I, too, tend toward the Moulton theory (but that may just be cognitive dissonance, since I own two Moulton bikes ). The mystery to me is why Dahon's official website would concede that small tires are intrinsically inferior in rolling resistance? What studies have they done, I wonder? Pretty poor marketing, I'd say....and I'm a SmoothHound/Hammerhead fan!
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On a totally different topic (is it kosher to hijack your own thread? ) While I was changing over to the Capreo setup on my SmoothHound, I took a ride with the stock 55t chainring and the 9-26 Capreo cassette. I had the bike over 41mph (downhill) and was still pushing gears with the 55/9 combination and 20" wheels. It was exhilarating to say the least! I had to quit at 41mph because of road conditions, but there was still room to go on the gearing! Crazy fast. Now I have a very happy setup with 53/39 in the front.