I've found it pessimistic for road bikes, unless I'm some kind of natural born athlete who somehow becomes ~50w more powerful when the road gets flat, and consider I wear jeans/tshirt to ride, old bike with box section rims, non-aero levers, bottle cages on the handlebars and so on... Then again, that simulator is made to sell Quest VM's.tomv wrote:http://www.kreuzotter.de/english/espeed.htm
I think their numbers are a bit optimistic though.
Fibreglass is too heavy (velomobiles weight ~ 90kg). Coroplast might be alrightfitek wrote:Tried doing a quick search but didn't find a thread dedicated aerodynamics, though I remember someone talking about mounting a trash can lid to their bike a while back.
Lacking carbon fiber molding skills and a wind tunnel, what can ebikers do to build cheap fairings and quantitatively compare them to other fairings?
I ruminate on inflatables everytime I use my van... it is shaped like a brick. Semi-trucks could use inflatable tailboxes. PMTG uses plastic tailboxes:paultrafalgar wrote:I've often wondered if you could make a fairing by having a double skin of, say polypropylene or polyethylene, and pumping it up to a high pressure. The weigh would be low and it would be rigid to promote lamellar flow. What d'ya think?
I seem to remember the statistic that at above 15mph 80% of you energy is spent overcoming wind resistance. On a delta bike, that is - one answer is to get lower (recumbent)fitek wrote: ...
Or is the rider just so much more frontal area that these little things don't really matter?
O.K. Let's brainstorm - Borrow a Quest or Mango (velomobile) spray with silicone to make a release material - lay a sheet of polyethylene film over it - spray on glue - stick a layer of bubblewrap to that - spray on glue - stick another sheet of polythene to that - allow to dry - cut lengthways - remove velomobile - duct tape the 2 halves together - swathe around own recumbent trike - fit tight fitting collar from neck to cockpit rim - inflate - Viola! One boil-in-a-bag cyclist!TylerDurden wrote:...paultrafalgar wrote:I've often wondered if you could make a fairing by having a double skin of, say polypropylene or polyethylene, and pumping it up to a high pressure. The weigh would be low and it would be rigid to promote lamellar flow. What d'ya think?
Inflatables can be quite strong, but I'm not sure they'd be any easier to DIY than rigid materials.
I'm ruminating on an enclosed delta that echos the styling lines of the SR71.paultrafalgar wrote: O.K. Let's brainstorm..
Yes, but from 21 to 15 mph sounds like something else's amiss. I'd check to see if the coaster brake's gotten too tight, easy to mess that up when installing such a wheel. The cog should be able to rotate pretty pretty freely in the slack between driving and braking. Otherwise a chain too tight steals power, maybe a rubbing brake? I assume you took pretty much the same position as on the other bike?fitek wrote:And whats up with the full suspension speed hit? Is it real? I swapped from a 20" kids bike to a FS frame (with the same wheels) and my max speed dropped by about 25%. That seems like a lot to lose from energy lost to the suspension bouncing around. The frame is heavier and probably less aero but the top speed before suspension was only 21mph anyway-- the aero component hadn't crept in very much yet. I'm gonna keep working on this bike, maybe a springy seat and front suspension is good enough.