smd4

Can you give me a cite for this? Might come in handy the next time I get into it about running my 700 x 23 Veloflexes at 140 psi.

Kontact

Why would you ride 23s at 140psi? Do you weigh 320 lbs?

All tires have an ideal pressure for the load they are carrying. Inflate above that and the measured rolling resistance goes down, but the actual street rolling resistance goes up because the tire won't conform. In rolling resistance tests that I've seen posted on this site and others, rolling resistance at realistic pressures favor tires in the 23-25c range, while larger tires have lower rolling resistance only when inflated well above recommended pressures for rider weight.


I've never been able to ride more than a couple miles on Veloflexes without a puncture.

smd4

Because they feel awesome?

wolfchild

I've been using disc brakes long enough to know that there are other minor advantages besides just preventing rim wear which is the main advantage of discs... Maybe I should of been more clear and used the word MAIN instead of the word ONLY, it would of saved a lot of unnecessary arguing.

smd4

“Have.”

tomato coupe

Yeah, it would definitely save a lot of unnecessary arguing if you didn't make statements that were FALSE. But, in this case, changing "only" to "main" isn't going to help you - it's still a false statement.

wolfchild

If it wasn't a train, it must of been a recumbent that caused a wreck.

tomato coupe

"Have" ... again

Kontact

Just like ultra stiff frames.

Lombard

Very few cyclists consider ceramic bearings valuable. Rather I should say only the gullible cyclists believe ceramic bearings are valuable.

Wrong. Maybe on a test in a controlled environment like those drums that bicyclerollingresistance.com uses. But real world conditions are very rarely like that. It is now known that the sweet spot is around 28-30mm for road tires. I will copy and paste what KerryIrons , a very experienced rider wrote over in RBR:

"Not what the data show in the real world (not on lab rollers). Suggest you get a subscription to Bicycle Quarterly and learn about the extensive research in this area. They have been leaders in providing the field data that has led to the transition from 19-21 mm tires to 28-30 mm tires in the pro peloton. Of course there is a weight penalty for ever-bigger tires and that shows up when you are constantly jumping speeds, though that extra energy is returned to the rider because heavier wheels/tires don't slow down as fast when you let off on the pedal pressure. Wider tires have different pneumatic trail and so there comes a point where the bike needs to be designed differently to get the best performance on wider tires."

smd4

Valuable? I like’em. Swapped out the steel balls in my Dura Ace hubs. They’re way lighter and smoother. What’s not to like?

Kontact

Jan Heine of Bicycle Quarterly both originated and retracted his findings on ideal tire size, later attributing rolling resistance to sidewall suppleness rather than volume.

My informal testing is that lots of tire sizes can conform very nicely to the road if they don't have to do all the work. Ultra stiff rims and ultra stiff disc forks transmit much more road chatter than what they replaced.

The rolling resistance problem with big tires is that a greater amount of tire surface area is involved in flexing for the contact patch, and that larger area changing shape means more energy loss to plastic deformation.

I do like the argument that everything should be heavier, though. Anyone ever heard of unsprung weight in a suspension system?

tomato coupe

I think everyone is aware that road condition plays a huge role in determining the best tire width for lowest rolling resistance, and that wider tires are often the best choice. But, let's not go crazy and cite "the extensive research" done by Bicycle Quarterly. That is about as far from real research as you can get.

Lombard

Your "informal testing" is wrong. Tires contribute way more to ride compliance than frame, fork or wheels. If informal testing is a valid argument, I can vouch from my informal testing that there is no perceived difference in speed between 23mm and 28mm tires, but the 28mm tires are way more comfortable. Using the 28's is a no-brainer for me. I would even go up to 32mm if my road frame could fit them.

You have this backwards. The wider contact patch actually causes the tire to have less rolling resistance.

Lombard

So then what do you define as "real research"? I certainly don't consider tests on a lab drum real research.

tomato coupe

I don't want to turn this into a discussion of JH and his testing methods.

Lombard

Of course not. Carry on.

tomato coupe

Look, I agree with your position on the tires, but I don't think BQ is a good source to support it. Start another thread if you want to discuss BQ and JH, but I don't want to do it in this thread.

Kontact

My testing was comfort testing - a direct measure of the transmission of road vibration to the rider.

You misunderstood my post. The contact patch is formed by the deflection of the sidewall. More patch means more deflection. The measure of this is hysteresis, which in tests increases with tire volume given the same percentage tire compression. All things Bicycle Quarterly talks about and says is true.

Point being, none of this stuff about tires is science. Heine's tests aren't controlled enough and lab tests aren't realistic enough. But the current assumptions about rolling resistance are based on suppositions from people like Jan that have changed their minds over time, and misreading of data at fixed PSI. The whole topic ends up being as fact based as acupuncture - maybe it helps, maybe it doesn't - but there is no real scientific data that has any surety to it.


And I'm not suggesting everyone should be running 23s. I'm saying that the right 23s on a reasonably maintained road can be the fastest overall choice - confounding the predictions of those pushing 30c tires. Low hysteresis combined with the minimum necessary suspension effect equals lowest total friction losses. But neither of us is riding in the TdF, so our tire selections don't have to be predicated on ultimate efficiency. I just don't enjoy seeing supposition parading as known science. That whole approach started to boom after Sheldon Brown published Damon Rinard's BB deflection tests - which were based on the completely theoretical idea that stiff bikes transmit force better. But I've talked to Rinard and he agrees that most of these things start with a guess, not a principle.

Kontact

Yeah, this thread is really sticking on topic. Valiant of you to speak up for its virtue.

tomato coupe

It's very odd to be criticized for not wanting to go off on a completely unrelated tangent.

Kontact

It is odd to criticize unrelated tangents in a thread full of them.

Lombard

I wasn't arguing BB stiffness. You were. Yes, most riders like the feel of a stiff BB, but to say that makes one faster? Nope. That one was debunked awhile ago.

So tell me. if 23s are the fastest overall choice, why is the pro peloton riding 28s and 30s?

Kontact

Why did the pro peloton ride Campy back when Shimano worked better and was lighter?
Why did the pro peloton remain celibate during the racing season?
Why is the pro peloton experimenting with zero setback seat positions?
Why did the pro peloton paint aluminum and carbon bikes to look like steel sponsor bikes?
Why did the pro peloton only recently start using low climbing gears when winning riders used triples in the '70s?
Why did the pro peloton resist aero bars?
Why is the (undoped) pro peloton no faster than it was in the early '90s or even the early '80s?


Do you think pros have access to any different data or biases than you do? It's bike racing, not aerospace.

Koyote

smh.