Drag reduction for upright bicycles

[jjackstone]

Originally Posted by JulianEdgar

The requirement was for a commuter bike, and - if we're up for outright low drag - a recumbent velo would kill a time trial bike.

(Basically all fast, low-drag pedal machines are banned from competition. It gets me very cross, because people then assume that fundamental bicycle tech stopped in about 1920.)

This is state of the art in low drag cycling, not a time trial bike...



It still brings me out in goose pimples watching this:

You should see what happens when it hits 88 mph.

https://www.youtube.com/watch?v=nUcyURXe5yU

JJ

[jjackstone]

For more upright fairings than you may ever want to see. Visit this long thread. I see that many of the photos no longer exist, but there are still a few around.

The Recumbent Bicycle and Human Powered Vehicle Information Center

JJ

[JulianEdgar]

Originally Posted by jjackstone

For more upright fairings than you may ever want to see. Visit this long thread. I see that many of the photos no longer exist, but there are still a few around.

The Recumbent Bicycle and Human Powered Vehicle Information Center

JJ

I see the OP is a contributor to to that thread so he's probably aware of all of the designs (even when the pics worked)!

But it gives me a chance to post these:

[Grant-53]

Uprightdave did display a road bike that used a Zzipper front piece and lycra stretched over a foam tail section. He cruised at 27 mph. I have a photo somewhere. I also have a National Aerocargo front piece that attaches to the handlebar and fork. It is the combination of a nose cone and a tail section that gives the best results. Sailplanes use either a space frame and aluminum skin or a composite monocoque. The SZD-9 bis Bocian 1E sailplane plans are available free (sheet 1) and I would look at making the Kamm tail at bulkhead 6.

[Grant-53]

The Moulton faired bikes hit 50 mph.

[JulianEdgar]

Originally Posted by Grant-53

The Moulton faired bikes hit 50 mph.

Just over, in fact.

[Grant-53]

One design criteria is easy ingress/egress. I am 67 yrs and throwing a leg over the top tube of a diamond frame is difficult. If I want a full shell then I can add side doors to my current design on a step through frame. The other option is to have a one piece shell that hinges near the nose and rotates forward.
As for a clear windscreen I would look for a piece from a motorcycle sport bike.

[freebeard]

I am 67 yrs older and throwing a leg over the top tube of a diamond frame is difficult.

I've go a scar on my left elbow for proof.

[JulianEdgar]

I think it's probably time to start building and testing your ideas!

It sounds like you're aiming for a step-through (lady's?) bike with a development of what you've already been trialling in the coroplast.

I'd be using a blown acrylic dome and lightweight frame (laminated plywood strips?) with stretchy cloth and zippers, on one or other of these:



(My restored/modified 1960s Moulton "billiard cue")

or



(My work-in-progress Moulton space frame.)

But neither is common or particularly attractive to many people.

Good luck - I think it is a great project. (I never realised how hard it is to improve the efficiency of a machine until I started working on pedal-powered vehicles... makes car stuff look easy.)

[freebeard]

(I never realised how hard it is to improve the efficiency of a machine until I started working on pedal-powered vehicles... makes car stuff look easy.)

“When one compares the energy consumed in moving a certain distance as a function of body weight for a variety of animals and machines, one finds that an unaided walking man does fairly well (consuming about .75 calorie per gram per kilometer), but he is not as efficient as a horse, a salmon or a jet transport. With the aid of a bicycle, however, the man’s energy consumption for a given distance is reduced to about a fifth (roughly .15 calorie per gram per kilometer).

“Therefore, apart from increasing his unaided speed by a factor of three or four, the cyclist improves his efficiency rating to No. 1 among moving creatures and machines.

www.bikeboom.info/efficiency/: How the bicycle beats evolution and why Steve Jobs was so taken with this fact

I like the space frame. Can you use the trusses as a luggage rack?