I really like this new “Cafe Racer” styled electric motorcycle. I don’t always write about every electric motorcycle I find, but I’m writing about this one, and here’s the information I could find out about it. The guy who designed it is Taras Kravtchouk. He lives in Brooklyn (New York), and he is the Co-Founder and CEO of Tarform motorcycles. He unveiled the first concept prototypes at the NewLab innovation center in the Brooklyn Navy Yard in October of 2018..
Years ago in the United Kingdom, men on motorcycles (who were too young to buy beer) were discouraged from hanging out at the pubs that are common in the UK. One place that didn’t seem to mind them is the coffee shops, so these young men formed a sub-culture that became associated with the cafes. I don’t need to explain in detail why a young man would want a used middle-weight motorcycle. Let’s just say that…they are cheap to buy, they get good gas mileage, and young women seem to like the young men who have motorcycles.
Taras Kravtchouk is a designer from Sweden, and he likes the Cafe Racer style. The pic above is an example of one of his earlier projects, a 1973 Triumph that has been made-over in the CR style. Many makes and models have been used to make a CR, but the classic base model is a vintage Triumph or Norton from the UK. Front disc brakes perform well, but when style is the primary consideration, front drum brakes are often used, and mounted on spoked rims (instead of modern cast wheels).
The dual rear shock style also seems to be preferred, along with using a chain instead of a shaft. Some have even swapped to a tiny 12V battery that is then hidden inside the seat-hump (seen below), in order to emphasize the de-cluttered look. Of course, this may require you to have a reliable kick-starter, which many modern motorcycles no longer have.
It is common among CR enthusiasts to hand-make their own light-weight “hump” seat, which copies a type that is used by racers. I recall the first time I rode a truly powerful motorcycle, and when I tried to open it up with full throttle, I found myself almost sliding off the back of the seat. I was only able to stay on by grasping the handles, which of course is a big problem when you are trying to let off the throttle. A bike that I had later was using a seat where the front half was “cupped” for the rider, and it gave me just enough butt-support that I no longer grasped at the handles when accelerating hard. If you have a powerful CR bike, the rear hump is not just for decoration, it really helps.
This style of seat may look uncomfortable for long rides, and it is. The people who started this trend would hot rod their bikes, and then test them by racing from one coffee shop to another. Of course there are motorcycles that are much more powerful than an air-cooled 2-cylinder Norton or Triumph, but those models were antiquated just enough that they could be bought in rough shape for very cheap. Here is a 7-minute video about the Cafe Racer culture that I enjoyed (click here).
A “Triton” was a hybrid that was Frankensteined together from a salvage-yard Norton “featherbed” frame and a Triumph engine. The Norton frame was considered to be the best handling frame you get at the time, but the Norton engines were widely regarded as unreliable. Triumph engines were readily available at affordable prices, and a young builder could easily find a variety of hot-rodding parts to buy one at a time, as funds allowed..
Where to put the motor?
If an electric motorcycle has a large direct drive hubmotor embedded in the rear wheel, that is the easy way to make an electric bike. Doing that may be the least expensive and most reliable system, because it does not rely on the chain and sprockets. A hubmotor also frees up the entire frame for the controller and battery. This may be a vital consideration for many lower-speed conversions, because an affordable gasoline donor-frame is not designed from the ground up to fit the battery, and the shape may likely restrict the size of the battery.
However there are two drawbacks to using a hubmotor. First, the motor spins at the RPM’s of the wheel, which is much slower than the most efficient speed of a motor.The high torque of an electric motor at low RPMs is one of its strengths, but keeping the motor at lower RPMs will drain the battery much faster.
The second problem with hubmotors is that it increases the “un-sprung” weight. Although having a responsive suspension system adds comfort to the rider, the most important reason for keeping the moving suspension components as light as possible is that it helps to keep the tire touching the road for as much time as possible when you hit a bump. A heavy wheel is resistant to respond to the bump, so it transmits more of the hit to the frame. Then, once the heavy wheel starts moving up, it will take longer to get it back onto the pavement.
Even with all of this affecting the ride of a motorcycle, I would still consider using a hubmotor for a lower-speed 2-wheeler, like a 45-MPH scooter.
The motor on the right (in the pic above) is mounted on the swingarm. Although this is not ideal, it is MUCH better than having the weight of a motor in the wheel. Having the weight of the motor located more forward (near the pivot) significantly helps the suspension, but then again, it also requires a chain and sprocket set. The chain adds another adjustment and wear component, but it also allows the motor to spin many times faster than the wheel, which helps wheel-torque and efficiency. Every choice is a trade-off of compromises.
The first thing I do when I see a “new” electric motorcycle, is look where the motor is located. The best place to put the motor (for the quality of the suspension), is in the frame, and mounted so that the swingarm pivot is in-line with the shaft of the motor. That way, when the swingarm moves up and down, the chain doesn’t change the amount of tension on it. Tarform mounts their motor at the pivot of the swingarm, which is the absolute best place to put it.
Is their Motor from Zero Motorcycles?
There is a very slick promotional video on the Tarform website, and they only briefly show the motor as just a glimpse through a fog. I immediately thought that it looked a little like the 75-7 motor from Zero motorcycles. Many motors of this size have three separate motor phase wires (instead of a fatter single bundle), but this motor locates them in exactly the same way as the Zero motor. The aluminum case fins have a distinctively squared outer-perimeter, made by varying the length of each fin…just like Zero.
Below is a motor-shell from a Zero 75-7 motor. Compare the two, and see what you think about it.
The second major component of a drive system is the controller, and it appears to be identical to the Sevcon Gen4 size-6.
The pic above is from the Tarform website, and the pic below is the Sevcon Gen4 size-6 from the Sevcon website. I find it curious that Zero ALSO uses a Sevcon Gen4 Size-6 controller…Do we have a winner?
A while back, I read that Zero was also marketing itself as a plug-and-play drivetrain supplier. The first place where I was able to verify that another company was using a Zero battery, controller, and motor is the Sine Cycles cruiser (seen below). If you go to the Sine Cycles website, they proudly declare that they are happy to use the Zero drivetrain.
I don’t have absolute proof that the Tarform drivetrain is from Zero, but I doubt they developed their own drivetrain given how they are such a recently-started company. This is actually good news. As you may have read from what I wrote about Zero motorcycles (click here), I am very impressed by their performance. I don’t want to sound like too much of a fan-boy (can an old man be a fan-boy?), but Zero makes the best battery pack in the business, and their drive-system is a brilliant design that’s taken over ten years to reach its current state of excellence.
I wouldn’t take the Tarform Cafe Racer on a long ride, but it wasn’t designed for that. It’s a city bike, and I suspect it performs quite well at that job. However, the news is not all sunshine, puppies, and unicorn farts that smell like roses on a fresh spring morning after a rain. If you like this style, and you want an electric drivetrain…a Tarform CR will cost about $18,000 (with first delivery around late 2019). That’s $1500 more than the top-of-the-line Zero SR.
That actually wouldn’t be horrible if it was a full-sized SR battery, but the range is listed as 90 miles. I am fine with a 90-mile motorcycle, because I live only 22 miles from work. However, It’s gonna be a hard-sell to retail a 90-mile electric motorcycle for that price.
The weight of the battery is located right where it needs to be for the handling to work well in a City street-fighter, so that is another plus. I hope they succeed, partially because I just like it, and also because I want other companies to see that it’s a good bet to use a Zero drivetrain rather than spend money and time to develop their own.
Written by Ron/spinningmagnets, November 2018