Bought a BC1200 and try to install it last night, and ... failed.

I trid to install like this:http://www.canyonchasers.net/shop/generic/sigma.php
but my magnet don't look like that, and at last it didn't work.

Then I searched on the internet, and thought this method bould be good.

http://www.pirmil.info/scoot/ssiburg/650_trip.shtml
But when I installed the sensor as the pic shown, I couldn't find my magnet!

 

A popular brand is from Sigma and can be found online (suggested) or at bicycle shops (not suggested). These give you a real accurate speedo/odometer, an additional tripometer, a CLOCK! plus more features like highest speed depending on the model purhcase. I have the 800. IMO, there is no need to buy anything close to top of the line as the additional features are only useful for bicycling.

They are magnetically triggered from the front wheel and battery operated so there's no electrical hookup. They are made for bicycles (duh) thus the wiring length is limited. You can mount it just about anywhere in the cockpit/dash area. Some make a mount, some use velcro (it's not heavy). I have a handlebar so I mount it as intended for bicycles.

The magnet is typically attached to the brake rotor or outer rim with strong epoxy. I, however, ground down the magnet juuuussst small enough to be pressed/tapped into one of the holes on the rotor. The magnetism along with the tight clearance keeps it there. Zip tie the wire from the pick up to the sensor along the fork and brake line and your done. The instructions from the german company are clear and easy to understand.

They are cheap but very accurate. The only downside is they aren't lit for night time use but there are mods for that!

 

The trick on installation is to get only about 1mm-2mm clearance between the wheel magnet and the pickup on the fork. Too large a gap & the sensor won't get the magnet's reading.

Here's a battery powered night light for your Sigma computer

Here's where you can buy one for $8.99
http://www.nashbar.com/profile.cfm?c...eid=&pagename=
Here's a Sigma Sport BC800 for $12.95
http://www.nashbar.com/profile.cfm?c...eid=&pagename=
And a Sigma BC1200 for $14.95
http://www.nashbar.com/profile.cfm?c...eid=&pagename=
Shipping is around $5.25
http://www.nashbar.com/help/shipinfo.cfm

Both SIgmas have instructions for setting the computer to exactly your wheel size.
Basically you mark the tire (say at the valve stem) and mark the garage floor, then roll the bike one complete wheel revolution, make a 2nd mark on the floor, then measure the distance between the 2 marks & enter that into the bike computer (millimeters). It's very accurate. Simple blackboard chalk will work for marking.

I broke down & bought a speedohealer instead.
Spent $70 more than the Sigma with light setup but it works with the factory speedo AND doesn't put any extra false miles on the odometer.
FYI - The factory error is about 5% and goes up to almost 16% with 15/43 gears. (that means your odometer reads more miles than the bike actually has....bad for resale)

 

This may be old news. If you use a rare earth magnet you can just about attach it anywhere on the rotor w/out epoxy. Radio Shack sells them. I've had mine on for over two years w/out it ever moving. I use a Panoram.