Bicycle Speedos on Motorcycles.

Why a bicycle speedo on a motor cycle?
Because they can be calibrated (made accurate) by the operator without fuss.
They are cheap and light.

Other alternatives exist
GPS units , and purpose built motorcycle speedos. Both of these are more expensive and heavier than the bicycle speedos.
There is a more expensive bicycle speedo by Topeak that has back lighting and a larger screen and about $10us more than a BC1400. A supplier. Another supplier who do an alu bracket to go around it as an accessory.

Why A Sigma?
Because they claim to work to 300 km/h (183 mph).

Missing features/problems?
Night lighting, is now a possibility with an accessory light, battery powered 15 hours life.
Length of cord to sensor is not long enough. Most people extend the cord themselves by soldering in a bit of wire. There is a rear wheel kit (for bicycles) that has a longer cord.
Larger buttons. The sigma buttons are at the top and bottom for most models, and these are reasonable for gloved use.
The display units are not waterproof; water-resistant... yes but best kept out of heavy rain. Mount it in a sheltered location.

How to calibrate (make Accurate).

Why does it stop working at high speed?

How it works (or doesn't)

Links

A description of each sigma model with it's features.
Update - December 2000. New BC1400 looks to have replaced the BC1200. Maybe the BC1400 has 14 functions? More - May 2001. BC400 replaced by 401 - no more automatic scrolling :( Uses one button to manually scroll through functions.
Basically the BC401 has 4 functions, BC600 has 6 functions, BC800 has 8 functions and the BC1400 has 12 functions.
They all display the current speed in the upper display area. The lower display area shows the other functions, mostly one at a time. The 401 cycles between odometer, clock and trip meter as the (single) button is pressed. The trip meter resets to zero if the machine is not moved for 3 hours. The 600 adds maximum speed during this trip, and elapsed trip time, with the trip reset to zero done by a button and the function displayed also controlled by a second button. The 800 adds average speed during this trip and a separate display to show if you are above or below your average speed. The 1400 adds yet more functions and button/s. The details are on the site.
The BC1400 has small buttons. The wireless kit is reported not to operate on motorcycles. The Targa model is a metal packaged BC800.
dead link http://www.sigmasport.com/ASP/A_Computer/A08_Night_Light/a08_e.asp#"> on A sigma night light accessory - about $AUD22. Your bicycle shop may not stock these. The on/off button is small. the home page requires flash player - I'm not installing it ...

dead link "http://www.zing.com/album/?id=4293241597" on Installing two Targas on a bmw R1150GS with a single sensor photos mostly .. Includes the night light accessory.
Installing a BC700 on a sports bike full description of why, how ..
The BC700 is no longer available but all the sigma models now (July 2000) claim to operate to 300 km/h.

dead link "http://www.bmwsearch.net/bmw-digests/tech/digest/V1996/N00/digest-19960047.html#subject1996004702" that had a report on 'Two models of Avocet, and one CatEye that don't go over 71mph.(114km/h)'

A commercial firm that has a page on installing sensors and magnets.

Sigma 800 to a ST1100.

article on Sigma 1200 on a VFR.
BC900 to a sports bike.
BC800 to a Concours. A bit on wheel dimensions - mph vs kmh ...?
Topeak alternative motorcycle speedo with back lighting and a higher price.
Topeak agent in USA. Price was around USD$75.
bmw K75 with a BC1100 in German.
A firestorm with a sigma BC800.

Other

My calibration data for


The BC 400 had some dirt on the inside of the display, making it harder to read. This reinforces my opion that the speedos are not water proof, if dust gets in then so can water. Mine you it has been through a lot of mud, dust, snow and more mud. I forced the top clear plastic off the body using my finger nails, from the black edges. It was held by some black double sided tape. Looks like the dust/water entered here through a section of the black double sided tape that had not adhered to the grey plastic body.
This does hide behind an LT flaring so it is not in the direct spray of water, but dust does float around.
The displays also lacks contrast at some angles that the newer BC 600 does not. Swapping the batteries proved that the lack of contrast is a battery voltage problem. So I need a new battery. When you remove the battery cover don't loose the small O ring seal! Removing a battery needs a small spike to leaver it out. Putting in the new one is a balancing act. Balance the battery on your finger with the negative terminal upper most. Lower the speedo on to the battery and push the battery home. Trying to put it in the other way ends up with the battery sideways in the hole!
Another problem was that some dust entered the unit masking some of the display. This came throught the seal between the face plate and the body. I forced this face plate off the body, it is held on with double sided tape which had not sealed correctly. I used silatstic to secure the face plate back on. The photo showes the face plate seperated from the body (upper pair) and the lower set shoes the battery in the body, battery cap and O ring. Photo of dissassembled speedo.
I'll put up the fitting to the K75G/S when I get to it. The problem is with the upside down forks running a cable to the sensor is difficult.

If you do have any other links, then please let me know.

Other

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back to my home page & start again        Dated 25 March 2002