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Interim update and request for opinions
Although I have been making steady progress, there have been no major “breakthrough” moments as many of the larger jobs are done, and there seem to be a large number of smaller jobs which prevent me from starting a test ride.
One particular issue is that of gear selection, and I would like to invite suggestions, comments and criticisms from anyone with relevant engineering experience. Here is an outline explanation of my plans, followed by alternative solutions.
The gear mechanism is the stock Honda C90 design, normally operated by a “up and down” foot pedal. Because of its location (under the seat) this will require a “remote” means of operation. I have chosen to make this selection mechanism hand operated, and prefer that it can be operated by either hand at handlebar height.
My first choice was to use a cable operated “push/pull” system because of its light weight and simplicity of engineering. However I have reason to reconsider the design because of other systems that I am planning to use on the bike. For two other systems (leg aperture openings and parking stand deployment) I need a powered operation. My options are mechanical, electrical, hydraulic and pneumatic, so it makes sense to integrate all systems using a single technology, but which one is best?
The cable system represents my “mechanical” solution but it has no involvement with other systems.
An option using “electrical” technology would be using two solenoids (one for upshifts, one for downshifts) triggered from switches on the handlebars. This would have simplicity benefits and uses energy already available in the form of battery power. However, electrical operation of the parking stand deployment is quite difficult, so its unlikely to yield big rewards overall.
An option using “hydraulic” technology would be to employ two rams (one for upshifts, one for downshifts) triggered by solenoids controlled from handlebar switches. A single pump and reservoir system could provide power for both the leg apertures and the parking stands. Hydraulic operation of the parking stand is ideal, but has a big weight penalty using fluid and bulky motor/pump design, and I’m not confident that the fast action necessary for gear selection is easy to engineer.
An option using “pneumatic” technology would be to employ two actuators (one for upshifts, one for downshifts) triggered by solenoids controlled from handlebar switches. A simple, lightweight and cheap pump could maintain pressure in a storage tank (approx 150psi) with about 1 litre capacity (I guess). This would keep a ready source of energy for all operations and speed of gear selection should not present a problem. Drag racing bikes often use this technology, and I would be very interested to hear from anyone with first-hand experience. Actuators are lightweight and relatively cheap so it looks like a promising solution.
Let me know what you think, or if I’ve missed anything.
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