Thursday, 3 April 2014

Bike 5

Bike 1 has now had the useless headlights and horn removed, and the ignition permanently on. I tested it today, and it works fine. I don't need a horn, I have a bell, and I don't need headlights that don't shine a beam, I use a head torch for that. And when I'm not using the bike, there's no battery on it, so I don't need an ignition switch.

And then I turned my attention to what will be bike.5

This started life as a birthday present, several years ago, when I realised that geocaching needed a bike. It's a 20 inch wheel folder, with an 8-speed Sturmey-Archer gearbox in the rear hub. It cost £180 delivered, I rode it quite a lot, but then I moved on to electric bikes. It's been sitting quietly in my shed for several years.

So today, I got it out. First I checked the front forks, and they're steel which is great for putting the motor in. The motor is a 250 watt from a Synergie electric bike; unfortunately, the frame broke one day as I was sitting on it, stationary, outside Tesco. The frame can't be fixed, but all the other parts of the bike are recyclable, and now I'm recycling the motor.

First I put in the motor wheel and checked the tires. The front inner tube was flat, and pumping it up didn't help. When I had a look at it, it had perished (as rubber does). No problem, I put in a thornproof tube, and now that's fine.

Next, I stripped all the electric bits (throttle, etc) from the old electric. Most of it, I didn't want; I'm only using the motor and the controller. I much prefer a thumb throttle, and I have a spare one I can use.

The motor was a surprise - only two wires come out of it! It isn't the  usual three-phase brushless motor, it's a brushed motor, and the controller is brushed too, of course. I removed all the old connectors (they seem to use really rubbish ones) and put on an EC5 for the power (because that's how my batteries are) and an XT60 for the motor. I connected it all up, tried the throttle, and it worked!

So, now to work. I put torque arms on the motor wheel (to counter any tendency to spin out of the forks). That's not really necessary for such a small motor in steel forks, but it adds very little weight, and if you can imaging trundling along at 20 mph down a bit of a hill, and suddenly your front wheel isnt there ... then you can see why I like torque arms. I oiled the chain, which was in a dreadful state, and I oiled anything else that looked like it deserved a squirt.

I used 14AWG wire for the motor lines; that can take 30-40 amps, a lot more than I'm going to give it. I added a bracket to carry the PDA, and then I took it out for a test run.

The bike worked, but it felt rather low power. Hmmm. Then I remembered, brushed controllers are really cheap on Ebay. The one I was using, limited current to 10 amps, but for £9.99 I bought a controller that says it limits current to 27A, so I'll probably get double the power, maybe even more. The UK law says that the motor must be rated at no more than 250 watts. It doesn't say anything about how much current you can put through it

Apart from that, it worked fine, and the 8 gears are somewhat easier to use than the more common derailleurs. My first ever bike, nearly 50 years ago, had a Sturmey-Archer three-speed, which was great for the hills of Cambridge, and I loved it. So maybe I'm biased.

Tomorrow, I'll wire up an ammeter/voltmeter and take it out for another run. It looks like bike.5 is a goer!

The rather flimsy bag I keep my tools and suchlike in, is starting to tear, so I need a replacement. I went to Ebay, thinking "cheap ladies handbag", but it wasn't as simple as I thought. There are loads of bags on offer for 99p, but when you look at the seller's page, the 99p is for a cloth shopping bag, the actual handbags are several times the price. It's annoying; basically it's called "bait and switch", you offer something really cheap to get the buyer interested, then switch them to something a lot more expensive.

Then I had another idea. Ladysolly has so many handbags, surely she has one that she no longer wants, that is the right size for my tools (27 cm long, and I'm not boasting, that's the length of the pump). She came up with a lovely leopard-skin bag by Jaeger, with the price label still attached (never been used) of £105. I now have the most expensive toolbag in the world. Actually, she got it as a freebie with some cosmetics.

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