I've tried the search feature but don't see much about these two devices. I've also looked at a couple of cheapys at the bike stores but haven't seen anything with speed and milage. I recall seeing a thread somewhere about digital vs, analog and some talk about ignition interference with the digitals but I can't find that thread again. What are you using for a speedo and are there ones out there with a built in odometer? Any help would be appreciated. I've been logging milage based on known distances between points and how many times I travel that route. I have a Tom-Tom navigator but my bike is currently set up for 6 volt and I'm concerned about vibration and shock to that device. My wife said it could be a Christmas gift but I don't know where to tell her to find one. Help!