Maxi-Scooters: Vectrix & Volta
I was off the forums when the discussion of the Volta from the show sprang up. There were a couple of disparaging comments about it's design. I think it's likely one of the few practical designs that they can achieve - so I figured I'd like to start a discussion about Maxi-Scooters (as ultimately this sort of bike is what I want to build and/or sell).
So, in the vain hope we can keep this to a function, features and technical discussion (rather than their business model, or whether they're scam artists, or whether it's pretty enough etc) I'm starting this thread...
1) Does anyone know how the Vectrix drives the rear wheel? I'm pretty sure it's not a hub motor (AFAIK, there aren't any 7kW hub motors available). Assuming it's not in the hub then where is the motor mounted? Is it a single gear design or does it transmit power through some form of automatic gearbox?
2) The Volta design with the motor out on the swing arm is a common design for DIY'ers. It was popularized with Bidwell's El-Ninja book. Aesthetics are a personal preference - but from a technical standpoint I'm aware of a number of advantages and one potential disadvantage. On the good side: (1) it's space efficient (allowing more inboard space to be saved for batteries and/or storage) (2) it puts the motor in the air stream for cooling (3) it mounts the motor on the swing arm which keeps it at a constant distance from the rear sprocket (no chain tensioner required). The downside is that it increases unsprung weight - which detracts from the handling characteristics of the bike.
3) Does anyone know if the Vex and the Vol use AC induction motors or brushless DC motors? I believe the Vex system voltage is in excess of 100V (maybe 125V?), whereas the Vol uses 72V. Based on that if I had to make a guess I'd say that the Vex is AC whereas the Vol is DC. AFAIK, AC systems are more efficient.
4) Does anyone know how useful regen braking actually is? It seems to me that this is one of those "must have" items if one wants to be considered a complete solution. However, I wonder how much it extends journey length vs. it's cost (in terms of weight, expense and complexity). On an AC system it tends to add very little complexity - not sure about DC.
5) I notice that the Vol comes with the option of belt instead of chain. This would reduce concerns of noise - however, for those that wish to "tweak" things a chain would give the customer the option of very easily changing ratios (which is pretty popular in the 2 wheel gas world).
I'd appreciate any objective answers to those above 5 questions (especially from the guy from Scotland who has a Vex!)
Now for the opinions: I think the Volta brochure looks very interesting. Definitely a company worth watching. I wonder if they're simply buying a gas scooter frame and converting it themselves - or whether they're having a custom frame manufactured (which would still look very much like the numerous other Chinese gas maxi-scooters). I guess the first.
The Vol was described as under-engineered and overpriced. Not sure how one can say either of those things (but of course it was probably just button pushing). On the engineering front - it will be interesting to see if they can commercialize what's essentially a DIY design. On the pricing front it remains to be seen how they will sell and service the bike. Based on specs (a dangerous thing - but one has to start somewhere) it appears as capable as the Vectrix but for 2/3rds the price.
I think this bike is a pretty exciting development - however, I doubt they'll be on the market as early as they said (Q1 '08). My guess is one year from now... (which would still be a quicker turn around time than the easier to produce Z-20 ;-) )
the Vectrix has a BLDC hub engine, with a planetary gearing built into the same hub. Output power is around 20 kW. And yes, nominal voltage is 125 V.
About the regen function, the lighter the vehicle, the less useful will it be. I have an e-max scooter, and based on how little I use the brakes I guess regen would add perhaps 1 or 2 percent to the range, in normal driving. Regen certainly is much less of value on a motorcycle than on a car. If you plan on building an EV motorcycle, I don't think you will be able to motivate the extra cost, weight and complexity of regen with rational arguments. Don't forget that you will need logic to protect the batteries from overcharge/overvoltage as well.
You could of course imagine an extreme usage pattern where it would be useful. Perhaps if your daily drive is over a mountain and back. Often though, people tend to live up the hill and work in the valley, so when they start the trip in the morning, the batteries are already fully charged and can't make use of the regen.
But every engineer-type of buyer would like to have it. It is such an obvious function for an engineer, we can't stand not having it. Vectrix markets it rather as a cool feature and a convenience thing, you can accelerate and slow down using only one hand - and even reverse.
Thanks for the info rgx. Good thing I didn't have to stand by my guess - wrong on all counts! The gearbox is automatic, right? Do you know how it shifts - or is it some form of CVT?
Yep, I agree with all you say about regen - if it was for the damn Prius nobody would even know about regen braking... ;-)
Now, will someone enlighten me why the swing arm motor design on the Volta is so bad?
Why the enormous motor on the outside is a bad idea?
What is the most costly/essential piece of equipment on an EV....the motor?
