As flat track racing enjoyed a dramatic rise in popularity in the US, companies were formed to support the burgeoning scene. One popular firm was Sonic Weld, which was created in 1967 by Neil Keen. Sonic Weld would eventually be marketed under the Trackmaster brand, but no matter the name they were popular frames for race and custom applications. They developed such a reputation that Cheney Engineering will still sell you a Sonic Weld replica for a Triumph twin for $1,200. Here’s a street tracker built around what the seller states is a late 60s frame.
This example was titled in California as a Special Construction, and it’s powered by a Triumph 650cc that’s been bored out to 750cc with a twin carb Bonneville head. THe surrounding components are also pretty trick: Ceriani road race forks, Progressive Suspension shocks, Bates folding foot pegs, Borrani front wheel, Akront rear wheel, Grimeca disc brakes, and more. There’s some minor cosmetic issues and the tires need to be replaced, but the seller includes a riding video so you can get a feel for what it’s like on the road:
Find this Sonic Weld-framed Triumph for sale in Altadena, California with bidding up to $7,101.98