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I have a bicycle frame with mounts for both disc brakes and conventional brakes. I'm curious to know what other accessories I can attach to the conventional brake mounts if I decide to use disc brakes instead. Aside from racks, are there any other gadgets or items that can be mounted on these brake mounts?

enter image description here

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    Frame locks maybe?
    – Rеnаud
    Mar 17, 2023 at 12:56
  • @Renaud that's an answer, not a comment. And noone's mentioned it yet.
    – Criggie
    Mar 18, 2023 at 0:05
  • Stücke, see if the title change is clearer. You can revert it if it isn't.
    – Weiwen Ng
    Mar 18, 2023 at 10:23
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    @Criggie I only put it as a comment as it doesn't look there are a lot of available products, I only found one reference from one unknown brand — AXA (unkown to me at least, and their adapter seem to be design to be used in combination with the brake). I imagine the spacing/positioning is not close enough to use a frame lock directly. So doesn't qualify to me as answer, but might still be useful to indicate as comment.
    – Rеnаud
    Mar 19, 2023 at 8:38

2 Answers 2

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No matter what you do, consider putting a greased bolt into these to protect the threads. You could even put some kind of cap over the bearing surface to protect them, in case you or a future owner wants to use rim brakes.

The threadded bosses can be used to connect cargo racks. They're quite wide compared to other mounting points, and that helps with lateral stability.

You generally can't use these for mudguards or fenders without making your own or modifying existing products.

Also consider that the bosses are at right-angles to the seatstay. They don't point straight back, so if you try and mount rear lights here, the fitment needs to account for that angle.

I might consider using 3D Printing to add a custom holder for something. A pump peg if you wanted to carry a full sized frame pump, or a holder for a track pump.

One downside is that there is only one boss accessible at a time.. So without two points of contact anything added can rotate. Sure, there's a second boss, but its on the other side of the wheel and you have to go over the tyre with enough clearance.

Thus I'd not try and carry heavier items like water bottles on one mounting point.


You might be tempted to install brakes, on the basis more-is-better, or for added redundancy. This generally doesn't work because you're unlikely to actuate both a rim and disk brake with the same lever, and having two levers on one hand is awkward.

The one bike that benefits from two rear brakes is a tandem, and that's where the second brake is only a drag brake, and is designed to cope with longer hot operation, like when going down a hill. These are often set with a barend lever or something like a downtube gearshift, providing a constant drag for the descent, and then deactivated. They get hot, so only drum brakes or roller brakes are suitable and rim/disk brakes are not.

You might choose to use the rim brake, and install a trailer mounting hitch on the disk caliper mounts.

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    chainstay -> seatstay? lights designed for seatstay or mudguard mounting often have wedge built in anyway, with a realistic light beam it doesn't need to be the perfect angle, just in the right direction. Similarly reflectors are *retro-*reflectors that work for a decent range of angles.Water bottles etc. can be carried with a screw for an upper mounting point and a strap for the lower; the bigger problem here is that these bosses stand quite some distance off the stay.
    – Chris H
    Mar 16, 2023 at 11:14
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    @ChrisH fixed - thanks. Yeah there's a lot of possibilities afforded by a threaded hole over just clamping around any part of the frame. I was particularly happy with this red torch holder tinkercad.com/things/0SRvpWOsT1e-red-torch-holder-v2-chrisbent it uses one bolt but clicks around frame. The cable ties really are a backup.
    – Criggie
    Mar 16, 2023 at 11:33
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    Had some suspension forks that had both IS disc mounts and bosses for linear pull brakes. When I finally broke and went to disc brakes, I removed the bosses and fit some stubby set screws in their place. Much cleaner look, protected the threads, and I felt maybe the structural integrity of the fork was maintained having something there besides empty holes.
    – Jeff
    Mar 17, 2023 at 8:34
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    The posts are screwed in. Rather than protecting the bearing surfaces the OP may screw them out and protect the threads.
    – gschenk
    Mar 17, 2023 at 23:37
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    Good spot @gschenk. I wonder what the thread in the frame is (in the bosses it's probably M6 which is a little bigger than accessories usually use but solvable)
    – Chris H
    Mar 18, 2023 at 19:00
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If your fork crown does not have a hole for accessories (or if it is already used), you could try mounting a headlamp onto one of your front brake mounts (or onto both of them for even more style). Of course you need to make sure there is enough clearance between the lamp and the tire.

Here is an example of the kind of lamps that could potentially fit:

enter image description here

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