M400 - 3.8 Series, rigid mountain bike converted to a single speed road bike. Not sure if year is 1992, 1993, or 1994 - If anyone knows for certain, please let me know. Currently set up on just one gear, using the original crankset and multi-gear cassette freewheel. Added a tensioner to align the chain line. Plans to change out crankset and rear hub to go fixed and/or singlespeed with a single gear cog that can be flipped to a single freewheel sprocket. Any advice? Suggestions are welcomed...