Tubs vs clinchers: Clinchers are faster..

[BroDeal]

Baldedash, a tire doesn't make one hurt vs one who has a different tire. It's not that dramatic. Marketeers want you to think so but it just isn't. If it were nobody would ever buy a 'worse' tire. Nobody would buy a Zaffiro or a Conti UntraSport.

Marketing has nothing to do with it. At recreational speeds, say 25 to 35 km/hr, rolling resistance is a significant percentage of the overall resistance that has to be overcome. While a pro may ride at a speed where rolling resistance is less than 10% of the total, recreational riders are confronted with a number that can exceed 30%. Rolling resistance differences between tires can be a huge factor at recreational speeds. The difference between tires can amount to a 10%+ difference in power required to maintain speed at 30 km/hr. So with good tires someone may be cruising at 100 Watts while his buddy on medium slow tires riding beside him has to put out 110 Watts to maintain the same speed. For a pro who has a ceiling of 400 Watts this may not mean much, but to a Cat 6 who struggles to maintain 150 Watts, that 10 Watts is a signifcant step up the suffering curve.

 

[JayKosta]

...
recreational riders are confronted with a number that can exceed 30%. Rolling resistance differences between tires can be a huge factor at recreational speeds.
...

=========================================
Where does that '30%' number come from? Is it your estimate or from some actual testing?
Also, what part of the 30% is just 'tire rolling resistance'?

My 'belief' has always been that air resistance is 90% (or more), even at recreational speeds.

Jay Kosta
Endwell NY USA

 

[BroDeal]

=========================================
Where does that '30%' number come from? Is it your estimate or from some actual testing?
Also, what part of the 30% is just 'tire rolling resistance'?

My 'belief' has always been that air resistance is 90% (or more), even at recreational speeds.

The formulae for this are well known. They present a simplified model using constants that are calculated from test data. The article in the OP shows a range of 30 - 50 W at 35 kph. Given the power required to hold 35 kph, those numbers are large, especially the 53 W (or whatever it is in the PDF; I don't care to open it again).

At 20 mph air resistance accounts for roughly 80% of the total on flat ground with no wind. At 25mph the percent goes to nearly 90. This assumes the rider is a typical weight for a competitive cyclist, like 65 kg. A heavier rider will result in a lower percentage due to air resistance. Drive train losses are small. I don't care to calculate it at the moment but I am pretty sure that a heavy rider riding at 15 mph with crappy tires can have a rolling resistance that accounts for 30% of the total.

This notion that 10 or 20 Watts is insignificant is ridiculous. All it takes is for someone to ride with a power meter and see for themselves how much effort it takes to increase a tempo effort by 20 W. A lot of recreational riders probably cruise at 100 - 150 Watts.

This Slowtwitch article I just found covers some of this. http://www.slowtwitch.com/Tech/The_Physics_of_Moving_a_Bike_163.html

 

[Alex Simmons/RST]

But minimizing wheel/tire weight is important for races with lots of climbing (where aero drag is less of a factor) or for races where there is lots of deceleration and acceleration.

Yes, aero influence reduces as gradient steepens, however aero still trumps weight on all but the steepest of climbs. Where possible, attain both. It's not an either/or scenario, but the better options are not cheap.

Accelerations are still a very minor issue (again it's 2 orders of magnitude smaller in terms of energy cost). And even though it's a very small influence, don't forget that something with more inertia also does not slow down as fast, meaning one can ease off the pedal pressure slightly earlier before corners etc.

But if you want some numbers to demonstrate, if you accelerate from zero to 50km/h in 10 seconds, and you added 200g to the rim of a bike wheel, the extra wattage required to accelerate is <0.4% of the total power demand.

Now if you are racing a very tight hot dog circuit, then this is what you'll experience. But most changes in speed while racing are not nearly so dramatic as 50km/h, nor last as long as 10 seconds.

Finally, BTR has a nice item on this issue, see here:
http://biketechreview.com/reviews/wheels/63-wheel-performance

While it's about wheels, it is pertinent because your questions/assertions were about the impact of the additional mass of a tyre (overall mass + rotational mass).

 

[Alex Simmons/RST]

=========================================
Where does that '30%' number come from? Is it your estimate or from some actual testing?
Also, what part of the 30% is just 'tire rolling resistance'?

My 'belief' has always been that air resistance is 90% (or more), even at recreational speeds.

