13.3 miles
2,892 ft
-2,891 ft
1.6 miles
High Point

The top of Thunderbolt Mountain offers one of the most outstanding 360-degree views in the Helena area. All of the surrounding mountain ranges are visible from the peak. The high elevation and thick timber make this trail one of the last in the region to shed snow, and drifts are common into late June. The first part of the trail to Cottonwood Lake is very popular with backcountry horsemen and horsewomen, so be alert, and make sure to park courteously, leaving room for horse trailers to turn around.

The trail to Cottonwood Lake is a moderate climb. From the lake, the trail climbs steeply to the top of Thunderbolt Mountain. The junction is at the north end of the lake; if you carry on farther than that you have missed it and are headed into the Little Blackfoot watershed. Near the top, the trail skirts the CDT and recommended wilderness areas where bikes are not allowed, so resist doing any further exploring on your bike.

This ride also offers opportunities for connections with Little Blackfoot Meadows and Larabee Gulch to the north.

Take the Bernice exit of I-90 (Exit 151) and follow the Boulder River Road (staying to the left). Stay on the Boulder River road to the Thunderbolt Creek road, which is directly opposite the Whitehouse Campground. The junction is a distinctive Y and is signed. The Thunderbolt Creek road ends at the trailhead.

Local Trail Association
Montana Bicycle Guild (www.montanabicycleguild.org)
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  • Difficulty rating
  • Route Type
    Out & Back
  • Bike type
    AM, XC
  • Direction
    One Direction
  • Physical rating
More Stats for Thunderbolt Mountain mountain bike route
  • Altitude min
    6,391 ft
  • Altitude start
    6,392 ft
  • Altitude end
    6,393 ft
  • Grade
  • Grade max
  • Grade min
  • Distance climb
    6.0 miles
  • Distance down
    6.5 miles
  • Distance flat
    4,636 ft
Avg: 4 (1 votes)
Layers winter
Map Style
Trail Style
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Trail transparency

Recent Trail Reports Along Route

Thunderbolt Mountain Trail 65
Aug 16, 2015 @ 11:17am
Aug 16, 2015
view all reports ยป
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