Swingrat
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I remembered I had 2 lucky 7 chainrings, a 42 and a 36 tooth. I had this idea for a 2 speed in the past by putting both of them on the crank arm. They are concave so they face away from each other and have enough space for the chain. The crank gets a large washer that I replaced with the chainwheel to keep the same spacing.
It never panned out and I don't remember why but I'm not seeing any problem with the idea.
It will provide two gear ratios; with an 18 tooth cog it will have gear indexes of 52 and 61. 61 would be good for regular cruising, 52 for swingin'.
There are two ways to shift, both manually. The first is to loosen the rear wheel and slide it forward or back to take up the slack in the chain when changing to the opposite chainring. With a coaster brake this is the only way. I'm not sure how long the dropouts would have to be. I'd have to size it up to see.
The second is to use the tensioner to take up the slack. The wheel won't need to be loosened, it can be done by hand using the tensioner. The rear hub would have to be a freewheel, the tensioner won't hold up to the pull of a coaster brake.
I'm leaning toward freewheel with a drum brake.
It never panned out and I don't remember why but I'm not seeing any problem with the idea.
It will provide two gear ratios; with an 18 tooth cog it will have gear indexes of 52 and 61. 61 would be good for regular cruising, 52 for swingin'.
There are two ways to shift, both manually. The first is to loosen the rear wheel and slide it forward or back to take up the slack in the chain when changing to the opposite chainring. With a coaster brake this is the only way. I'm not sure how long the dropouts would have to be. I'd have to size it up to see.
The second is to use the tensioner to take up the slack. The wheel won't need to be loosened, it can be done by hand using the tensioner. The rear hub would have to be a freewheel, the tensioner won't hold up to the pull of a coaster brake.
I'm leaning toward freewheel with a drum brake.
I thought I was done for the day, but I just spent another half hour in the shop. I dug out my best band brake and the drivetrain is just about ready to go. I cleaned up a seat I've been saving for a few years.
Very cool project. I'm really liking the dual chainring idea!
I've also got a couple of 10mm lock pins ordered. I may just use one but maybe two. I plan to drill a hole right through the headtube and fork in the rear to lock it in place, then just pull the pin to swing.
The steel place wants to sell me 20' of tubing or nothing, so the wife says we'll go to the junkshop and get me two bike frames. 
My new wheels should show up today.
My new wheels should show up today.
Cool build video. Flying sparks are great.
Looks like a lot of components are coming together. Liking the 2 speed freewheel with a band brake on back.
I need to get a pin or two as well. I see two modes here. Swing and Wiggle mode, or straight classic mode.
Your wife has great ideas. :-D
Looks like a lot of components are coming together. Liking the 2 speed freewheel with a band brake on back.
I need to get a pin or two as well. I see two modes here. Swing and Wiggle mode, or straight classic mode.
The steel place wants to sell me 20' of tubing or nothing, so the wife says we'll go to the junkshop and get me two bike frames.
My new wheels should show up today.
Your wife has great ideas. :-D
I just remembered a car I had in the late 70's, a 69 Dodge Swinger. Just a slant six but a 2 door hardtop!
While waiting for my parts and a trip to the junkshop, I made up the seat post. A 45 degree cut was all it needed. More sparks!
The cut needs to be the same angle as the wedge so it slides up as it tightens. Then a good heavy washer on top so the bolt won't pull through. I'm using 2 washers to be sure. The seat will have to go on the post first then the bolt added because the collar won't clear the washer.
The cut needs to be the same angle as the wedge so it slides up as it tightens. Then a good heavy washer on top so the bolt won't pull through. I'm using 2 washers to be sure. The seat will have to go on the post first then the bolt added because the collar won't clear the washer.
I was waiting on my wheels, so the wife went to get two unseen junk frames from the shop down the road.
I have another frame she brought home awhile back, also junk that is an exact match for the women's frame, so they will be the donors. The boy's frame will be saved for another project.
I painted it but she liked the tiger bike better, so it's been a bare frame there just to look at. Between the two I may be able to connect the top and down tubes and make it look right. I'll check it later but the length is also a concern, it needs to be long enough to clear the cranks with the front tire.
The seat height was a concern. I measured my other bikes to see how far the seat was from the center of the BB. For me, that's about 28". This is at 29" in the pic and I can lower it an inch, but also can cut some of the fork tube to get lower. Then it's depending on the size of the head tube and to make sure I have room to drill a hole through for the lock pin without obstructing the seat post. I'm hoping to get through the whole build without destroying a set of forks.
I have another frame she brought home awhile back, also junk that is an exact match for the women's frame, so they will be the donors. The boy's frame will be saved for another project.
I painted it but she liked the tiger bike better, so it's been a bare frame there just to look at. Between the two I may be able to connect the top and down tubes and make it look right. I'll check it later but the length is also a concern, it needs to be long enough to clear the cranks with the front tire.
