4 ms·
(20 mph is really fast for a bike, eh?) Anyway, 400W to avoid getting creamed by a car seems cheap to me. Eat a Clif bar; stop at red lights. Goddamnit.
by carapace 7y ago
(20 mph is really fast for a bike, eh?)
Anyway, 400W to avoid getting creamed by a car seems cheap to me.
Eat a Clif bar; stop at red lights.
Goddamnit.
- icebraining 7y agoThe worry is that you won't be able to output 400W. My approach is to reduce speed earlier and hope the green comes before I'm forced to stop.
- carapace 7y agoThat's a good idea. What I want is some gadget that caches my momentum (in a little compressed air cylinder or something) for the stop.
- icebraining 7y ago"Caching the momentum" is essentially what "regenerative breaking" does. An engineering student designed something like that, using a flywheel: https://www.treehugger.com/bikes/engineering-student-builds-flywheel-energy-recovery-into-bike.html https://www.treehugger.com/bikes/engineering-student-builds-... But if you want something commercially available, you have to get an e-bike with that feature, and those models seem quite pricey.
- carapace 7y agoI have an ebike w/ regenerative breaking (a Bionix conversion kit, $1500 w/ labor) but I can't say it seems to do much. But then again, with no other non-regen bike to compare to I can't be sure. It doesn't recover anything like the charge it spends going up a hill (with assisted pedaling) when you're coming back down, but that's to be expected, eh? Thermodynamics and whatnot. The flywheel thing is exactly it, except I think it would be safer and lighter to use compressed air, also stores longer than a flywheel. With something like that you'd eliminate most of the work penalty for brief stops.
- bdamm 7y agoCompressing air isn't a very efficient operation, pumps usually have leak, spring compression, friction, and heat losses.