Tire Rolling Resistance

Krazyderek said:

Did you, or do you expect to see a 20w increase in your avg power by slapping on a set of the top 3 tires ?

No one expects that, they expect to go faster because 20w or 20w x 2 is not being dissipated by their tires.

The same question can be raised about deep dish, bladed spoke wheels. Do they really make that much difference? The test data suggest that they do. The reality is that there is a lot of misinformation floating around about tires (e.g., tubulars are faster). There are now beginning to be some hard data about tires (and wheels and frames and helmets, etc.). Whether a particular piece of equipment that appears to reduce resistance (air or rolling) is worth the cost or other consequences (e.g., less puncture resistant) is a personal decision. But, it's nice to have some hard data and get away from the anecdotes. I know this -- I don't plan to race on the tires at the bottom of the list because for me 20w is a big deal.

RapDaddyo said:

I don't plan to race on the tires at the bottom of the list because for me 20w is a big deal.

Me neither. Now quit spreading this secret information!

(actually, I even have a secret Michelin weapon that's no longer in production...mu hu ha ha ha!)

beerco said:

Me neither. Now quit spreading this secret information!

(actually, I even have a secret Michelin weapon that's no longer in production...mu hu ha ha ha!)

LOL. Okay, I'm done with promoting truth. BTW, I'm thinking rolling resistance has not yet seen the surge of improvement that we've seen with wheels. There will probably be some tires introduced in the future that will obliterate the rolling resistance of today's tires. I just hope they have a cool sound.

RapDaddyo said:

I just hope they have a cool sound.

I'm with you on the sound. If you feel fast, you ride fast, and I feel fast on my Cosmic Carbones, even though they're tanks.
Well, I should say Carbone, singular, since i have such a hard time not running my PT wheel. :o

re: Rolling resistance - I a firm believer in the data I've seen (it helps that I love Vittoria Evo CX's) but when I share the superiority of clinchers v. tubulars in this regard with others, I invariably get the "well, if it makes such a difference, why don't the pro's use clinchers?"

My usual response is something about the difficulty of teaching old mechanics new tricks, but it does seem curious. You think some, especially people like Armstrong who was always searching for miniscule advantages, would have jumped on clinchers. And sponsors would love it - they sell many more clincher tires and wheels than tubulars and would be ecstatic if they could get some wins for ad purposes.

Thoughts?

peterpen said:

when I share the superiority of clinchers v. tubulars in this regard with others, I invariably get the "well, if it makes such a difference, why don't the pro's use clinchers?"

I think two things come into play here. One is that the pros don't have to worry about maintaining their wheels, including the gluing and cleaning the glue residue from the rims. I think if one uses track glue and applies the glue in certain ways that the rolling resistance benefits of clinchers at least partly disappears. I might opt for tubulars and track glue if I had a full-time mechanic to do it. The other is puncture resistance. Many of the stages don't require the ultimate rolling resistance (or air resistance for that matter). They may be placing a higher value on puncture resistance than rolling resistance. I'd be more interested in what they run on the ITT and TTT stages. And, then there's the ever-present issue of sponsorship dollars. I'm not burdened with having to take into consideration my sponsors in selecting my equipment.😄

peterpen said:

My usual response is something about the difficulty of teaching old mechanics new tricks, but it does seem curious.

Thoughts?

I think it's that old dog thing plus it seems that the best tubs mounted perfectly are as good as or even a little better than the best clinchers. That in conjunction with the better run flat ability of the tubs is my guess.

RapDaddyo said:

I just hope they have a cool sound.

You had better hope they have no sound at all. If there is a sound they are acting like a loudspeaker and like any speaker it takes wattage to produce sound.

one flaw i can see right away with their testing proceedure is the surface they used to test the tires on... when is the last time you road on a perfectly smooth shiny surface like the one used to test the tires? unless you are lucky enought to have ridden on a nice board track... the answer for almost everyone is never.

on perfectly smooth surfaces you can simply put more pressure in your tires to decrease your rolling resistance but doing this on real roads actually increases rolling resistance. on real roads or even your typical track there are all sorts of surface textures, cracks, bumps etc. your tire can do one of two things 1) lift you and your bike over all the surface textures, cracks and bumps or 2) deform such that you and your bike remain at the same height over the road. the effort to lifting your and your bike over all those tiny bumps is probably one or two orders of magintude greater than it is to flex your side walls so option 2 is actually the much, much better option. this is why race cars have suspension systems of which tires are an integral part.. not for comfort but because they really do make the car go faster.. all of the force generated by the engine goes into forward movement and not into lifting the car over bumps and imperfactions in the road. for road bikes your tires are all we have in terms of suspension. and that's not even talking about, comfort, tire patch size/traction in cornering and rain etc. and having high pressure leads to having your tires actually bouncing off these little bumps and imperfection in the road.. if your rear tire isn't in contact with the road, you can pedal as fast as you like, you are not going anywhere. you want a tire width that allows you to pump your tires such that you get low rolling resistance an don't pinch your tubes (wider tires can take be loaded more at a given pressure). the optimal pressure for most tires is usually no where near what the max pressure and is usually around 100psi.. don't believe the hype that you need super high pressure tires 'cause if you pump them up to their max you'll actually go slower not faster. you need a nice supple tire that deforms easily of appropriate width.. what you need to look at is tpi (threads per inch) not the max pressure of tires... and whatch out hear too because some manufactures will list tpi of overlaping layers not single layers of threads.

high pressure = lower rolling resistance is a myth when riding on real, non-mythical roads.

peterpen said:

"well, if it makes such a difference, why don't the pro's use clinchers?"

