyanH

Ladies, this thread is not about tubular vs clincher, particularly with respect to rolling resistance. Take it elsewhere. Reread my OP.

User avatar
LouisN
Posts: 2676
Joined: Mon Feb 19, 2007 3:44 am
Location: Canada

by LouisN

RyanH wrote:
Thu Jan 10, 2019 8:14 pm
Hambini suggested elsewhere that if you're crafty enough, you can accomplish the same with silicone caulking.
I doubt this is UCI ;) ...

Louis :)

sungod
Posts: 1701
Joined: Fri Dec 24, 2010 9:37 pm

by sungod

RyanH wrote:
Sat Jan 12, 2019 2:20 pm
Ladies, this thread is not about tubular vs clincher, particularly with respect to rolling resistance. Take it elsewhere. Reread my OP.
that clearly wasn't the intent of my posting either

given the 'ladies' comment, probably best to give up on ww

RyanH
Moderator
Posts: 2565
Joined: Tue Jan 17, 2012 4:01 pm
Location: Los Angeles, CA
Contact:

by RyanH


sungod wrote: given the 'ladies' comment, probably best to give up on ww
I'm offended that you're offended. My understanding was that the PC forward thing to do was to use the female gender pronoun when addressing unknowns like using "her" or "she." Image

tonytourist
Posts: 1297
Joined: Sat Oct 10, 2009 7:13 am
Location: 93306

by tonytourist

That’s like clean39t getting triggered for us calling you Rianna! Lame.
I am reporting your offensive post! :shock:

Mep
Posts: 491
Joined: Fri May 28, 2004 4:11 pm

by Mep

RyanH wrote:
Sat Jan 12, 2019 1:39 am
@mep

Check the link I put in my OP. In part 2 they added the aero drag to the crr penalty to come up with a total system cost.

Unless Hambini suggests otherwise, it seems there is a concensus that tread pattern matters. Conti Gp4k seem to be the optimal tread pattern.

Thanks Ryan, I compared their 40km numbers in part 1 vs. part 2 and tried to infer whether aerodynamics or rolling resistance is more important for a tire. After messing around a little bit, below is what I'm seeing.

It jumps out that there is more potential for gains/losses from rolling resistance compared to aero (steepness of the red line), at least for the tires that they tested. 5 of the 6 top-ranking crr tires came up in the top 6 for the overall ranking. In contrast, only 2 of the 6 top-ranking cda tires came up in the top 6 for overall fastest tires, which suggests rolling resistance is more important than aero.

For the chart, instead of benchmarking against a super low crr or cda tire I have benchmarked against a very average tire in both areas i.e. Bontrager R4. Two tires jumped out: Zipp Tangente Speed 25mm and Specialized Turbo Cotton 24mm. Both tires have extremely good rolling resistance but extremely bad aerodynamics, which results in them landing somewhere middle of the pack.

I wish FLO had included the watts numbers from their aero drag tests, which would have made it easier for us to quantify how much difference aerodynamics really makes for tires. That said, unless I'm misinterpreting it appears that rolling resistance is more of a factor than aerodynamics. Thoughts? Is there more that can be gleaned from this study?


Image

RyanH
Moderator
Posts: 2565
Joined: Tue Jan 17, 2012 4:01 pm
Location: Los Angeles, CA
Contact:

by RyanH

Actually, they provided cda which is a lot more useful. Watts is a function of air density, speed and cda, which can vary a lot depending on where you are. Use this:

https://www.cyclingpowerlab.com/PowerSp ... arios.aspx

I think 0.27 to 0.28 cda is reasonable for an aggressive on the hoods faux aero position. Sub 0.26 cda and you're in TT position territory.

I need to check the Flo study again but did you see what psi they used? Everyone seems to use unrealistic pressures, which I guess I understand why but who rides at 140psi for a 25mm tire???

Mep
Posts: 491
Joined: Fri May 28, 2004 4:11 pm

by Mep

Ah good catch! I'll play around with that tool. FLO used 120psi for the crr test and 95psi for the aero test.

