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
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.
ReplyDeleteDear Hephaestus,
ReplyDeleteI love your blog, it is probably one of my favorite blogs of all. I agree with you an all your criteria for commuter HPVs and would love to see such a design be built and even sold.
Moreover, I have learned so much about HPV design and history when reading all your posts that I am always looking forward to new articles by you. I hope you are doing fine and will continue to publish in this beautiful blog!
Cheers.
urac
Nice blog!! Thanks for posting it. I love your blog, it is probably one of my favorite blogs
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