Having acquired a DIY tandem last night (Thanks Mat) I now have some slight challenges to overcome! First up is the front seat.

The rear frame (DMR rhythm 24)’s head tube is welded to the seat tube of the front frame (DMR Switchback I think?). I have a seat post which fits (from an old road bike, no idea what diameter but I can work that out later). However, there is no way of securing the seat post!

Given that there is 3 inches of headtube to pass through before reaching seat tube, I’d also need to fill this space to stop it rattling bending, so here are my solutions…

Get some 1 1/8 steerer tube that the seat post can then fit through, place this through headtube/seat tube so it sits tight. Drill a hole through the seat tube of front bike and attach post at appropriate height.

or

adjust post to required height, fill empty space with solder. Pray.

Or

Any other suggestions? I’m sure this problem has been overcome before, but google doesn’t have the answer!

I’d weld a donor seat tube with a small diameter (with existing clamp) into the old head tube. You might find a kids bmx in a skip with a 26mm tube/ 22mm post. It’s a shame it was welded like that. ‘Conventional’ diy tandem wisdom is to cut the headtube of the rear bike and weld it to the back of the front bike down tube, leaving a working seat tube. Bear in mind you’ve got to attached the stoker bars here so it needs to be pretty solid.

Love to see a picture of this Frankenstein special!

thats an idea…

gotta find me some seat tube and a crazy welder! Pics coming soon!