Jeff Wills

No, that's typical of Schwinn electro-forged BB shells. They were made from a plate of steel which was punched for the tube joints, curved in a circle, and welded. The seam was only partially smoothed over.

Darn shame about the fender bracket.

JacobLee 

Well, it took almost two years, but I finally got the Twinn that my wife bought me some twenty-odd years ago back together. I think I’ve moved three times with this in non-op condition. I didn’t realize what a huge weight would be lifted by the completion of this project.



Got lots of great tips from members, which were very helpful. bulgie recommended an mtb fork with canti mounts, but those are hard to find with 7” steerers, so that didn’t happen. I did, however, find this crazy, huge dual-pivot Tektro in the case at an LBS, and it works pretty darn good!



I built the front wheel around a Shimano disk hub because it was the only thing I could find at the co-ops with a threaded axle that I could swap for solid w/nuts. Plus, I figured it’d be a useful wheel down the road (fork with disc tabs?). The funny thing is this hub has a 10mm axle with turned-down ends, so that threw me for a loop when looking for a solid axle.



Built the rear wheel with burly 12g Sapim spokes to fill the hub flange holes. I saw this mod for the Atom drum brake, which is almost useless, on Sheldon Browne. Used the pulley from a Travel Agent that I haven’t used in 20 years, and it’s pretty slick. Needs a little work still before I trust it 100%, but if you trust the brakes 100% on this bike, you’re in trouble anyways!



Swapped the stem shifter for a Suntour XC thumbie that I only had one of, and it works fine. No reason to shift on the stem when you’re a captain.



And finally, among the items missing when I got this bike was the idler gear, so I made one from the guts of two Sram X9 derailleurs which have these weird off-center mounting holes. Used the pulley with sealed bearing.



It’s clattery, but I can’t imagine the original metal unit was any quieter. We’ll see how it holds up.



Rides about as well as a Twinn is gonna ride!

Hobbiano 

That turned out great. I think you made good decisions choosing your parts without getting too carried away with modifications. Something to keep in mind, if you ever need a replacement headset, is that Tange makes some nice BMX headsets that will likely drop right in - I have a Schwinn Sports Tourer with high quality Tange BMX 125 cartridge bearing headset . It's pretty nice.

J.Higgins 

That bike turned out nice!

Hobbiano 

Is that a single speed master link to the left of the idler pulley? If it is it looks like its missing the clip that keeps it from coming apart.

JacobLee 

Yes! Thanks for catching that! I’ve never been able to get it apart, so I think I had forgotten about it. I’ll get a new master link.

Thanks again!

Senior Ryder 00 

Great job with solid, practical components. Should serve you well!
Cheets,
Van

bulgie 

It could be, but I'm 92% sure it's not. I think it's the type of master link that doesn't use the spring clip. It works by the thin outer plate having holes the nestle into grooves in the pins. The way you remove it is by flexing the chain sideways with both hands, to move the two pins closer together, allowing the outer plate to come off. Hard to explain but easy to demonstrate; maybe I should make a YouTube on it?

JacobLee , I'd say if the plate is hard to remove then you have the type I'm thinking of and it's working as expected, no need to replace it. Maybe try the flexing trick and see if the plate can be wiggled off. Can be tricky since both hands are needed to flex the chain, so you may want to have a helper wiggle the plate off while you do the flexing. I know I can do it myself (have done, many times over the decades), but I don't remember the exact proceedure as in which fingers are free to manipulate the plate while flexing the chain. I don't have one in front of me to try it to remind myself but ISTR it was easy enough..

Mark B

JacobLee 

I suspect you’re right. I spent a few minutes with clamps and pliers trying to see the groove where a clip would go, but that plate doesn’t want to move. I had tried flexing the links as you described, but I’ll give it another shot, just to see if that’s the ticket. Again, I’ve never needed to break the chain, or been able to, so it’s probably fine, but I’d like to figure it out either way.