Rickman Trials Prototype

RICKMAN TRIALS PROTOTYPE

CYCLE WORLD ROAD TEST

More Development Time Should Make It Competitive.

RATHER THAN DESIGN an all new frame and running gear for their prototype micro trialer, the Rickman brothers opted to use as many components from their Micro Metisse motocrosser as possible. The end result of this parts merger is not a competition ready trials mount, but it does show enormous potential nevertheless.

In spite of this parts sharing, the Rickman trials prototype appears to be an all new design. The characteristic fiberglass side panels and body components are totally absent. Gas tank, fenders, and chain guard are polished aluminum and give the machine a businesslike appearance.

The machine is slim and the seat is minimal, allowing the rider to move about freely to maintain the precarious balance that is trials riding. Because of its 195-lb. weight (with a half tank of gas), the Rickman is easily controlled, but handling is impaired somewhat and the ride is unnecessarily harsh because the springs in the Metal Profiles Limited front forks are too stiff. However, substituting lighter weight fork springs and then experimenting with oil viscosity On til the proper damping characteristics are achieved would cure this.

Still, in situations which require a great deal of body english, such as steep off camber downhills and narrow rocky gullies, the micro trialer is easier to handle than heavier 250-cc trials mounts. Steering is light and precise, but it is not overly quick. In fact, with the addition of a more deeply padded seat, Rickman’s prototype could do double duty as a trail bike. Flat out trips around a TT course or an occasional blast across the desert are not out of the question either.

Attacking uphill sections is a different story. The 125-cc Zundapp engine is willing enough, if the rpms are kept up, but this is difficult on the prototype because the overall gear ratio is too high. Lowering the gearing will cure this for the most part, but low rpm torque will still be lacking.

The 125-cc Zundapp engine is a good choice though. It has a relatively broad powerband, produces 15 bhp at 6500 rpm, and has proven to be virtually indestructible in competition. The main reason for this durability is that the cylinder bore has been chromed, and chrome bores resist wear better than conventional iron liners.

The remainder of the engine is completely conventional with a single intake, two transfer, split exhaust port arrangement. Inordinately large cylinder barrel and head fins, now a Zundapp trademark, prevent overheating, even in extremely hot weather. Equally desirable for competition is the crankshaft and connecting rod assembly. The crank rides in ball bearings and the rod is fitted with needle bearings at both ends.

The five-speed, constant-mesh transmission shifts on the left side with a conventional one-down-four-up pattern. Ratios are ideally spaced, but gear changes cannot be rushed or the unit will overshift into a false neutral between gears. Fortunately, it is possible to have this shifting mechanism modified, which completely eliminates this annoying trait.

Those desiring to compete will also need to modify the footpegs. They are well placed, but are fiat and smooth. Even in dry weather, they don’t provide an adequate foothold. More preferable are pegs of the non-clogging variety with either a knurled edge or rough top surface.

Of interest is the expansion chamber/silencer system which passes over the engine in between the frame tubes, where it is completely out of the rider’s way. An expansion chamber has been cut off where it would normally taper down into a stinger. A silencer, consisting of a slotted reversed cone that is capped with a steel plate drilled full of !4-in. holes has been fitted into the end of the pipe. An end cone with two 3/8-in. ID stingers completes the system.

The frame is identical to the Micro Métissé unit. Its construction is typically Rickman with flawless bronze welds and nickel plated Reynolds steel tubing.

Instead of a single toptube, three small diameter tubes pass from the steering head to a crossbrace at the rear of the gas tank. The outer two toptubes curve downward at this point and are welded to the double cradle at the swinging arm pivot. Two additional parallel tubes, welded to the outer toptubes, support the seat and provide the upper shock absorber mounts. This subframe is braced by additional tubing which runs from the swinging arm pivot to the rear shock mounts.

As on other Rickman products, the chain is adjusted at the swinging arm pivot. Mark III and Mark IV Métissés, however, use a series of numbered washers with offset holes to relocate the swinging arm, while both the trialer and Micro Métissé use a conventional slotted tab and through-bolt arrangement. The disadvantage over the washer setup is that the swinging arm can now get out of alignment.

Since an airbox is not used on the prototype trialer, a conventional rear fender is fitted to prevent the dirt thrown forward by the rear tire from clogging the air cleaner. The positioning of the rear fender, however, is too close to the tire, both at the top where it bottoms, and at the front where it will encourage mud clogging. The front fender, as well, could stand to be moved out slightly farther from the tire as a precautionary measure.

Trials pattern tires are fitted-a 4.00-18 at the rear and a 2.75-21 in front. Steel rims are laced up to Rickman ultra light alloy conical hubs which keep unsprung weight to a minimum. A frame-mounted speedometer is driven from the right side of the rear wheel hub. Rim locks, installed on both the front and rear rims, allow the use of low tire pressures without spinning a tube.

Both front and rear brakes are superb. Lever pressure is light and rear brake pedal travel is not excessive, even though the rear unit is cable, instead of rod, actuated. Neither unit grabs and no fade should be encountered, regardless of what the machine is used for.

Rickman’s prototype trialer isn’t a winner. Not yet. But then few prototypes are. If development is continued, it should be a lightweight to be reckoned with, and a more stylish mount will be difficult to find. [Ö]

RICKMAN TRIALS