Because, if a clincher has a tube pinch or blow out on a decent, you can pretty much kiss your life goodbye, metal rims don't exactly grip the road to well-i know this from personal experience, only i was lucky, it happened on the flats.
You get a flat on a tubular an your control goes from optimal to pretty sluggish, but unless you're pulling a 200 degree hairpin turn chances are the tire won't even move or roll and you can come to a controlled stop and wait for the wheel car.

I'm still skeptical about the real world differences, so how much faster are you going to go with 20w? 0.7kph?

Krazyderek said:

I'm still skeptical about the real world differences, so how much faster are you going to go with 20w? 0.7kph?

20w average difference in power can be the difference between getting dropped and hanging with the pack. e.g. it takes about 250w NP to hang with the "A" group thursday night race in my area (Not place, just to hang with the pack till the finish). If your FTP is 250, but you're running bad tires, you might get dropped instead of finishing with the pack.

Krazyderek said:

I'm still skeptical about the real world differences, so how much faster are you going to go with 20w? 0.7kph?

given that the test is not realistic in terms of the road surface and the types of irregular deformation the tires will actually encounter on a real road vs a completely smooth regular surface that they are tested on i'd say those tests are pretty meaningless... and the actual rolling resistances are likely much greater and the differences between tires is likely greater.. but that is just speculation.

beerco said:

20w average difference in power can be the difference between getting dropped and hanging with the pack. e.g. it takes about 250w NP to hang with the "A" group thursday night race in my area (Not place, just to hang with the pack till the finish). If your FTP is 250, but you're running bad tires, you might get dropped instead of finishing with the pack.

Well i'm running tufo's right? some of the worst tires on that chart, maybe i'll pick up a set of the michelin's after all and do some of my own testing on my rollers using my powertap, keeping gearing, cadence, wheels, bike, me, and the rollers the same, the only thing i'll change is the tires and i'll see what kind of speed / power differences i observe on my powertap if any.

Again, not real world, but..

A long flat indoor parking lot with standard ashfalt would be the best testing grounds, or a tunnel, somewhere flat where wind won't really affect performance.

Either way, i'll try and maintain a speed of 30,35, and perhaps 40kph, note the wattage, do a couple of runs to get a good average. Then maybe try a constant 250 watt at 90 and 100rpm tests. switch tires and do the same then compare results.

Again, with the effects of drafting, and just normal variance in power from one pedal stroke to the next, i highly doubt 20w will make a noticable difference in the real world. I still say a slight gust of wind is more noticable then a different set of tires.

peterpen said:

I invariably get the "well, if it makes such a difference, why don't the pro's use clinchers?"

(snip)

Thoughts?

Wheels. A tubular wheels could save 100-200 grams simply becuase they have to add less carbon. The best/lightest,aero, wheels are usually tubulars. Plus a high quality tub save another few grams against tubes+clicher tires. Feel?

Greg

doctorSpoc said:

Jobst Brandt regularly demolishes this logical fallacy, i.e. smooth rollers is not a good test, on rec.bicycles.tech...

gvanwagner said:

Wheels. A tubular wheels could save 100-200 grams simply becuase they have to add less carbon. The best/lightest,aero, wheels are usually tubulars. Plus a high quality tub save another few grams against tubes+clicher tires. Feel?

Greg

I agree, look at the weight difference between a Zipp 404 clincher vs. tubular rim. Only one brand, but Zipps are very popular and it is a significant difference.

Plus, safety as others have mentioned. I blew out a tub downhill at near 40 mph, front wheel. Tub just flattens out and I was able to stop. Still puckered up, for sure, but no fall and in control. Over the years, I've crashed a couple of times from clincher flats (mine or other guys around me).

I ride both and really don't think the gluing is that bad. More time than clinchers, certainly, but if you know what you are doing you should not make much of a mess and not much of a hassle. Frankly, I tend to ride clinchers more nowadays because of the high cost of a quality tubular than the glue issue.

gvanwagner said:

Wheels. A tubular wheels could save 100-200 grams simply becuase they have to add less carbon. The best/lightest,aero, wheels are usually tubulars. Plus a high quality tub save another few grams against tubes+clicher tires. Feel?
Greg

I'm primarily puzzled by use of tubulars in long, flat TT's where weight is not as important and there's always a follow vehicle directly behind the rider. cRR may not be terribly significant elsewhere, but when you can theoretically save 1'30" in a 40K TT just by running Vittoria Evo CX clinchers vs. Conti Competition tubies, I don't understand why pro's don't use 'em. (time saved based on Tour Magazine cRR test, 85kg rider + bike, at 310w on a flat course, courtesy Scot Thor via analyticcycling.)

On regular road stages, the ability to ride a flat tubie until neutral support can get to you is more pertinent. Catastrophic clincher flats are a bit exaggerated in my experience - (knocks wood.) I front flatted last weekend in a race dong 35+mph and rode it out, have front flatted in a gravel section while descending and rode it out, etc. Not saying it doesn't happen, just that it's not guaranteed death.

I dunno, most of it probably has to do with tradition, then feel (also tied to tradition,) then maybe weight concerns. I'd imagine safety last on the list for a pro in an important TT.

Krazyderek said:

Again, with the effects of drafting, and just normal variance in power from one pedal stroke to the next, i highly doubt 20w will make a noticable difference in the real world. I still say a slight gust of wind is more noticable then a different set of tires.

20w is HUGE in the real world, you're just looking at it the wrong way. Running bad tires is like having a flat tax thrown on to your FTP. Do you think having your brake rub just a little bit all the time would put you at a disadvantage compared to the chums you're racing against? Do you think that running your tires at 50psi would put you at a disadvantage compared to the guys running 100psi? Do you think running aero bars in a tt makes no difference?

beerco said:

20w is HUGE in the real world, you're just looking at it the wrong way.

I think we should let people believe what they want to believe. Just think of it as a competitive advantage. 🙂