Mountain Biking - rim/tire weight questions for XC

So a pound on a rotating part is the equivalent of having 3 pounds of a non-rotating part? Obviously this would help you while spinning... but once the tires are already up to speed, seems like that kinetic energy could help too. Does anybody race XC with heavier tires? I switched my Maxxis 2.35's out to some 2" tires, saved a pound and a half overall, but it feels so much more unstable like on rocks and turns. Obvioiusly the extra air would help, but they had much more traction, more stability, etc. I'm just wondering what most people thought a good trade-off was between light and stable. Seems like I would go faster if I had more confidence, but then again, I just lost a race due to a couple of really long boring slight uphill sections. I originally wanted the Maxxis High-Roller semi-slick, but they're 1,050 grams. I'm wondering if the single ply version of the same tire would be a good compromise, since they're only 655 grams. Or, even the Bling-Bling duals... they're 700 grams. Looks like I'd have at least 150 grams more on each tire... not sure if that's a big deal or not. Since I'm not high-caliber or anything, I'm guessing not.

many XC tires are around 600 grams, and grip pretty well. of course the wider the more stable, and more traction, but rolling resistance is the cost and since you race, speed might matter.

Has anybody ever done a study on rolling resistance? I mean, I've really got no clue as to what I'm gaining or losing by having one amount of rolling resistance over another. I can tell a big difference on asphalt, but otherwise I'm not sure if I'm gaining minutes or microseconds over the length of a course. Now that I've got two sets of tires, one fat and knobbied, and one skinny and smooth, I guess I can test for myself.

Corn this may be something better left to roadies. They have a greater understanding typcially of rolling resistance as they are all Anal about that kind of thing :)...

Most mtbers I know just want a good running tire that gets them from a-b the fastest on rough terrain. :)

Originally posted by Maelstrom
Most mtbers I know just want a good running tire that gets them from a-b the fastest on rough terrain. :)

Ya, me too, that's exactly why I wrote this, to try to figure out what would be fastest for me without buying every tire out there and test driving them all on several courses. After this experience yesterday, I'm just thinking why should I be a weight-weenie / resistance-weenie when I'm suddenly not as confident as I used to be? Yeah if it shaves a few minutes off consistently, sure, but otherwise it seems like the increased confidence and stability on technical terrain would be worth far more than a second or two on flat hardpack.

I would rather conifdence and traction over speed and no confidence.

You have to compromise. There's no big knobbie that's going to roll fast, and there's no light tire thats going to hook up very well. I find that a 2.0 or 2.1 inch tire rolls quickly and efficiently, while providing the best amount of grip for braking and turning. I've actually had VERY good luck with Michelin's tires.. they ALL seem to roll fast and have awesome traction, even the full knobbies. I think it's the silicium compound.. just flat out fast! I'd recommend either the Comp S or XLS.. both great tires.

yeah i got to agree. ride with what you are comfortable with. what good are better rolling tires if they cause you to pull the brakes more?

I use contis twister supersonics pro - about 380 grams 1.9"
I aslo use latex tubes (experimental) which are light

The feeling is nice - you can feel how easy is to accelerate - even on a fully - which has some kind of dully feeling. Would I recommend it? It depends - after few days the air gets out of latex tubes - somewhat annoying. About tires - you have to treat them nicely to last long for you - they are also a little bit expensive - but should last one season of riding (not in mountains - where they would be used very fast)....

By the way, I am still undecided about going tubeless