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Folding bicycle alterations...

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Old 05-22-13 | 09:15 PM
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Folding bicycle alterations...

Hi, I recently post a thread about my vintage 24" foldling bike. I was riding my Schwinn Varsity this morning and I imagine something but I don't know if is possible... (My father was the one who always modified and fix our bikes so I'm not the expert)

I have another Schwinn Varsity from the 70's that needs a lot of restoration but I'm not planning on working with it any time soon so here is what I was thinking: using the gear of that Varsity with the folding bike.

The folding bike has a Torpedo Duomatic 2 Speed Kick Back Hub and the Varsity has a Positron II with the handlebar post shifter.

I just need to know if is possible and how hard can it be...

Feel free to share any comments or ideas

Here are some pictures...

Schwinn Varsity



Folding Bike

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Last edited by lalivntg; 05-22-13 at 09:33 PM.
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Old 05-22-13 | 10:43 PM
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Go for it, restore the bike to its former self.
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Old 05-22-13 | 11:27 PM
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I would say it i quite lot of work, and I would say that you may not have enough knowledge to do it and you`ll end up with two dismantled bikes that you can not use.

Is the gears on the folder not enough for you?

Do you live in a hilly area? Do you use both gears when riding it or mainly one gear?
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Old 05-23-13 | 12:04 AM
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Normally the dropouts in the frame where the wheel screws in are different depending on if the bike uses a sprocket cluster or an internal hub gear - there is almost certainly a workaround somehow, somewhere, if you really had your heart set on swapping. Mucking around with bikes is a great way to learn, but it's often the hard way and any special adapters and connectors you might need tend to add up.

You would also need a new rear brake on the pink folder to replace the coaster brake the hub has now.

Ih it were my decision I'd keep the Duomatic just where it is. It's far nicer than than the Positron anyhow.
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Old 05-23-13 | 04:46 AM
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I'm going to recommend taking both those bikes apart, cleaning them (that Varsity stem/shifter area needs a oxalic acid bath BAD!) and then putting them back together as original. Some of the matters you're dealing with include:

Taking down and rebuilding the rear wheel on the folder. The folder is a 24" wheel. The Varsity is a 27". Even if in good condition, you're probably not going to be able to reuse the spokes, as the hubs are probably a different diameter. And, to do it right, you'll be rebuilding the front wheel, too. And . . . . . . have you measured the rear hub width and rear dropout width on the folder? I'm assuming the Varsity is 120mm.

Making the crank work. Does the folder have the same style Ashtabula crank as the Varsity? I'm assuming the Varsity doesn't have a front freewheel setup on the crank. If so, the bearing used in Schwinn one piece cranks are different from anybody else's one piece crank.

OK, let's say you've got the wheels swapped, and the Varsity crank working. Now, does the front derailleur from the Varsity even fit on the folder? Little matter of strapping it around the seat tube. If its a normal folder, I doubt it.

Then we get up to mounting the rear derailleur (is the right rear dropout amenable?) and the vagaries of the setup.

Obviously, it can be done. I have no doubt that I can do it. Then again, I'm a bicycle mechanic with 40+ years experience, a fully equipped shop on the other side of my driveway (I do vintage restorations professionally as a hobby-business), and the time, confidence, and patience that absolutely nothing cannot be done and there is no bicycle that cannot be fixed. Hopefully you share my experience (OK, five years experience would probably do it) and confidence before diving in.

Best off, just restore the bikes the way they were. You're going to have a wonderful learning experience that'll possibly set you down the path that I followed, and two nice bikes to ride when you're done. What you're not going to get, despite your dreaming, is a cheap answer to a Brompton, Bike Friday, etc. If you want a derailleur equipped folder, at least start off with a more modern frame that's designed for that kind of drivetrain. You're attempting the equivalent of adding a derailleur to a three-speed roadster like I did 40 years ago as my daily commuter. It worked, but the labor involved to make it work was more trouble than the final product was worth. I'd have been better off just buying a 10-speed commuter bike (Schwinn Suburban or Raleigh Sprite). And I was working from a commercially available conversion kit, not rolling my own from the moment go like you're proposing.
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Old 05-23-13 | 07:20 AM
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Originally Posted by sykerocker
I'm going to recommend taking both those bikes apart, cleaning them (that Varsity stem/shifter area needs a oxalic acid bath BAD!) and then putting them back together as original. Some of the matters you're dealing with include:

Taking down and rebuilding the rear wheel on the folder. The folder is a 24" wheel. The Varsity is a 27". Even if in good condition, you're probably not going to be able to reuse the spokes, as the hubs are probably a different diameter. And, to do it right, you'll be rebuilding the front wheel, too. And . . . . . . have you measured the rear hub width and rear dropout width on the folder? I'm assuming the Varsity is 120mm.

