Friday 6 May 2016
Building the new bike
Why a new bike? Because I can. OK, I admit it, I have a bike habit. OK?
So the motor arrived from Xiogda. It's a dual speed motor, the same as the one I
got from Panda, but this one is rated at 48 volts, plus I told them I wanted the
winding to be for maximum torque, not for speed. That's because I'm mostly
bumping along rough ground, and half of that is uphill.
A couple of days before it arrived, I realised that I needed spokes, so I
ordered those from Tiller Cycles, and they arrived the day after the
motor. I already had a rim, because last time I did this, I bought a pair
of rims. So yesterday, I started the build.
The first, and most difficult job, was to lace the hub motor and rim together
using my new spokes. That went well, except that I lost a nipple inside the hub.
I couldn't get it out, so it's going to stay in there for ever. I tightened up
the spokes with my spoke key, and found that I'd build it so well, I didn't
need to true or balance it, it was already fine. So I put on rim tape to protect
the inner tube from the spoke holes, then one side of a Kevlar Schwalbe
Blackjack tire, then one of my special thick thorn-resistant inner tubes, then I
fed a Dr Sludge gel insert between the inner tube and the tire (more thorn
protection), then pushed on the other side of the tire, using tire levers for
the last few inches, my thumbs being not quite up to the job. I inflated the
inner tube, and it was good.
When I tried to put the wheel on the bike, the motor was fouling the front
forks. I had this problem last time I did this on the other Haro bike, so I
knew what to do. I got the jack out of the Volvo and used it on the forks. They
were 10.1 inches apart with I started, 11.25 when I'd finished. The forks
are steel, I wouldn't want to try this with aluminium.
I used a couple of washers to maintain the separation, and when I put the
wheel nuts on and tightened them, it looked fine.
Next, I sorted out the handlebars. I needed to add the gear-change switch
for the motor (high gear, low gear and autochange). I mostly ride in low
gear, because I'm running at low speed over rough tracks, but when I get onto
tarmac for a bit of a ride, I switch to auto. When the high gear kicks in, it's
like someone just switched on the afterburner!
I also installed a thumb throttle, the control panel (which shows my speed, and
the battery voltage, and a few other useful things). And I added an extension
bar, which gives me a bar a few inches above the handlebar - that's where I
mount my Fujitsu Loox, which I use for navigating.
The controller terminated the power leads in a tiny plug; I stripped those off
and replaced them with an EC5, which is my standard plug and socket for bike
power. The power lead from the controller is too short, so I also made an
extension for it; EC5 to EC5. I put a segment of inner tube over all these
connections, to help keep water out.
I tidied up the cables using a curly-wurly outer and a few cable ties. Then I tested it - I connected up a 50 volt battery, and tried to switch on the power using the bike's ON button ... nothing happened. Panic! What's wrong? So I put a voltmeter on the battery, and it showed zero. So I fiddled with the leads a bit until it showed 50 volts, then connected it back to the bike, powered on, and it came on! I lifted up the front wheel and gave it a bit of throttle, and the motor powered the wheel. Great!
The front brakes were rather worn, so I replaced the brake shoes. The kick stand was one of the cheap rear kickstands that so many bikes come with, so I replaced that with a decent on in the middle of the bike. The pedals were a bit wobbly, so I replaced those.
Then I put the back end on a support, and adjusted the gear cable until I could get all seven of the gears - I want the lowest gear for climbing steep tracks, and the highest gear for zooming along tarmac.
The bike is now ready. I'm planning to give it a test tomorrow, first with three 4s batteries in series (which gives 50 volts) and then with four, which should give me 62 volts, and which I'm hoping gives me very good hill-climbing. I want it to feel like I'm being winched up the hill!