Aerodynamic baseline: Motorcycles.

[sheepdog 44]

Sport Rider-Testing Suzuki Hayabusa and Kawasaki ZX-12R aerodynamics in the wind tunnel

They did 6 different motorcycles in a wind tunnel to get both the CD, and Frontal area. They also used a the pixel counting technique of a picture to tease out the frontal area of the bikes. A method that has been used for cars.

I've been trying find a baseline for motorcycles, to estimate what mpg is possible by lowering the CD using the aerodynamics calculator.

Heres one of the better examples:
"Again using a Photoshop image, we measured the frontal area of the '96 RS125, which proved to be 3.40 ft2 (0.316 m2 ), leading to a CD of 0.644" or 2.2sq/ft CDA.

.644 cd is absolutely terrible! But shows how much of an improvement can be made if a 125-250cc stock bike is already getting in the high 80's mpg.

Messing with the CD verifies that some streamliners indeed are capable of 300-500mpg as shown from previous Vetter challenges.

[Grant-53]

Yes, this is similar to a bicycle Cd with the same back angle for the rider. The rider's chest acts as a pump vane. The case of Sendler riding his CBR 250 in a racing tuck with some help from the cargo bags is the first step in drag reduction. The flow behind the rider is critcal as the SR article mentioned. Can you imagine a 50cc scooter with bicycle aero bars and a Yamaha Rifle style fairing slipping through local traffic? Rider protection and 300 mpg easy.

[beatr911]

You hit the nail on the head. That is exactly where the big gain for motorcycles is. The nut to crack is how to do it so people will buy it.

[alvaro84]

Originally Posted by beatr911

You hit the nail on the head. That is exactly where the big gain for motorcycles is. The nut to crack is how to do it so people will buy it.

Good question. I (being a hypermiler!!) can't even stomach racing tuck. An enclosed chassis is out of question too, because that's just another car. A car on two wheels, without a car's stability and carrying capacity.

A non-winter commuter car with superb FE...? That's good to have, but not for a new vehicle's price.

And the 'ideal' bike (for me) can provide good aero sitting upright, lets me look through my helmet's visor (not an additional windscreen), doesn't block the view in any direction, lets me help with my feet if needed, and even push the (not too heavy) bike. Is this possible at all...?

[redyaris]

Originally Posted by alvaro84

And the 'ideal' bike (for me) can provide good aero sitting upright, lets me look through my helmet's visor (not an additional windscreen), doesn't block the view in any direction, lets me help with my feet if needed, and even push the (not too heavy) bike. Is this possible at all...?

People will slowly get accustomed to streamlined motorcycles on the road as they see more and more of them. I can only think of 6 to 10 people in the world who build and ride streamliner on the road...

The first versions to be sold to the public will look like Vetter streamliner's with a trunckated tail, that ends within the first foot [30cm] behind the rear wheel. The width at the back will be about 20cm, the width of a licence plate, the seat will be quit low; around 65cm.

Lots of design details will need to be discovered before the public will buy in...

[renault_megane_dci]

I don't believe we will see streamliner bike any time soon.
Honda is just beginning to sell reasonably powered (read at least efficient engine) bikes. (NC 700)
You can bet every competitor have a thorough look on their sales.

If they don't meet sales expectations, that's an other decade wasted ...

There is so match to win on the engine already, just by tuning it less power oriented and it is pretty much free and will bother your customers much less.
Unfortunately it is one step at a time and it is based on what people actually buy.

Now you have to wonder how many of us there are out there.

Efficient bikes will eventually come from regulations but the price might be deerer.

I believe the streamliner breakthrough will come with electric bikes since they are already a revendication from their user as their right to think differently and it might add so much to their range.

[beatr911]

Originally Posted by renault_megane_dci

...a revendication from their user as their right to think differently and it might add so much to their range.

Well said. It is a pity that the lemmings that subscribe to the Harley Davidson (or most other rider type) mentality believe they are thinking differently.

At least in the USA, the motorcyclist community is among the most conservative that I can think of. Put someone on something truly different like an aero bike and the motorcyclist community just doesn't know how to handle it. Being different, it gets a thumbs down.

Now, isn't that ironic.

[alvaro84]

Should I feel like conservative scum for not wanting to sit in an utterly uncomfortable cage when riding a motorcycle? I see and know all the motives behind, I can even agree with them, yet I want something not a car. Sorry about that.

And it kind of hurts, because I always have to fight that very conservative crowd who always take their time to criticize me for the very dangerous practice of coasting...

See, I totally embrace efficiency until the point I have to give up too much for it. I'm much into alternative driving techniques. Some streamlining is very okay. But racing tuck is beyond that point (just imagine riding in that position for like 16 hours). Cruiser position is better, but simply not comfortable on the long term. Recumbents scare me sh*tless. Enclosed bikes are not bikes anymore, just unstable cars never to take on frozen roads.

[Frank Lee]

Speaking of "enclosed cars", I've been meaning to comment for several months now that it appears our two resident home-built recumbent streamliner bikes have fallen off the map just when it looked like real progress was happening. What's up with that?

[cRiPpLe_rOoStEr]

Regarding motorcycle design, I must admit I'm quite conservative. I can't sacrifice some comfort for extreme streamlining, altough I've already considered to built an enclosed motorcycle with a side-car.