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[NoiseBoy]

Looking at Terry's bike has got me thinking.  Aerodynamics obviously play a critical role in range on a motorcycle but most of us don't want to be riding a fully faired Vetter bike.

I'm a keen cyclist and spend a lot of time and money making my bike lighter and friends think i'm mad paying big bucks for something like a saddle that is only 100 grams lighter, but add that to the pedals, brakes, chain and wheels etc. and before you know it you are saving kilograms.   Applying this theory to aerodynamics could we make a meaningful difference to range by making small changes to the bike?

Hopefully ReverseTrike will chip in some expert opinion but I'm thinking things like filling in gaps at the front between battery box and fairings, filling in the frame tubes, providing something to improve airflow over the riders legs and so on.  My understanding is that aircraft-like shapes aren't all that great on a bike because you are riding in turbulent air and actually 'tripping' the air with winglets and the like can improve aerodynamics significantly.

Unfortunately I can't test my theories because the longest reasonably straight road here is just over 2 miles long!

[BrianTRice@gmail.com]

Well, I just added a windshield which probably makes a small difference in aerodynamics, but the real question is whether a statistically good measurement can be made.

(Pictures at my previous post: here http://electricmotorcycleforum.com/boards/index.php?topic=3226.msg16888#msg16888)

[kingcharles]

Going on a diet and loose a few kilo's is probably cheaper and also better for your health...

[benswing]

We have a lot of gains to be made in the aerodynamics dept.  I spoke with Terry about this quite a bit and even had a chance to chat with Craig Vetter on the subject, too.  Here are some ideas:

1)  Terry and I discussed adding battery vs adding the full Vetter fairing treatment, and assuming they cost the same and gave the same increase in range, it would be a better idea to get the fairing.  That way you don't have to charge extra battery capacity, you use the same battery capacity to get longer range.

2)  I asked Craig if he would consider making a fairing that has good aerodynamics, but still looks good.  His answer was basically - over my dead body.  So he's not going to do it, but that doesn't mean someone else can't.

3)  Just found a website that makes custom fairings and some of the bodywork looks good.  Terry basically doubled his range with the full bodywork, so we can probably get a 40-60% gain with better fairings that doesn't look like Mork from Ork's spaceship.  Here are some examples that range from egg-shaped to sexy curves:
http://www.airtech-streamlining.com/landspeed/landspeed.htm

I'm hopeful that Zero will start streamlining their bikes a bit, but expect it won't happen just yet.

[BrianTRice@gmail.com]

Going on a diet and loose a few kilo's is probably cheaper and also better for your health...

I'm doing that, too. Lost 5 lbs so far, looking forward to another 5. After that, I'd just convert to muscle mass. Honestly, I just expect to switch to more street-oriented rain tires for a tiny mileage bump.

[NoiseBoy]

Going on a diet and loose a few kilo's is probably cheaper and also better for your health...

With all due respect that is a terrible argument. If Rider A loses 5kg and rides a stock bike but rider B loses 5kg from dieting AND makes his bike 5kg lighter he has a significant advantage. Besides I am 5ft 10" and weigh 54kg. Do you still think I should lose 5kg? 

Just with a few small mods not even a fairing you could gain 3-5% easily and that is the difference between making it to the charging point or pushing it the last 2 miles.

[emotofreak]

Couple facts for you to munch on...

1. Body position is the #1 factor in determining aero drag on most bikes. On a stock 2013 Zero S, I use about 15kw at 70mph in "standard" riding position. In a full-tuck in my synthetic (bulky) jacket and pants I can get it down to about 11kw. Biff can get under 10kw in his leather jacket. Oh yeah, he's skinnier, by a lot, than me It's not comfy, but it can be done, and directly translates into about 1/3 more range at highway speeds. This can all be verified by anyone with a 13 bike and the app on a handlebar mount. It's kind of fun to play around with body position and such and watch your power change real-time. Don't crash while watching your app though

2. As above, leathers have better aero.

3. Weight makes almost no perceivable difference in straight/level power consumption. Sorry but it's true. Now being "wider" does make a difference

4. You can buy/install after-market windshields and fairings. Lots of cool stuff on http://www.airtech-streamlining.com/

5. In general, filling in all cracks/crevices and trying to make one smooth monolithic surface will translate to better aero.

6. Disc wheels. Might gain a few percent by covering the wheel spokes with solid disks. Might also make the bike "spooky" in cross-winds.

[benswing]

These are the kinds of aerodynamics I think would be beneficial.  Some are from the Airtech landspeed page.  I wish there was a way to compare the coefficients of air friction on each model.  Would be sweet to add some mileage to my Zero!

[WindRider]

Be careful about where you stop airflow... I think that the air scoops on the front of the bike are meant to throw air over the motor and controller so stopping that air flow could lead you to overheating the motor or electronics.

[protomech]

The biggest improvement from fairings is probably not range, but rather effective charge speed.

Cutting highway power consumption by 1/3 - which will require aggressive streamlining, a la Terry's bike - not only improves range by 50%, but also improves effective charge rates by 50%.

[Justin Andrews]

Weight makes almost no perceivable difference in straight/level power consumption. Sorry but it's true. 

Changing mass has an appreciable effect, but its harder to adjust than drag, and drag does tend to scale well as Speed through Air is the real killer in terms of power requirements.

[emotofreak]

With approx 100lb weight difference on the same bike, I could perceive no difference in power to sustain 70mph as reported via the Zero App. I agree there must be some small change, but I think it's less than 1-2%.

I have a TRI4 fairing just begging to go on a Zero.



Actually, I already had it on a zero. Now it needs to go on a "new" zero.

[protomech]

It's probably below the noise floor of different throttle positions, changes in elevation, varying wind and crosswinds.

Here's my old guess at punching parameters for the 2012 bike into ecomodder's calculator.

At 70 mph the estimate is 10.8% power used to overcome rolling resistance (based upon weight and drivetrain losses), the rest is used to fight the wind.

Total power estimate is 13.5 kW from the motor controller to maintain speed.

Adding 100 pounds increases power requirements by about 2% to 13.8 kW.

[benswing]

Which fairings from the airspeed website do you think would fit on a 2012 Zero S? 

Are there specific fittings or sizes I can look for?  Or can someone look at the fairings and list the ones that would fit on a Zero?  I'm legitimately interested in putting an aerodynamic fairing on my bike, but only if it will help my road trip efforts.

[emotofreak]

It's probably below the noise floor of different throttle positions, changes in elevation, varying wind and crosswinds.

Here's my old guess at punching parameters for the 2012 bike into ecomodder's calculator.

At 70 mph the estimate is 10.8% power used to overcome rolling resistance (based upon weight and drivetrain losses), the rest is used to fight the wind.

Total power estimate is 13.5 kW from the motor controller to maintain speed.

Adding 100 pounds increases power requirements by about 2% to 13.8 kW.

As usual, your analysis sounds spot-on.