We have 27+ years and counting. We're starting to look out 15 or so years towards retirement, making certain our ducks are in a row and quacking soundly! I've interested my wife in more biking. Had her out for a 28 miler on a rails to trail path today. She did great!

Thanks for checking on the tooth count! I just checked all my spare chainrings and I can't make a match, either 36-36 or 40-40. I have yet to determine the exact BCD of the primary chainrings (the ones under the Stoker). They are tough to measure while attached.

Does any one have a 36 tooth 110 BCD chainring to swap for either a 38 or 42 tooth 110 BCD (both new)? Or I have several used Campy 144 BCDs and even a big 55 tooth 151 BCD. Let me hear from all you chainring collectors!

Bob, I think I have a 110bcd 40t or 38t. PM me.

-Kurt

I am familiar with it. Driven that way many a time!

If I go I will be sure to let you know.

Here are a few update photos of the Twinn Sport. I've made some changes. Added leather saddles, upright stoker bars, different pedals, changed the front caliper to a centerpull, added a centerpull rear, converted the drum to a drag brake, and the biggest change, a triple crankset. Everything is not quite yet up to snuff, drive wise, but I'm working on it.



It cleaned up very nicely despite all the chips in the paint

Looking very nice there, Rev. It's still a bit of a beast though, isn't it? Mine hangs on the ceiling of the garage, and requires a bit of effort to take down/put up, and may go up for sale before too long. The Mrs has taken quite a liking to the new/old Merckx.

Bob, it looks terrific! You did a great job cleaning it up.

I drove down to the Performance store today to pick up a trainer and a couple of tools, and passed a seventies Paramount tandem with a young couple on it in the bike lane on Market St. I gave them a "thumbs up" and they were grinning ear-to-ear.

Any day on a Paramount is a thumbs up grinning from ear to ear day!

This Twinn is a beast, but something fun to tinker with. I've modified the stoker crankset to add the triple. It was an idea I pulled from another website that I'll post the link to later. I'm not convinced it will work. The crank arm hits the chain as it comes around. I might have to go to a more conventional tandem crankset.

John Allen deserves the credit for how to build this crankset. I found it on his website.
https://www.bikexprt.com/bicycle/tancrank.htm

I'm resurrecting my old thread on my '79 Schwinn Twinn Sport (say that 10 times fast) instead of starting a new one.

Last year I did nothing with this bike. It hung in the basement gathering dust. Over the winter I decided to re-visit the lack of success I had trying to make it more suitable for the mountains.



This time around I had several goals:

1) Convert it from a double to a triple, which meant moving the timing chain from the right to the left.

2) Improve the braking by having "Quad Brakes" operated from two levers.

3) Make it into an upright position bike with fenders which Mrs. PB will enjoy for trips to town, picnic, MUPS, etc.

Last night I took it for a solo test spin and I'm very pleased!

Here are a few of the specs:

Drivetrain: Huret Eco Duopar RD and Duopar FD, Suntour barend ratcheting shifters, Suntour Perfect ultra spaced 6 speed freewheel (14-32), Sugino crankset 48-40-30. The rims are Alex 27" ones from Nashbar and the tires are Panaracers 1 & ¼" with kevlar. I'll probably use SPD pedals in the front and platforms in the back.



Timing Cranks: Moved to the left side from the right. Added the single speed pulley for tension. I wanted to add an eccentric BB but my shell was not large enough. Eventually I made the right hand captain's crank arm out of a crankset I pulled off a junked Peugeot.



Brakes: Originally it had a front sidepull caliper and the rear drum. Now it has rim DiaComp centerpulls, as well as front and rear drum brakes in the hubs. The levers are dual pull MTB syle. The right lever pulls the centerpulls and the left the drum brakes.



Frame & Accessories: I added the chrome fenders, rear rack, front bar bag, Brooks B-72 saddles, and Northroad captain & upright stoker bars. The grips are leather ones from Nashbar.

Now that's a work of art, Bob - especially the dual-cable MTB levers.

Curiously, how is that singlespeed jockey wheel kept under tension? I can't seem to see any spring device on it. Looks sharp nevertheless.

-Kurt

Looks great Pastor. The Brake levers look trick. The setup sounds interesting too. It reminds me off the linked brakes that I had on an old Moto Guzzi.

Does the lever offer more cable pull in the lower housing?

You have done a lot of nice work. Is the rear crankset a tandem set up or did you modify a single crankset? If it is modified, how did you add the left side timing ring?

Neato brake setup! Is that ss pulley sprung?? On our tandem we had an RD setup to tension the sync chain at one point but now its back to rigid. I'm wanting to put a sprung tensioner back on as they do a much better job imo...

There is no spring. Originally there was a jockey like wheel which slid up and down in the bracket you see this attached to. The bracket is well positioned for a right side timing chain. Moving to the left side created the challenge of tensioning the timing chain. This unit works very nice and is simply bolted on. I added the spacers to assist with proper positioning. The red wheel can move left to right on its bearing several mm. The mounting arm is tighten down with that nut and a heavy lock washer. Seems to do the job nicely. I'll see after a 15-30 mile ride.

If you look at the pictures at the beginning of the thread you can see how the Twinn was set up when I bought it. Both the timing chain and drive chain were on the right side. The rear crank was a triple and the granny gear acted as the timing gear. The captain's crank was a Sugino triple (110 & 74 BCD).

I needed a triple on the rear for my mountain climbs. First I tried moving the timing chain outboard and you can see pictures of this earlier in this thread. It did not work due to the stoker pedal hitting the timing chain as I cranked.

Then I picked up tandem timing cranks (left side only) as a bargain on ebay. While I found two captains right arms, neither worked because they had different "Q Factors" from the right hand side. Eventually, I cut a swagged on chainring off of a "dump find" crankset and created my own right hand Captain's crank arm.

Now the other challenge was the BB. The Twinn Sport comes with Astubula style BB shells. Therefore I had to convert these with euro adapters, and then find the correct sized cartridge BBs. The front uses a 115mm Tange, and the rear uses a 118mm Shimano.

See above reply to Kurt. There is no spring tension and I don't believe any will be needed.

The brakes were an interesting adventure. Originally there was a sidepull caliper on the front original steel rim, and the Atom hub brake in the rear. Stopping was horrible. I swapped the front for a centerpull and added a centerpul on the rear steel original rim. I only had a little improvement. I knew that if I wanted to see improvement I had to swap the rims for aluminum ones. I figured while I was doing this I might as well add a drum to the front, thus the quad brakes.

When I first tried them, I had both front brakes hooked to one lever and the same with the rear. Pulling two different types of brakes did not work well and there was a great deal of friction in the line. When I reworked them to have the right lever pull both centerpulls and the the left lever to pull both drums, the friction went away and it was significantly easier to to adjust and sync the two brakes on one lever. I don't believe there is more pull in the lower or upper cable attachment.

Last night on my solo ride I got the bike up to about 20-25 mph and tried an emergency stop. I was very impressed and satisfied.





Here's the catalog page for the 1980 Twinns from the Findley collection.
https://www.trfindley.com/flschwinn_1...0/1980_42.html