And there was light!

May 17, 2011

Night-time riding on a recumbent trike has some specific safety concerns. Because the road-footprint of the trike is much wider than drivers expect from a bicycle, the edges need to be clearly marked to avoid being clipped. Also, in country terrain like the kind I ride in, putting a lot of light ahead can be critical to avoid hitting fallen tree debris, roadkills, pot holes, and other undesirables. This all calls for a permanently wired lighting system with a rechargeable power source.

Here’s what I did and how I did it.

Cyclist lighting has two purposes: helping you see and helping others see you.


To help me see, I selected a pair of MagicShine MJ-808 – this is a lighting system based on a very high intensity LED (actually four LED emitters on a single die) and wants 8.4V or so to run. It has High, Medium, Low, and Strobe as available settings and indicates the estimated level of battery charge remaining on the battery with a colored LED under the push-button you use to change modes; Slick.

 

On a recumbent trike, most of the frame parts sit quite low to the ground. This is desirable in terms of riding, handling, and stability, but it makes mounting lights rather a pain at times. The reason is simple, the angle of light needs to be higher than that. If your headlights are too low, little bits of gravel cast Boris Karloff shadows on the road ahead, and potholes are invisible until you are too close to do anything about them. This would make the top of the fenders seems like an ideal place to put headlights, but the MagicShine headlights are designed to mount to handlebars with a big rubber O-Ring which catches integrated hooks on the housing, not to be permanently affixed with a screw from underneath. While one could perhaps put a screw into their aluminum housing it would leave absolutely no capability to adjust the angle in either direction. I stewed on this for some time before coming up with this solution.

The rubber O-Ring is wrapped around a slice of 7/8″ OD Acrylic tubing (PVC would work fine, I’m sure) The tubing has a hole drilled into it, and is bolted to the fender through a spacer made from a rubber furniture bumper. This allows the light to be tilted up and down and panned left to right for the best light distribution.

MagicShine sells two different front lenses for the MJ-808, a clear lens which produces a fairly narrow spotlight effect and a spreading wide-angle lens which creates a wide swath of light. In this application, I’ve used one of each, which gives me both good peripheral illumination, and a nice bright hot-spot in the middle for seeing obstacles.

I had expected to use these lights on High most of the time, but that is simply not necessary. On Medium these lights are easily as bright as most automotive headlights. You should be aware that you should not use High mode on these lights while stationary, as they rely on the air moving over them for cooling purposes.

To help others see me, I decided I would use three tail lights. One on the rear fender of each wheel, this would indicate to drivers both how wide and how long the trike is in a lane.

I selected the another MagicShine light, their MJ-818, as a tail light. It is mounted using the same Bumper/Tube arrangement as the headlights. I had originally intended to mount them directly to the fenders but once I had my retinas bleached by the CREE LEDs that run the things, I decided to put them on a mount that would let me angle them down at the road, to spare drivers behind me their eyesight.

The MJ-818 has three modes, but only the “ON” mode is useful for night cycling (bright blinking lights at night can make it hard for drivers to estimate their distance from you. Use solid ON instead and save strobing for the day time.) These modes are accessed by twisting the metal ring on the housing around, which is rather a pain, and once the lights have been running for an hour it becomes a quite literal pain because they run quite hot.

All MagicShine lights revert to “OFF” mode when the power is removed and then restored (say for example by removing / charging / reinstalling the battery.) On a bicycle with a single headlight and single tail light, this wouldn’t be a bother. With three tail lights and two headlights, it’s a bit of a procedure.

Speaking of batteries, MagicShine sells purpose-built batteries for these systems, but their capacity is too limited for extended night riding with five separate lights running simultaneously. Clearly, a larger capacity battery is called for. Since the battery-indicators on the headlamps count on 8.4V batteries, I bought a 9AH Lithium-Polymer slab-battery to run the system. After a few hours lopping off the barrel connectors that come on the MagicShine products and replacing them with weatherproof automotive connectors and we were in business.

Two things to note on this picture – the headlights are pure white to the naked eye (not blue) and the picture was taken before the third tail light was wired. Still and all, it looks from all angles like an automobile, and that is about what I was going for. Overkill? Probably. No driver will ever hit me because they couldn’t see me, and that’s priceless.

Next up : Turn signals!

Update : Here’s a better picture of the system in action…This time while off-roading.

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