Resistance × psi ÷ steel
 

So you dont have to look far to find credible people in the racing world saying that the old ways of skinny tires pumped up to the max are wrong and what you need is larger softer tires to absorb shock and decrease rolling resistance.

what i dont see being discussed is that this is simply the result of bike construction being radically different... In other words what used to work better no longer does because the CF set ups are so much stiffer.

my question is, if youre trying to minimize resistance on an old school rig(springy steel on 36h 27s), should you ignore this new jargon and use the old school method(1" tires hard as rock)?

Yes

I believe it's not being discussed because it's not true. Rolling resistance testing showing such findings has been done with steel frames and also on wheel resting rigs with no frames. Try reading some of Jan Heine's Bicycling Quarterly articles for example.

I think not. The old school method was based on perception and prejudice (both notoriously unreliable), not science.

Ill look into what you suggested...

just seems unlikely the whole industry would ignore/not notice such a simple solution... For many decades. And suspicious that it come to light after the standard of construction changed.

but i really dont know thats why i asked.

I think track riding on a surface unmolested by pot holes and deteriorated asphalt is different than what most of us experience on our rides. That uneven , unpredictable surface is better ridden on tires that relieve fatigue not encourage it. Just my observation after about 50 years of riding, but no formal racing experience. I used to ride on 23’s but found that switching to 28’s improved not only my average speed but improved the experience…. But I am not 20 years old any more either!

Didn't the change to slightly wider tires occur long after the pro's switched to carbon fiber frames??

Steve in Peoria

The switch to wider tires came directly from motorcycle tire technology, and was arrived at about the same time by both Michelin and Continental. They determined, almost by accident, that the wider tires they were developing for F1 racing actually had decreased rolling resistance. The purpose was to improve adhesion and durability. This moved down to bicycle tires, at least at Continental. I don’t think it had a thing to with carbon frames, climate change, steel frames, the Potato Famine, or Elvis.

OK, maybe Elvis.

well idk the answer to that and i should admit i know very little about bike racing(i just want to go faster!) but i do believe carbon fiber technology has significantly improved since its become standard

pehaps i should take a minute to explain my recent
obsession with rolling resistance:

A few weeks back i noticed a bulge on my front tire, about to blow. I was sprinting a half hour earlier, could have been bad. Only option was some bells at a nearby ace to get home. I IMEADIATELY noticed the resistance. Now the tires about to blow (kendas, junk but bot as bad as bells) were worn thin. While i shouldnt have been riding and definately not sprinting they were probably, being thin, at their best considering efficiency.

now, after noticing that difference, i just gotta feel what high end tires are like. Ive been buying the cheapest crap available my whole life. Without many options in 27" i got conti ultrasports 1 1/4 coming in a few days. But should i get thinner ones? The set i already ordered will find a home if they dont go on this particular rig

​​​​​​​

I think the move to wider tires has come from the road bike world (through gravel) finally realizing that wider tires are faster and more comfortable. Something the MTB world has known for years.

I would also say that my old steel bike with 23mm tires pumped to 120 PSI does not feel terrible.

@Sailboat Bob, definitely get yourself the best tires you can/will pay for. Cheap Kenda and Bell stuff may be ok for utility use, but there is no comparison to the good stuff. None.

I will say that the Conti Ultrasport is a surprisingly nice riding tire for the price. Not much choice for 27", but they are actually a nice tire.

okay... that background helps explain a lot!
Some of the folks here have been doing this stuff for a long time.. 5 decades or so?? My first good tires were silk tubulars, and that was pretty much as good as it got.
Nowadays, I think I'm spending at least $50 for a decent tire, and a fast tire is considerably more. I think you need to do some research and see what a good tire is like, and maybe go learn what racers have been using over the years.

Personally, I suspect that tire choice is a much smaller influence than what sort of doping the racers are engaged in. (not kidding at all)

Steve in Peoria

Every psi over about 100 with 23’s has very little effect on rolling resistance.

Strange stuff. Momentum (inertia), ballistic coefficience, friction, a marble on granite....? Best guess i can come up with is the wider tire spreads the weight out over a larger surface area, like a bulldozer track, or laying on a bed of nails, and therefore the overall weight is reduced in relation to contact patch, thus friction (resistance) is reduced.

Just be sure to exit through the gift shop.

Rolling Resistance Mythology
 

Hear, Hear!

From the horse's mouth!
https://cimg0.ibsrv.net/gimg/bikefor...778fe8010d.jpg

4 types of Energy Loss due to Resistance that occur when cycling - 1 and 2 are most relevant to this discussion:

1. Wind or Air Resistance - Energy lost due to pushing air out of the way. This is by far the greatest loss ranging from ~40+ % to near 60%. Except for bars that change a rider's position and disc wheels, most other aerodynamic components have very little overall effect on these numbers.

2. Rolling Resistance of the Tires - Energy lost due to the tires deforming as they rotate. The overall loss seems to universally be ~11%.

3. Gravitational Resistance or Weight - Climbing turns kinetic energy into potential energy. The energy is returned when going downhill, but most of it is lost due to additional Wind Resistance and braking. Not very relevant for riding on a flat area of road. This is about 25% to 40% based on the rider's weight and strength and to a much lesser degree bike weight.

