Question About Changing Dropout Width on a 70's Huffy Tandem

[kc27]

The inside gap from dropout to dropout on my 1970's Huffy tandem (links below) is 100mm. I'd like to expand it 120mm. I've seen a few articles on the web on how to do this. Besides confirming that the frame is made of steel, is there anything that should be considered prior to attempting this. I'd like to swap out the rear wheel to go from a single speed to a multi gear bike.

Any advice would be appreciated

http://www.polar.icestorm.com/sfl/images/huffy_tandem_01.jpg
http://www.polar.icestorm.com/sfl/images/huffy_tandem_02.jpg
http://www.polar.icestorm.com/sfl/images/huffy_tandem_03.jpg

 

[user 135]

no problem. grab a friend and try springing apart enough to slip in the new wheel. you may not need to actually bend the frame.

 

[sensor]

or if theres no one around this is how i got an axle to fit into my stays when i was fitting & lining things up....

round peg/square hole right? no problem!
just notch some tubing about an 1" wider than the stays...

then slide it in at an angle and tap it up until it sits level and then slide youre axle in...when done just tap a corner loose and itll pop right out(i got mine opened up to 9" with that).
if youre worried about the paint i suppose a wooden dowel would work as well(although i dont think id use anything under 1" thick if you go the wood route...since itd probably snap)
good luck

 

[outskirtscustoms]

I always use a scissor jack like what comes with you're crappy foreign cars nowadays, place it between the drops and crank it till it fits. works great.

 

[kc27]

I was naively thinking that all I needed to do was expand the rear drop-outs and install a wheel with an internal hub, add a gear shift, and go. Then I was informed that expanding the dropouts to fit a wider hub will also affect the chainline. With the wider hub, the rear sprocket will be outboard of where the current rear wheel's sprocket is now.

It seems there will definitely be bottom bracket and crankset considerations in order to make this work.

 

[sensor]

you can dish the wheel and also shim the chainring out some(the one on the b.b.) to get it back inline
good luck!

 

[kc27]

Thanks Sensor

I read through some of the other posts in these forums and saw the amazing things people have done with their bikes, and began to think the parts may be out there to make this work.

It seems I would need at a minimum new cranks, chainwheels, and bottom bracket, because the stock one wasn't made to be dissassembled. It looks like it is rivetted together. My question would be, what kind of specs do I need to gather to see if off-the-shelf parts exist to make drivetrain that has chainring spacing for a properly aligned chainline?

And I assume this would mean I would be changing out both sets of cranks, chainwheels, and bottom brackets.

 

[deorman]

If your rear cog is flat, you can get a dished one, or if the existing cog is dished, you can reverse it. You should be able to drill out the rivets and replace or use a spacer for the drive sprocket, assuming it's the outer one. I wouldn't bother collecting parts until getting the wheel in place, so you can visually check the actual chain alignment :| .