I tested the Hammerschmidt gearing over several weeks on assorted terrain from Exmoor's muddy slippery tracks to the dry dusty Moze Arabic trails of Spain's Marina Alta ranges high above the Costa Blanca.

From the first I was impressed by the concept; a fully enclosed mechanical gear set that is protected from the elements, operates as slickly and quickly as the automatic shift on a Porsche, but fortunately much more economically priced. Together with the added ground clearance and in this case being fitted to a Marin Quad Attack Trail 150 allowed me to give it everything whatever the trail or obstacles were encountered.

On the trails in the Marina Alta mountains
I found that with the low gear climbing was effortless be it on slippery mud inclines or dry trails and technical climbing (not always my best area) was made significantly easier as a result of the gearing and ground clearance. I was better able to attack the terrain and climb through ascents which previously had sadly defeated me.

I soon discovered that only having a High and Low set up on the front meant that I was shifting though the rear set rapidly and frequently as the terrain changed. Apart from having to get accustomed to the shifter's lack of indicators this didn't spoil the experience.

My fear that dirt, grime, dust or water ingress would result in an on-the-trail technical disaster was soon proved to have no foundation; the Hammerschmidt never missed a beat no matter what I subjected it to. Although there is an odd whining whirring note to the high gear, but this is purely mechanical! Not as my mates insisted, a seperate drive that made me look good! Shifting between high and low speeds is typically Germanic: very positive, definite yet instant making that last minute shift down on the trail much less embarrasing than the clunking chain grinding, calf and quad burning that I do display far too often!

The construction proved tough enough to withstand several hits from hard rock particularly on the dry hard trails of the Marina Alta and my fear of a major on-trail gearbox rebuild was never realised. Under the same circumstances I have lost several teeth in the big ring in the past.

Off road this is a superb piece of technology but the downside comes at the end of a ride coming in on the roads. Without a high enough gear I was like the kid with the Chopper in the Seventies left several hundred yards behind pedalling furiously while the conventionally geared guys spun on ahead.

On the whole, I would buy one!

The Truvativ Hammerschmidt comes as standard on the Kona Coilair Deluxe and the Marin Attack Trail 6.9