Instructables
Picture of Diy tandem
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Ok, to begin with I'm sorry about the limited amount of pictures taken during the actual build. I was a little bit too excited while building this to think of regularly taking pictures, some of you might know a little bit about this... So if the pictures don't make it clear enough, feel free to ask questions!
I've wanted to build a tandem for quite a long time but never really found the will power to do so... until I met my girlfriend! :D
I asked her "If I build a tandem, would you trust me and my creation enough to ride it with me?". The answer was "YES", so from that moment I was determined to build ourselves a tandem!
I scavenged two old bikes, one with a frame large enough for me and another with a smaller frame for mademoiselle. Oh, if you didn't get it yet, the idea was to cut and weld two bike frames together to make the tandem, and that's pretty much EXACTLY what I did.
 
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Step 1: Cutting and preparing the frames

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So, first of all, take off all the parts: pedals, chains, derailleurs, seat posts etc... From both frames. AND remove the fork of the frame that will be usesd as the rear part of the tandem.
  • FIRST CUT: You need to cut off the rear triangle of the frame that will be used in the front. I did this with a hacking saw and then smoothed everything out using a grinder.
  • SECOND CUT: Here, you only need to cut the head tube of the rear frame in half (vertically!) straight down the middle.
Then, once you have made these two simple cuts you need to find a way to align the two frames perfectly before welding them together. I did this by clamping two metal rails to the frames (see on pics). Once everything is in place (with the cut head tube of the rear frame set against the seat tube of the front frame) tack weld the two frames together. Now, before making the real weld pop the wheels back on and make sure that the two bottom-brackets are at an equal distance from the ground (roughly) and that that distance is AT LEAST 25 cm. If you're not able to do so, you'll have to figure out another way of welding your frames together or consider finding other frames. I was lucky and it all worked out fine; if it's your case as well, finish your weld (wich is easy because of the straight cuts!!) but keep the clamps and rails on.
Well done! And the joyful pictures in step six show the whole reason for the build. I've used two large ghost rings together in one build and even linked them together with a wood dowel acting as a locomotive push rod between them. Visually entertaining. I don't have instructables on them but you might like my 3 unusual tandems on woodenbikes.com
Hey, nice build! Very impressed with your ghost ring. I was foolish enough to put my girlfriend's seat in front! (that way I can stop pedalling and she won't know)!
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Gael - Tim (author)  andrew.spencer.21 year ago
Thank you! Awesome tandem as well; it must be fun to have your girlfriend as the captain hahaha :D . The bottle holders make it look very pro, really a neat build.
I was wondering, how did you tension your chain? was it just the right length?
Yes, I guess I just got lucky and the chain fit perfectly, although I did have 3 different chainring sizes to chose from. Have you had any trouble with the pedals falling off on the left side of the bike? I eventually had to crossdrill the little ends of the cranks and put a set screw in each one to keep the pedals from loosening
Gael - Tim (author)  andrew.spencer.21 year ago
Oh ok, I also tried the three different chain rings but couldn't get a perfect fit on any of the three... So far, I've had no problems with the pedals falling off, I just tightened them a lot and if I ever have a problem I guess I'll try thread-locking adhesive or do it the way you did. Thanks for the input!
Edgar1 year ago
Nice!
Spring is in the air, and building stuff and, and appeasing the Wife at the same time, (for the junk on the Garage, for example), is always a good thing. LOL
Went to my Blog:
http://faz-voce-mesmo.blogspot.pt/2013/05/a-newsletter-da-cncking-e-carradas-de.html
Gael - Tim (author)  Edgar1 year ago
Yes, indeed!
Thanks a lot for the Blog post dude! :-)
My pleasure, I collect good ideas. :)
The "Ghost" ring tension-er is AWESOME! (amazing how motivating a girlfriend can be!)
Gael - Tim (author)  paganwonder1 year ago
Thank you! I like it a lot too. :-)
Very cool, good job on the build and getting your girlfriend to say yes to a tandem bike. I have been trying to get my wife to ride tandem with me for a while now, no luck so far.
Gael - Tim (author)  troopersmachine1 year ago
Thank you! And good luck with your wife, don't give up; I find that riding a tandem is really a good experience for a couple.
rimar20001 year ago
Very clever solution, that floating "ghost" ring. I suppose it is the comment of all your neighborhood.
Gael - Tim (author)  rimar20001 year ago
Yes, it's definitely the comment I hear the most.