With the first TTXGP completed and the eGrandPrix about to get under way, we’ll likely see many designs surfacing for electric racing motorcycles. Luca Bar, who we’ve seen here before, sent over this one of his E-Carver.
The design mounts a 130/65-16 tire up front and a 190/55-18 on the rear wheel that has a hub mounted motor. The riding position is nearly horizontal with the feet placed to the rear, since no shifting is required, and the legs partially protected from the wind by the battery pack which is formed around them in the front. Most of the technology incorporated in the design is either current or what Luca expects will be coming soon.
I think the design is interesting but I have two reservations, the first is the difference in front and rear wheel sizes and the effect it may have on handling. The second is the foot position. I understand the ability to place the rider’s feet to the rear could be advantageous but, at least as this design is shown, a misplaced foot at speed could lead to rather uncomfortable results, though extra protection for the feet to keep them from getting tangled in the wheel should be pretty easy to add.
There will certainly be a lot of other designers adding their ideas to the electric racer category, we’ll have to see what turns up.
Link: Luca Bar
Also by Luca Bar:
Link: Ducati D-66
Link: BuellRod
pabs says
hub motors are perfect for bicycles with rigid suspension and even suspended bicycles due to their small size and weight
for bikes they are a non starter as the added unsprung weight so far back would not be best positioned for handling
Ceolwulf says
^ I was about to point out the same thing … a hubmotor is no good for something that requires both strong power and excellent handling.
As a design though, it certainly looks good and some of the other ideas are good. It’s a challenge to completely rethink something like a motorcycle given an entirely new type of propulsion (well, not that new, it’s still wheel-driven etc) – one is so used to taking certain design aspects for granted because that is how it’s always been done with a combustion engine.
Marvin says
I quite like the look but it almost needs full on knee shelves so that is where you take the weight of your body, it looks like you would be fighting slipping down and bumping you chest into the “tank”. Just out of interest does there come a point when you are too low on a raceing bike? I thought with a lower centre of gravity you have to lean further to keep the same speed? eventually some part of the bike will touch or the tyres will give up won’t they.
Tin Man 2 says
I wonder what the Hub motor weighs? If it acts as a brake and power source it may not be heavier then a conventional wheel with chain and sprocket. The designers used the Buell front brake so they are curtainly aware of unsprung weight.
Thure says
This is obviously only an exercise in design, not an enginered usable concept. A hub mounted motor with the power levels suggested by the tire sizes and the braking system would cause so much jacking of the swingarm, that it would be considered unrideable. GP bikes would surely have experimented with a footpeg position like this if there was any advantage to it whatsoever.
Jimmy says
I think the hub motor is a great design for street apps’ but for racing I would think that a hub generator to put a little power back to the batteries at certain speeds would be better. Then run the motor thru a transmission for better acceleration and top speed. The foot peg location is no good for racing,anybody that knows about racing set-up knows that the pegs must be directly below the hip for applying weight to the pegs for steering and to lift your butt off the seat with-out putting input presure on the handlebars.Just my thought’s,I should be careful how much I say,I am working on these idea’s for my own e-bike.
trickMETRIC says
A note about the front wheel size:
Safe braking is the reason we typically see motorcycles with the same or larger diameter wheel in the front. If the center of gravity of the bike is higher than the front axle, during braking the rear end will come up fast. Uncontrollable stoppies. Not fun.
nobody says
Stoppies are caused by decelleration’s relationship with the CG and the front tire’s contact patch. The axle’s placement relative to the CG has absolutely nothing to do with it.
Motors become generators when they are controlled accordingly. Do you really want heavy braking at the back end?
Some hubmotors have planetary gears – make one with a band clutch and you have a multi-speed hubmotor.
frozen prairie says
Hi guys,
As long as we’re experimenting, why not put a hub motor in the front wheel as well?
todd says
I’m working with some hub motors right now. The size of the one on there looks to be about the equivalent of 2.5 HP (if running @ 72 volts or so).
I do think you would want the swing arm pivot to be a bit higher than shown to control squat and straight to reduce flexing.
The one important idea that it does touch on is that your feet do not have the same constraints as they do now, what with no braking or shifting responsibilities. This may not be the best location for them but it is an important revelation regardless.
-todd
todd says
The cable on the left hand lever is peculiar, especially when relying on the rear hub for a rear brake. Maybe there is some other function?
