Reflections on the potential of human power for transportation

Wednesday, December 23, 2015

The Velotilt: a Pedal-Powered Commuter Trike for a Bike-Friendly World




 
In 1980, after the Vector trikes shattered the Human Powered Vehicle Championship speed records, people began to believe that human-powered vehicles could travel fast enough to be viable transportation vehicles. The ultimate nod to HPV recognition was an illustration of a Vector trike on the cover of Scientific American magazine. The age of pedal-power had arrived.


 
Well, not really. Vehicles like the Vector were low to the ground, and, as a result, not very visible in traffic. Their extreme streamlining kept the wheel-track narrow so high-gee turns were not possible.
One vehicle, the Cyclodyne did come close to being a practical commuter vehicle. A tadpole-layout trike with front-wheel drive and steering, the Cyclodyne could be pedaled over 30mph by a fit rider. Its practicality was compromised, however, by its width. It was too wide to fit in a 36” bike lane next to a car lane, but not fast enough to keep up with 35mph traffic in the car lane. A noble effort, but a dead-end.

Now to some extent, the lack of a fast commuter vehicle may be as much a problem with a lack of suitable places to ride them as the vehicles themselves. The really fast vehicles (>30mph) are low to the ground for minimal aerodynamic drag. Such vehicles are difficult to see in traffic. On the other hand, dedicated bike paths, where vehicle visibility may not be an issue, have 15mph speed limits that prohibit high-speed vehicles. (Riders on the Burke-Gillman trail in Seattle have received tickets for exceeding 15mph.)

If there was a bike-commuter infrastructure that separated bicycles from car traffic and allowed for very-fast pedaled vehicles, Wim Schermer’s Velotilt would be the vehicle to ride.

 

The Velotilt is a delta trike where the front wheel is driven and the rear wheels are attached to beams that can pivot. The act of pivoting allows the Velotilt to lean into corners like a bicycle.

 

 The degree of leaning is limited so the vehicle cannot tip over statically. The beams are interconnected by a mechanism that causes one beam to move down while the other moves up. The middle link in the mechanism is composed of a sector of an arc. As the mechanism moves the sector rotates. This sector can be clamped in any portion of its extremes of travel and thereby lock the leaning.

 

In addition the entire mechanism can translate, allowing both beams to pivot together. This motion is resisted by a mountain-bike shock and provides suspension for the rear wheels.
The rider’s legs wrap around the front-steered wheel. The cranks are located in front of that wheel and the wheel is driven through a very pricey Rolloff 14 speed internal-geared hub.

 
All three wheels have disc brakes but in all the photos, the rear disc are lacking calipers and actuation cables.

Commercial vehicle weight is expected to be 55lb. The vehicle height is approx. 40”.

The Velotilt body and the rear-wheel pants make the vehicle extremely aerodynamic. Schermer calculates that it will take 150W to do 40mph. Bicycling Science 3rd Ed (D.W. Wilson) estimates that an ultimate HPV would require 200W to do 40mph, so the efficiency of the Velotilt is indeed impressive.
 
An optional 750W motor could help propel the Velotilt to 60mph for a duration of over 2.5 hours, but where would you ride it? Too low to mingle with car traffic and too fast to mingle with regular bicycles.

Possibly, one could transform the high efficiency into something other than raw speed.
For example, the Velotilt might be able to sustain a constant 15mph on solar power alone. Or the vehicle could be made higher than its current 40"to be more visible in traffic. As it stands, I believe some evolution remains in the Velotilt’s future.

 

Some of the pictures in this post came from Adam Ruggiero’s article, “The Future of Human-Powered Transport is a Trike” in the March 18 issue of GearJunkie.
Hephaestus

1 comment:

  1. I agree that it needs to be taller. I gave up my Catrike Villager (already one of the highest tadpole trikes on the market) for a recumbent bike simply because I want to be the same height as the driver of a car, so they can see me and I can see them.

    ReplyDelete