Canti brake bosses missing - what do I need?

[Stressed]

I'm sure the diameter is slightly smaller than standard. I found some bosses in my spares, but they don't screw into the holes.

The brakes I'm trying to fit are Avid SDs. Unless I'm missing something really obvious, I cannot see how the spring can be adjusted.

Are there no little screws near the base of the arms?

 

[ishaw]

They might use the sane size bosses as forks, or use a different thread pitch.

 

[Stressed]

@slackboy can probably tell you what you need- he's built a couple!

 

[retrobate]

On my bonty frame the cantie studs are not like other frames.
The bolt that holds the brake on also makes up part of the stud, from memory there is the 6 mm bolt about 35 mm long that goes through the brake and screws into the frame. There should also be a stepped sleeve about 22 mm long that has the same external dimensions as a normal cantie stud 8mm OD stepping up to 10 mm OD.

 

[Carge]

Standard brake bosses don't fit - I know - I tried
I think KB used an M6 thread.

Good news is - I think Synlos might have the answer......
Check out his MIG Repro parts thread.

Down near the bottom of the first post is....

Canti-studs for Bontrager frames and forks. Titan 3.7165

40€/pair (8x)

 

[slackboy]

The bonty rear studs are just a loose sleeve and the bolt goes directly into the frame, as said above.

There are some detailed pictures here:

https://www.retrobike.co.uk/threads/bontrager-race-lite-1997.92986/page-6
Haven't got much advice re: the spring tension, other than bending the springs in the v brake a bit to create tension there

 

[Spanner]

TriAligns are direct fix to the stay stubs. The bolt provides rigidity. And the spring can be tightened or loosened just by using a spanner. When I removed those old Avids, I found myself with neither boss, nor any methos od tensioning the reaplcement brakes.

 

[Spanner]

Standard brake bosses don't fit - I know - I tried
I think KB used an M6 thread.

Good news is - I think Synlos might have the answer......
Check out his MIG Repro parts thread.

Down near the bottom of the first post is....

Canti-studs for Bontrager frames and forks. Titan 3.7165

40€/pair (8x)

That sounds like a solution. For the stud, anyway. If I cannot find a way of increasing the tension in the Avid SDs, I'll have to look for a more adjustable brake. I've found the thread you referred to, so I'll make contact with Synlos. Thank you.

 

[retrobate]

Are you sure that you dont have 4 sleeves? The 2 that belong to the Avids (see pic (hopefully)) and the 2 that are from the frame as shown above and also see here

https://www.retrobike.co.uk/threads/bontrager-fork-canti-studs.222590/
One may be stuck inside of the other.

 

[ishaw]

That's the point I was trying to make. There must have been a boss/sleeve or something on there if the brakes came off the frame. They don't pivot on thin air.