It sounds like the trail is too rough for mountain bikes. The land manager is at fault for permitting them.
Mike
http://www.kxlh.com/news/mountain-bi...man-on-sunday/
Mountain biker rescued south of Bozeman on Sunday
BOZEMAN -- A woman was rescued on Sunday after a mountain biking incident in the South Cottonwood Canyon, south of Bozeman.
According to Gallatin County Sheriff's Office, the woman, in her 40s, was carrying her bike through a rough area when her foot was tangled on something in the trail, and she fell.
The accident occurred about four miles from the trailhead. Her riding partner rode 2 miles to get cell service and dial 911.
With the assistance of Gateway Fire Dept and AMR ambulance, 10 rescuers hiked in and used a specialized one-wheeled stretcher to carry the woman out. She was then transported by ambulance to Bozeman Deaconess.
It took rescuers almost 4 hours to get her out.