Installing a Bicycle Computer on a Scooter

Alright so I have said in the past that one of my biggest gripes with my Chinese scooter is that the speedometer was way off. On my first scoot it was a steady 5 mph off but on my new scoot it is 10 to 15 mph off. Also the odometer never has been the most reliable piece of measurement equipment as well although as long as you convert what should be miles into kilometers it seems to be halfway close. So the question came to mind: How do I fix this? Well I pulled from my past and decided to install a bicycle computer to my new bike. So I started my research and found that not only cheap scoots like mine have a problem with giving accurate speeds but just about every 2 wheeled vehicle on the market so there were plenty of posts about installing a bicycle computer to a motorcycle, so I figured if it can be done on something that goes much faster than my little scoot can use one than I should be able to use one too. Also I found that not all brands of bicycle computer would work for the task for instance some bicycle computer stop being able to calculate speed at 30 mph so those wouldn’t work at all, also the wireless kind get all sorts of messed up by the starting motor and other electronics on the bike. After research I found out that Sigma brand bicycle computers are rated up to 200 mph and that will cover my needs quite nicely and even though the cadence feature wouldn’t be used the additional wire to hook up the cadence feature will come in handy to lengthen the wire on the harness. One of the other features I wanted to have was a backlight, and after reading up on a few models I also found a new feature that I thought would be kind of nice, temperature.

I ended up purchasing a Sigma BC1609 off of Amazon.com and must say I think it ended up being a pretty sweet deal. About 25 bucks including shipping came with everything I needed to install it for the most part and it came in less than 3 days so I can’t complain about that either. After doing a bit of test fitting I did find that the wire was about a foot short so some splicing would have to be done. Some of the other obstacles I had to find a solution to were: Where do I mount the computer itself? How do I mount the magnet that sends the information to the computer? and How do I get the sensor close enough to the magnet to read it?

So I started by splicing the wire which when I first cut the wire on the cadence cable I thought it was just a single wire… It was not. It was 2 very small separately insulated wires inside of an already skinny wire. When I saw the size of them I didn’t trust just twisting and taping the wires and went ahead and soldered them together before taping. Now that I had enough wire it was time to figure out how to mount the computer its self so I could be able to see it as well as not have to make any permanent holes anywhere. I found that the easies way to mount it for me was to use the rubber o rings that came with the unit and wrap 2 of them around the brake oil reservoir which worked out quite nicely. Next was to find a good place to mount the sensor unit. Ironically I chose to mount the sensor to the unit that currently keeps track of my speed using cable ties along with wrapping the cable I was able to get it nice and tight without any sagging in the cord. Now on to the Magnet. This was a bit trickier, how do you mount a magnet on a wheel that doesn’t have spokes when it’s designed just for that. Well you make your own spoke out of a coat hanger of course… duh. Basically I bent a couple of circles on both sides of a small piece of wire then bent them to a 90 degree angle along with bending it in half in the middle so that it can stand on its own. Then I could slip the magnet in place and stand it up on the wheel attaching it more cable ties and securing it more permanently with some JB Weld. This worked perfectly! I was even able to bend it to adjust it closer to the sensor once everything dried. Last but not least was figuring out the distance my tire travels every time it goes around in millimeters. To do this I put a bit of butter on the ground, ran over it and moved forward until I left another smudge of butter on the ground. Measured from beginning to beginning of the marks and converted the inches to millimeters and I had my measurement.

So far the computer has worked great, it gives me a much better idea of what speeds I am going than the orignal speedometer and also increases the accuracy of my odometer so I should soon be able to tell you exactly what gas mileage I am getting. Sorry if this post was a bit boring for some of you but for other scooter riders out there I hope this helps you in getting one installed on yours. Be safe all!

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One Response to “Installing a Bicycle Computer on a Scooter”

  1. Great writeup!

    One thought about mounting the magnet is you CAN drill the rim without any ill effects. You might want to balance the scooter with some of the lead balancing weights you can get to balance motorcycle tires.

    When I tried mounting a cyclocomputer I mounted the magnet to the valve stem (very bad idea) and it wiggled a bit too much. It was only temporary until I replaced the speedo puck. I was planning on making a wooden “insert” that would fit in the oval holes on the rim, but I removed the cyclocomputer before I got around to doing that.

    Scooter

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