Small front tire larger back

paskyhawk said:

Small front tire larger back

Has anyone ever put a small high-pressure tire on the front, say 700x20 145-psi, and a larger back tire 23 120-psi? It seems to me that the tradeoff of a large tire is air resistance but better rolling resistance because of the shorter contact point along the circumference.

The back tire is blocked from the air by a larger frame tube. The front tire carries less weight and would deflect less, with a smaller profile the sir resistance would be less.

Anyway just a thought, I was looking for the best clincher tires and tubes for racing only, any suggestions would be appreciated.

Rich

Some tests support using a narrower tire on the front for time trialing where the aero advantage may be important. However this concept must also take into consideration the profile of the rim. I don't have the links but you can find articles about these ideas on the internet. A smaller tire will be less comfortable also.

Well I gave it a try Cont Force in back 23-120psi and Veloflex Record in front 20-140 psi (9-10 bar recommended pressure). It was smooth pavement 22 mph but I’ve got to say it felt a little faster, not very scientific. I tried some hard corning with no problems and the ride was fine. I’ve got a club ride this weekend and I’ll let you know how it feels in a pace line.

Rich
Go Sabres

I've been using a 21c tubular front with 23c clincher rear for over 9 months now and it works well, but the tires have been as close to the same construction as possible to minimize the differences of traction or compliance between the F and R. In the past I've also used 23c fronts + 25c rears with no problems.

For example, right now I'm using a Vred Fortezza Pro 21c tubular with a Fortezza Tri-Comp 23c on the back, since the casing and rubber are very similar if not the same. I would also use say a Vitt Corsa CX with an Open Corsa CX, or a Schwalbe Ultremo clincher & tubular, or two similar Conti's, etc. But I wouldn't think two fairly different designs like your Conti Force + Velo Record is a good combination, but who knows (?) - they could work well together too.

The main reason I do this is not so much the width differences but for the safety factor of a tubular up front in case of a flat or blowout on a high-speed descent, and the cost savings of not having to replace a rear tubie when it flats, which is where I get 90% of my flats. Handling and performance-wise, there is no problem with this clincher/tubie combo.

As for PSI's, I determine that based on my weight, the particular tire's behavior at certain PSI's, and whether it's mounted F or R. In this case with the Fortezza's I use around 130 F/130 R, +/- 5 PSI depending on conditions.