KendallF

I've been working on a home-made tandem for a few weeks, and tonight I pedaled it around the block. It still lacks rear handlebars, brakes, and cables, but the drivetrain seems to work fine and it rides well.

If anybody's interested, I'll try to take pictures in a few days when I've had time to get it cabled and fabricate some sort of rear handlebars. I had to tell somebody about this stupid thing!

I started with an old Centurion road bike frame and a Huffy (whoo-hoo!) mountain bike frame for the rear. I modeled the frame after a couple shown on Sheldon Brown's web site. I cut the front of the Huffy's head tube off, welded it to the seat tube of the front frame. Then I cut and bent the chain stays of the front frame to mate with the down tube of the rear frame and welded them.

I didn't want to use an idler pulley so I ordered an eccentric bottom bracket from Nova Cycles (a frame builder supply), and machined it to fit in the rear bottom bracket shell. I split the rear bottom bracket shell, fabricated pinch bolts and welded them to it.

The drivetrain is a single sided setup with 42 tooth chain rings and a double on the back; modeled after one shown on John Allen's site. If anybody knows where to order longer chainring bolts and spacers, I'd appreciate a source; I have them bolted together right now with hardware store stuff and would like to find some 15 mm long chainring bolts and 4 mm spacers.

Total cost so far has been about $80 for used cranks and chain wheels and a new chain. The road bike was a $10 flea market purchase originally, and the Huffy frame came from a scrap pile. Wheels, derailleurs, etc. came from the road bike. My goal is to ride it in the MS 150 ride in September with my wife.

ohiorider

[If anybody's interested, I'll try to take pictures in a few days when I've had time to get it cabled and fabricate some sort of rear handlebars. I had to tell somebody about this stupid thing!]


Hey! Go ahead - post some pics! I for one would like to see it!

Not so sure I'm ready to place an order quite yet! ...

Ohio

KendallF

Don't worry, I only do crazy stuff like this for myself.



Here it is; the paint is Walmart's finest metallic, $4 a can. I am holding off on doing anything more expensive paint-wise until I decide if I'm going to upgrade the wheels and shifters to 700C/STI. I'd have to weld some mounts for the cable stops, and probably change the brakes.




Here's the drivetrain and a picture of the rear chainwheels. It's basically scrounged Shimano cranks, with 52/42 chainwheels in back and 42 tooth timing wheels. The front bottom bracket is the original 125 mm one, with a 108 mm one in back for a good chainline.



The rear frame had a BMX style bottom bracket shell with a cheap one piece crank. This worked out well as the eccentric is just slightly larger than the BMX shell. I turned the eccentric's OD down on the lathe to fit, split the bb shell, and welded pinch bolt bosses to it. Now you adjust the timing chain tension just like a normal tandem.

Hopefully I can get moving again this weekend and give it some rear bars, cables, and something other than "Fred Flintstone" brakes!

Brian

With some shimming, you should be able to mount a long stem backwards on the captains seatpost, then maybe a flat or riser MTB bar? If the stoker is bent over drops, they'll be dangerously close to the captain's "Exhaust". You can get 17mm titanium (woohoo!) inner chainring bolts on ebay really cheap. I'd consider welding a boom tube between the BBs, which would simplify cable routing as well.

Good luck. It looks far better than your first description made it sound.

KendallF

I'm going to do something like that for a rear bar..probably use a seat post clamp section cut off another scrap "ladies" frame with a piece of tubing welded to it, allowing a normal quill type stem to be inserted. I have a MTB bar, though I thought perhaps a set of bullhorns would work well also.

I may put a boom tube in as well later; that's a good suggestion. It would certainly stiffen it with a small weight penalty. That would allow routing the derailer cables much more cleanly.

For now I'm just going to cable it as-is and take some test rides. It would be nice to take it on our Saturday group ride, and maybe that way I won't blow my legs up before doing a Sunday time trial.

zonatandem

That 'Huffturion' (or 'Centuffy'?) looks like a real neat project!
Definitely would advise a boob tube to beef things up a bit between the 2 bottom brackets. Also try to make stoker's rear stem/handlebars adjustable (up/down, in/out).
Suggest using barcons instead of STI shifting (cheaper/more reliable).
Looks like a rather short wheelbased tandem too.
Have fun on the MS ride!
Pedal on TWOgether!
Rudy and Kay/zonatandem

KendallF

Figured I'd post at least one more updated picture.



I picked up a set of 7 speed STI shifters for $60, put the old wheels from my road bike on it with a spacer for the 7 speed cassette. I welded bosses for the cable adjusters on the down tube, and also had to relocate the rear brake bridge (again!) for the 700c size wheels. The rear bar is made from a scrap seat tube and the MTB stem and bar from the Huffy.

We've ridden it perhaps 30 miles so far; short 'round the block jaunts and one 16 mile trip to the library. It's getting lots of attention and I think we're going to enjoy it!

Brian

And I see you've lubed the chain as well. Looks good.

Jim Bonnet

Are these shifters 7spd Sora Triple? May I ask where you got them for 1/2 the price Im being asked to pay at my LBS?

Bike looks really nice by the way! Congratulations.

Wind 'N Snow

Thing of beauty, well done.

KendallF

The shifters are a used set of Sora (I think!) double, take-offs at a local bike shop when someone else upgraded. They come up on Ebay pretty regularly as well, if you have the patience to keep bidding. Some of them get bid up to crazy prices, it seems.

ElRey

That is the absolute $heeizit!!! I was picturing duct tape and baling twine; you really did a nice job. Hope it rides as nice as it looks.