SunRace Juju M90 Magnesium

SunRace Juju M90 Magnesium derailleur main image

I feel this derailleur demonstrates three points of interest:

  • The Taiwanese have clearly realised that producing me-too replicas of Tourney models is not going to do it for them anymore - added value is their only way. This derailleur is an object lesson in ‘added value’.
  • Shimano is extremely conservative about the materials it uses (and has a historic embedded memory of the Simplex plastic horror). This leaves the door open to other brands to innovate. Here we have both magnesium and ‘engineering polymers’.
  • Cynicism. The use of exotic materials on the customer facing side of this derailleur and steel on the hidden side is beautifully cynical. To be able to make a derailleur using magnesium and ‘engineering polymers’ weigh in at 310g is a masterpiece of the Marketing Manager’s art.

The basic design is almost that of a SunTour V GT with a single sprung pivot, and the guide pulley almost concentric with that sprung pivot. In this case the guide pulley is offset by a millimetre or two - in the style of some SRAM models.

Whatever I say about 310g, it would be churlish not to recognise that this is an interesting and innovative derailleur. Hats off to SunRace!

  • Derailleur brands: SunRace
  • Country: Taiwan
  • Date of introduction: 2005
  • Date of this example: 2007?
  • Model no.: M93LD00KBX
  • Weight: 310g
  • Maximum cog: 32 teeth
  • Total capacity: 41 teeth
  • Pulley centre to centre: 89mm
  • Index compatibility: 9 speed?
  • Chain width: 3/32”
  • Logic: top normal
  • B pivot: unsprung
  • P pivot: sprung
  • Materials: This is a rich and varied menu - the knuckles are ‘engineering polymers’ (plastic), the outer parallelogram plate is magnesium, the outer pulley cage plate is aluminium and finally steel is used for the inner parallelogram cage plate and the inner pulley cage plate.