The Tribsa, or Tri-B.S.A., was a custom built café racer or off road motorcycle of the 1960s and 1970s. Its name was an elision of Triumph and BSA.[better source needed] 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 650 cc twins engines were overhead valve (OHV) 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.
A batch of nine TriBSAs were planned by the factory for the 1966 ISDT using 348 cc, 490 cc and 'special capacity' 504 cc 'short' Triumph twin engines in a frame using geometry from the BSA Victor scrambler, Victor front forks and wheel together with a Triumph QD rear wheel in a Triumph swinging arm (swingarm in American English). A light-alloy Gold Star type fuel tank and a steel oil tank were fitted together with three ignition coils, one as a spare.
The 490 cc prototype was finished and tested in Wales with the remaining batch utilising the other engine sizes scheduled to follow. Some bikes were intended to be named Triumph and the others BSA.
A Tribsa was built experimentally at Meriden by Triumph in 1973 using surplus BSA A65 frames. This led to a 'factory Tribsa' which was to use the BSA A65 frames with the 650 cc TR6 engine. Not many of these hybrids were produced and factory records are vague.
- Harwood, James; Coe, John J., Life's a hoot: the autobiography of James Harwood, p. 206, retrieved 2011-09-26
- Walker, Alastair (2009), The Café Racer Phenomenon, p. 11
- The BSA Gold Star by Mick Walker, 2004
- Motor Cycle, 21 April 1966. On the Rough, by Peter Fraser. Accessed 2013-06-29
- Motor Cycle, 8 September 1966. ISDT Full report and final standings. K. Heanes, J.Giles 348cc Triumph. S.Miller 490 Triumph. Messrs. A.J. and A.R.Lampkin, 502cc BSA. Accessed 2013-07-01
- Motor Cycle, 25 August 1966. Shell BSA advert featuring Messrs Alan and Arthur Lampkin. Off-road Competition bike with Triumph twin engine badged as BSA. Accessed 2013-06-30
- Triumph: A Century of Passion and Power. P. 142. Lindsay Brooke, 2003
- "Bell dominates at temple cloud moto-x." Europe Intelligence Wire 4 Aug. 2009. General OneFile. Web. 26 Sep. 2011.
- "Frost leaves rivals in the cold to win Enduro class." Europe Intelligence Wire 10 May 2005. General OneFile. Web. 26 Sep. 2011
- "Crease reigns supreme in muddy trial." Europe Intelligence Wire 2 Dec. 2003. General OneFile. Web. 26 Sep. 2011.
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