The seat height was a concern. I measured my other bikes to see how far the seat was from the center of the BB. For me, that's about 28". This is at 29" in the pic and I can lower it an inch, but also can cut some of the fork tube to get lower. Then it's depending on the size of the head tube and to make sure I have room to drill a hole through for the lock pin without obstructing the seat post. I'm hoping to get through the whole build without destroying a set of forks.
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Make sure to be able to set the saddle a bit lower than usual, especially for the first few rides (speaking from experience here 
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The donors frames headtubes are short enough that I'll be able to shave off an inch or two of height.Make sure to be able to set the saddle a bit lower than usual, especially for the first few rides (speaking from experience here
The wheels showed up!
I was out in the heat measuring the frames. It needs a length of 36" between headtubes as a minimum.
The headtubes on those 2 frames are identical, but they aren't solid tubes, the lugs are part of them. If I cut them off it will leave big holes in the headtubes. I think they will work as they are. I checked the angles and lengths and think I can cut them all off at 10" which will give a straight line, no curves. Then the angles look pretty close to what is needed but I'll check again after chopping them up. They will need center piece to connect front and rear and to be long enough. I think the next size bigger tubing slid over them and welded might work.
Confusing pic.
Now I'm going to relace the new wheels with good hubs.
I was out in the heat measuring the frames. It needs a length of 36" between headtubes as a minimum.
The headtubes on those 2 frames are identical, but they aren't solid tubes, the lugs are part of them. If I cut them off it will leave big holes in the headtubes. I think they will work as they are. I checked the angles and lengths and think I can cut them all off at 10" which will give a straight line, no curves. Then the angles look pretty close to what is needed but I'll check again after chopping them up. They will need center piece to connect front and rear and to be long enough. I think the next size bigger tubing slid over them and welded might work.
Confusing pic.
Now I'm going to relace the new wheels with good hubs.
If you're lucky, you might be able to use at least the smaller (usually the upper) of the two down tubes as an inner sleeve for welding the lower tubes together...
I think they're the same size tubes. I'll know after I do some chopping up tomorrow.
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Slant sickness!!!!
I did some more cutting.
I laid them out to see how they might go together. The minimum length is 36" as they are there. The tubes are all the same size so some kind of sleeves will have to be used. I may not be able to keep the head tube angles and make it flow together. I might go back to my original plan and use new 1/2" steel tubing so I can keep the angles and make it look right.
I couldn't use my high flange hubs with the new wheels, the spokes were too long, even for 4 cross. So I used an extra rear hub from my leftovers and laced it up. They are ready for truing at the shop. The front has a slight wobble probably from shipping.
Then I thought of the good wheelset on one of my builds. Splat Rat. Sealed bearings and good rims I laced up a year or two ago that never get used. I'm going to use them with the whitewalls and put the cheap set on the unused bike.
I laid them out to see how they might go together. The minimum length is 36" as they are there. The tubes are all the same size so some kind of sleeves will have to be used. I may not be able to keep the head tube angles and make it flow together. I might go back to my original plan and use new 1/2" steel tubing so I can keep the angles and make it look right.
I couldn't use my high flange hubs with the new wheels, the spokes were too long, even for 4 cross. So I used an extra rear hub from my leftovers and laced it up. They are ready for truing at the shop. The front has a slight wobble probably from shipping.
Then I thought of the good wheelset on one of my builds. Splat Rat. Sealed bearings and good rims I laced up a year or two ago that never get used. I'm going to use them with the whitewalls and put the cheap set on the unused bike.
Still liking those gold hubs a year later 
My friend juan taught me a couple years back how to thread custom length spokes. The big thing is having the treading tool and the dies. At some point I will have one. Some day I can justify the purchase. 8 sets of spokes would pay for it. But not this year.
If I change over to 12g spokes, I will be able to justify the tool cus lengths are not avaliable in most cases.
My friend juan taught me a couple years back how to thread custom length spokes. The big thing is having the treading tool and the dies. At some point I will have one. Some day I can justify the purchase. 8 sets of spokes would pay for it. But not this year.
If I change over to 12g spokes, I will be able to justify the tool cus lengths are not avaliable in most cases.
Frankenscoot has a set of those also, just not high flange but gold spokes too.
I've got enough extra threads on the rear fork to lower the seat another inch and a half. That's the good news. But I don't think the top tubes are going to cut it. They will be long enough that they may have too much flex at 36". I'll trim them off at the lugs. I will still use the head tubes, but have new tubing extend from headtube to headtube. I figure 1" tubing 1.5 mm thick 40" long x 4 should do the trick and it will not look pieced together. They may be straight or curved if I can find a way to put an even curve in them. Then they will get welded on each side of the head tubes, like twin twin bars.
