DISRAELI GEARS

BSA 4-Star

BSA 4-Star derailleur main image

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 (you can see this all explained in UK patent # 640,473). 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.


  • Derailleur brands: BSA
  • Country: UK
  • Date of introduction: 1950
  • Date of this example: unknown
  • Model no.: unknown
  • Weight: 219g including integral hanger plate, but excluding drop-out bolt, external spring and spring chainstay clip
  • Maximum cog: 22 teeth?
  • Total capacity: 8 teeth?
  • Pulley centre to centre: not applicable
  • Index compatibility: friction
  • Chain width: 1/8”?
  • Logic: low normal
  • B pivot: one sprung pivot
  • Materials: steel
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Browse associated documents.



BSA Fine Quality Bicycles

BSA Fine Quality Bicycles

  • Publisher: BSA
  • Date: July 1950
  • Derailleur brands: BSA
  • Derailleurs: BSA with original cage design, BSA 4-Star
BSA Fine Quality Bicycles - scan 1 thumbnail


It’s time you had a BSA

It’s time you had a BSA

Its time you had a BSA - scan 1 thumbnail
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