This was the second incarnation of BSA’s unique ‘tube’ design. The cable nipple lives inside the pulley hub and the cable runs up the tube (around the smoothly radiused bend) and out by the adjustable cable outer stop. The cable is clamped at the lever. As the cable is pulled, the pulley hub slides along the tube, moving the chain. Chain tension is provided by a spring running along the chainstay and attaching at the eyelet close by the adjustable cable stop.

Fiendishly simple and beautifully made, but wasted on a single pulley design that was never going to change gear accurately.

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1. •Brand: BSA
   

2. •Country: UK
   

3. •Date of introduction: 1952
   

4. •Date of this example: unknown
   

5. •Model no: unknown
   

6. •Weight: 219g including integral hanger plate, but excluding drop-out bolt, external spring and spring chainstay clip
   

7. •Maximum cog: 22 teeth?
   

8. •Total capacity: 8 teeth?
   

9. •Pulley centre to centre: not applicable
   

10. •Index compatibility: friction
    

11. •Chain width: 1/8”?
    

12. •Logic: low normal
    

13. •Pivots: one sprung pivot
    

14. •Material: steel
    

0266/I