There are many possibilities. Mounting a GPSR involves two sets of components, the first is a bracket that is designed to hold the specific GPSR you own, second is generic attachment hardware that connects the bracket to your motorcycle.
AFIK there are at least three companies who make brackets specifically for motorcycle mounting of Garmin 26xx series GPSRs, they are Garmin themselves, RAM, and Touratech.
Ram and Touratech also make attachment hardware. The attachment hardware is usually generic (not specific to any one model of GPSR or motorcycle).
You could try looking at these manufacturer's websites. Or, look at a motorcycle GPS specific website, such as
Cycloactive to get some general ideas, then go look at the individual manufacturer websites.
I use a Garmin SP 26xx motorcycle bracket and a Garmin motorcycle electrical cable, and RAM-Mount brand hardware for the attachment to the motorcycle. This is fully satisfactory if you plan to stay on normal roads. If you plan to do off road riding, you might want to consider the Touratech bracket, which is designed specifically for off road use.
PanEuropean