Thanks to one of the mechanics at the Recyclistas shop in Victoria, BC for this tip. It seems Sekine bikes have an odd 70mm bottom bracket shell size; but use the common 1.37"x24TPI threading. Many older road bikes would be the ubiquitous English-standard 68mm shell, although Italian BBs were also 70mm (with a different threading).
Not sure exactly how many of the bikes used the 70mm size, but they were probably on most models, at least up to 1979. Need to check some more frames.
|1974, model SHT|
|1977, model SHL|
Some more technical information. While I had the above pictured frames stripped down, I weighed them both. Both frames have the same lugs but predictably the mixte frame, with its plain steel and extra tubes, is 2lbs heavier. Here's the numbers:
20" Sekine SHT: frame 4lb 7oz, fork 1lb 10oz (Combined 6lb 2oz)
This was Sekine's second from top-of-the-line frame. Lugged, with chromed stays and fork. Built with butted Cromoly tubing and Shimano drop-outs and fork tips.
20" Sekine SHL: frame 6lb 8oz, fork 1lb 13oz (Combined 8lb 6oz)
This was Sekine's nicest mixte racer frame. Lugged, with chrome-dipped fork. Built with Canadian-made hi-tensile tubing, stamped dropouts.