disc mounts on to a retro frame? am i out of order?

[Uncle Grumpy]

Further to the above... here's a bit of process related stuff...

I used a wheel and clamped a cable disc caliper to the rotor, "bolted" some cardboard to the mount to give me a rough template. Also did the same for the support brace to get it roughed in. In the photo below, it's been cut and trimmed to make it a little sexier than a squared piece of steel.



I transferred the cardboard template across to some steel to make the mount, also using some international standard dimensions that you can track down on the interwebs.



I also made a jig to mount the mount so the mount could be mounted. There are commercially available ones available, but I used threaded rod, nuts and also a rotor to check alignment.



Then comes the marking, trimming, test fitting, trimming, test fitting, trimming... etc. Measure twice, cut once? Bullsh*t. Measure once carefully and trim dozens of times until you get it sitting right. Grind off a little at a time. I should point out that this is all done with fairly basic tools, scribe, rule, angle grinder, bench grinder and vise.

Oh, and a brazing set up. You could also use a TIG welder. You could get away with a MIG if the frame was made out of chunky 4130 - not so anything thin walled. I'd try to avoid using a stick welder.

Part 2 to follow...

 

[Uncle Grumpy]

Part 2...

Eventually, you get the mount sitting flush with the frame, and at the correct offset to the axle. Also, you'll need to hack out some space for the caliper to sit.

I should add that you should continue to check the alignment of everything as you go. Like, make sure the jig is sitting in the dropouts correctly, all that sort of palaver. I also had to knock off the higher of the 2 rack mounts to fit the mount.



Eventually, you'll get the mounting alignment and then you can fire up the torch, put on your brazing goggles and pretend you're Tom Ritchey.

You'll get it brazed up. I know you can. If I can, you can, because I'm average at everything so you'll likely do far better than me.

Do a test fit, and find that everything works just as it should with no rubbing of the disc*.



*Okay... I had to shim the caliper across with a couple of washers - big deal. Moral of the story is "yes, by all means add a disc mount and don't be afraid to do it yourself if you have the tools.