4. Mechanical Resistance - Energy lost due to friction of metal parts rubbing together, which this chart divides into resistance in the wheel hubs and efficiency losses in the drive train. 5% - 6% which is very efficient.
https://cimg7.ibsrv.net/gimg/bikefor...0b2a7c3431.jpg

Data gleaned from this website among others:

https://ridefar.info/bike/cycling-sp...istance-types/

Several other things to consider:

Higher tire pressures results in more likelihood of punctures. I don't know how many folks who quote results from the Pro Peleton take into consideration the level of team support provided to the riders. Also tires are changed after each ride!

Back in the mid 70's the data we were seeing in the research from sources like Schwinn and the Japanese tire manufacturers indicated that there was only a 7% reduction in rolling resistance between 90 psi and 110 psi. With modern tires there's probably wider spread.

What we found in goat head country was the likelihood of getting a puncture flat went up exponentially with tire pressure over 90 psi. We were ridding 21mm to 26mm sewups for our subjective anecdotal results but we sold LOTS of sewups back then.

https://cimg9.ibsrv.net/gimg/bikefor...2b03d0b325.jpg
https://cimg2.ibsrv.net/gimg/bikefor...4bf279a52b.jpg

Some caveats, when riding small cross section tires like 20mm to 23mm sewups and 20mm to 24mm clinchers, tire pressure should be increased according to the riders weight to prevent pinch flats when impacting road hazards. This Michelin chart is a good starting point.

https://cimg5.ibsrv.net/gimg/bikefor...f1d3462d64.jpg
Following the "recommended" pressure on many tire sidewalls and specs is a marketoids greatest fantasy come true - SELL MORE TIRES! :love:

Another issue, Where, When and How? A lot of contributors talk about their SUBJECTIVE experiences with various tires and tire pressures.

Where do they ride? What part of the country? What kind of riding? How much do they weigh? How many flats and other failures do the REALLY get in a given time period? How many miles do they ride on the tires? How much do they spend on tires? (Seems like a lot of BF members like to spend other member's money! :rolleyes: )

Factual Data needs to be compiled not American Bandstand results: "I liked that song because it was easy to dance to".

verktyg :50: Retrogrouch

Thank you Verktyg! You are right and for me the fatigue is also a factor as the roads in my area(some) can knock the teeth out of your head, not to mention the energy from being knocked about transferring into my shoulders and neck. The main road leading out of town has gotten so bad that I am having to tune my rims more frequently and forget riding the bike that I own that still run 23c tires. I only have 1 or 2 sets left in my stable and they will be replaced with 28c when the time comes. At my age fatigue is a huge factor to my riding experience.

No argument with your experience, I have some quite nice 21 mm Gommitalia tubulars which really feel great. I use 105 psi.

I think Bicycle Quarterly started pushing the point about bigger tires and rolling resistance way before gravel riding became a big thing. BQ started printing as antiquarians praising the French urban and randonneuring styles of 30 to 40 mm tires on roadish bikes intended for riding across France in all weather.

I am perfectly happy riding my 700x23s at 140 psi. I'm not looking for "comfort" in my racing bike, any more than I would be looking for comfort in a Ferrari. I want to feel every molecule of road surface.

I always assumed it came from the MTB world, which quickly realized that 2.4" tires were faster and more comfortable than 1.95" tires. Now, I will say that under certain conditions, those skinny tires were fast - but not over the long haul on a good MTB track.

Surely that depends a fair bit upon how many pounds over 200 the rider is :eek: (I'm @ 220 :lol:)

Continental's chart appears to comparing an underinflated tyre to a correctly inflated one.I believe that when the different sized tyres are inflated so as to achieve the same deflection, the rolling resistance difference will be negligible.

And has a lot to do with the road conditions and terrain. I mean, just look at https://www.bicyclerollingresistance.com and one thing you will notice is that RR decreases as tire pressure increases. Is that meaningful in real world conditions? That I would leave to each person individually. Ride how you want and what you want.

I'm not quite at that point, but I hear you. I attribute "comfort" or "cushiness" to slowness. I don't want to feel slow or "comfy" on pavement. I want to feel swift and silent.

25s work for me.

There's also a chart out there about tire inflation, weight distribution, and the "85%" rule on roundness. I looked that over, and went from 105F/115R on mine (180 lbs) to 95F/103R and I've only noticed a bit smoother ride. What no chart tells you is that a beautifully riding tire, like a Veloflex Master, will behave well within those guidelines, but wear out like single knee jeans on a playground.

Aha. Human nature!.

Those of us who feel that a 140psi tire is faster than a 110 psi tire with the same shape are partially convinced by what we think.
(I'm guilty of this.)

One way to solve this is with a 700x18 Panaracer Technova or Hutchison Fusion.
You will not be faster.
And your fillings will fall out.
And your wheels will go out of true.

There was a day when people rode 130-150 psi 700x19 tubulars on Fiamme Hard Silvers, and tossed the rims after two good crits or races.
Would they be faster on 100 psi 700x25 tubeless? I don't know, but the pro's feel it so.

I no longer know any track racers, but I'd like to know what they think about the psi/tire width environment.

:foo: I wouldn't have it any other way. I want to "feel comfortable" with my thinking, my experience, my knowledge, my riding. When it comes to my bike, I'd rather not be forced to feel something that somebody else is feeling or thinking.