The holes are threaded and 20mm apart. There are identical holes on the other side where the gears are. Can I install disc brake calipers through these holes?

  • 2
    One way you can tell they're not disc brake mounts is that you can't use a disc brake on the gear side.
    – Batman
    Jul 9, 2017 at 0:57

1 Answer 1


They are rack and fender mounts and you cannot install disc brakes with them.

I.S. mounts are 51 mm apart, and post mounts are 74 mm apart (and look totally different). For more details on these mounts, see this answer.

  • Bummer, guess I need an adapter if I want to mount disc brakes. Thanks for the answer and the reference!
    – watchTower
    Jul 10, 2017 at 2:35
  • @watchTower - by the time you include cost of something like Braketherapy or another adapter, the cost of calipers and rotors and a disc ready wheel, you're well on the way to the price of a new low end bike with disc brakes already fitted (and certainly in the territory of something decent on the used market). Retrofitting disc brakes is almost never a good idea.
    – Batman
    Jul 10, 2017 at 2:39
  • Also, note that rim brakes (e.g. V-brakes) aren't bad, especially if you don't go offroad.
    – Batman
    Jul 10, 2017 at 2:41
  • Is it possible to do with these parts: 6 Bolt Adapter , brake cable , frame adapter
    – watchTower
    Jul 11, 2017 at 14:43
  • and calipers/rotor
    – watchTower
    Jul 11, 2017 at 14:48

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