Author Topic: 80mm -> 50mm tail light  (Read 535 times)

JimK

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80mm -> 50mm tail light
« on: October 15, 2020, 09:37:14 PM »
I had a dynamo powered B&M DToplight installed on my bike when I ordered it. The wiring from the headlight to the taillight has always been a bit finicky... one problem is that I have S&S couplers so the wire needs a way to disconnect and reconnect there. Also I found that turning the forks to steer had a tendency to loosen the connection to the headlight. Over the years I have tried one thing and another, and mostly things seem to work by now.

But then a few months ago I noticed, ugh, the taillight isn't working. A few weeks ago I finally got around to working on it. To my surprise, I seemed to be getting voltage all the way back there. I unmounted the taillight... which seemed to get it working again. Hmmm. My best guess is that the taillight has failed, that there is some loose connection inside.

I ordered a new Toplight Line Plus as a replacement, not paying any attention to the details. Ugh, yeah, the old light had 80mm spaced mounting bolts, the new one has 50mm. My Thorn rack has lots of holes back there, for reasons beyond the power of my imagination, but none spaced 50mm. So I then ordered a nifty B&M Single Hole Mount. The fun thing is that I could use the 80mm holes, as well as the central threaded rod, to fasten this little bit of metal to the rack. I used stacks of 4 washers between the mount and the light, so the light clears the heads of the bolts I used to fasten the mount to the rack at the 80mm points. Any, remarkably enough, the first guess at the polarity failed, but with the second guess... light!




PH

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Re: 80mm -> 50mm tail light
« Reply #1 on: October 15, 2020, 10:08:22 PM »
That's a neat solution, at least from the rear. 
What are you using to connect when you split the frame?

JimK

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Re: 80mm -> 50mm tail light
« Reply #2 on: October 15, 2020, 10:33:56 PM »
These days I am using some very cheap banana-plug type things from Radio Shack. I bought some of those really slick Supernova connectors but I didn't have them securely enough on the wires ... once you crimp them and the wire pulls out... it's a loss! I just bought another set of those Supernova things... surely I can get them on there properly? Someplace I saw an explanation, like loop the wire back and twist and solder... don't just rely on the crimp! I'm not in a hurry to tackle it... I can just tack the connector plastic bag to the wall and admire the beautiful gold plating!

JimK

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Re: 80mm -> 50mm tail light
« Reply #3 on: October 15, 2020, 10:42:22 PM »
On that subject, though... one little nuisance... right at the S&S coupler, where the electrical connection is, those wires kinda flop about. And that's where I keep my coffee thermos! Too much going on right there! I found this flexy wire fastener thing they sell nowadays... this is a nice application, to secure those wires! Probably it will withstand the sun and rain etc. - we shall see!


Andre Jute

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Re: 80mm -> 50mm tail light
« Reply #4 on: October 17, 2020, 04:14:17 AM »
The problem with electronics on bikes is what to do with the excess wiring; the problem multiplies with computer control of anything, like on my Trek Smover, and breeds further complications with a custom installation of an electric motor and its multitudinous control and power wires running hither and thither. Fortunately I discovered a solution.

First you need to decide where the main control nexus is, because that will shoot out the maximum number of wires, like snakes on Medusa's head. Then you need to raid an obsessively tidy person's computer-room. Finally you need a third hand, prehensile toes like chimpanzee, or a good selection of vice grips to implement my solution.

On the Trek (a fully automatic gearbox and suspension and lamp system, for those who don't know: http://coolmainpress.com/BICYCLINGsmover.html ) the main control computer was under the downtube but it on and near the handlebars that the maximum number of electrical lines ran between various control switches. So I collected all the control lines together, folded surplus length back or down the conductor, held it all together with tie wraps, and then robbed a complicated computer system of its grey segmented cable routing system, which I wrapped around this by now thick conglomeration of cable on the bike. (The bike had come from Trek's Benelux factory with right-length wires, but they were all cut for a sportsman leaning forward. I sit upright on my bike, like a human being, and the only lines Trek had available for my reengineering job -- which, plus more goodies, they supplied free of charge -- were too long, and the internals too fine to cut and solder. Here's a photo, on which you would hardly notice the cable if I didn't point it out: I've never heard a single comment about it from people I cycle with -- they assume it is an integral part of the bike; I got lucky with the colour matching. The tube runs from the handlebar to the bottom of the head tube, where the standard routing down the fork and the downtube takes over.


When I electrified my Utopia Kranich the second time, I didn't have to ask for longer wires: all Bafang central motor wiring is too long, in some instances grotesquely so -- except, bizarrely, the wire to the battery, which I had to extend. Bafang unified all the wires up the downtube from the control board in the bottom bracket motor to the handlebar but the handlebar itself was rat's nest of bifurcating cables and plugs. Because of medical problems, I rode the bike for several months before I did the tidying work, and each time I was disturbed by the untidy wiring. You'll feel a lot better when you've done the work, Jim! Once able to bend over the bike, I did my thing with tie wraps and computer tidy, folding surplus wires double and making a thicker cable which ran behind the handlebar bag and again down to the junction of head tube with the downtube (the Kranich has a whole bunch of "downtubes") where Utopia's own beautiful custom machined cable routing system took over.

happytourer

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Re: 80mm -> 50mm tail light
« Reply #5 on: October 22, 2020, 07:22:02 PM »
I have a Nomad2 originally with Son hub/Edelux2 front light, which I partly dismantle to fit in a bag for further flung trips using European express trains. The fork has to be dropped out and rack removed, as well as wheels. As I plan (hope?) to get back to European touring when that's possible, but also wanted to fit a dynamo powered rear light. Similar challenge to wiring on an S&S frame.

Eventually went for it during the summer, and fitted B&M Toplight on the rack, used twin core cable running down the rack, forward on the stay, under the bottom bracket then up to the fork. I fitted a pair of Supanova gold connectors about 120mm forward of the rack mount, and about 100mm down from the fork. The twin core is fixed with zip ties, but with just enough slack where the connections are to unplug/plug them without straining anything. Using wire that just fits into the end of the Supanova connectors I was able to solder them in place. Just remember to get the heat shrink on the wire first....  So far so good.

JimK

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Re: 80mm -> 50mm tail light
« Reply #6 on: October 23, 2020, 11:06:15 PM »
Thanks for the tips... when I got the bike, SJS had routed the wires down below the bottom bracket. I have a tendency to do some wild exploring than can involve dragging the bike over downed trees etc. ... the wires down there got destroyed pretty quickly. I may try some fancier wires at some point. Anyway, for now my setup is working ... I tend to leave well enough alone!

JimK

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Re: 80mm -> 50mm tail light
« Reply #7 on: October 24, 2020, 11:21:53 PM »
I generally leave my lights in the automatic mode and let them decide when to turn on and off. Today was rather gloomy so they turned on mid-day... the tail light even works!