Having trouble installing this bike computer

I don't think it cares anything about direction, it's just counting how often the magnet passes the sensor.

You do need to make sure the magnet passes pretty close to the sensor, though.  Make sure the sensor just about touches the magnet.

Not sure about screws vs. ties--maybe somebody with the same unit can help.

I have this unit on my trainer.  Its VERY accurate and yes, very cheap, but is worth the money.  It does use the "bread ties" to hold it on.  It will stay on just fine like that even though it doesn't seem to do so.  The directions say to put it on your front wheel..... this is not true in regards to tracking speed and distance because I compare it after a ride with my garmin and its dead on accurate.  Noticed in the pictures I drew a line for you to show you where I ran the cable.  You will need to get more straps (lowes) and route the cable correctly.  Hope this helps.  If you need more pictures, let me know.

Your welcome... put that magnet on the back and from there if you put it in a way that gravity will push where the wires fork and it will stay that way.  I think this unit comes with two magnets, therefore put one on the front and one on the back in case you lose one.  Also be sure to set the computer to be exact on the instructions.  If you cant find them they have them online or just pm me and I can send them over as well.