Amateur aerodynamics

Jim Gerwing

Jim Gerwing

Well-Known Member
Paint it red

Shakespearean aside:
Did he say red?
Knowest he not that red be accursed upon the site Cruzbike?
Yeah, if she be made of red, her faults will ne'er be known.
But what of the greenest hue?
Green? Cast it off. None but fools do wear it.
Blue eyes and blue skies. . . Make it blue.
And pinch the maids as blue as blueberry.
Methinks that leaves only yellow (like the Beatle's submarine).
Some painters transform the sun into a yellow spot,
others transform a yellow spot into the sun.
 
Eric Winn

Eric Winn

Zen MBB Master
Jim, I thinkest thou

Jim, I thinkest thou needest more ventilation in thine workspace.

tongue_smile.gif


-Eric
 
Jim Gerwing

Jim Gerwing

Well-Known Member
Details

Last year I tried a similar set up but could not control the bike on rollers. During the outdoor season I discovered that it was possible so I fitted a couple of variations and this one seems to work: hand hold behind and within the upward swing of my knees (yet does not interfere with maximal flection (knee bend toward the body).
For materials I used the original V2 handle bar cut to @14 inches (they were damaged in a fall anyway). The uprights were cut from an old set of aerobars that had about the right bend in them. The brake levers are the backward sort, the cable feeds back toward the bar. The shifters are not optimal as their arc of action is still exposed to the channel that permits forward vision.
This set up allows a grip that is straight and without fittings pinching into hand or wrist. My upper arms are tucked into my sides. From my avatar you can see that the length of my arm was catching the airflow.
I'm considering how I might yet clean up the air flow around the arms/body which will still admit steering.
Note in the background of the preceding picture the low tech pace calculator.
 
Eric Winn

Eric Winn

Zen MBB Master
That looks cool Jim. Can you

That looks cool Jim. Can you ride it on rollers? I've ridden on the road with my hands in close to the handlebar clamp and it feels pretty twitchy to me there. I'm not sure if I could ride on rollers that way.

-Eric
 
Jim Gerwing

Jim Gerwing

Well-Known Member
Yes, but

Last year I would have said, not yet, because I tried a similar set up that I gave an honest try but 'twitchy' would have been an appropriate description. With another season of experience added I adapted quite quickly.
I have been inspired by such YouTube sensations as the unicyclist on rollers, the guy drinking a glass of wine whilst blindfolded (on rollers) and the flevobike guy riding no hands in a figure eight (but he wasn't on rollers, so everything has not been done yet).
 
Eric Winn

Eric Winn

Zen MBB Master
Bar feel

How does the bar feel in your hands? Do you notice the cable housing under the tape?

Have you done long distance or duration with that setup? E.g. do you find an interest in finding a different hand position after longer periods?

I'd like to see some photos of Charlie Ollinger's latest version. He has something sort of along these lines.

-Eric
 
Jim Gerwing

Jim Gerwing

Well-Known Member
Cables, hand holds, stamina

I ran the cables so that they lay under my fingers. From recent experience, cables under the palms are uncomfortable. I have two hand holds (close to the horizontal bar and out nearer the brakes, as well, I can either wrap my thumbs around the handles or, alternatively, 'sissy-fist' style. Not highly variable but my indoor sets are 10 minutes max and outdoors 30 minutes max.
 
MrSteve

MrSteve

Zen MBB Master
Looking Good!

For the skeptics, this is easier -by far- than riding hands off the handlebars.
When I sprint for speed, when my bike is pushing through the air above 25 mph
or so, I grip my bars in the center.
Like Mr. Gerwing says, this hand position pulls my arms out of the slipstream.
And, with practice, you really can generate a lot of power without any upper-body
help.

I'll just go out on a limb here and point out that these narrow bars may not
work too well with most first-time MBB riders.

;)

-Steve
 
Jim Gerwing

Jim Gerwing

Well-Known Member
Paper/cheese cloth/white glue

I tried a few lay-up options with the above mentioned materials and found that a 2ply/cheese cloth/2ply/cheese cloth/2ply regimen gave a fairly robust product that feels about right. The test piece pictured above is not wetted with as much glue as I applied to the actual fairing, so I've got a stiffer result even more to my liking. I was careful to pull off sections as I went along else I would never have been able to remove the fairing from the plug. I used Vaseline as a release agent which worked quite well.
I didn't mind the pace of this phase. I could invest about an hour and a half at a time. Total build time for the lay-up being about 40 hours over two months. The mold itself took about 50 hours. Cost of materials so far about $200-250. (Getting my handle bars to their present 'good enough' state has probably cost me $600-700.)
As the fairing cures, I'm leaving it on the mold but I'm noticing some uneven spots, puckers and wrinkles. Not enough to put the project in danger of incompletion nevertheless smallish imperfections that deviate from the shape of the mold, the design of which, I admit, is whimsical yet measured for inside clearances. Different materials next project?
A next step is fittment to the bike frame which will yet allow ingress/egress and operation. From experience with past projects like this one, I anticipate some challenges, attachment issues, shall I say?
 
Charles.Plager

Charles.Plager

Recumbent Quant
O.k.  If you're going this

O.k. If you're going this far, you might as well sock the darn thing.

This is so much fun to watch this develop!!! :D
 
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