by mark » Mon Aug 08, 2011 9:43 am
There are a number of different trains of thought. All depends on what sort of features you want and how much you want to spend. It comes down to two basic variations: automotive-type GPS units and multipurpose ones.
The automotive units use a landscape display orientation (these days, most of them are widescreen) and usually include lots of convenience features such as spoken directions, MP3 players, and in some of the high-end models, even XM radio, weather, and traffic notifications. However, their actual GPS functionality tends to be more limited, pretty much just basic Point A to Point B routing with or without some stops along the way (beware of some of the low-end automotive units, which are Point A to Point B only, making it impossible to plan an indirect route). If you want to get one of these, go for a motorcycle-specific model, such as Garmin's Zumo series; these are waterproof, whereas the car models will get fried the first time you hit rain.
Personally I use a multipurpose GPS unit, in my case a Garmin Oregon 300. This gives up the convenience features like spoken directions and MP3 player, but I don't need those anyway. On the other hand, it gains some serious navigation features. The display is portrait orientation and high-resolution, which I find to be a lot more useful than a widescreen landscape orientation because it lets me see what the road does ahead (ie, tight corners, etc) instead of showing me a bunch of irrelevant stuff off to the sides. Also, it's got a much more flexible interface and can be configured to display a lot more useful information on screen than the automotive models (I have mine display speed, time of day, distance to next turn/waypoint, and distance to destination; there's a long list of other bits of information that can be displayed, and you can customize the number of data fields that appear on screen). Another extremely useful function is the ability to record and follow tracks. A track is basically a breadcrumb trail of where you've been; after a ride you can download it off the GPS and display it on Google Earth or whatever. Tracks are also really useful for sharing rides and for offroad riding on trails/etc that aren't displayed on the map (you can just have your GPS follow a track that someone else gave you). And finally, this type of GPS allows you to install not only the City Navigator mapset (that's the set of routable road maps), but also all sorts of other maps such as topo and custom maps (there's a procedure Garmin documents on their website for converting scans of paper maps, for example, into maps that can be displayed on the GPS unit), and you can have multiple maps active at the same time. I use this function all the time so I can display a topographic map on screen while still having the full road routing functionality of the City Navigator mapset.
Garmin has a new GPS out in this second category called the Montana; it's probably the most versatile GPS currently on the market. It can be used with a rugged mount designed specifically for use on motorcycles, ATVs, boats, etc, and with the addition of helmet speakers plugged into the mount, you even get the spoken directions. Plus it has all the features of the Oregon, and the screen orientation can be changed between portrait and landscape just like on an iPhone. This is without question the GPS I would buy if I were currently in the market for one; I'll probably replace my Oregon with a Montana next year.
For what it's worth, I wouldn't bother looking at anything but Garmin. Tomtom's GPS units work well for cars but just don't include the functionality useful to motorcyclists, and all the other companies lag behind in terms of functionality, user interface, etc. Plus you can download Garmin's BaseCamp software for free onto your computer so you can do all your route planning, etc, there and then upload it to the GPS when you're done. I find this absolutely invaluable for trip planning.
--mark