"The Tribsa, or Tri-B.S.A was a custom built cafe racer or off road motorcycle of the 1960s and 1970s. Its name was an elision of ‘Triumph’ and ‘BSA’ and the purpose was to combine the best elements of each marque to give a superior bike to either. A Tribsa involved a Triumph parallel twin engine installed in BSA motorcycle frame. Although both the BSA A65 and the Triumph twin engines were overhead valve units, only the Triumph had twin camshafts which facilitated tuning for greater power output. The BSA frame was a duplex-cradle design which was considered stiffer and stronger than the Triumph's single downtube item hence the best of both and Tribsa was built experimentally at Meriden by Triumph in 1973 using surplus BSA A65 frames which led to a ‘factory Tribsa’ which was to use the BSA A65 frames. Not many of these hybrids were produced and factory records are vague.
This Tribsa has been estimated as a 1954 built motorcycle, BSA records show the frame was manufactured from 1954-1959 and Triumph records show the engine was manufactured between 1953 and 1954. The motorcycle is described as being in good original condition, although she will require tuning due to lack of use. The vendor seems to think the bike was raced in the 1957 Isle of Man TT although has no supporting evidence to confirm this. These café racers are handsome machines and this interesting example is supplied with a V5C registration document."