I faced massive problems when I tried to mount a wireless computer on my Moulton. The distance between the handle bar and the front tire is too big – too big for most solutions from Cateye, VDO or Polar.
I found a perfect – but not cheap – solution for the Moulton within two devices from Garmin. Both – the Edge 205 and the Edge 305 – were announced to the public in early 2006. Those GPS-receiver are designed as cycle computers and for training purposes.
I selected the Edge 305 with an integrated heart rate monitor, wireless speed and cadence sensor. In addition, the Edge 305 incorporates a barometric altimeter – the 205 has to use the GPS data to calculate the altitude. If you don’t need cadence and heart rate, then the 205 is perfect for you (and you don’t need to mount any sensor on your Moulton).
Practically you can just snap the Edge into the mount and go. The Edge can calculate the speed from the position and distance travelled – the accuracy is ok – the faster you go, the better it gets.
The speedsensor and the magnet are needed for normal cycle computers, with the Edge they are optional. When you mount the sensor and the Edge doesn’t see enough satellites, the data collected by the sensor will give you the current speed. This happens not often (the new SiRFStarIII chip inside the Edge is very sensitive – impressive compared to older GPS receivers) but I wanted the sensor to have a perfect setup. To get the cadence you have to mount a sensor near the cranks and here we run into a problem on our Moulton. Garmin build an integrated sensor for cadence and speed but the wheel magnet mounts to the rear wheel for speed and the cadence magnet has to be attached to the crank arm.
This is no problem on “normal” bikes but the distance between the rear wheel and the crank is too large on the Moulton.
You have to mount the sensor close to a crank arm on the rear chain stay to let the sensor collect the impulses of the magnet glued to the crank. There is no alternative to this position on the Moulton. The small arm you see in the front of the picture contains the speed sensor. You can change the angle but for the Moulton you have to separate this arm from the sensor housing.
You have to cut those tiny little wires (a weird feeling considering that this is a 50 Euro Sensor). The wires on the housing should be long enough to allow new wires to be soldered on. We will pull out the wire out of the arm, so here is a little more substance.
Now you need a piece to mount the arm on. I solved this with a milling cutter and a piece of wood.
Now you drill a hole into the arm (1.5cm away from the old fixing screw) to get access to the wires. Next you solder the connecting wires on and fix the arm to the new mount with the screw and some two-component adhesives. See the picture on the left. We do the same with the cadence sensor (without drilling any holes).
The finished Special-Moulton-Sensor looks like this:
And mounted on my Moulton it looks like this and works perfectly:
The Edge 305 is not only a cycle computer but also a GPS receiver and so we can watch our tracks on the PC. You can examine all data collected and – if you like – you can display the track on a map.
If the options of the Garmin software (Garmin Training Center™) are not what you look for, you can download the free SportTracks software and now even watch your Moulton track on a Google-Earth image.
Some features of the Edge 305 are at least something you should like. The Edge works with an internal lithium-ion battery that will last for round about 10 hours. This is a good thing first of all. But you have to refill the battery regularly while a “normal” cycle computer will run for a year or more. You can use an A/C adapter or the USB port of your PC to load the Edge. On a trip of several days you need to be prepared for this task. Also you have to get used to the fact that the Edge will need around a minute to collect the satellites. So: to jump on your Moulton and off you go needs some time. I don’t want to bring in the price of 400,- Euros…
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