Jay Kosta
Endwell NY USA

The relative proportion of the power demand from the various resistance forces varies somewhat depending on several factors (e.g a rider's CdA) but yes, as speed drops, the relative proportion of rolling resistance increases.

For a typical club rider say at bike + body mass of 85kg, a CdA of 0.33m^2, and a Crr of ~ 0.005, then on flat windless road, the relative proportion of energy demand from air, rolling and other resistance forces at various speeds is as follows:

Speed (km/h) - Power (W) - Air% : Crr% : Other%
20 - ~ 60W - 57% : 39% : 4%
30 - ~150W - 75% : 22% : 3%
40 - ~320W - 83% : 14% : 3%
50 - ~590W - 89% : 9% : 2%


As things like Crr and CdA vary, then the relative proportions do change, but notby an awful lot.

As for the earlier comments about relative importance of a 20W difference - that's worth ~ 2 seconds per km in speed terms.

So in a 40km TT, we are talking ~80 seconds difference.

Crr matters at all speeds.

 

[Bustedknuckle]

I beg to differ. I think we've all had that experience where you're 60 miles out on a seriously fast, no mercy group ride and half way up some monster climb you start losing contact, and you know it has nothing to do with your inability to say no to a third slice of pumpkin pie or those rides you missed due to your late-night research into the most recent developments in small-batch bourbons--it's all because you chose the wrong tires. Damn rolling resistance!

tee hee

reality, what a concept.

 

[ElChingon]

I get a chuckle out of all the people who post numbers (not necessarily you) and debate rolling resistance, drag, contact surface area to no end then have a out of true wheel that rubs the brake pads or the hub(s) is so dry or loose that its all for nothing. We won't go into the chain that sticks to anything that it touches or a BB that sounds like a sand grinder.

Anyway, I still ride the Conti 4K's just because I liked them, starting when I tried them a few years ago and I didn't have any of those numbers on hand when I bought the tires, my main attraction to them was their new kevlar belt to prevent flats and some marketing BS, so I tried them after cutting the Nth Vittoria and thinking this just sucks. Whether it was luck or a bad tire who knows but I still dumped the Vittoria's for Conti 4K's and no numbers or time were ever wasted on my decision. They still ride well and so the tire rotates...

Yea, I've also tried other brands along the way and didn't like them as well for some reason or another but again I have no idea if they were theoretically better.

 

[simo1733]

He sure did. When I pointed that out a number of months ago on another tubs v clinchers thread here the response from one poster was "yeah, one guy" you can't win against that - I still remember folks saying it's only one guy when Lemond used the clip on aero bars in the 89 Tour. Fignon sitting weeping begged to differ ...

Tony Martin now rides Specialized TT clinchers.Even faster than the Conti's apparently.Based on the numbers we are hearing,Wiggins and Cancellara literally have no chance.
So much for SKy's marginal gains.They don't have a tyre sponsor and so can use any rubber they want.For some reason they mostly use Veloflex tubulars instead of Specialized clinchers.

 

[BroDeal]

Tony Martin now rides Specialized TT clinchers.Even faster than the Conti's apparently.Based on the numbers we are hearing,Wiggins and Cancellara literally have no chance.
So much for SKy's marginal gains.They don't have a tyre sponsor and so can use any rubber they want.For some reason they mostly use Veloflex tubulars instead of Specialized clinchers.

You have to wonder whether these guys are using production versions of the tires.

 

[oncehadhair]

But minimizing wheel/tire weight is important for races with lots of climbing (where aero drag is less of a factor) or for races where there is lots of deceleration and acceleration.

Overall weight of the bike (and rider) is what is important in acceleration and climbing, not just wheel weight. The lower inertia of light rims and tyres is irrelevant when the acceleration of the bike is limited by the overall mass (and therefore inertia) of bike and rider.

Common misconception tho'.

 

[Bustedknuckle]

Overall weight of the bike (and rider) is what is important in acceleration and climbing, not just wheel weight. The lower inertia of light rims and tyres is irrelevant when the acceleration of the bike is limited by the overall mass (and therefore inertia) of bike and rider.

Common misconception tho'.

Well said and very true.

 

[avanti]

Overall weight of the bike (and rider) is what is important in acceleration and climbing, not just wheel weight. The lower inertia of light rims and tyres is irrelevant when the acceleration of the bike is limited by the overall mass (and therefore inertia) of bike and rider.

Common misconception tho'.