-todd
Buellman says
Other than the unsprung weight issue, why wouldn’t you also put a hub motor on the front and go the all wheel drive route? While we’re at it, the swing arm pivot no longer needs to go aft of the drive sprocket (because there is none). What about an unequal length A arm rear suspension which lengthens the wheelbase on compression? Assuming that you can get enough power down to max out on the CG under acceleration (wheelies) you should be able to get enough motor braking to max out on the CG slowing down (stoppies) reducing the size the batteries and eliminating the need for conventional brakes. Now your only constraints are rider position and steering geometry.
pabs says
hi tin man 2
buells permiter brake doesnt make engineering sense for the application, its a false economy, ie any advantage of gripping th rotor further out from the axle and thereby have a smaller caliper is negated by having the unsprung weight of the rotor further away from the axle because both inertial and steering effect are both negatively effected ie its harder to turn in
buells perimiter brake make no more sense than the oil in the swingarm or gas in the frame from an engineering perspective, from a style and marketing perspective however they make perfect sense so i champion both schools ! depending on the brief
anyways not to rain on your parade just a summary 🙂
Paulinator says
What is the greater evil? unsprung weight or gyroscopic inertia??? If I knew that I could form an opinion about rotor diameter and such.
Also, I know there are seat height restrictions, but I don’t recall anything about chin height. Has anyone built a helmet with groung effects?
nobody says
The TTXGP rules specify 1 wheel drive – which is really stupid. Hence, no dual hubmotor bikes.
nobody says
Since the expert(s) are here on perimeter brakes (and everything else), I really would like to know:
Why did Braking stop making their perimeter setup?
Why didn’t AP Lockheed sell their version, which was tested both in racing and traffic – almost 20 years before Buell patented it? You already knew that, right?
How does the diameter of the front wheel/tire have any effect on the diameter of the rear wheel/tire? If so, then why doesn’t the difference in WIDTH matter?
Why do I care about theoretical comments about an imaginary bike from people who have never designed, built, or raced a bike in their life and probably never will?
Jimmy says
just for your info/ NOBODY/ I race I wrench and I build motorcycle’s and have over 30 year’s experience with motorcycles!
FREEMAN says
I like the look of the front end and that’s about it. It’s a bit fugly. I want to see more than just the battery box. Somebody needs to design some eye candy batteries for these bikes. Kind of like what the Motoczysz guys did with their sketch of the e1pc.
FREEMAN says
Dual front perimeter brakes?
Buellman says
Pabs, while you are welcome to your opinion, I’d argue that the reduce inertia of the lighter wheel which doesn’t need to be built strong enough to withstand torsional loads are significant.
I’d even take this a step further and install permanent magnets in the perimeter disk and implement a linear motor AKA bullet train and eliminate the hub motor entirely. Hmmm.
nobody says
Jimmy,
Thanks – glad to know people here do things. Best of luck with the e-bike.
FREEMAN says
The E1PC batteries.
Luca Bar says
Hi Everybody,
it’s always nice to read comments on “the kneeslider” because I can read opinions of people who really rides and work with motorcycle.
In this project I tried to rethink about motorcycles from the beginning, I really wanted to design something far from conventions but still “on the ground”.(no wings or magnetism flights) That was the challenge.
I agree with most of you about the hub motor today, but in my opinion in 5 to 10 years the tech spec of electric motors will be very different from now, different materials will be experimented and weight will be reduced, the same will be for the swing arm torsion and so on. Nothing to say about the riding position, but who knows how you’d better sit with this strange wheels??
What you are seeing and writing about is just a vision of the future from a designer who believe that humans will always race and will always take risks to be the first.
The big deal will be to increase the emotional and the ecological factors.
Thank you all for spending time to discuss on my work.
Luca Bar
Kenny says
With perimeter discs as a structural part of the rim, a dual set up, the weight difference is reduced. If a race bike say like this was designed with a wheel of some sort of carbon-ceramic compund(assuming it could be used as a structural material) I imagine there would be huge weight savings. Admittably there is still a larger moment to deal with when the weight is concentrated at pretty much the farthest point from the axle. I’m assuming that is why Buell’s have always used 6 or 8 pot callipers with their perimeter setups. But they must be doing something right because I have heard nothing but praise for the Firebolt and Lightning in regards to their handling.
Jimmy says
re Luca Bar I like you ideas very much and I am glad to see someone thinking outside the box in a good direction.you are so right lightweight motors are very close along with high output for size.People like yourself are the future for our sport,keep up the great work.
Bill says
Surely the rear tyre is far too wide for a machine with less than 30bhp ? The ideal proportions should be that of a 125cc racer (albeit beefed up to take the extra weight).
Skygod Mike says
It appears that your knowledge of bikes exceeds your knowledge of parachutes by several orders of magnitude. I wonder what JSM would say about your use of that fine intellect.