Sunday, March 11, 2007

Sigma speedo: Finally!

My motorcycle gets a sigma speedo .. finally!

After I bought my bike in october 2006, it was lying in my drawer. Before which it was lying in Dada's drawer. Finally after a lot of delay in getting to mechanic/welder's shop I found out that I could do it myself, no need for the welding and stuff!

Sigma! What Sigma?
Though its basically made for bicycles, its very popular amongst biking enthusiasts. Reason being the speedo's high accuracy (it is acclaimed to be accurate till 180 mph speeds!) and the other functions. Well I am not going to reach that speed on my bike, whatever little I do I need the most accurate information not only in top speed but also in parameters like average speed, trip time, odo etc. It comes with three units - one magnet, that is supposed to fit on the spoke, a sensor along with a wire that goes to the mount, and the bike computer that can be latched on to the mount.

How it works?
When the wheel rotates, the magnet passes the sensor & the event causes the sensor to generate a pulse. This pulse is used by the bike computer to process various parameters, which it does on the basis of the wheel circumference fed in it.

Sigma installation: A herculean task?
It took me around five months to install Sigma on my motorcycle. Finally I did some googling and found out methods by which I could install it all by myself ;) and so I went ahead and all it took me was one day!

Well the first method was the one which caused delay. Sigma is made for the cycles and hence it fits a cycle spoke, and the sensor gets mounted on the bicycle fork. However when doing the same thing one has to take care of couple of other things. The distance between the magnet and the sensor should not be more than 5 mm. Now the idea was to take a cycle spoke, fix the magnet onto it, weld it onto one of the spokes and fix the sensor in the inside edge of the fork.

Don't do it, because of this I procrastinated sigma installation for five months! There are easier methods available, which you can carry out easily.

I selected a different magnet which is more powerful than the stock magnet (Easily available in the stationary shops in the button type stick ons, just take the magnet out), and can be fixed to the spokes. The sensor goes along the original speedo cable itself. The wire from the sensor to the console is around one and a half feet short for the motorcycles, so I sacrificed my Sony headphone wire, which is a thin wire with a dual core wiring same as the sigma speedo wire. got it soldered to the original wire, and done!

Glued the magnet to the spokes, sensor to the stock speedo cable and used insulation tape to hold them at their place. I glued the mount to the left side of the handle.

Thats all ;)
Now I get the speeds based on the wheel parameter and no errors on account of no mechanical mechanism.

It is zimblee awessssum!!

For the various models available in Sigma check out:


Anonymous said...

Nice Stuff!!


born_in_the_woods said...

cool hai
so did you notice the difference between speed in bullet speedo and the sigma?

At speeds say 40, 60, 80, 100?
is the difference constant? i doubt so..

Kam said...

Yeah man, there is a difference, not constant though! As the speed increases the bullet speedo becomes more erratic! I checked out on last ride: 98.4 kmph on the sigma and 104 kmph on bullet speedo! The mechanical errors get intense as u go up the speed curve.

Rocky said...

I thot the magnet can be fixed on the rim instead of spoke. Lotsa flat surface compared to the spokes

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