If you haven't paid for the 660 yet, check out the Garmin Nuvi 500 - designed for auto/motorcycle/marine/hiking - it's shock and waterproof. Wife got me mine for Christmas and I use a Ram stem mount. Works flawless and looks sharp! It's much less bulk than the Zumo 450/550 and half the cost of the 660. TONS of features as well. I was going to have her get me the Zumo til I saw the Nuvi 500. It also has an 8hr lithium battery so you don't necessarily have to hard wire it to the bike and still use it for extended periods of time. Our Magellan in the car is lucky to run for 2 hours on the battery which is the case with a lot of GPS units for autos.