There's more than one truth to HPV suspension, but in this article
we'll elaborate on the choices that were made developing the WAW as a single person
ultralight vehicle. General principles from the automotive industry
have limited use for a vehicle with a mass several times smaller than
it's payload, and limited power. On the other hand, the hefty torque on a
trike's rear wheel in cornering makes velomobile rear suspension differ
Large travel suspension on a driven wheel causes a number of undesirable effects I can hardly get into now (more info on many HPV web pages: see pedal-induced bob, pogo, squat, torque-reactive etc., or this article in Flemish about suspension geometry optimization ), commonly summarized under the term 'suspension loss'. Active suspension mechanisms also add considerable weight to a bike - in the case of a three wheeler this extra weight quickly multiplies due to the large torsion moment. Some inherent problems can be solved by a cunning geometry and an increasing number of pivots, but again at the cost of even more weight and complexity.
But you can't be both, is an
ancient saying in the bicycle world. Suspension
losses and extra weight are to be weighed against shock absorption. For a downhill bike, the ergonomic benefit of full suspension outweighs the loss. Fast road bikes, however, will benefit most from a light, small travel suspension, especially on the driven wheel where transmission efficiency matters. This isn't meant for the big bumps but it eliminates road vibration, the main cause of rider fatigue - and nerve damage! A body in effort will happily cope with jolts and bumps it wouldn't
appreciate in rest, e.g. in an automobile. The recent development of curved seat stays for road bike frames are a good example of light and fast suspension design. (or a bad one for that matter, as they're often in carbon fibre, which has a lot of qualities but bending isn't one of them.)
WAW's semi-monocoque base is made of aramid fibre, better known under the
commercial name of KevlarR, in our case TwaronR. Aramid fibre
composite has tremendous
energy absorption capacity (famous by the bullet-proof vests) and we put its elastic and dampening properties to good use. In fact the aramid fibre rear architecture performs
leaf spring and dampener (by hysteresis) in one. Road shock and
vibration energy is diverted and largely neutralised on its way
from the wheel to the rider.The geometry of the rear suspension is such that no compression is possible along the chain line, so the WAW rear suspension induces no loss at all! We believe our Aramid suspension is the lightest, most efficient form of suspension for a velomobile.
these principles, the WAW has been designed and optimized through many iterations over the
years. We aim for the best balance of performance and comfort, of ergonomics and transmission efficiency.