Locomotief

I'm not sure if this is the right place for this project but the basis for this project is an old French bike. I wanted to build my own folding bike because I commute regularly between two big cities in the Netherlands. I used parts off a scrap folding bike and a unknown french frame.


first I cut a two cm piece out of the bottom pipe and welded in the separating part from the folding pipe. Then I cut the top pipe.


To connect the top pipe for now I'm using a piece of pipe that fits over the two parts of the bike. Need to make something stronger in the future. But first I want to make a test drive.



this is how the bike looks now.

TenGrainBread 

Cool project.

For the downtube - so you need a wrench to undo the nut on the threaded rod to separate the two halves of the bike? Could you use a quick release skewer, cut to length, instead? That would make opening it faster and you wouldn't need to bring a wrench with you.

For the top tube - Is there nothing holding the top tube together besides the piece of pipe you slipped over the two halves? I think you would want something more secure.

Locomotief

Brakes work but I have an issue with the rear derailleur. The sprockets are made for thinner chain than the rest off the bike. Now I want to replace the two small sprockets off the derailleur but I don't know how to take it apart.



this is rear derailleur. its an huret. Does anybody have any experience with these derailleurs?

Locomotief

TenGrainBread your right about the top part being the weak point at the moment. I'll have to think something to keep the two halfs together. So sort off locking magnetism.

And do you have a picture off a quick release?

TenGrainBread 

In English it's called a "plunger"-type derailleur. They were the design of choice before the modern parallelogram was developed. What you are calling "sprockets" are called "pulleys" in English. They are easy to replace - see the bolt that takes a flat-head screwdriver that runs through the center of the pulley.

TenGrainBread 

Rene Herse had a very successful method for his demontable bicycles...

The smaller tube slides into the larger tube. He slit the larger tube at the end and brazed on a binder to mount a quick release skewer so that the ends of the larger tube can be clamped onto the smaller tube once in place.
Notice also how he avoided putting the shift levers on the front of the bike, so that all the shift cables stay with the rear of the bike when the bike is split. I'm pretty sure the bike in the first picture used push-rod derailleurs. The bike in the second picture had the levers mounted on the seattube.

scarlson 

The way René Herse and Panasonic did it basically is with a piece of pipe, like yours, brazed to one end and with clamps on the end like a seat post clamp to squeeze it down over the tube that slides into it. That top tube is French so who knows what diameter, but it should be easy to slit the pipe and put a clamp on it to squeeze it a little bit. They do sell seat post clamps that you can braze on, and also seat post clamps that you can fit on the end of the tube if you have the correct diameter tube.

I think you're well on your way to having this thing working, and I admire your willingness to dive into something that few others have done

edit: TenGrainBread beat me to it.

Locomotief

TenGrainBread thanks for the English technical names for all the parts.

I tried twisting the flat screw but it will only move a little and then it won't move at all. I'll try it from the other end next time.

Locomotief

I like what he did with his bike. I was planning to have a pipe or piece of steel made that fits inside one of the two pieces to connect them. And use a clamb to hold them in place.

im curious how he separates the cable to the rear brake?

scarlson 

I'm sure that will work, as long as the clamp is strong enough. It needs to be a pinch-bolt type clamp. A hose clamp is not enough!

On the René Herse, the rear brake straddle cable is simply disconnected from the brake arms, and the housing is removed from slotted cable housing stops if necessary.

repechage

Makes one wonder where Herse sourced tubing to get a tube of proper inside diameter tube for the aft section of the 26.0mm top tube.

TenGrainBread 

With cantilever or centerpull brakes, the straddle cable can be removed from the straddle cable hanger without undoing the cable mounting. On custom bicycles meant to fold or at least be packed (such as these demontable bikes or Japanese rinko bikes), the cable guides are generally slotted to allow the cable to be pulled out of the guide once the straddle cable has been separated from the hanger.

There are also cable splitter attachments that you can use to split cables with an allen key, without fully uninstalling them from the brakes. These should be unnecessary when using brakes that require a straddle cable.

TenGrainBread 

A lathe with a boring bar would work! Did Herse have a lathe? If not, perhaps a friendly metal supplier in St. Etienne provided the tubes?

Chr0m0ly 

This is SO the right place for this project.

Locomotief

I'll have a look at the rear brakes next time I'm in my other place. Would be nice to disconnect the two halves completely. And I'll have to find a single shifter somewhere.

scarlson 

I'm pretty sure he did. There are quite a few things on my '46 Herse tandem that couldn't have been done any other way, and quite a few tool marks with chatter and grooving from dull tooling or aggressive feeds, which indicate to me in-house production rather than production runs at a shop.

Locomotief

My uncle has a lathe he can use. I have to figure out the shape of the insert. Because of the lower connection I can't use something straight at the top. It folds in under an angle. (Hope it makes sense what I'm trying to explaine

The rear brake is of this type.


disconnecting at the rear brake is gone be a challenge I think. Have to think of something half way.

canklecat

Take a look at the Co-Motion design for ideas on other methods for assembly/disassembly. The fellow in this video has toured the world on Co-Motion bikes, with lots of takedowns and packing the bike into a single large case. Co-Motion seems to have figured out a pretty good approach to the full size takedown bike.

Kuromori

I wish dumpster bikes were nearly ad interesting where I am. In regards to telescoping tubing and lathes and constructeurs don't forget that since they had 26mm metric top tubes, they also had access to other metric tubes, including 28mm metric downtubes of which a 9/10 cut off would be ideal, and 30mm tubing which is a pretty standard metric size. I'm not sure how thick the tubing is, but I would probably reinforce the ends with an external sleeve or internal plug. A sliding clamp sleeve could be made like the ones used on the downtubes of demountables.

non-fixie 

Nice project! Sawing a vintage French randonneuse in two is always an excellent way to make an entrance here at C&V.

I'll be following closely, if only because I have a similar project in the pipeline, using these:

Locomotief

I wish I joined this forum years ago. I'm impressed by all the interesting replies you guys and girls have given me with my project. There have been some projects in the past I would have loved to share with you guys. Projects would have gone faster and probably been nicer.

and I love all the projects and bikes I've seen on the forum. Very inspirational.

Locomotief

canklecat the bike in the video is really high end. Those connections are next level. Wish I had a set off those somewhere in a box.

Locomotief

Hi Kuromori thanks for the advice. I'll check the tubing size on the frame. Maybe your right about strengthening the ends. There will be quite some pressure and stress on the ends while riding. I have a bunch off old frames lying around maybe the size I need is in there.

Locomotief

Hi non-fixie Those are scaffolding parts right? I'm curious what your plan is? Are gone weld them on?

Locomotief

Found these at my local bike shop yesterday. I'm not sure if the simplex schifter is the right size for the down pipe but it was cheap and nice. I could weld a piece of tubing on the bike if necessary. The roller wheel is for a future project. I suspect that my local bike shop has some interesting stuff lying around. There where parts everywhere and the prices are very reasonable.