No Weld Rear Wheel Drive Recumbent “la Vronimatik”

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Introduction: No Weld Rear Wheel Drive Recumbent “la Vronimatik”

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This bicycle is really easy to do, cheap, and does not require any welding skills.

Front wheel drive recumbents not requiring welding are popular in instructables:

https://www.instructables.com/id/Front-Wheel-Drive-Center-Steer-Semi-Recumbent-Bicy/
https://www.instructables.com/id/Chucks-No-Weld-Recumbent-Bike/
https://www.instructables.com/id/No-Weld-Recumbent-Modifications/
https://www.instructables.com/id/DIY-recumbent-bicycle-made-from-recycled-parts/

I did one myself :  https://www.instructables.com/id/simultaneously-pedalling/

These front wheel drive bicycles are easy to build, cheap and do not require welding. However, they have two main  problems: steering is affected by pedalling and traction is lost uphill because the weight is shifted to  the rear wheel. You may get used to compensate the steering influence of pedalling but it will always be impossible to use the bicycle on a hilly terrain. My rear wheel drive bicycle overcomes these problems while keeping the simplicity of construction of the front wheel drive ones.



Step 1: Materials

For building this bicycle you need:


- Two bicycles. From one of them only the crank related parts are used.

- Two clamps (10 €) of the kind used to fix parabolic antennas.

- Two plastic tubes, inner diameter should allow passage of the chain. I bought chain tubes made specially for bicycles (5 €), but you may use any tube, for instance those black tubes used for irrigation.

Step 2:

Cut the frame of one bicycle and fix it to the the other one with the clamps as in the photos.

Step 3:

Join the two chains (https://www.instructables.com/id/How-to-repairassemble-a-bicycle-chainwhile-keepi/  https://www.instructables.com/id/How-To-Fix-a-Bike-Chain/) and guide them through the plastic tubes.


The upper section of the chain should be straight, the lower doesn't. Keep the end of the tubes close and aligned to the gears.

To guide the chain with tubes is easier an cheaper than using pulleys, springs and gears.

Step 4:

The distance of the seat to the crank should be adjusted to your legs lenght. You may either move the seat or move the crank when fixing the clamps.

The position of any bicycle seat may be shifted some centimetres horizontally, just by loosening the nut and moving the seat. In order to move it even further; I turn 180 degrees the seat clamp, as in the image.

Step 5:

In recumbents it is convenient to have a backrest, not just for comfort, but mainly because you can put more force when pedalling.

I mounted a handlebar with a threadless stem because it happens that the tube of my seat is exactly the diameter of a front fork steerer tube. However, all kinds of diameters are used for bicycle seats. You may find many other ideas for seats in the instructables relating to recumbents.

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15 Comments

Nice mod! It looks like you flipped the rear fork though. Did you remove the crank set and reinstall it on the other side? Is that pice of metal on the side a spacer because of it?

Thank you.

The rear fork used as backrest comes from another bicycle. Is supported with a threadless stem, which I bought. It is explained in step 5.

Yes, that I understood. But the close-up in the second picture in step 2, the rear drop outs are upside down. So I'm guessing that the piece of metal between the crank arm and case is to take up space if you flipped the parts around... Don't know if I'm saying what I mean very well.

Sorry for the misunderstanding. You are right, the section of frame with the crank is upside down. The mysterious piece of metal you are referring to was used in the former bicycle to hold the chain guard. Now it is useless, I didn't dismount it because it is difficult to dismount the bearing without the proper tool.

Ahh, okay. Now I've got it. Thanks :)

very nice, your build changed the design of the one im doing

Thank you! Please tell me about your bicycle when finished.

Nice job. Now I don't need to pay someone to do some welding for me- clamps!! One of those "Why didn't I think of that?" things. Thanks!

Clever way to fabricate something without welding; good use of a sacrificial rear triangle in order to obtain and attach a bottom bracket/crank housing shell.
--Not sure I agree with the "traction" logic about weight over rear wheel. More weight over the drive wheel actually improves traction. The fore-and-aft weight distribution on many recumbents does affect steering though, as you said. It makes the front lighter than on a traditional bike. The steering wheel doesn't respond as well, the front wheel can 'wash out' more. The rearward weight distribution makes the front get even lighter on an incline, with less ability to move your body's ballast over the steering area due to the recumbent position. Perhaps you meant to refer to this dynamic, because 'popping a wheelie' inadvertently on a hill certainly affects traction; inasmuch as most of us on a recumbent would then fall over... But with low enough gears I daresay hill climbing isn't 'impossible,' just more difficult.
I still like your build, it fits my 'Swiss Family Robinson' ethic of being able to make what you need with what you have on hand!