Friday 1 August 2014

Bike maintenance

After spending the day on bike.3, it needed a bit of maintenance. That's part of the fun of a bike.

While I was doing a cache, I spotted a piece of aluminium tubing, just discarded rubbish. And I thought, "If I flattened that, and drilled a couple of holes, and attached it to my rear carrier, it would keep the pannier away from the back wheel". So I grabbed the tubing, and installed it on the bike, and I think it's going to work just fine. So maybe I didn't need the dogleg carrier that I bought.

I also fixed the speedometer, although I still don't know why it wasn't working.

I usually run the bike with a wattmeter on the battery, so I can see how many amp-hours I've used. But the answer tends to be fairly boring - I'm getting about 90% of rated capacity, pretty consistently (although yesterday, one battery gave me a tidge over 100%, so don't tell me "it's impossible to give more than 100%"). And yesterday, I noticed that the wattmeter was a bit warm, maybe even a bit hot. That means that it's consuming power, which is power that isn't going to the motor. So I'm going to run without it; I have an assembly that's just a switch (with charging resistor) and fuse, and I'll use that.

The purpose of the switch is this. If I just plug the battery straight into the controller, there's a big blue spark as the controller's capacitors charge up. That spark is definitely bad for the contacts, and maybe not too good for the capacitors. I can avoid the spark, by putting a power resistor between the battery and the controller, so that the capacitors charge up slowly and there's no spark, but then, of course, the rsistor stops the controller from getting full power from the battery. So the switch is there to short-circuit the resistor. I have the switch off, plug in the battery, plug in the battery monitors, and by the time I swith the switch on, the capacitors have charged. Occasionally, I forget to plug in with the switch off, and I get that big spark, so I know it's a good idea to use this arrangement.

The LCD voltmeter is perfect. I can see it in full sunshine, and in the shade, and I'll be able to read it at night. I've found that I don't really need an ammeter on the handlebars.

The inner tube on the back wheel moves. Well, it's meant to move, of course, but I mean it moves relative to the rim, which means that the valve starts to stick out at an angle instead of at 90 degrees, and if that gets bad enough, it can shear off the valve (that happened to me once). I deflated the tube and moved it back to where it's supposed to be, at 90 degres, but it keeps working its way round, and I'm not sure why.

And I got a phone call from DHL, they want me to pay £14 before they'll send me a delivery. That must be my two-speed motor from China!

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