Varna handcycles
- navigate to cycles + sprite trike - this one has
simplest construction of any "leaner" I've ever
seen. http://www.apax.ca/ http://www.wisil.recumbents.com/wisil/Wood/delta_trike.htm http://www.ticon.net/~rabender/hpvs/pilot.htmA leaning trike with suspension but no hinges is possible. Assuming two rear wheels, if you have a circular 'leaf' spring with the stub axles attached at opposite points (shown as { and } in the diagram below - seen from the rear) and the rider's seat and front frame attached at two points on top and bottom of the 'spring' (shown as * and * below). Shifting the rider's weight will deform the spring so that the wheels tilt over as shown in the right-hand part of the diagram (use fixed-space font, eg: courier, to view):
If this is unclear, take a look at some
photographs of a model that I recently built of such
a trike suspension.I actually doubt this mechanism can be made to keep the wheels effectively in alignment, but it might be worth a try. However, the 'spring' would probably need to be made from carbon fibre.
My son Paul has built two leaners. The 1st was a FWD delta which was convertible to bike - the purple FWD bike he had at Canberra.
It had a "clutch" which was just disc brake mounted on the frame so that the angle of lean could be locked at anytime, by just squeezing an extra brake lever on the handle bars.
It rode exactly like a "normal" FWD bike which has the cranks attached to the front forks, i.e. takes some time to master, but once mastered can be ridden no hands. And when the clutch was locked, then it behaved just like a trike. It had a lean capability of *45* degrees.
One problem was it would not stay upright at 45 degrees at rest.
However the rolling resistance during tight cornering while leaning was much lower than a fixed trike.
He also built a 2F 1R leaning trike, with one lever to control roll, and one for steering, but this was much more complex, and it was difficult to control the influence of the weight of the rider and machine on the degree of lean, esp. at low speed.
The only advantage he sees for leaning trike is racing on tight circuits where the rules prohibit bikes! Time may tell!
Ian Sims, GREENSPEED
From: Tim Taylor
List-Id: For velomobile enthusiasts <velomobile.ihpva.org>
Zoetech Trike leaning towards fun
I recently had the opportunity to visit Wayne Soohoo near Chicago and ride three different versions of his leaning trikes. I had reviewed all the information I could about Wayne’s trikes including his patent. The background prepared me for understanding the workings of the trike, but only a ride can answer the final questions; what is it like to ride?
The trikes are based on Wayne’s patented lean control system. The system is simple in theory, slightly more complex and subtle in application. The system is comprised of two one directional locks (friction clutches) that allow the trike to be locked in one or both directions of roll at a time. If you lock the right lock the trike cannot lean right, but can lean left. Same for the left lock and with both engaged the trike is fixed in place.
The critical thing to realize is the locks are only used when stopped or at very slow speeds. The rest of the time the trike is in balance just like a bicycle. This is what Wayne call a virtual bike. Wayne has implemented three versions of the trike; an upright two front wheel steer-rear drive, a front wheel steer two rear wheel (single drive wheel) and a low recumbent trike with two front wheels and a rear drive wheel. Each of the trikes mimics the feel of an equivalent upright or recumbent bicycle.
The upright trike mimics a standard bike. It rides and feels like an upright with the advantage of locking the lean capability out so you don’t have to put your feet down or can prevent the trike from falling over in slick conditions. The single front wheel two-rear wheel feels like an SWB ASS recumbent. With the single front wheel the riders view and steering feels like a standard SWB recumbent.
The two in front (tadpole) low recumbent trike is similar to an SWB ASS low racer. This is the one most similar to the traditional tadpoles that many of us ride. This was the trike I had primarily come to see.
The learning curve for the trikes is short, about one minute to get used to transitions from stopped to rolling and back again. You use the left brake lever to hold the trike locked in the upright position. Start pedaling and gradually release the lever. This releases the double clutches and the trike becomes a bike. It responds and feels just like an SWB racer. As you come to a stop you apply both the brake lever (right hand) and clutch lock (left hand). You can ride in this mode like a traditional trike.
