Bumping this old thread instead of starting a new one.
I've been using the Wally World/Schwinn 12 function speedo, wired, with no problems. As far as I can tell comparing it with a friemd's motorcycle speedometer, A Tom-Tom GPS and my wife's car it is pretty accurate and I haven't had any RF interference problems. I've had four of them and went to Wally's place today to get another one for the newest bike and found they don't sell the old style anymore. The new one is bigger and the display is easier to read. It has the same 12 functions, mounts the same and so far, after a couple of miles, is working perfectly.
Of course, instead of the $10.00 I was used to paying they have increased the price to $16.00.
Wally also sells Bell. I've had two of them, both wired and both would not work with the engine running. I tossed them in the trash box. This new Schwinn is a good speedo but too bad they raised the price so much just for a bigger display.
Tom