The Greenspeed Anura Quad
Why a four
Now one of the main features of the Anura is that it is built high, simply to allow easer mounting and dismounting, and to allow a better view in traffic. Plus it is built narrow to allow easer access through gateways and doorways. Thus while it was more stable than expected, some people would like more stability. So how to improve stability without making it wider or lower? Answer - add another wheel! And because there is little weight on the front of the Anura, and the new front wheels are of a lighter pattern, there is not much more drag. Yet the stability is improved by a whopping 50%!
There is also, I believe, an improvement in appearance, in that the machine looks more "complete" and we have had a lot of favourable comments from people who have seen and ridden the machine. They like the look of it, and say it is like riding a Go Kart with pedals.
Technical Design Features
Anura Quad neatly over comes these problems by using the delta configuration (two rear, one front) as a basis. The standard Anura Trike has 75% of the weight on the driving wheels, which means superior traction, plus it means the both drive wheels stay in contact with the ground over uneven surfaces, and the differential balances the drive to the both rear wheels. So like the Anura Trike, and unlike tadpole trikes, the Quad gives good traction in winter conditions on slippery ground. Furthermore the steering geometry has been designed so that when one front wheel leaves the ground, the other seamlessly takes over all the steering control. Having 75% of the weight on the rear wheels also means that the two rear wheels disc brakes are powerful enough to hold the trike on the steepest of hills, and are adequate for normal, everyday use. So there is no need for front brakes, which saves weight.
Like the Anura trike, the Quad frame is made from 7005 aluminium alloy, so it is light and strong with the same 300 lbs rider weight limit. Leg length adjustment is made the telescoping the front frame inside the main frame, so shorter riders can take advantage of a shorter machine.
Plus, like the Trike, the Quad can be used to tow an Anura Trike, to form a Quad/Trike tandem, but care must be taken, on the corners, as the Quad is more stable than the Trike.
Ian Sims C.E.O. December 2011
with optional rear fenders and rack.