KarlC
Posts: 926
Joined: Fri Dec 05, 2014 2:08 am
Location: San Diego Ca USA

by KarlC

Mep wrote:
Sun Jan 13, 2019 2:49 am
RyanH wrote:
Sat Jan 12, 2019 1:39 am
@mep

Check the link I put in my OP. In part 2 they added the aero drag to the crr penalty to come up with a total system cost.

Unless Hambini suggests otherwise, it seems there is a concensus that tread pattern matters. Conti Gp4k seem to be the optimal tread pattern.

Thanks Ryan, I compared their 40km numbers in part 1 vs. part 2 and tried to infer whether aerodynamics or rolling resistance is more important for a tire. After messing around a little bit, below is what I'm seeing.

It jumps out that there is more potential for gains/losses from rolling resistance compared to aero (steepness of the red line), at least for the tires that they tested. 5 of the 6 top-ranking crr tires came up in the top 6 for the overall ranking. In contrast, only 2 of the 6 top-ranking cda tires came up in the top 6 for overall fastest tires, which suggests rolling resistance is more important than aero.

For the chart, instead of benchmarking against a super low crr or cda tire I have benchmarked against a very average tire in both areas i.e. Bontrager R4. Two tires jumped out: Zipp Tangente Speed 25mm and Specialized Turbo Cotton 24mm. Both tires have extremely good rolling resistance but extremely bad aerodynamics, which results in them landing somewhere middle of the pack.

I wish FLO had included the watts numbers from their aero drag tests, which would have made it easier for us to quantify how much difference aerodynamics really makes for tires. That said, unless I'm misinterpreting it appears that rolling resistance is more of a factor than aerodynamics. Thoughts? Is there more that can be gleaned from this study?


Image
Wish someone would do some more testing on the Zipp Tangente Speed 27mm tubulars, rolling resistance and aerodynamics

.

Jannekallio
Posts: 4
Joined: Tue Jan 15, 2019 2:44 am

by Jannekallio

Mep wrote:
Sun Jan 13, 2019 2:49 am
RyanH wrote:
Sat Jan 12, 2019 1:39 am
@mep

Check the link I put in my OP. In part 2 they added the aero drag to the crr penalty to come up with a total system cost.

Unless Hambini suggests otherwise, it seems there is a concensus that tread pattern matters. Conti Gp4k seem to be the optimal tread pattern.

Image
Where can i find the study related to this graph?
Are these tubular tires?

Jannekallio
Posts: 4
Joined: Tue Jan 15, 2019 2:44 am

by Jannekallio

This triggera the main question?

1. What is current consensus. Which is the fastest tubular to be used in front and back with wide aerowheels (ie. enve + zipp super9)?

The front is more about CDA and back more about CRR (if we expect that bike is modern aerobike that shields the rear wheel).

2. If the timetrial/triarhlon is longer distance, how this selection would change as you would like to have a better puncture protection?

Mep
Posts: 491
Joined: Fri May 28, 2004 4:11 pm

by Mep


Jannekallio wrote:This triggera the main question?

1. What is current consensus. Which is the fastest tubular to be used in front and back with wide aerowheels (ie. enve + zipp super9)?

The front is more about CDA and back more about CRR (if we expect that bike is modern aerobike that shields the rear wheel).

2. If the timetrial/triarhlon is longer distance, how this selection would change as you would like to have a better puncture protection?
Those wheels are clinchers not tubulars. You can see the actual study linked from the OP's first post.

There's not quite a consensus which is why we're having this discussion. Some folks are suggesting that the aerodynamics are important, but from what I'm seeing it's not that much. So when choosing a tire, I'd say prioritize rolling resistance first and avoid those with a completely smooth tread. The tread pattern helps the airflow stay attached.

Puncture protection is a more subjective question. Personally I wouldn't run something with poor puncture performance even if it was super fast, especially with tubulars.

by Weenie


Post Reply
  • Similar Topics
    Replies
    Views
    Last post