This project arised as a concept for Czech bicycle companySuperior (and also as a diploma thesis for Department of Industrial Design ofUniversity of Technology in Brno, Czech republic). Superior´s main reqiurementwas the ability of using the Carbon Drive belt. Bike should be also moresporty, just an e bike for younger people living especially in cities. Superiorcompany also wanted to manufacture the bike from carbon fibre, but after seeinga few of my skteches, they decided to use hydroforming technology, because theyliked my designs of bikes made from duralumin. Also the bike could be madecheaper than from carbon.
The goal was to design a bike lighter and better to controlthan common e bikes standard. For the best control is ideal to place the centerof gravity to the middle of the bike. The engine is placed inside the bottombracket shell. Of course, it is easier to place it inside the hub, but you willnever get the right weight distribution of the whole bike. Also the battery isplaced nearby the middle – in the down tube. Battery is relatively small – downtube can contain about 750 cm3 cylinder, according to the company´s data, thisdimension could ensure about 50-60 kilometres travel.
The company wanted touse the belt instead of chain (combined with Shimano Alfine in the rear hub). Ithink, the belt is great idea especially for city bikes and it has a bigfuture. Using the belt radically influented the final design. After trying theto design the frame with standard diamond look with compliacted dropouts system, I decided to eliminatethe seat tubes which enabled to put on the belt easily. This solution requiresa small weight increase (about 200grams), on the other hand manipulating withthe belt is much easier and enables also a little bit bigger deflection of therear „triangle“, which brings better driving comfort. The bike aslo increasesthe comfort with using the wide tires(Schwalbe Super Moto 2,35“). It was reallycomplicted to design the shape of rear stays for so wide tires, because thelength of rear stays is very short. I divided dropouts to the moving andnon-moving parts. Left moving part of the dropuout is connected to (of coursein Post Mount standard) flange for the brake caliper. Compared to the othersolutions, its much easier to set the right position of the rear wheel and thebrake – the whole caliper simply moves with the rear wheel, so the brake willbe always in the right position.
Special design solution also deserved the stem and handlebar.They are connected in one piece (this part is made from carbon fibre, the shapeis too comlicated to manufacture it from metal) and contain also small computerfor controlling the power of motor, checking the speed etc. The computer can bereplaced with cell phone troughout the reduction. The stem continues the shapeof frame´s headtube, the goal was to make the stem and frame tolook like one piece. The stem eliminates common outer screws, instead of ituses fixing system via simple worm gear (system similar to Crankbrothersstems). Superior company wants to produce a few stems with different length aand handlebars with different angles of bending to assure a perfect sittingposition for everybody.
For diploma thesis was made a model in scale 1:1, alsoexhibited in Fall 2011 in Bike Brno exhibition. The project was appreciated theDean´s Prize and was selected in the best diploma theses of graduationprojects.eu.