gun-n-gal

I'm currently riding a Trek X01 cyclocross bike with the original tires. I have found that I'm only averaging about 1 mph faster than I was with my hybred bike. If I go to road tires will I gain much speed? I'm signed up for the MS150 in July and I'd really like to get my average speed up to 15mph from my current 13.

Couple of things I like about these tires are: they have lower pressure in them so its a smoother ride, and I've only had 1 flat in almost a 1000 miles. What kind of thoughts do you folks have?

threadend

Yes, you can definitely pick up a MPH or two with a change of tires because of gains in reduced rolling resistance, rotational weight and static weight.

The harsher ride can be compensated for with good bar tape or cycling gloves, a carbon fork or handlebar and / or a suspension seatpost although the latter would negate the weight savings to some extent.

High pressure tires need to be kept at high pressure to help alleviate flats caused by puncture and pinches. Will your present tire pump get to PSI of 100 +?

With a cyclocross bike you shouldn't have any frame clearance issues but be sure the tires will fit on your rims correctly.

Best wishes in the July MS150.

oscaregg

Proper fit of tire to rim is, a tire that is wide enough so that the sidewalls still have a visible curve to them--you don't want a tire that's so narrow that it's sides rise vertically from the rim, this will give you no shock absorbtion, be prone to pince flats, and protect the rim less. If the Trek cross bike has the Bontrager hybrid rims, use at least a 700 x 28mm tire; two I'd recommend are the Rivendell Ruffy Tuffy and the Panaracer Pasela. I have been using the Rivendells for tandem tires on very wide Mavic Mod 4 rims and they're a PERFECT fat road tire; they roll fast, corner well, and don't flat easily.

gun-n-gal

Threadend, yes I do have a floor pump that will do up to 160 psi, so it won't be a problem pumping up road tires.

Oscaregg, the tires have Bontrager on them, I'm not real sure about the rims. Thanks for the suggestions on tire brands. I think I'll get some and try them out in the next couple of weeks.

Prosody

Below is a link to Sheldon Brown's article on tire sizing. It includes a table showing which size tires fit which width rims:

Tire Sizing

MichaelW

You will definately pick up a lot of speed with some slick, higher-pressure tyres, it is the single best upgrade you can make.
There is no need to go smaller than 25mm, but 28 is probably a more sensible general purpose tyre.
Different manufacturers have different ideas on what a tyre size should be. The Panaracer 28mm is really the size of a traditional 25mm tyre. I use the 32mm version, which I count as a true 28mm size.

Due to variations in rim and tyre diameter, some combinations are a tigher fit than others. This has nothing to do with the designated width. An easier fit will make puncture repairs less troublesome.