The Birk Butterfly has been designed to maintain as far as possible the speed and the allure of fully faired recumbent bikes built solely for racing purposes and transfer them to an everyday craft. The result is a tricycle with a very sporty character that is perfect for everyday life.
The cross sections of the air intakes can even be adjusted while riding in order to avoid overheating in summer temperatures or at low speeds on inclines.
The hood, to be set up when raining, can be transported fixed into the rear casing.
The visor can be fully opened to provide more fresh air in the face during slow ascents or only partially to prevent condensation forming on the screen. Those who want the wind to blow through their hair even more can also remove the visor altogether.
We put a lot of emphasis on ease of entry and exit. Raising the upper part of the casing – supported by gas pressure suspension – ensures:
- easy entry and exit,
- easy loading of the luggage compartment
- easy access to allow adjustment of the seat and bottom bracket
It is also possible to dissemble the entire top part. The open three-wheeled version is great fun in good weather and during leisure time.
The basic lighting and the indicator lights are LEDs and very energy efficient. Where there is street lighting these lights are sufficient for use at dusk. Either one or both 3 watt LED headlamps can be used for cross-country riding.
The drive mechanism works via two intermediate gears, the second of which has three switches. This makes 27 gears together with the 9 gears on the rear wheel, with an expansion from 2.3 to 9.7 meters per pedal revolution.
A special feature of the Butterfly is that the distance between the seat and the bottom bracket can be adjusted. The leg length can be changed in minutes, without having to adjust the chain length, as with other recumbent bikes.
The seat height is adjustable by 6cm and its position can be moved forward up to 5cm to ensure a good view of the track for smaller riders. The moulded bucket seat is wider at points to accommodate the buttocks and hips and in order to provide good lateral support on fast bends.
All wheels are held in check with hydraulically-operated brakes. At the front by lockable drum brakes (for parking) and at the rear by a rim brake.
|Delivery time||Depending on the status of the orders.|
|Total length||2710 mm|
|Overall width||950 mm|
|Total height||1105 mm|
|Seat level||230 – 290 mm|
|Eye level||ca. 950 mm|
|Wheel size||20″ x 1.75 406|
|Weight||Prototype 34 kg|
|Turning radius||8.8 m with no wheel covers
11.2 m with aerodynamic wheel cover
|Luggage room||about 55l volume in the underbody|