I ride an 80's nishiki singlespeed started @ $30 from craiglist took off from there, has 48x18 gearing has never changed, Done my first solo century on it from Escondido to Dana point harbor and back. Organized a Out & Back Pie ride up Palomar and Mesa Grande and pedaled this beast up and over for close to 8k ft of climbing on that same gearing.
Before the roadie SS, I also had converted one of my MTB's to SS, loved it but kept dropping the chain so I had to put the gears on it. After riding with JAMMER at Aliso I copied his idea of a three speed on the full suspension 5"x5" travel. Triples up front and one gear in the back, using the rear derailer to take up the chain slack. Done Aliso many times with it and Santiago Truck Trail with it (7 miles of climbs, and 7 miles of fune DH). Currently looking for a SS 29er on the cheap. Hope to pick up a Monocog or Haro sometime after the wedding next month.
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Rule #10 // It never gets easier, you just go faster.