After building up many klunkers from his family's Cove Bike Shop in Tiburon, CA, and then helping his brother Don Koski and Mert Lawwill launch the Lawwill-Knight Pro-Cruiser in 1979, Erik Koski launched the Trailmaster on his own. Only 55 to perhaps 75 were produced over three years 1). Koski resurrected the brand in 1998 to co-produce a Titanium version with Steve Potts 2). See also: mmbhof and mombat.
Erik Koski 1988 mombat
1980 Koski Trailmaster #2 SFO museum
1982 Trailmaster facebook
“#51/53 built”. Converted to single speed. Originally with a 2×7 SunTour drivetrain. SunTour roller cams, PMW dropouts.
1984 Koski Trailmaster #51 facebook
Not enough credit is given to Erik Koski in the history books. Joe Breeze used Koski forks for the first set of Breezers. The Cove Bike shop printed the very first mountain bike catalog in 1980. Koski mountain bike components were sold for decades.
This photo comes from China Camp State Park were mtbtimeline personally used to ride off road in the 1980's each weekend - never once seeing another bicycle - probably because all the action was next door at Mt. Tam…
2014 group ride in China Camp, Marin blackmtncycles
[1]. As Trailmaster #2 was 1980, 1980 is a good guess as the start date. See: SFO Museum
[2]. Less than 100 Trailmasters ever built. Fat Tire Flyer, page 117.
[3]. End of production in 1982? Mombat Koski Catalog