Aerodynamics thread?

[truckerzero]

Here is my 2 cents. On the simulater the most aerodynamic you can get without a full streamlined body is a lowracer and maybe add that tail box and if you did that you could hide the batts and electronics in there maybe even throw on a etec or etec brushless motor and have a very fast and efficent ride just check out the difference of power use on a mountin bike verses a lowracer at 30 mph its alot. with a 220lb rider and a 175lb bike(100lbs batt/25lbs motor/35lbs bike)a moutn bike is 1000 watts, a lowracer 500, and with a tail box 400 @30mph.{ 400watts at 80% effiencicy =500 watts total divided by 30mph=16 watts permile 100lb sla=2000 watts divide by 16 equals 125 miles times 80% dod =100 miles @30 mph }not bad (on paper anyway) uh i mean monitor lol

[recumbent]

These fairings work great, even at peddaling speeds it has noticable difference, and it looks way cool , everybody admires it. They clean-up and finish, if you will, the whole front end the bike, and the laid back comfy seat looks better when the rider is lounging inside. Best designed bike I've ever rode in my life.

[D-Man]

The simplest way to reduce drag would be to simply get in a better position. That means a recumbent, or for us on mountain bikes, an aerodynamic tuck. A "superman tuck" with aero bars would work wonders. Perhaps when my setup runs again, I'll check out what my lbs has.

I can get into a pretty good tuck position. Thanks to my cruiser type seat, I can put my butt behind the seat and rest my hamstrings on the sides of the seat and it works. I've heard some people say that they can't get behind their fairings. I believe I'd be able to get behind any fairing shown above with my cruiser seat. I did make some slight angle changes on the plastic seat using a heat gun and removed some of the structural plastic bracing as it was set up for a 300+lb dude. The plastic now gives more and is more back friendly.

[truckerzero]

here is a picture of the type of low racer that could cut power consumption in half and dramaticly increas top speed what do you think?

[D-Man]

How much does that cost? That might be too low. You might drag your arms on the ground if not careful.

[lazarus2405]

Well, that's a beautiful bike. I bet it'll do 70 easily, 80 at about 4kw. But, I wouldn't want to ride on that at those speeds on anything but a salt flat. Or, I'd hate to see that hit a pothole at any speed.

[truckerzero]

salt flats and set a record for hub motor electric bicycle sounds like fun ps you could weld some battery brackets and a place to put controller and hide it in a tail box like this lowracer

[truckerzero]

if done right and well hidden think you could convince a cop that this is just a very fast human powered bicycle ? lol

[truckerzero]

oh ya were exactly do we draw the line between a electric bicycle and a electric motorcycle ? <30mph =bicycle >30mph = motorcyle or what

[lazarus2405]

There is no line. Here we generally just distinguish based on the frame it's based on, just for simplicity. I think that, to be fair, anything using an x5 is a "motorbike".

[TylerDurden]

We uh... don't really. (Around here, anyway.)

That said, some jurisdictions will draw lines on speed, power, etc. Check your state and local laws.

[kbarrett]

The proper answer to most cops in the US is "20 MPH without pedaling on a flat", and under 750 watts.

Some states are different ( WA is 18 mph for some silly reason ).

Admit to going faster without pedaling or using a hill, and you legally have either a moped ( 30-35 mph limit depending on state ), or a motorcycle ( anything higher ).

[Mathurin]

Some upright bikes by order of speed on road.

Downhill:

Cruiser:

Cruiser_Bike_Whole.jpg (41.11 KiB) Viewed 2395 times

Hybrid:

prod_2232.jpg (40.72 KiB) Viewed 2347 times

Cross country:

seven_solasteel.jpg (51.11 KiB) Viewed 2393 times

Touring:

IFSteelIndependance.jpg (49.52 KiB) Viewed 2395 times

Road:

IFXS.jpg (53.24 KiB) Viewed 2395 times

Track:

grenoble-b-bt.jpg (47.33 KiB) Viewed 2392 times

Note the general trend in saddle to bar drop, faster bikes generally have more of it and the slowest bikes have negative drop. Hybrid before the XC because the XC places the rider a lot better.

