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...as stated above, Gatorskins ride like bricks. I have ridden on every 27" tyre I could try out over the last five or six years, and Panaracer Pasela gives me what I consider to be the best result in terms of both rolling resistance and road feel. If you look at Bike Tires Direct, they sell them in the 27" size in the USA in both 1" and 1 1/8" widths.

The narrower ones will probably feel a little faster to you.

the rest of the ones I've tried are a mixed bag, and usually end up weighing too much in comparison.