Making the crank work. Does the folder have the same style Ashtabula crank as the Varsity? I'm assuming the Varsity doesn't have a front freewheel setup on the crank. If so, the bearing used in Schwinn one piece cranks are different from anybody else's one piece crank.

OK, let's say you've got the wheels swapped, and the Varsity crank working. Now, does the front derailleur from the Varsity even fit on the folder? Little matter of strapping it around the seat tube. If its a normal folder, I doubt it.

Then we get up to mounting the rear derailleur (is the right rear dropout amenable?) and the vagaries of the setup.

Obviously, it can be done. I have no doubt that I can do it. Then again, I'm a bicycle mechanic with 40+ years experience, a fully equipped shop on the other side of my driveway (I do vintage restorations professionally as a hobby-business), and the time, confidence, and patience that absolutely nothing cannot be done and there is no bicycle that cannot be fixed. Hopefully you share my experience (OK, five years experience would probably do it) and confidence before diving in.

Best off, just restore the bikes the way they were. You're going to have a wonderful learning experience that'll possibly set you down the path that I followed, and two nice bikes to ride when you're done. What you're not going to get, despite your dreaming, is a cheap answer to a Brompton, Bike Friday, etc. If you want a derailleur equipped folder, at least start off with a more modern frame that's designed for that kind of drivetrain. You're attempting the equivalent of adding a derailleur to a three-speed roadster like I did 40 years ago as my daily commuter. It worked, but the labor involved to make it work was more trouble than the final product was worth. I'd have been better off just buying a 10-speed commuter bike (Schwinn Suburban or Raleigh Sprite). And I was working from a commercially available conversion kit, not rolling my own from the moment go like you're proposing.
You said it, I was too lazy to do it. My thinking is if the OP want to use the folder and really need more gears a gearhub with more gears is the best solution. Could be helped with a bigger rear sprocket too if the two gears is not the right two gears.
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Old 05-23-13 | 08:05 AM
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positron stuff needs to find a new home, new wheel in back. with normal freewheel function.
86 the rest of the POSitron.

it can be a single speed.. or another 3 speed, maybe get a wheel built around the Sachs hub.


cant say anything from your keyhole pictures , so Ill say good luck,,

a bike shop can see stuff, i see nothing .
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Old 05-24-13 | 05:00 PM
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Thanks for all the info. I thought about this because I'm very short (less than 5ft) and even with the changes in the seat post of the varsity sometimes I feel uncomfortable in a 27" bike or even a 26". And I feel so much comfortable in the 24".

I don't want a cheap version of a Bike friday or a Brompton Bike, if I want a small folding bike I probably just buy Brompton Bike but is not the case. I just want a vintage 24" with more than 3 speed... I live in Puerto Rico so flat terrain is not common here... I guess I will change the hub for a Sachs Torpedo 3 speed and use the bike for very short distances.

I'm always looking for a 24" Schwinn Varsity 10 speed but is a challenge here in PR... The "thing" for Schwinn and vintage bikes it's something I used to share with my dad and siblings and we are keeping up the tradition...
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Old 05-24-13 | 05:56 PM
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You could get a five speed hub for the folder. Sounds like 24" is a good size for you . I`ve got a similar 24" detatchable bike, same hub.







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Old 05-26-13 | 04:16 PM
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Thanks for sharing!

Someone send me some pictures of a Gitane 24" with a Huret Rear Derailleur...

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Old 05-26-13 | 06:28 PM
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Neat bike, but if you're not over 55 and aren't used to the action of a Huret Allvit, I don't recommend using one. Performance wise, their biggest plus is a massive casting protecting the mechanism and making the workings impervious to damage on a right side fall-over. The next biggest plus? By modern standards, there aren't any. It was a wonderfully designed and performing derailleur when it was introduced . . . . . . . in 1962 . . . . . . . but by ten years later it was hopelessly obsolete. With a stiff action and incredibly imprecise shifting. Not that that stopped Schwinn from using them for something like another ten years.
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Old 05-27-13 | 04:24 PM
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What about using a Shimano Alfine internal hub? (8 speed or 11 speed...)
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Old 05-28-13 | 12:05 AM
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Originally Posted by lalivntg
What about using a Shimano Alfine internal hub? (8 speed or 11 speed...)
not without coldsetting the rear fork.
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Old 05-29-13 | 10:52 AM
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"not without coldsetting the rear fork. "


Do you think is worth it, taking the bike to my LBS for cold setting or just go with a 3 speed hub?