BTW, the blades on the BT go for ~3K each.

[truckerzero]

i must be one of the lucky ones in st louis mo except were there is a local law like arnold mo the state law is any 2 or 3 wheeled vehicle with 3 hp or less 50cc or less if gas and 30 mph or less is concidered a motorized bicycle and they have all the same rights as a bicycle like driving on the sholder and such the only differance is a motorized bicycle cannot drive on a pedestrian side walk and a regular bike can

[paultrafalgar]

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.

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!
What d'ya think?

I knew I was on the right track! Me and BMW!
http://www.youtube.com/watch?v=kTYiEkQYhWY

[safe]

The proper answer to most cops in the US is "20 MPH without pedaling on a flat", and under 750 watts.

The speed record for human powered is 80 mph, so I think a 750 watt rule is fair. Such a machine would be totally impractical and dangerous (cars can't see you) so you wouldn't be able to use it for much, but for straight line speed that's the way to go.

[Jay64]

Just do a Rollie Free. Strip down to your underwear and lay flat on your seat. I may just have to try this now that I have my C.A. to see a qualitative difference in the two riding techniques.

[recumpence]

here is a picture of the type of low racer that could cut power consumption in half and dramaticly increas top speed what do you think?

That is a No-com (No Compromises). They are $8,000 and, believe it or not, require some finishing to make them road worthy.

The web master who hosts my bike build page has one. He is coming by this summer for a ride together. I told him I want to ride his No-Com! Heck, I let him ride my E-cumbent.

Those bikes average 5mph faster than a typical low racer with the same rider.

E X T R E M E L Y efficient!

Matt

[Mark_A_W]

How do you go up and down gutters/kerbs on all these recumbenty thingys? Can they manoeuvre through a tortuous pedestrian train crossing? I barely get through on my XC mountain bike..

And how do you weave through traffic when you are so low and can't see over the cars?

I love the idea of the improved aerodynamics...but I can't see them being practical in the real world, at least for me....am I completely wrong?

For me the ideal ebike is a downhill with grunt, and some bar ends so you can tuck

[recumpence]

High recumbents are fine in the real world. Lowracers are the problem. You have to scout the ideal road before you ride it.

Matt

[fitek]

Just ride a short wheel base recumbent. Pretty easy to convert a 20" wheeled kids bike to one. Check out Tom Kabat's bikes at woodenbikes.com. I never had problems with traffic. What my bikes may lose in overall height (which isn't all that much) they make up for in length, weirdness, and by being painted bright yellow. People seem to give a wide berth like it's gonna bite them The long wheel base is definitely tough to squeeze through in tight spots, but the short wheel base handles like a BMX bike.

[Toshi]

Some upright bikes by order of speed on road.

[...]

Note the general trend in saddle to bar drop, faster bikes generally have more of it and the slowest bikes have negative drop. Hybrid before the XC because the XC places the rider a lot better.

BTW, the blades on the BT go for ~3K each.

Amen. Note how my e-bike and my road bike (when on the hoods) are pretty similar in terms of drop from the saddle to the handlebars. I attempted to align these photos such that the wheels were level with the bottom of the image.

[cerewa]

And how do you weave through traffic when you are so low and can't see over the cars?

If you have to ask, you probably don't want a recumbent bike.

Low bikes are not so good for filtering-forward in traffic.

[recumpence]

True, but they are FAST!

Matt

[recumbent]

High recumbents are fine in the real world. Lowracers are the problem. You have to scout the ideal road before you ride it.

Not sure if my bike is considered a low racer, but i sit the same height on my bike as a driver in a car.
Visibility is excellent, eye to eye, ride height.
Riding trails on a weekly basis surprisingly had zero issues, naturally we cannot compete against moutain bikes in thier element.
Cars notice recumbents more i think because of thier weird shape, so your likely more safe on a bent bike.
And i never had to scout for ideal roads, the only problem that irritates me with a 7 foot long bike is maneuvering in hallways in an apartements.
Just clearing up any questions that may arise