WOKKBIKE WORKBOOK # I THE WtiEELCH(ilK TKJKE By Jason Moore If you can only travel in your specialized wheelchair, and your friends or family are going for a bike ride, you usually sit at home. But human-powered technology offers an alternative. Most wheelchair cycles are single-wheeled attachments that use a standard chair as the front of the vehicle. The stress of being part of a tricycle, however, is too great for many wheelchairs. Other trikes, such as the one built by Neatworks (see Lees Stables, p. 52), build a solid chair and attachment as a unit. But the makers of this combination are in Europe, making the chair hard to customize at a distance. The wheelchair carrier pictured on this page places the chair on a sturdy steel frame on the front of the trike. The design is based on traditional front-load hauling tricycles — a workbike modified to carry special cargo. The trike was built by Jan VanderTuin and Human Powered Machines of Eugene, Oregon (see article on The Center for Appropriate Transport, page 54). He was aided by students in his class on Workbike Design and History, taught in conjunction with the University of Oregon. The students used old bike parts and teamwork to help build the first prototype, learning about bike design and manufacture, while doing service for a member of the community. The owner of the trike had some pressing issues that led him to seek an alternative to available bikes. He wanted to use the custom wheelchair he already owned, both because his daughter needs to recline slightly due to poor blood circulation, and because he had already spent $5,000 on it. He had tried carrying the wheelchair in a trailer in the past, but there was too much flex in the connection between the bike and the trailer, and a crew was required to load it. He points out that the bike has greatly increased the range for daily outings with his daughter. Before using the trike, they ventured out in only a one mile radius during their daily walks. Now, with the added mobility, their domain has a ten mile radius. They can cruise to the nearby river bike path, or to any number of new destinations to keep the outings interesting. They can even put the trike in their van and travel to new riding spots. The whole family can go on long bike rides now, whereas before one person always had to stay with the young woman. Technically, the bike posed some interesting challenges. The greatest was the head tube angle, which is actually at a negative angle when measured by traditional diamond frame standards. To determine this, an adjustable head angle was built into the first prototype, and the correct angle determined by test riders. The dynamics of a front loading trike are so different they almost can not compare to those of a standard bike. It has two sixteen inch wheels in front and a twenty four incher in back. The small wheels help lower the center of gravity, making the bike more stable. The wheels are all plastic, for strength and ease of maintenance. Braking duties are handled by two rear brakes: one drum brake and a cantilever. Both brakes are on the rear because the front of the bike has two wheels, and because the pivot point of the bike is in the center. The owner of the bike says the set up works just fine, and there have been times when he has been glad to have both brakes. To put his daughter in a wheelchair on the bike, he stands behind her and pulls her up an aluminium ramp into channels which stabilize the wheels. The channels each have wheel stops to hold the chair in place. The wheelchair’s brakes are applied, and two simple pedal toe straps attach the wheelchair to the frame. Although simple, this maneuver does require a strong person. So how does a front-loading-articulated-wheelchair- carrying-tricycle ridel Quite well, actually. On flat ground, and at low speeds, it handles much like a regular bike. But one shouldn't try fast turns: it wants to jackknife like a truck. Also, if you turn too sharply, it’s easy to hit your feet on the frame. It is a tricycle, so it feels tipsy on off-camber turns and slopes — the third wheel prevents it from leaning like its two-wheeled relatives. An intriguing characteristic is its tendency to veer to the side of the pedal downstroke. If you push hard on the right pedal it veers to the right, and vice versa. This feature is more amusing than annoying, and can be easily compensated for. The bike was rideable a mere 90 days after its conception, at a cost of around $1,500. Not bad compared to a six month wait the owner of the bike had for a custom attachment for a wheel chair carrying trailer. VanderTuin hopes that when the design is perfected the plans of the bike can be shared with others so that it can be built and used elsewhere. A third generation design is planned, and undoubtedly the small improvements needed will make this good trike great. VanderTuin can be reached via Human Powered Machines, PO Box 1005, Eugene, OR 97440. (503) 343-5568. RAIN Spring 1993 Volume XIV, Number 3 Page 53
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