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Equipment > Components > Brakes > Disc Brake Adapters / Small Parts


The IS disc brake tab system is still found on older frames and forks, yet few currently produced disc calipers are designed for the old system. The SM-MA90 Disc Brake Adapter series is the second generation of Shimano's adapter that allows you to use 74mm Post Mount disc brakes on IS51 tabs, and in this version Shimano reduced weight by machining excess material off. Perfectly threaded and precisely shaped for ideal interfacing.

Machined from aluminum alloy and anodized black, the SM-MA90 series adapters come in Front (fork) or Rear (frame) models, and are size specific, for 140mm, 160mm, and 180mm disc rotor set-ups. The adapter creates the necessary offset and height to allow you to update, replace, or upgrade your bikes even with an older IS mount system. Clearly marked information on the adapter body instructs you on how to align for proper installation.

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  • Disc brake adapter for converting IS51 disc tabs to 74mm Post Mount disc calipers
  • Machined to reduce weight without sacrificing stiffness or strength
  • Clearly marked for proper installation alignment
  • Includes the Shimano flanged head steel bolts and wires (or clips) for securing adapter to frame/fork tabs
  • Options:
    • Rear 140mm (Shimano # SM-MA90-R140P/S)
    • Rear 160mm (Shimano # SM-MA90-R160P/S)
    • Rear 180mm (Shimano # SM-MA90-R180P/S)
    • Front 160mm (Shimano # SM-MA90-F160P/S)>/li>
    • Front 180mm (Shimano # SM-MA90-F180P/S)
  • Sold as single adapter, with hardware
  • Color: Black
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