How to open the sensor on rear wheel of Sigma BC1609 wireless odometer. I need to change the battery and there is no slot (to use a coin to open.) Instructions say "use a tool" what tool?

If it the distance is not changing either the problem is that the unit is not receiving a signal from the sensor - bad connection, sensor out of place, bad sensor, etc. If distance is working but mph is not then there's something wrong with the unit itself, and if still bad with a fresh battery it must be replaced.

Have you checked the manual? Pages 24 & 25 should be able to help you.
If you don't have a copy its available on the Sigma Sport site. http://www.sigmasport.com/en_media/produkte/bikecomputer/topline_2009/topline_wired/bc1609/allgemein/visuals/ba.pdf

-Nothing will last. Keep charging when it's low.

Good luck
Mai

http://www.sigmasport.com/en/service_center/produkt_support/bikecomputer/

I had this problem as well. What I found was that the transmitter path from the magnetic sensor to the computer is very narrow, a 15 degree cone. Reposition your computer to fall within this cone. It should pick up the signal.

Well, it IS wireless. Perhaps the distance or line-of-sight isn't right. As a test, hold the receiver in your hand and hold it closer to the spinning wheel transmitter.

Well, it IS wireless so it need ssome good juice and line of site from the sensor to the receiver to work.

Take the unit off the handlbar mount and hold it close to the transmitter while you move the wheel magnet past the sensor.

If it starts to work begin moving the computer farther away toward your handlebar mount and figure out where it dies and why. Some units have distance specs that must be adhered to.

Same here. Can't find the part online. Local Schwinn dealer said they haven't made that part in at least 10 years. I put on a regular bicycle Cateye odometer. At least I have a measure, although it does feel like it agrees with the Schwinn odometer, even when I set the wheel size to just 100 cm I think it is still ~20% high.

I don't have this model but understand many odometers, like mine, reset the wheel size to wrong setting when battery replaced. Go to setup screen to reset to correct value. Setup screens normally appear if buttons held for about 2 seconds or more. Some models require millimeters and some centimeters. If you don't have a figure for your tyre measure the distance on the ground for one complete revolution of the wheel.

You can remove the battery using a coin or flat head screwdriver. You will see the cover of the battery on the backside of the computer. Turn it clock wise. When you remove the battery all information will be lost and you will have to recalibrate the computer. If you need a instruction manual on how to reset the computer it can be found at www.sigmasport.com

Hope this helps. Thank you