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Top of the sissy had a dent.

So welded in some patch and smoothed it out. Just about ready for chrome.
At first I was thinking of adding a welded tab to give it a cleaner installed look. But I think the caliper needs a good bit of adjustment and play to get right, so I think I’m going to stick with a frame strap.

The rotor has a very slight warp, but I don’t know if it can be trued. I think with enough space between the pads it won’t bind.

Maybe I’m thinking too much into this. It seems like it’s a sure thing, but…

When I take the wheel off, the caliper flops. Originally it’s supposed to have a derailleur nut and bolt that fits into the dropout to hold that mounting arm that fits over the axle in place. But it’s not designed for a 20” frame. So instead I was thinking about drilling a hole through the dropout and mounting arm, and tapping the mounting arm with like a small M5. But I’m worried about the aesthetics with a little bolt head staring at you when the dropout will be black.

Hmmmm maybe I should get a black bolt?

X marks the spot.
You could drill/tap the dropout, put the bolt through from the back and cut/file the bolt. Not sure if you have enough material but if it’s just to keep it from flopping around might be ok.
@CRASH , I don't know what you use for an alignment tool but I made one from a couple of axles that fit those big diameter pegs the BMXers stand on. They are adjustable and the bigger dia. makes it easier to push/pull on to align. I"ll try to remember to throw one together this weekend and post on tips n tricks.

That’s a few steps ahead. Have to solve the caliper installation problem, then finish dropout alignment. Then drivetrain
My local hardware store has those button cap screws in a variety of sizes in black.

I'm intrigued by your disc brake set up. I've never seen a caliper like that one; or disc for that matter. Has a very 'muscly' vibe to it!

And your freewheel set up on the other side is just as cool. Along the way, tell us a little more about this event / show you are entering this build into. Sounds like there will be entries from many different genres?
Because I’m using a beefed up sissy clamp that was originally used on Murrays, it has a mounting hole for a 3/8” bolt that threaded into the frame. Since this will be holding an adult, I wanted the weight capacity to be higher. So I’m going to be bolting through using a 3/8”.

The original mounting hole on the Rail is too small for a 3/8”.

So I had to drill them open. I am using a pan head because a hex head will interfere with the chain. (Voice of experience talking)


These are way too long, so they’ll be cut down.
My first round of crimping wasn’t enough at the front of the chain stays. So i went another round.

This round didn’t work. And I damaged the tube.

That will be fixed with welding later on.

So I tried pounding on it. No luck. I tried heat and pounding. No luck. So then I thought if I grind the lips created by the crimping, that would open up some room. It did, and I got a little thin in a couple spots, but I’m welding one repair anyway, why not several.

The clearance isn’t great, even with all this work. I just don’t have anything, or at least any idea, how to “cross-crimp”. Maybe I should make another tool with the crimp bar perpendicular, but that seems wasteful. There’s go to be something I’m not seeing. An idea I’m not getting. Maybe you guys can help?

I’ve hit a wall. Maybe the heat is has worn me out today.

Another problem is the tire. The wheel is a true as can be. But the tire juts over at one point and hits the edge. Maybe it just needs seared better? I’ve never been good at seating them.
For the tire you can examine where the tire seats on the rim. Should be the same all the way around. To seat the bead I like to have just a little air in the tube so you can push the bead off the rim. Then just go around the tire and twist/pull the bead against the hook in the rim then pump up with lots of air to make sure it’s good.

Looks like maybe you could spread the stays a bit? Only suggesting this because I know you have access to a welder if things go sideways. You could clamp your crimp tool right under the brake bridge and twist it with another big wrench.

Looking dicey but I know you’ll figure it out.
I was going to suggest possibly cutting out this cross piece and do any additional widening you can, then welding a wider cross piece back in.
However, I am guessing that you don't have much leeway for that because of the tollerance between the cranks and the frame at this location.

That had crossed my mind, but like you said, I’m trying to widen without compromising sprocket clearance.

I think my little propane torch just isn’t hot enough. I’m going to try to find someone with an acetylene torch so I can get that spot to a red hot rosebud and smack it with a hammer.