It happened again this year on the downhill course in Willingen: A protruding boulder rips the rear derailleur off a rider's frame. No point in cranking on, no point in winning, trophy and prize money gone. This would not have happened with Bergamont's new "Big Air G9" geared bike, where small cogwheels in an aluminium housing shift gears well protected from boulders and branches. Suntour calls its gearbox "V-Boxx". The Japanese company is the first to launch a gearbox for mountain bikes that is not based on the Rohloff gearbox. Instead, the gear train resembles a motorbike gearbox. The cogwheels run into each other at the front and are separated by an integrated clutch when changing gear. The rider does not notice this. The gears engage smoothly with a click when stationary or travelling at full speed.
PRACTICAL TEST
In principle, the "Big Air G9" is similar to Bergamont's "Big Air Enduro". The geometry is almost identical. Only the dropouts have been fitted with single-speed mounts for the extra-wide hub and the main frame carries the mounting points for the gearbox. The Fox "DHX 5.0" provides 180 millimetres of suspension travel. A Rock Shox "Lyric" works at the front. Braking is provided by Magura's "Louise FR" and grip is provided by Schwalbe's "Muddy Mary". This means that the 19-kilo freerider is ideally equipped for the bike park. We tested the first ready-to-ride bike there. The course, full of berms, drops and tables, demands an agile, manoeuvrable bike. Bergamont's "G9" fulfils these criteria surprisingly well. The low centre of gravity allows enormous cornering speeds and the bike is very stable in the air. The suspension responds extremely sensitively, which is also due to the low mass on the rear wheel. The gears shift precisely, you just have to get used to the grinding noise of the teeth. On the other hand, the range of the nine gears is enormous: even steep ramps can be cranked up in the lowest gear. All in all, despite its weight, the "G9" is not a downhill bike, but rather a fun freerider with potential for more. Perhaps a geared enduro bike?
FACTS
WEIGHT: ACTUAL: 19 kilos / TARGET: 17 kilos
SPRING TRAVEL: 180 mm
LENGTHS: nine
PRICE: 3000 Euro
DETAILS BIG AIR G9
The supported single-joint shines with well thought-out details. (see pictures on the right)
HOW IT WORKS
Suntour supplies the heart: the 9-speed gearbox.
Suntour's "V-Boxx" resembles a motorbike gearbox. The so-called "spur gear" gets its name from the fact that the teeth of the nine different gear wheels are located on the outside, i.e. at the front of the wheels. A type of clutch temporarily separates the gears when the handle is turned so that another gear can be engaged. This works both when stationary and under load. It doesn't take long to get used to the shifting logic of the Suntour "V-Boxx". You shift through the nine gears as if you were using a "grip shift" twist grip. At around 600 per cent, the gear range even exceeds the 27 gears of a conventional derailleur gear system (519 per cent) and the 14 gears of the Rohloff hub (526 per cent). This means that cranking is no problem even on steep sections. The transmission is driven by a conventional Isis crank. The power is transmitted to a cogwheel via the gearbox. This then drives the rear wheel via a pre-tensioned chain. Thanks to the unchangeable chain length and the ideal pivot point of the rear triangle around the drive sprocket, drive influences are fundamentally excluded.
