No mountain biking
I didn't see any trails on the property to actually bike on. There might be some around it but I'm not familiar with the area.
No mountain biking at St. Gaudens. Great mountain bike trails at the Ascutney Outdoor Center in Brownsville Vt just across the river
There are a couple paths you can walk/bike. Not sure the difficulty you're looking for, but it's worth a look.
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