I have the Oregon 450 and use it in my car, on my bike, and while hiking. The bike mount that Garmin sells works very well, though I needed to use my brake cable puller to get the zip ties tight enough. YMMV

One item to note with the 450, is that the software only supports microSD cards up to 4Gb. I installed a 16Gb microSD and it worked up until the stored data exceeded 4Gb. This is unfortunately not mentioned in the documentation for the unit.

I have both 24k series topo maps and the City Navigator maps (just for D/FW) installed on the card. Works great and uses 2 AA batteries. They last me about 8-10 hours, though I am using NiMH that I've had for awhile.