Electric Bicycle with Hydro-formed Frame

This thesis project by Vojtech Sojka for Superior Bikes looks to change the game without straying too far from the norm. It has a hydro-formed 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.

The designer 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.”

Hopefully, Superior will move forward with the concept, and we will see continued development of Sojka’s design in the near future.

Designer: Vojtech Sojka for Superior Bikes

17 Comments

  • Mike Barnard says:

    Very interesting and carefully thought out. Not bad looking when aiming for the assisted bike category. However, the lack of fenders, mudguards and baskets seems to be out of keeping with the genre and significantly limits the potential, especially with the lack of normal attachment points around the seat stays.

    Cheers,
    Mike

  • save that for the hipsters! Who the hell wants baskets on a bmx looking bicycle?

    Design is amazing, love it. Can’t wait to see it hit production.

  • Vojtech Sojka says:

    Thank you for comment Mike. The absence of fenders etc. is already explained at bicycledesign.net For the production version would be probably used commercially avaliable set of accesories for keeping the price reasonable. I agree, absence of seat stays complicates installing the carrier, but it is definitelly not unsolvable. For instance, my friend from Superior designed very simple and light plastic basket placed in the front frame triangle – something like this seems to me to be more convenient for this type of bike.

    And one notice for everybody – the battery pack is placed inside the down tube(the blue part), not inside the seat tube. It was misunderstanding already written at bicycledesign.

  • I tend to agree with Mike. My thoughts regarding use of electric assisted bikes are very utilitarian directed. Towards that end the ability to outfit the bike with reasonable carrying capacity is key. The space in the front triangle would provide some use towards that end but it dies seem a bit small.

    One question – does the battery assembly become a stressed member of the frame? The relatively large cutout in the down tube in that area would seem to need some “help”.

  • I love the lines of this design – simple and elegant.

    I tend to agree with Mike. My thoughts regarding use of electric assisted bikes are very utilitarian directed. Towards that end the ability to outfit the bike with reasonable carrying capacity is key. The space in the front triangle would provide some use towards that end but it dies seem a bit small.

    One question – does the battery assembly become a stressed member of the frame? The relatively large cutout in the down tube in that area would seem to need some “help”.

  • Vojtech Sojka says:

    Good question – my first idea was to make the battery as a supporting part of the frame. But there is a danger, that somebody could try to ride the bike without the battery. So in final design, there should be a small rib welded inside the tube – there is a need to make an adequate slot in the battery pack to fit it together. Of course, easiest way is to make the frame from carbon fibre – you can control the thickness of the tube, so there you don´t have to make additional supporting elements, but hydroforming is still cheaper

  • Mick Allan says:

    All respect to the designer for producing an interesting concept and some great renderings. But what is it actually for? No fenders, lights, stand or carriers (selling them as optional extras doesn’t reduce cost it adds cost, because it’s cheaper to fit these at point of assembly than at point of sale). The frame geometry and riding position is clearly copied from or at the very least ‘based around’ a mid nineties cross country mountain bike. ie: short top tube – long stem, low bar with little back sweep. While this may look good from the point of view of ‘styling’ – none of this is practical. So it’s not a city bike. And it’s not a mountain bike. When a style element affects practicality – such as the lovely curved top-tube which reduces stand-over – we should beware… So what is it? The punch line for me is that it has only one gear. That tells us all we need to know. It’s a design exercise, nothing more and nothing less. Attractive, undeniably. But it’s a confection, a styling exercise. A concept. Please let’s not pretend it’s anything else.

  • Vojtech Sojka says:

    Well Mick, with all respect, you are wrong about it. Front light is placed inside the stem. Tail light is part of saddle – Superior buys saddles from Fizik – they offer tail lights especially designed for their saddles(but I confess- it is not at the renders). Try to read the conversation above – the absence of fenders is explained there and at the bicycledesign.net.
    I really admire you, because measuring exact geometry of frame from render is very close to magic. The frame geometry is very similar to cannondale bad boy´s geo – I really don´t think it is mid nineties cross country bike (top tube length is 580 mm in M size,that is certainly not short). Stem is 100 mm long – also absolutely standard lenghth. And if you look properly, top tube is connected with seat tuber lower than commonly – the standover is lower than ordinary, even with lovely curved top tube. The whole bike´s geometry was designed for making sporty city bike – more comfortable than common mountain bike, but not as lazy as common e-bikes. It offers alternative view, nobody says, it is solution for everybody.
    And the punch line for me is writing about one gear – everywhere is written, the bike uses shimano alfine with 11 speed gear. Don´t accuse me of making styling excercise, because obviously you are telling nonsenses very unbased on truth.

  • Good to see a bike with electric assitance with a beautiful design.
    Could be a perfect bike to go to work during the week and have extra fun in parks, forests in the week end (for the latter, more gears should be better).
    Nice concept, I really would like to see it in stores.

  • cool design and great innovation

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