Tate Labs, the maker of the successful line of Bar Fly Garmin mounts, will soon have a mountain bike model that puts the cycle computer just above the stem. The US$25 handlebar mount will be available July 1 (UK pricing TBC).
With an adjustable viewing angle, the Bar Fly MTB mount could be a good Garmin-holding solution on bikes that have negative- or steep-rise stems. The production units will have a similar finish to current Bar Fly mounts (BikeRadar recently gave the Tate Labs Bar Fly 2.0 mount a rare five-star review).
Tate Labs Bar Fly MTB Garmin mount