paulhus@euclid.DEC (Chris Paulhus 223-6871 MLO8-3/T13) (01/17/85)
Aerodynamics of the Zipper fairing I've used a Zzipper fairing for 3 years. The aero data on the fairing says that it's use will produce a drag reduction of about 20%. If all your effort were fighting drag, this reduction would give you a 7% increase in speed, or 1 mph for every 14 mph. BUT, at touring speeds - 10 to 20 mph - rolling resistance is of the same order of magnitude. This means the delta is actually less than 7%. The 20% drag reduction is the same as the recumbents claim. Practical testing. A friend and I used to hold coasting matches, who could get into the best "tuck". One day he cheated and replaced his 1 1/8" tires with 1" ones. He would then creep ahead of me. Next time I attached the Zzipper. Back to dead even. These coasts were down a 2 or 3 % grade at roughly 15 mph. Summary - Zzipper farings are neat looking, slightly aero effective, cause steering problems in cross-winds, block cooling air on hot days, BUT, they are a god-send on cold or wet days. Every commuter cyclist should try one! (I get as many "Neat Bike"s from the teeny-bopper set with my diamond-frame + Zzipper as with my Avatar recumbent.) another 2 cents worth from: N. Chris Paulhus DEC-Maynard, MA decwrl!dec-rhea!dec-euclid!paulhus