Stuart Boyes opened Boyes and Rosser Cycles, Ltd., of BC, Canada in 1972, selling motorcycles, bicycles and all manner of sports equipment. Starting in 1983, BRC started importing mountain bikes into Canada until at least 1990.1) Interestingly, a “Boyes and Rosser Ltd.” opened in 1957 in Auckland, New Zealand selling bicycles and motorcycles. 2) Large numbers of BRC bikes fill Craigslist and other online markets in British Columbia today, which is a testament to their popularity and success.
..
If the rear Shimano RS22 derailleur (1981-83) is original, then this frame should have originally come with bullmoose handle bars. Many components have been swapped, so its dating is uncertain. 1983 is a likely start date for BRC, as may online sources corroborate this starting year.
1983 Explorer
adobe
The frame and bullmoose bars are the same as the 1983 model. Shimano Z503 (1984-89) derailleurs with a Sugino RT crankset (1983-88).
1984 Explorer
usednanaimo
Shimano AL11 derailleurs front and rear (1984-86)
1985 Explorer
bikeforums
Shimano RD-L541 GS (1987-89)
1987 Explorer
usedbicyclesvancouver
Shimano Exage Sport (1988)
1988 Sierra
teamcow
Shimano Exage 300LX (1989-91)
1989 Sierra
pinkbike
Deore LX (1990-92) derailleurs, brakes and crankset. It's likely that 1990 was the last model year for BRC.
1990 Banzai
pinkbike