Industrial Design student Vojtěch Sojka recently designed this ‘city electric bicycle’ as his thesis project at the University of Technology in Brno (Czech Republic). The school project was developed as a concept for the Czech bike company Superior, who helped Sojka with the production of the prototype. Sojka’s goal with the design was to create a lightweight, sporty e-bike that would appeal to young people in urban environments (not unlike this student designed e-bike that I posted recently). His design features a hydroformed aluminum frame with the motor positioned in the bottom bracket, for a clean look and better weight distribution than a motor in the rear hub. The battery is also centrally located in the seat tube, and a carbon belt drive with a Shimano Alfine hub completes the drivetrain.
Sojka chose to eliminate the seat stays in his design for more than just aesthetic reasons. He explains:
“After trying the to design the frame with standard diamond look with a complicated dropout system, I decided to eliminate the seat stays which enables the user to put on the belt easily. This solution requires a small weight increase (about 200grams), but manipulating the belt is much easier. Also, it enables a little bit bigger deflection of the rear ‘triangle’, which improves rider comfort.”
Speaking of comfort, the wide Schwalbe Super Moto 2.35” tires also cushion the ride. Even though they complicated the design of the short chainstays, Sojka felt like the extra tire clearance was a worthwhile feature work through in his design. His solution features rear facing dropouts and a pivoting brake caliper flange. “Compared to the other solutions, its much easier to set the right position of the rear wheel and the brake – the whole caliper simply moves with the rear wheel, so the brake will be always in the right position.”
The one-piece stem and handlebar assembly is to be made from carbon fiber, and continues the shape of the headtube to unify the overall design. Outer bolts are eliminated with a work gear (similar to Crankbrothers stems) to further the clean aesthetic. Sojka mentioned that the integrated computer for controlling the power of the motor, checking speed, etc., could be replaced with a smart phone mount also integrated into the stem.
In addition to more of Sojka’s renderings, you can see a couple photos of his prototype below (rushed shots taken with a cell phone, but at least they show that the prototype exists). I am always happy to see concepts like this that can potentially expand the market for e-bikes by deviating from the stereotypical ‘electric bike look’. Hopefully, Superior will move forward with the concept, and we will see continued development of Sojka’s design in the near future.
niiice… this design is really effective.
but… motor specifications, battery? images?
It will use a small (750 cm3) cylindrical battery, but Vojtech did not mention the supplier. Perhaps he can comment with further information about the battery and motor that he used as a basis for the design.
Fenders?
Rack?
It’s not often you see a student project for a bike which makes you think, “Mmmm, I’d like that”
Last one was the Strida…
Hi guys, thank you for your comments. Let me answer your questions:
First – the fenders and rack are of course logical question – It would be probably quite expensive to produce bright new accesories compared to the number of sold e bikes. if the bike was produced, Superior would (at this time) choose these accessories from their current offer of from some of their suppliers. I can imagine something really simple and cheap like Bender Fender. So as always, it is primarily the question of money and I wanted to keep the reasonable price
The second question – motor and batteries. Batteries are ussually produced by copmanies like Sanyo, Panasonic and others. The batteries are composed from smaller cells like classic AA battery. In the final shape you can bend them to each others, so you can get varied shapes. Suppliers can produce battery in certain shape, but this production must have reasonable quantity of sold pieces. I rather counted with smaller possibilty of creating special shape, so declared 750 cm3 are for straight cylinder shape, which would be easy to produce. In the case, the cylinder was a little bit bent (similar to the shape of down tube), the battery volume could be bigger – more than 1100cm3.
And the last one – motor. The maximal power is 250W, according to the EU laws. Motor propels the bottom bracket of cranks, similar like Grubber assist, only the powertrain is not in the seat tube. Nearby the bottom bracket is a torque sensor and control unit for assuring the right amount of motor´s help to rider. The diameter of bottom bracket shell is1 20 mm. I think, even a bigger diameter is useful and it doesn´t affect the styling, but the company told me, it was enough for them.
Yes, he has a prototype. Is there a working motor in there? Realistic production price-point? Still think powered scooters and bikes are fish and fowl: better to get one or the other, or both, than lose the advantages of each.
Unfortunately the motor is not there, it is only maquette. Price is a question of the level of used parts. I´m convinced, the price could reach 2500 – 3000 Euro, comparable with the rivals. If you look at comparable bikes and the number of sold e bikes in the world, people are obviously willing to pay for these products. And I can´t agree that e bikes are fish and fowl. Can you ride a motorcycle or car in a pedestrian zone? Sometimes, going to work with bike is faster than with a car and many people can´t get sweat. E bikes have many advantages for a certain group of people, their are not for everybody, but for many customers they really do make sense
How much does the Headshok license add to the price?
I´m not sure, if Cannondale has patent for this type of fork. Probaly, they have rights for the system of Headshock, but many manufacturers are producing similar looking forks and I doubt, they pay Cannondale for it…But honestly, I don´t know it for sure
battery is located inside the down tube, not seat tube, right ?
Sure in the down tube
Nice bike and nice wheels
Rechargeable battery by solar or electric? Also how long is the duration on full charge? is it possible to make collapsible version? Also a suggestion: to help in remote areas where electricity may be a problem in developing countries..solar charge will be ideal. Also it will be nice if the coatings on the frames “glow” in the dark. What do you think?
The battery should rechargeable by electricity network. The estimated duration is about 60 km of reasonable riding – it means that you use also your power a bit, not only the power of engine. The solar charge is great idea, question is how effecitve it could be and also the price, because this kind of recharging system is probably quite expensive. And glowing in the dark is also usable, but I don´t know, if glowing coatings can be made in nice looking colors – maybe it would be more suitable to make glowing spokes or something less visible in the sunshine. And the bike could be made collapsible, but I haven´t designed it with this intention. I believe, for collapsible designs is better to use smaller wheels like Gocycle does. And one notice for everybody – the model doesn´t have engine and battery, so I would not call it working prototype. But I hope, the real working prototype will be available soon and I will give you more inforamtions
I want one now.
I LOVE this bike !!! do it and sell me one !!!!!
From France
mediocre visualization of absolute nonsens:
- not enought space for battery
- rear part of frame will crack
did you done any analysis or simulation of forces actuating the frame?
Vojtech,
I respect your job, but with price of 2-3.000 euro, I do not believe anyone will buy it!