Clincher or tubulars for time trials?

Proper doesn't mean much. There are over a lot of ways to measure pressure, some more common than others. If kilograms per square centimeter isn't a measure of pressure, then neither is pounds per square inch.

http://www.sciencemadesimple.net/pressure.php
http://www.onlineconversion.com/pressure.htm

 

Here's a long winded discussion of the study. I haven't read much of it yet, so I don't know what it addresses and doesn't.

http://www.terrymorse.com/bike/rrdiscuss.html

 

Further underscoring the wretched confusion that results from the English system. A kilogram is a unit of mass and a pound is a unit of force. Force per area is pressure, mass per area isn't. The kilogram-force was rather prudently rejected by the ISO in 1955. It was defined as 9.80665 Newtons, which is exactly the kind of clumsy conversion factor that the metric system was developed to avoid.
Proper notation aside, I have yet to see a tire pressure gauge that reads in kilograms-force/cm^2.

 

While we're on the subject of tubulars or clinchers, I was wondering if anyone has heard of problems when mixing the two (like mixing bias ply with radials on a car)? I've got a set of Zipp 909 tubulars on a race bike (triathlons) and I could foresee an event when I get a flat and need to swap out wheels quickly. I've only got one set of tubulars (the Zipps) the the replacement would have to be a clincher. For what it's worth I would have prefered to get the Zipps in a clincher but the price was right for tubulars.

 

Never heard of problems mixing tub's/clinchers per se. Mixing two different types of tires w/different tractions can result in some handling weirdness tho.

 

I figured it might get a bit weird on the bike if you have a mix. There is a big pressure difference between the tubulars on the bike now and any potential clinchers (170-120 respectivly). I can't imagine that it would be a problem at lower speeds but going down a hill at 50 mph or around a sharp turn would magnify any differences. Thanks for the reply.

 

Whoa there, sounds like you may know too much for your own good!

 

I have used tubular on my race (triathlon) wheels (Zipps) and only ever had one flat with them, they are great in the dry and fast, and not to difficult to put on (if you get the right glue). Only down side, some can be real dodge in corners when wet because of high pressure, and can be expensive, but so can good clinches.

 

You can run the numbers on clinchers and tubs for yourself over at analytic cycling. Tubs come up with more rolling resistance. You can even compute how much faster you would be, in time, over a length, with the different tires. Nice little exercise. Does make one wonder why the big boys are still on tubs though? The science would appear to not be on their side.

 

In the above posts, there is a discussion of the base data used by Analytic Cycling to feed their calculations. Unless there was some more data used that we haven't seen, would say some valid science questions exist.

Personally, I wouldn't put much credence in the results the calculator spits out. Would think results of side-by-side coastdown tests on real roads could be a better source of comparison data.

 

I'm not positive on this but I'd think the pro's more often use tubs because (1) there is a real weight savings, and tire/rim is the most critical weight to save (a spare tub in your pack tends to negate some of that savings for we mortals who need to carry our own). (2) since tubs are less prone to pinch flat it can mean less flats in a race, especially on pave or rough terrain.

 

I didn't understand that discussion to be of the base data used by analytic cycling. You can compare 23Cs not 25s or 28s like the data sets that are under discussion above.