I started taking this bike everyday to work and I really really feel the difference riding a 24" I feel so comfortable that I don't want to go back... The 2 speed hub is Ok for short trips (without hills) but my route to work is not an easy one and I'm getting too tired. This is why I'm worried that the 3 speed hub is not going to give me enough gears for that route and I will get stuck with the 27" for work...I don't have a car so I just used my bicycles to move around.

Someone from work offer me a new NIB Shimano Nexus 8 Speed with coaster brake (with shifter for $180). This one is 132mm instead of 135mm of the Alfine, but still I have to take the bake for cold setting... and I like the Alfine better.
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Old 05-29-13 | 01:29 PM
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A home-brew "dual drive" isn't too hard. Take a couple of sprockets and a spacer from a 7-speed cassette and find an older Sturmey-Archer 3-speed hub. Grind away all but three tabs on the sprockets so they'll fit on the hub. The hub is just wide enough for two sprockets, and the diameter of the hole in the sprocket is the same as the diameter of the hub body. Get a second-hand derailleur from the local co-op, or use the positron. Build the hub into the wheel, cable it up and go- 6 speeds with good ratios. Here's mine:



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Old 05-29-13 | 01:34 PM
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First read this carefully to find out if you can do it yourself or have a friend that can help: https://sheldonbrown.com/frame-spacing.html


I did this to two 20" bikes. Since they are that small the chainstays and seatstays are short so I had to cut the brakebridge and the bridge behind the BB (forgot the name) to open it up enough. Then had a local welder weld it up again in the new spacing. I think this may not be the case with your bike since it is 24" not 20".

I think you should go with the hub that makes you happy in the long run. You can get 3 and 5 speed hubs (without coasterbrake) that should fit in without altering the rear fork but if you need more go for it. If you use the bike a lot you need a bike you like and trust.
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Old 05-29-13 | 01:39 PM
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Originally Posted by cycle_maven
A home-brew "dual drive" isn't too hard. Take a couple of sprockets and a spacer from a 7-speed cassette and find an older Sturmey-Archer 3-speed hub. Grind away all but three tabs on the sprockets so they'll fit on the hub. The hub is just wide enough for two sprockets, and the diameter of the hole in the sprocket is the same as the diameter of the hub body. Get a second-hand derailleur from the local co-op, or use the positron. Build the hub into the wheel, cable it up and go- 6 speeds with good ratios. Here's mine:

Great job you did there but I am not sure I would suggest a newbee do this when that person is also trusting that bike as the only transportation. This I would maybe try on bike number two or three..
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Old 05-29-13 | 03:26 PM
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Originally Posted by cycle_maven
A home-brew "dual drive" isn't too hard. Take a couple of sprockets and a spacer from a 7-speed cassette and find an older Sturmey-Archer 3-speed hub. Grind away all but three tabs on the sprockets so they'll fit on the hub. The hub is just wide enough for two sprockets, and the diameter of the hole in the sprocket is the same as the diameter of the hub body. Get a second-hand derailleur from the local co-op, or use the positron. Build the hub into the wheel, cable it up and go- 6 speeds with good ratios. Here's mine:



Thanks for sharing! I'm going to need my brother's help but I want to try it someday but not with this bike.
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Old 05-29-13 | 04:06 PM
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Originally Posted by badmother
I think you should go with the hub that makes you happy in the long run. You can get 3 and 5 speed hubs (without coasterbrake) that should fit in without altering the rear fork but if you need more go for it. If you use the bike a lot you need a bike you like and trust.


Can you suggest a 5 speed hub? Sturmey Archer?

I'm guessing with the 5 speed, 3 is the direct drive and I will have 2 lower gears and 2 higher gears... Is definitely better than just direct drive and 1 higher gear...

Sharing a story... (a short version of the story) Yesterday we helped an old man with his old rusty bike (he needed some tools) and he wanted to try my bike. After he used it he kept talking about brakes and he told me I needed a front brake. Then he took his backpack and he had two weinmann calipers type 810 and brake levers and he just gave them to me. He told me the levers were broken but I fixed them. This morning I add the front weinmann caliper and is working very well. I guess he was right about me needing that front brake
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Old 05-29-13 | 05:31 PM
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Originally Posted by lalivntg


Originally Posted by badmother
I think you should go with the hub that makes you happy in the long run. You can get 3 and 5 speed hubs (without coasterbrake) that should fit in without altering the rear fork but if you need more go for it. If you use the bike a lot you need a bike you like and trust.