I agree with you that total weight including wheel weight is key. Over a speed of 20 mph aero drag is important and increases with the square of velocity with tire/rim profile also being important.

 

[oncehadhair]

I agree with you that total weight including wheel weight is key. Over a speed of 20 mph aero drag is important and increases with the square of velocity with tire/rim profile also being important.

My post was more in response to riders who fit light rims because they "spin up faster", totally unaware that the factor limiting their acceleration is overall mass.

Your comment about wind is correct. That's why i find it amazing that i am turning myself inside out to average anything more than 35 ks and the pros can average 50 - where the air drag is huge and mass becomes of minor significance.

 

[Flux Capacity]

It really surprises me that the GP4000S tested so well, because they don't feel too quick to me, and on the Bike Tech Review test they tested no faster than the Pro Race 2 and 3. I read another (perhaps crude) on-the-bike test done by another magazine (I think it was Road Bike Action), where the GP4000S tested slower than a Pro Race 3. In fact, I'm surprised that they were equal to the Pro Race 2 and 3 on the Bike Tech Review test, because, to me, they don't feel much faster than Gator Skins.

In my opinion, the GP4000S is just a 'decent' training tire, so that's what I use them for. However, I sometimes will leave one on the rear for races, because I ride to the local crits, and I like their puncture protection; and I sometimes can't be bothered changing both tyres. I usually race on Vittoria Open Corsa CX or KS.

Is there a chance the German magazine is biased toward the German tire company?

While I'm at it: why the hell did Michelin stop making Pro Race 2s?!?!? I loved them. I reckon, for the price, they felt and handled great, and had decent wear and puncture protection.

 

[durianrider]

Ive been killing the local Strava KOM's lately on Pro Race 3, Conti 4000s and Vittoria CX Evo's.

Conti's 'feel' the fastest.

 

[ElChingon]

Good to know its not the bananas

 

[laziali]

?... The mfg's adoration thing was pointed more at the OP than you. I know you laziali, we go way back, kind of.

Tubulars rule on race day, no if, ands, or buts.

Hey Beppe, I just saw who you are - my fellow Colnago aficionado. why the change of name? I always thought the Roger for Roubaix handle was one of the coolest on here.

I don't race anymore (well except on Strava), but agree that tubs on race day was definitely the rule back in the day. I can't comment from personal experience now, although I do find the Tony Martin thing interesting given pro time trial rigs are tweaked and tested to the nth degree.

 

[Giuseppe Magnetico]

Hey Beppe, I just saw who you are - my fellow Colnago aficionado. why the change of name? I always thought the Roger for Roubaix handle was one of the coolest on here.

Well, I retired the user RDV4ROUBAIX for 2 reasons. First and most importantly I DO NOT LIKE TOM BOONEN, and I don't think he's worthy of sitting equal with RDV in the record books for Roubaix. Secondly, RDV4ROUBAIX was a mod here, realized I was spending waaaay to much time babysitting absolutely reprehensible personalities and cleaning up spam. Not my cup 'o tea.

I don't race anymore (well except on Strava), but agree that tubs on race day was definitely the rule back in the day. I can't comment from personal experience now, although I do find the Tony Martin thing interesting given pro time trial rigs are tweaked and tested to the nth degree.

Still are. When more than 50% of the teams in the PT show up to race with something other than tubulars, only then can you use phrases like "back in the day", or "old school". The Tony Martin TT clincher tire choice will have about the same effect on the rest of the Peloton as when Guesdon won Roubaix on clinchers, which is almost nil. Until then, it's still more than 90% still on those old, outdated tubulars.

All the sheeple here that are caught up in the numbers are exactly what the manufactures want. You drop extensive amounts of loot on race gear, even non-racers because they believe that their hero won with it must have been the gear. 10% lighter, 20% stiffer, 30% more aero is 100% marketing fluff designed to take money out of your wallet. Take a hard look at these tests, reviews, and so called "independent research" and what you'll find is that most of them are funded by the very manufactures that somehow magically come out on top. Just about every single manufacturer in the bike industry is guilty of padding their numbers, some even fabricating lab results from thin air. I fully agree that Conti makes some of the finest tires available, but they're not going to propel you to victory in a race, or win a Strava$$hole segmet over a Vittoria, Challenge, Michelin, or Veloflex user. Sorry, if you think tires are winning races you might want to ask the UCI to add a manufacturers competition to bike racing as in motorsports.

