31 Mar 2015

31st March 2015 No Question leaning ATB trike with differential.

The No Question bike builders have put together another interesting and sophisticated trike. Leaning mechanism, hub gear, differential and balanced disk brakes all on a welded aluminium frame with one hand control:


The hub gear provides chain crossover to the differential behind it without needing exposed dérailleur gears and a vulnerable rear changer hanging down. Though a rear changer is arranged here as a chain tensioner for the chainset it is sensibly lifted almost horizontal to maintain ground clearance.

A leaning mechanism makes good sense for an ATB trike because it should help to reduce the extraordinary acrobatics required of the trike rider on rough ground.

Another view showing the differential between the split shafts of the rear axle. Despite the complexity of the tubing, the weight must presumably remain low thanks to the aluminium, construction.

Trikes will always faithfully follow the landscape regardless of ruts, camber and rocks. Stability is always marginal if the rider's centre of gravity  falls outside the triangle formed by the wheel patches. The degree of body lean needed is often far too much to keep all three wheels safely on the ground. Due to the wide track it is impossible to apply enough pressure through the handlebars to ride on two wheels. Beyond a certain point the trike will simply fall over. Usually throwing the unfortunate rider "downhill" to the ground. Often from a considerable height if they were already standing on the pedals.

A normal touring /racing trike is a very poor beast to ride on the rough stuff. It takes very little camber before it is completely impossible to hang far enough off the uphill side to remain stable. The top tube is usually the major barrier which limits the rider's compensating lean. This is the reason that trikes need specialist oval race tracks with very little camber on the turns. It being completely impossible to reach sufficient speed by pedalling alone for centrifugal forces to allow a trike to ride the usually steep banking. While having no banking at all would severely limit cornering speeds. It being very difficult to pedal hard and lean 'inwards' at the same time.

Tuesday 31st, 33F, 1C, overcast and windy with 2" of snow plastered to everything! April 1st joke a day early? It was already white when I got up an hour ago and has been snowing hard ever since. The previously forecast 25m/s gusts have now been reduced to [only] 20m/s [45mph] at around 18.00. It never was remotely that windy but I'm not battling with wet slush just for the sake of it.

Click on any image for an enlargement.

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