Is pre-planning a must have option
What's wrong with just inputting the destinations on a daily basis?
If the questions sound daft (they probably are ) it's because I don't want to waste money on something like a Zumo if I'm not really going to use all its singing and dancing options.
Hawk
I got a Garmin Nuvi as a pressie a year ago, and now use it on the bike when I need to - RAM make an appropriate mount, and I've navigated across Europe with the Nuvi. The main issue, that Glynn has already indicated, but you may have misinterpreted, is that most (if not all?) car orientated ones (such as the Nuvi series) dont 'do' routing. Forget for a minute about the pre-planning and uploading from a PC, and think about the basic idea of a car based system...in a car you tend to want to go from A to B via the quickest road - these systems do that extremely well. On some occasions you might want to go from A to C via B, again as efficiently as possible.....and again, they do this very well. Very few such systems are waterproof - I dont know if any are, but to some extent, you can work around this (ie stick it ina tank bag map pocket - not ideal to take you eyes off the road, though). Remember that you will definitely have difficulty (=danger!) trying to operate these on the move with a gloved finger as they are simply not meant to do this!
On a bike however, you are likely to want to go from A to Z, via scenic/interesting waypoints B,C,D,E, F etc.........this is where you're snookered - car systems do not generally allow more than one intermediate point. You may think that you only want/need a GPS to get you home from some unknown point, and for this a car system will suffice, but you will pretty soon outgrow this functionality and want the flexibility that a 'proper system' gives, and this is where looking at PC mapping and plotting your ride for the day/holiday then uploading it to the device comes in.
My Nuvi is fine, but if I knew more at the time, I'd have held off and organised a Zumo or the like..................!
Rgs
Vireo