Montana Mountain is the most accessible of the Gilpin County ten thousand foot peaks. It is also the highest and just shy of 11,000'.
From the summit of this almost above treeline peak you will be rewarded with amazing 360 degree views (only slightly obstructed). The slopes are draped with mining relics. Its proximity to the ghost towns of American City, Nugget and Apex ensure that Montana Mountain has played a role in the history of the area.
The most obvious evidence on the mountain that people once lived and worked in the area in much greater numbers are the thousands upon thousands of treestumps. You can imagine at one time the mountain was probably completely denuded and the trees had been used for construction above ground in the mining towns and underground as mine supports and beams.
Take the Peak-to-Peak Highway north out of Black Hawk (remount your bike just outside the city limits) and after 1.4 miles turn left on Apex Valley Rd (County Rd 4S). Follow Apex Valley Rd for about 4.4 miles to the semi-ghost town of Apex.
Turn left on Mammoth Gulch Rd. Follow Mammoth Gulch over a ridge. You'll crest and begin dropping down into an amazing sub-alpine valley called Elk Park.
Montana Mountain is the obvious high point to your left (south). Drive a bit further to an obvious pull-off/trailhead on the right. Walk a few hundred yards back down the road (east) to a 4WD road on the south side. Follow this up the north slopes, bearing to the right through the forest before the road curves back down the slope (and is posted "No Trespassing").
Alternately you can bushwhack SSE from the parking area up the north slope.
The summit is more open than you would expect and the views are stunning.
Be very cognizant of private property in the area. Much is posted, but a good map is crucial to staying on Nat'l Forest property.
There are no fees for this area.
Also, as you approach Apex take note that per Gilpin County ordinances you cannot park along county roads. Play it safe and park only at the pulloffs once you're on the Nat'l Forest.
The area around Elk Park is a mix of private and USFS. Make sure you're on public land and obey all regulations. This is a windy area and presumably the temperatures could get very cold at night.