I say that because, A) there really aren't any bike-specific GPS-compatible maps out there, and B) handy as they are, I honestly don't think GPS units make great route-finding gadgets, at least not when you're moving moderately quickly as you will be on a bike. Really, if you come to a fork in the trail, it's probably quicker and easier to whip out a paper map and description than it is to peer at a GPS screen and puzzle out where you are.
If you do go the paper route, one new option you might want to look into is a Bend Treadmap ($8; www.lledmaps.com) from a Pacific Northwest mapmaker called Lled Smith. These give 3-D renderings of 36 trails around Bend, with trail descriptions, driving directions, elevation gains, and lots of other good stuff modeled off GIS and GPS data. Better still, the big foldout map has a UV-coating to protect from dirt, rain, and other MTB trail scourges.
Of course, it is possible to copy maps to your Garmin GPS V ($375; www.garmin.com). An example: Garmin's MapSource Topo maps ($116), which cover hiking trails and other features for most of the U.S. They're based on USGS 1:100,000 scale paper maps, so detail isn't great.
The alternative is to purchase one of the newer GPS/PDA combo units, such as the Garmin iQue ($535-$590). It can hold lots of detail, including maps from Maptech's Navigator state-by-state series ($99 per state).
Finally, I leave you with this piece of wisdom: A paper map's batteries will never croak.
For reviews of the year's best adventure electronics, check out Outside's 2004 Buyer's Guide.