 

[Alex Simmons/RST]

Sorry, if you think tires are winning races you might want to ask the UCI to add a manufacturers competition to bike racing as in motorsports.

At my National championships last year, I was one step higher on the podium of the TT by 1/100th of a second. If my competitor had a better tyre, he'd have comfortably had that place by at least 20 seconds.

As for being sheeple here that are caught up in the numbers perhaps that's true, but the numbers I check are my from my own testing, and the testing of people who have no vested interest and have sound, rigorous testing process and analysis.

I consider "what the pros use" as a pretty poor way to evaluate equipment suitable for (i) me and (ii) best performance. They use what they are given, they are after all, rolling billboards.

 

[simo1733]

At my National championships last year, I was one step higher on the podium of the TT by 1/100th of a second. If my competitor had a better tyre, he'd have comfortably had that place by at least 20 seconds.

As for being sheeple here that are caught up in the numbers perhaps that's true, but the numbers I check are my from my own testing, and the testing of people who have no vested interest and have sound, rigorous testing process and analysis.

I consider "what the pros use" as a pretty poor way to evaluate equipment suitable for (i) me and (ii) best performance. They use what they are given, they are after all, rolling billboards.

What is the best TT tyre/tubular from your own testing?

 

[BroDeal]

Still are. When more than 50% of the teams in the PT show up to race with something other than tubulars, only then can you use phrases like "back in the day", or "old school". The Tony Martin TT clincher tire choice will have about the same effect on the rest of the Peloton as when Guesdon won Roubaix on clinchers, which is almost nil. Until then, it's still more than 90% still on those old, outdated tubulars.

I don't think it will take much time before most contenders in pro time trials are using clinchers. They are faster and there is a heck of a lot more development going into clinchers than tubulars, so the performance gap between the two will widen. We will see clinchers optimized for 23mm rims that are better than what we have today.

 

[Alex Simmons/RST]

What is the best TT tyre/tubular from your own testing?

My personal testing is not comprehensive as say, Al Morrison's roller testing data, but of the tyres I have used, I always seemed to get good numbers with Veloflex record and Vittoria Chronos. I am not saying they are the best, just the best of a limited range of options I had available, and knew were already rated pretty well. Nevertheless, some others who also have looked carefully at these matters and there are aero considerations as well as durability on some road surfaces.

Some tyres I know others have tested as better, but were not so easy for me to attain (my funds are limited for such things).

 

[Giuseppe Magnetico]

At my National championships last year, I was one step higher on the podium of the TT by 1/100th of a second. If my competitor had a better tyre, he'd have comfortably had that place by at least 20 seconds.

As for being sheeple here that are caught up in the numbers perhaps that's true, but the numbers I check are my from my own testing, and the testing of people who have no vested interest and have sound, rigorous testing process and analysis.

I consider "what the pros use" as a pretty poor way to evaluate equipment suitable for (i) me and (ii) best performance. They use what they are given, they are after all, rolling billboards.

No way in the world you can attribute that time split to a tire because of what an indoor lab test that doesn't recreate real conditions is telling you. A million other factors are defining those times.

I respect you Alex, you've put in a lot of time on and off the bike to promote the sport and you are to be commended. Several of the last 22 years I've worked this industry in marketing and consulting of wheel specific goods, and have sat across the table with companies that have laundry lists of professional race wins, sponsoring the who's who of racers telling me flat out "we have to lie if this is going to sell"! Keep that in mind when you empty your wallet for the sake of chasing the all mighty Unicorn. In the last few years I have since dissociated myself from the kind of work I used to do due to ethical reasons and ran back quickly to what I love to do most, is build wheels that make sense. I'm completely aware that I'm the Atheist in the room of a bunch of religious fanatics.

 

[Giuseppe Magnetico]

I don't think it will take much time before most contenders in pro time trials are using clinchers. They are faster and there is a heck of a lot more development going into clinchers than tubulars, so the performance gap between the two will widen. We will see clinchers optimized for 23mm rims that are better than what we have today.

When Guesdon won Roubaix in '97 on Michelin Pro2 clinchers we were saying the same things for a minute. I will eat my words if all of a sudden clinchers become the preferred choice for TT's, but I'm not holding my breath. History has a weird habit of repeating itself.

 

[simo1733]

If rolling resistance is so important, shouldn't we all ditch our racing 23s in favour of 25s