And would you want that thing sticking outside, unprotected, abuse by the enviroment, road tar, stray cat or dog (or worse a deer).
I've been riding motorcycle for quite a while. The swingarm and everyting near it, get pretty filthy.
God forbid you don't crash and take the motor out too.
And the number one reason I don't like it. It's just seem like an afterthought.
The no reason why the motor can't live inside except for ease of installtion. The motor on the swingarm is ridiculous.
I even told Mr. Bidwell that when I was working on my El Ninja project.
Well, you ask for it and got my opinions. hehe
Yep, I did ask. Actually the most costly piece of equipment is the battery pack (well if you get a good one! ;-) )
With a well designed cover damage can be minimized. Same deal with dirt - an appropriate cover would fix that concern.
Your number one reason is actually your weakest one (from a technical standpoint!). Hardly an afterthought - purposefully put there because of aforementioned reasons. Plus why hide a beautiful motor deep inside the bike? Your Guzzi hardly hides it's power plant away, does it? (nor should it! :-) )
So, I'm dying to know - what did Mr Bidwell say?
Also, I'm curious - what's your profession? You talked about taking your mechanic to the show and losing business - what sort of repair shop do you run? Just curious.
Thanks for the answers - at the moment I'm still working on my CB-750. But after that, the maxi-scooter idea is still bubbling away at the back of my mind. I'm thinking of an inboard motor mated to the existing CVT - any thoughts on that? Or does it have to be a hub motor and nothing else will do?
for some reason, my quote function don't work,
So I'll reply to John.
There would be advantages to mounting the motor on the swingarm. Mainly ease of installation and cooling.
But it still look like a wart.
Form should follow function. In the exterior mount, it seems like it's just done to make thing easier.
If you want to show off the motor (ie, MotoGuzzi, Ducati naked, etc). make the scooter a naked scooter.
I don't think the chain tension loss is much of an issue. Bikes been powered by sprocket and chain since the it's beginning.
I just think the EV two wheel product is going to migrate to hub motor anyway.
Vectrix could of done it many way and they chose the hub motor.
Mr. Bidwell didn't say much. I just told him it's asthetically not pleasing and he told to read the book on motor mount chapter.
As for what's my profession:
I was a professional musician for many years, stardom didn't happen. work for the family print shop for many years.
Got the riding bug. start my own moto acceessories/service shop to finance my track riding, racing, and just be a plain hooligan on two wheel.
Started looking for alternative mean of transportation once the speeding tickets and gas price went wild in california.
That's how I got here to the V forum.
So I'm setting up shop to start an EV division beside my moto shop.
Been tinkering with gadgets and mechanic stuff since little wee-wee.
I built a race car once (Factory Five AC Cobra replica) to race in the NASA and SCCA series.
All in all, I'm just a speed junky. Nothing special.
I've seen so many beautiful motorcycle, that the lump of motor on the swingarm rubs me the wrong way.
There is a better way to achieve it.
I'm not going to hate anyone mounting the motor that way. I'll even test ride your cycle.
But I won't be happy. not at all.
Good luck with your venture. Don't worry I won't hate you even if you hate swing arm mounted motors. I'm not even sure I am going to do a swing arm mount...
All in all it just doesn't look that bad to me.
The chain tension thing is more of an issue dependent on where you mount the motor in relation to the original gas motor mount. If it's close to the fulcrum of the swing arm - like the original - then you're right it doesn't much matter.
I'm a biker first, EV tinkerer second - much like you. I never raced - but my brother did - I then crashed his race prepped bike on one of the busiest motorways (freeways) in the UK. Ouch! That was many years ago now...
All the best!
the Vectrix gearing is fixed, no shifting of gears. You can see a picture of it here
The reason for the gearing is to keep the size and weight of the motor down. Without gearing, the motor would have had to be several times larger, to produce the same torque and power on the rear wheel.
I am a big fan of hub motors for two-wheelers (which, incidentally, is the only type I have experience from), but there is one major disadvantage: the unsprung weight. So for instance in an off-roader, you might be better off with a traditional engine mount. But not on the swing-arm, though.
I would agree with most here that the protruding motor is exposed to a whole bunch of road hazards, especially if you crash. It would damage the motor, the swingarm and the bolts that balance it, no doubt. I also feel the way it looks, if you corner extremely, it might scrape the ground.
As to why some think why a "beautiful motor" should not be hidden inside the bike....I don't know man, sure looks UGLY to me. I mean, UGLYYYYYYYY!
Vectrix hub motor is the real deal, they got it figured out. Falcon says they designed the bike from the ground up. But it's got a steel frame as far as I know which you could get from China. This is what the bike looked like to me, a simple china knock-off, re-engineered as a EV. But that's just my opinion ;-)