The ZEV Company thinks the other guys are doing it all wrong.  And not without some good reasons…

ZEV has built up a solid line of electric scooters with some remarkable claims.  In spite of some early skepticism about the relatively unknown (to me, at least) company “domiciled in Nevada” with demo facilities at the airport in Waynesburg Pa, I’ve now been having lengthy exchanges with ZEV and am gaining a newfound respect for the thought behind the products.  Here were my big questions.

Do you have a hub motor?  Answer: Yes.

I’m already a big fan of hub motors, for all the reasons that ZEV uses them.  They live in the wheel.  When your motor is in the wheel, you get more space for batteries.  You get a low center of gravity.  The C/G of the wheel/motor configuration sits squarely at the axle, which is, by the image above, right where the Enertia motor sits, too- so no basic advantage there- until you figure the batteries.  With the motor out of the way, you can run the batteries where the motor is on other bikes- as low as possible in the frame.

Take a look at the place I guessed the C/G is on both bikes…  with that cool battery/frame setup on the Brammo you’re getting batteries from just above the motor, right up to the headset.  Keep in mind the batteries are your heaviest element in the entire system, even lithium…  If you’re trying to keep the C/G low, this ain’t the way to do it.

Now, look at the ZEV- this is the Trail version, but the other scooters are based on the same layout.  The batteries lie as low in the frame as they possibly can, so the C/G is remarkably low.

Does this make a difference in the handling of the bike?  This is an emphatic “Yes”.  Just imagine, you’re zipping along at a good clip- 70mph, say, and you muckle on to the front brake.  On a bike with a high C/G, that mass is going to try to keep going, and in that case, is going to try to keep going right over top of the front wheel…  that’s how you do a front wheelie.  On a bike with a low C/G, it’s going to try to do the same thing, except it will have nowhere to go.  Instead of lifting the rear wheel, it will plow the mass right through the front wheel- actually increasing the control and force on the front brake.

Not to mention cornering and other handling issues…  Low C/G is Good C/G.

Here’s another cool thing about hub motors.  They can be very large, in terms of their diameter.  The ZEV hub motor has a full 11.32″ of outside diameter, which translates to huge torque.  Huge torque means the motor is working less, it’s not heating up so much…  there’s a cascade effect that happens with motors due to the buildup of heat when you load them.  Heat up a conductor, it loses the ability to conduct.  The more you load a motor, the hotter it runs.  The hotter it runs, the less efficient it is at conducting through the windings.  That makes it have to work harder.  …which makes it heat up more.  If you run a bigger motor that’s not working as hard, you’re avoiding the entire cascade of Physics.   With a bigger diameter motor you’re also getting more surface area- which translates to more cooling.  AND the wheel itself acts as a heat conductor- more cooling still.

Oh, one more thing.  No power loss through transmission.  There’s no chain, no sprockets, none of the power loss (albeit slight- most chain drives are in the neighborhood of 75% efficiency) and not to mention you’re not carrying or spinning that weight, either.  The wheel in a hub motor is as close to being an actual part of the motor as is physically possible.

So what’s not to love about hub motors?  Unsprung weight.  Unsprung weight is the part of the wheel and suspension that has to respond to the road surface.  More about mass, actually, if you have very little unsprung weight the suspension has less mass to fight so the bike is more nimble over bumps.  When you put a 50+ lb motor in the wheel, that’s a big mass to deal with on the bumps.

The ZEV answer is that it’s not going to make any difference at any normal speed on the street.  Until you’re going over, say, 75mph, the effect of increased the unsprung weight is not noticeable.

This is something I’d have to feel to believe.  I don’t think you could possibly make this claim for an off-road bike, even a street bike on, say, a dirt road at 30mph or a Boston side street, but maybe on my favorite stretch of smooth open road, yeah, OK.  Unfortunately, a dirt or potholed road is a much more likely place to run a scooter like this.  We’ll see…  ever the skeptic, but I’m keeping an open mind.

One other question I have on the scooters.  The wheels.  More specifically, the diameter of the wheels…  they’re running a 13″ rim, vs the 16″ on the Zero and an 18″ (front) on the Enertia.  Most scooters run a smaller wheel- 8 and 10″, I’m pretty certain a Vespa is 10″.  Now, OK.  Having seen my wife dump her scooter with 8″ wheels in loose dirt, riding at 30mph (and breaking her wrist in the fall, no less), I have some pretty well-founded issues with small scooter wheels in terms of safety and handling.  ZEV’s reasoning behind the wheel diameter is that there’s not much difference between a 13″ and a 16″ wheel, that they’re bigger than most other scooter wheels and that they allow a lot more room in the frame for batteries.  

These may all be valid points, but I’m still a little queasy about it.  You’re talking a bike with a top speed of over 80mph in real-world riding, by all reports.  I’ve felt high-speed wobble on a bike, and it’s not a pretty thing.  In fact, on more than a couple of motorcycle crash videos on YouTube you’re seeing badass sport bikes go into a high-speed wobble.  These are bike built to handle at speed…  and it’s just plain ugly.  I’ve tried to scale the shots above to show the difference accurately, have a look at the difference.  Now, after we’ve picked up all that sweetness with a low C/G, I keep thinking that when you muckle on those brakes, and you have all that mass trying to drive itself through your front wheel, and you have is this smaller wheel to handle all that force.  ZEV points out that the tires are wider than the Brammo, and ultimately it’s the tire outer diameter that matters- you can see here, it’s not all that different…  but still.

My final question…  Why a scooter?

In the rest of the world, scooters are huge.  ZEV said their scooter sales in the US to non-US sales are 1:18.  Considering the US attitudes and the challenges of the suburban car-oriented infrastructure compared to, say, the typical European village, it’s easy to see why a scooter is a much easier sell in other parts of the world- except in the urban centers of the US.  In particular, the electric scooter.  It’s no wonder China is one of the biggest electric scooter market- or why Vectrix was focused on Europe and not the US.

Conclusions?

ZEV seems to have started from the ground up, and designed an electric vehicle from a completely clean slate.  Rather than deciding to build an electric motorcycle, they decided to build a two-wheeled electric vehicle that makes the most sense- from an engineering standpoint.  It happens to look like a scooter.

Does it make sense from a motorcycle riding standpoint?  That remains to be seen.  Suffice to say, the only way you can ride one is to fly to Philly, and, tight as my time and money is right now, I’m checking flights.  (Now, don’t be shy about using that PayPal button over on the sidebar, baby…  you know, if you really want some answers. :) )

Here’s the big question.  If Brammo wanted to hit the scooter market so much, and a scooter configuration makes so much sense… then why not build a scooter?