Recumbent tricycles may make use of steering systems that differ from those of conventional bikes. In more conventional, upright bike designs, you sit up or lean forward to grasp the handlebars and steer. Recumbents allow you to recline against a back rest, leaning in a manner that places your feet near the front wheel and your hands farther away. Some recumbent bicycle and trike designs may make use of elongated handlebars, which stretch back from the front wheel to reach your hands. Another steering system, which makes use of your arm position while reclining in your chair, places the steering mechanism under your seat. By steering from under the seat, you are able to keep your arms in a more natural position at your sides while you steer.
Reasons for Direct and Indirect Steering
On recumbents, notably on tadpole-style recumbent trikes, which have two wheels in the front and one in the rear, under-seat steering is the common choice for steering systems. This form of steering utilizes handlebars that rest below the seat height. This is because you mount the trike by standing ahead of the seat, straddling the body and then sitting backward into the seat. Over-seat handlebars can get in your way when mounting and dismounting these vehicles. While over-seat steering makes use of a large handlebar connected directly to the front wheel, under-seat steering is accomplished by a linkage, which makes use of either a direct or indirect steering mechanism. Exactly which mechanism is used depends on your needs, riding style and skill level.
How Direct Steering Works
In direct steering mechanisms, the handlebars are composed of two short pieces that attach directly to the kingpins. The kingpins are connected by a single linkage, and there is no central pivot under the seat. Of the two types of steering mechanisms, this is the simpler one, as each steering grip is connected directly to one of the wheels at a right angle to their axis. Each of your hands controls its respective wheel, which are kept in alignment with each other via a cross bar.
Mechanics of Indirect Steering
There are several variations on the basic design of indirect steering mechanisms. Some utilize horizontal pivots, but a central vertical pivot with links to the hub carriers is more common. Two linkages protrude from under the seat, where the steering pivots, and connect to the kingpins, which hold the front wheels and brakes. Your steering motions exert force on the center point. This force then transfers to the wheels' respective tie rods. In this manner, indirect steering is similar to conventional automobile steering.
Advantages and Disadvantages of Direct and Indirect Steering
Direct steering boasts advantages over indirect steering in that the mechanism is much lighter, which diminishes the vehicle's total weight. The simpler design also lends itself to more ease of adjustment than indirect steering, but it transmits more road vibration from the front wheels to your hands.
Indirect steering mechanisms create a slower steering sensation, as they require larger movements to accomplish a steering angle comparable with their direct counterparts. This allows for easier steering at low speeds and more precise control at high speeds. Indirect steering systems are more difficult to adjust for sensitivity, but they can often be adjusted to alter the width or angle of the vehicle's turns.
Tadpole and Delta Recumbent Trikes
Typically, when you envision a trike, you think of a vehicle with two tires on a rear axle and a single tire in the front. Trikes with this arrangement are called delta trikes. The delta trike may make use of traditional handlebars, which sit above the seat and in front of the driver, or it may employ either direct or indirect under-seat steering, depending on your preference. Trikes that have two wheels in front and one in back are called tadpole trikes. While these trikes can utilize over-seat steering, direct and indirect under-seat steering are far more common.
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