A quick start, then a light press of the thumb and the shift ring glides upwards: The slim Velo de Ville pushes forwards with direct power as soon as your thighs increase the pedal pressure. In a narrow housing between the bottom bracket and chainring of the test bike sits the new Kappstein Doppio, a slim planetary gearbox, dirt-proof encapsulated, with two gears in a ratio of 1:1.57. My chainring suddenly has 61 teeth - purely virtual. It's actually 39, if you count.
The new Kappstein-Doppio gearbox: two-speed turbo from Gotha
In Gotha, Thuringia, the young company operates its own CNC milling machine park, which otherwise spits out sprockets for singlespeed bikes, components for the Flipfree hub with switching between fixed gear and freewheel or a pedelec motor with integrated 3-speed gearbox. The six planets of the Doppio gearbox distribute the forces over a larger area than other gearboxes and the inner workings are made of hardened steel. All this promises a long service life. At the moment, a mileage of 15,000 kilometres can be guaranteed. But these are only the initial results of the in-house test bench tests. Testing also takes place in the BDR team's cross bikes under competition conditions.
The young company is currently approaching wheel manufacturers who would like to install the gearbox in their standard wheels. Such a Doppio wheel would cost around 400 euros extra. The first bikes should be in the shops from the start of the 2017 season.
Red light, quick stop. With my right hand resting on the traffic light pole, my left thumb presses the Doppio shifter back to "1". I quickly shift into 4th gear on the Alfine 11 with 39 teeth as soon as the light turns green. When downshifting while travelling, however, you have to interrupt cranking briefly to engage first gear. Once you have learnt this, the two-speed is an efficient and low-maintenance addition to any hub or derailleur system.
Plus:
- Quick start-up aid,
- generous overdrive;
- Robust construction, unobtrusive, lightweight, dirt-protected
Minus:
- Gear jump relatively large;
- To downshift, the crank must stop briefly
