Can I replace my damaged rear cantilever brake with a caliper brake?
I assume there are two things to consider: frame and lever.
The frame has a black, hook-shaped part, which I believe Sheldon Brown would call a "device to prevent the transverse cable from snagging the tire if the main cable parts".
How do I assess if I can replace this part with a caliper brake? Do I need to measure the distance to the rim? Would it be enough to get a ballpark measurement from the bolt's centerline to the crown of the tire, and then add the tire diameter?
I assume it would need to be a Single-Pivot Sidepull Caliper brake. In any case, examples of specific compatible types/models would be much appreciated, just as an indication. I am not asking for "traditional" product recommendation: if compatibility is confirmed I will likely be sourcing the brake from a bike jumble or similar. Chances are I would need a model which is out of production anyway.
What about the brake lever? If I am reading this old answer correctly then I can just keep the current lever, originally intended for cantilever brakes (as opposed to direct pull, aka v-brakes). Is it as simple as that? If they are not directly compatible, will it show in insufficient pull (weak braking)? Or excessive pull (reduced modulation, harsh braking)?
Acknowledgment: this question is a child of Brake post broke off the boss. How do I replace it?
One of the comments on the original question was "is there a hole to install a caliper brake in the bridge above the wheel?"
I think it's an idea worth exploring, but it's probably better to address this in a separate question instead of a combination of edits and comments - but opinions on this are welcome.
EDIT: The first answer I received was skeptical. Only when I read it I remembered I used to have a Gemini Outrider with caliper brakes. So it seems appropriate to include some example photos - they aren't great but they were not taken to document the brakes. I believe these bikes were MTB BSOs sold by Halfords UK. I think the rear tire was a Michelin Wildgripper 26 x 1.95 which I put on myself, and there seems to be reasonable clearance remaining.
I can easily imagine that brakes like these were only ever put on at the BSO factory, and never available as a standalone part. So they might not even have a make and model - well, I guess it's still worth asking.