Do a search on Kalispell and motorcycle rental and some places show up. I know nothing about any of them but you might want to check that out.
We are driving out to Glacier National Park in mid-September 2011 and entering near Saint Marys. Any recommendations for dual sport rentals and/or guided trips? We probably won't travel any further south than Helena, MT. Cheers!
I rode up the Going to the Sun Highway and it was great. The other paved roads in the park offer some nice rides. There are many trail and off road alternatives in the area, but not in the park itself.