Can you suggest a 5 speed hub? Sturmey Archer?

I'm guessing with the 5 speed, 3 is the direct drive and I will have 2 lower gears and 2 higher gears... Is definitely better than just direct drive and 1 higher gear...

Sharing a story... (a short version of the story) Yesterday we helped an old man with his old rusty bike (he needed some tools) and he wanted to try my bike. After he used it he kept talking about brakes and he told me I needed a front brake. Then he took his backpack and he had two weinmann calipers type 810 and brake levers and he just gave them to me. He told me the levers were broken but I fixed them. This morning I add the front weinmann caliper and is working very well. I guess he was right about me needing that front brake
My only experience with 5 speed hubs is with vintage Torpedo 5 speed hubs (both one and two wires) plus the older (two wires) 5 speed SA hub on my Brompton.

The hubs I am thinking about for you is some of the SA 5 speeds. Peopel use the narrow ones on bromptons but also on other vintage bikes. I suggest you look at what is available and decide if you want one or two sprockets (if you go for two you could later do someting similar to what cycle_maven suggested and get ten gears) and if you want a coaster (or drum) brake or if you want to avoid spreading the frame and use your Weinman (or other) brakes.

https://www.sjscycles.co.uk/sturmey-a...&page=1&page=1

Is it a 36 hole rim you have on the bike now (and are you using that or a similar rim)?
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Old 05-29-13 | 08:05 PM
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Originally Posted by cycle_maven
A home-brew "dual drive" isn't too hard. Take a couple of sprockets and a spacer from a 7-speed cassette and find an older Sturmey-Archer 3-speed hub. Grind away all but three tabs on the sprockets so they'll fit on the hub. The hub is just wide enough for two sprockets, and the diameter of the hole in the sprocket is the same as the diameter of the hub body. Get a second-hand derailleur from the local co-op, or use the positron. Build the hub into the wheel, cable it up and go- 6 speeds with good ratios. Here's mine:



Very nicely done. Just the same, I'd be looking for an easier alternative, like taking the time to find a two or three speed cog designed for the S-A hub. Which are more available than most people think, just take the time to look.
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Old 05-29-13 | 08:59 PM
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I believe Sturmey-Archer has an 8 speed hub for 120mm dropouts (Over Locknut Dimension = 120mm).
https://www.sturmey-archer.com/produc...5/id/6/specs/1
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Old 05-30-13 | 08:48 AM
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Originally Posted by badmother
My only experience with 5 speed hubs is with vintage Torpedo 5 speed hubs (both one and two wires) plus the older (two wires) 5 speed SA hub on my Brompton.

The hubs I am thinking about for you is some of the SA 5 speeds. Peopel use the narrow ones on bromptons but also on other vintage bikes. I suggest you look at what is available and decide if you want one or two sprockets (if you go for two you could later do someting similar to what cycle_maven suggested and get ten gears) and if you want a coaster (or drum) brake or if you want to avoid spreading the frame and use your Weinman (or other) brakes.

https://www.sjscycles.co.uk/sturmey-a...&page=1&page=1

Is it a 36 hole rim you have on the bike now (and are you using that or a similar rim)?
Yes, the rim is 36H.

Thanks for the link.

Both the SA SRF-5 (5speed) and the SA X-RF8(w) (8speed) will fit the bike without spreading the frame. The price is about the same (with a $30-40 difference) but I could not find a US seller the 5 speed so I have to add about $40 for shipping.
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Old 05-30-13 | 08:53 AM
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Originally Posted by BassNotBass
I believe Sturmey-Archer has an 8 speed hub for 120mm dropouts (Over Locknut Dimension = 120mm).
https://www.sturmey-archer.com/produc...5/id/6/specs/1

Thank you! I found it yesterday after reading the description of every SA hub...

Any experience with SA 8 speed?
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Old 05-30-13 | 08:55 AM
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Originally Posted by BassNotBass
I believe Sturmey-Archer has an 8 speed hub for 120mm dropouts (Over Locknut Dimension = 120mm).
https://www.sturmey-archer.com/produc...5/id/6/specs/1
Brompton/Bickerton size, that - nice...
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