26" vs 27" Wheels

[bulldog1935]

exactly correct, friend - something else they've addressed in dynamometer testing using rough rolling surfaces on the dyno drums.

...You're saying harder pressure tires can actually 'bounce' over bumps and cracks and therefore lose speed?

And not just low-frequency cracks and bumps - chatter is the tire bouncing over the high frequency finer features in the road texture.
Jan is not the only one who has done this testing - you can find many independent tests, though still aimed at comparing (and selling) quality road clinchers.

On last Sunday morning's crack-of-dawn Alamodome sprint, the very athletic gentleman (pretty sure USAF officer and at least 25 years my junior) on the late Specialized road bike, and whose gatorskin flat we fixed before taking off, followed me through all the downtown lights. Not intentionally, I scraped him off on the Chavez St. stretch, and was first to our stop.
I was on my '74 International with fenders and front rando bag - 32mm Compass tires, about 73 psi rear, 70 front - and it was wet, which I have no worries on these tires, but did point out a slick turn onto Broadway to the guys right behind me.

you can see I dropped it onto granny for the climb up the wheelchair ramp switchback to our landing - I love my half-steps+granny, and have two bikes set up this way.

ps - fast is only a byproduct of this tire choice - the reason to pick this tire is ride comfortably and stay up on rocks and slick in the real world.

 

[fattyre]

Ahh. Nothing like a good old fashion tire debate....

I’ve always wondered what the tires themselves would say if they could talk.

I take this approach. Who cares? Air em up and go. Cycling is all calculated risk. Through the years it seems to me it’s the motor that makes the biggest difference. You can put the nicest tires on a crappy bike and guess what? It’s still up to your will power, your strength and your fitness.

 

[bulldog1935]

Falling is always faster than staying upright on a flat surface - independent of tire chatter. Any time you lean to turn, you get free acceleration, especially on courses that you know.
(add chatter to that turn, and you're way behind)
I love that mash feel of accelerating uphill just after a sweeping turn - when they raced steel bikes, though mostly trial and error, they built steel frames to take advantage of this.
My Carlton-built Raleigh definitely falls in that category (32mm tires barely fit the round chainstays, which are without tire crimps).
If you put good wheels on the crappy bike, you change its nature.

Two approaches to tire debates - seat of pants and math. I'm a licensed professional engineer of 40 years, and apply it to everything I do - fishing tackle, kayaks.
Any time myth is involved in an argument, so is see no evil, hear no evil

 

[harpon]

Professionals raced for years on clinchers before tubular tires. Thinner is always a better roll at the same pressure. They usually weigh less too, a consideration accelerating and climbing. You can't "myth" what so many learned for so long doing mile after miles for years and decades. No one who raced on sew ups would ever want to return to them for casual or touring rides- they puncture much easier. So on the one hand these arguments seem based on practical need and comfort favoring wider tires- ride them, they have more rolling resistance- yet on the other hand is this annoying obsession with dead and largely less reliable sew up formats. Let me guess, you find vinyl 33's better sounding than CDs or digital files. Pop Musak!

I like 23mm tires and find they roll even better than 25mm, but they don't last long. Both can be replaced each year for less than a decent sew-up cost even back in the '70's. Many sew-ups had cheap cotton casings, and were heavy and crap, and if they had spent any shelf time or survived a year, the rot factor on cotton sew-ups was especially bad, and they had high rates of failure. Gluing them on and taking glued tires off was a messy tiresome pain- you couldn't just let glue collect repeatedly either, but had to use solvent to remove it from the rims periodically.

We had an ABL of A state rep in Indiana at the time who took pride in rolling the tires of the rims of riders on the starting line, There'd be groans and cursings from riders as he'd go through the pack before the start, but he did this again and again for several years. In one of my first junior races, I once had a cheap Wolber cotton sew-up roll off its' own stitch covering in the middle of a corner- which was still solidly glued to the rims. The rear tire was still holding air but twisted up and held the rim fast. They said that sparks were flying off the wheel behind me. It was only fortune that a tall chain link fence was outside the corner I was going through and I stayed upright coming to rest against it. I never used Wolber Sew-ups again and called them Wobblers. A 23mm clincher is similar in profile to a tubular, and the tube can be replaced and while heavier the tire is also usually more reliable than a sew up casing. I think they are a major leap forward from the old days for a lot of casual riders and training.

 

[juvela]

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note on NIVEX for our Don Ron -

came across this listing for a Nivex ensemble including instructions, dropouts and hubs:

Owner located in The Levant * -

http://rover.ebay.com/rover/1/711-5...0001&campid=5335809022&icep_item=382790179013

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* not Oscar

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