I had one of the expensive ones that would occasionally misread second and third. The seller of the unit said it was because of the wear on my shifter sensor. He cheerfully refunded my money. The problem is that if you think you are in third, but you are really in second, a downshift drops you to first, and can slide you tire if you don't realize which gear you are going to. I also tried the cheapies that use a sensor attached to the shift pedal, and two magnets on a bracket. Same type of problem, only caused by any extra movement of the shift lever. If you feel the gear isn't all the way, and shift it in again, it reads as another shift. The only way back is back to 1st or 6th, and start over. I removed them both. I would like to have a shift indicator, but one that reads wrong is worse than none. If you want to try one, buy the plug and play expensive one. If you shift sensor is good, it should work. I've gone back to speaking the shifts in my helmet.