The half locks are activated by tilting the handlebars slightly to each side. This allows you to prevent rolling further in one direction, but allows you to roll in the opposite direction.
With the mechanic and details out of the way, what is it like to ride? First my bias, I currently ride a Leitra and in the past rode my homebuilt Cyclecoupe tadpole trike with side stick steering. I tend to be a USS fan for trikes and prefer side sticks to all other forms of steering. My interest in trikes is primarily as functional practical daily transportation. I like speed, but will trade some for safety. I am looking for a test bed to build a fully faired trike on.
The Zoetech trike rides like an SWB recumbent. You can blast into corners faster than any other trike without giving up energy to tire scrub and not worrying about pretzeling the wheels. I rode it on the local streets and the Wayne had me go down to the local school so I could ride on an open paved play area. I would accelerate directly at a corner at nearly 20 mph and at the last second turn as hard as I could losing very little energy and not worrying about rolling over at all. The front parallelogram system helps to absorb the road shock. I rode it over curbs without any problems. A fun trick is to ride with one wheel on a curb and the other off.
The trike is easy to start and stop. Within a few minutes of practice it is a natural process, similar to wearing clipless pedals. The trikes that Wayne has built are prototypes to prove the concept so are not fully refined yet. He is working on solving the lean issues as well as designing a trike at the same time. Anyone who has built a trike knows just one of these is a major project. I rode an alpha version of the trike. A more refined beta has been built since I visited Wayne and I am sure it is even better.
The only negative I had for the trike was the steering feel when riding in locked mode as a true trike. It has that tiller steer feel of an ASS combined with that awkwardness of some of the old upright trikes (two in back, one in front Schwinn’s). You feel like the trike wants to go the other direction from where you want it to go. The last time I felt this was on a Rickshaw trike at Roskilde, Denmark in 1998. You get used to it, but it is not as smooth as a traditional trike. I think this could be designed out with more refinement. The Zoetech is not meant to be ridden very much as a fixed trike so I am sure this has been low on the design criteria list so far.
The positive side is it is a blast to ride. The ability to have a trike that can lean into the corners reduces most of the side loads and energy wasted in corner of a traditional trike. With the half lock system you gain the safety of not falling over on slick surfaces and don’t need to put your feet down. The trike can be very narrow (under 24” wide) so that you can take it through doorways without any problems and the wheels can be light because of reduced side loads. It would be great platform for a fully enclosed velomobile in that you can lock into trike mode, yet get the extra wheel stability for cross-winds and the narrower width of the entire trike.
Overall I think that Wayne’s trike is great idea. As he refines the size and weight of the clutches there is no reason to not see the weight of a complete trike comparable to a standard trike. Looking forward to my next ride on a Zoetech.
From: Barnett
WilliamsDate: Sat, 14 Oct 2000
Subject: [trikes] lean steer trike simplified
List-Id: Recumbent Human-Powered Trikes <trikes.ihpva.org>
Imagine this:
tad pole trike
two front wheel are connected with two parallel cross links with ball joints allowing them to tilt.
The main chassis and rear wheel is connected to the cross links such that it tilts with the front wheels.
Under the seat handle bars are connect to the lower cross link such that they always stay level, while the chassis, seat and pedals tilt.
The handle bars pivot about a vertical axis.
The front wheels have a head tube angle and trail similar to a standard, two wheeled recumbent bike.
The possible result: The trike handles and leans like a regular bicycle, but you can hold yourself steady with the handlebars when stopped, going very slowly, and when losing traction while turning.
This system is unlike the Tripendo and the Zoetech leaning trikes which are more complex. It hit me yesterday, and seemed like a possible functional design for a simple, low cost, narrow, velomobile that corners well.
I do not have the time currently to persue this design right now, but I thought someone on these lists might be interested in trying it out.
I have not seem this concept in my travels which indicates to me that the design is highly flawed and is not worth trying, or possibly has not yet been carefully considered.