aerodynamic (dis)advantage of a recumbent bike roof

December 24, 2011 4:24 AM

Is there any chance that the recumbent version of "veltop" reduces (total) drag?

The rider sits mostly below the cover, so there's a substantial increase in front surface area but maybe this is compensated by the big windscreen and teardrop shape?

posted by Akeem to Sports, Hobbies, & Recreation (4 answers total)

I'd guess it provides a modest reduction in drag. The windscreen and cover are a fairly aerodynamic shape. The problem is the open sides have the potential to set up some scoop effects. Interesting product. Maybe ask the company?
posted by werkzeuger at 6:48 AM on December 24, 2011

Best answer: I don't have the stats at my fingertips, but from what I've read, those windscreens do surprisingly little to improve aerodynamics. The canopy has got to be a serious hit. So I'm going to semi-speculatively say No, that veltop increases drag.

As you may know, fully faired velomobiles have much lower drag than an open recumbent bike or trike. They're expensive, of course, but if that's your goal, that's the way to go (compared to an open recumbent bike with a CdA of about 2.5, a velomobile will have a CdA of about .95)
posted by adamrice at 6:49 AM on December 24, 2011

Best answer: I would also say "no". Aside from the "Wow, it sure doesn't look like it reduces drag." there is also not a single mention on the web site that it does reduce drag. And if it did reduce drag it would be stupid to leave it off the ad copy. The copy only talks about how it can protect the rider from the elements, I would assume that's all that it does.
posted by Ookseer at 9:44 AM on December 24, 2011

Best answer: From the list of things that don't work so well:

"For a fairing to be really fast, it needs to fit the rider like a glove. If you just want to go halffast you can build one a bit bigger. If you add a couple inches to your total shoulder width, that's going to be slow."
posted by morganw at 1:20 AM on December 25, 2011