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Splicing tubing

2001, John S. Allen

To make tubes longer than you can salvage from solo bike frames, you can splice them together.

You first step is to cut square ends on the tubes for splicing. Clean the ends inside and out, so that brass will adhere to them and so you will not burn paint as you braze.

Make an internal sleeve out of a short piece of tubing. Cut the internal sleeve lengthwise. The sleeve should spring tightly into place inside the tubes to be joined, aligning the joint.

Drill several holes around each tube near the joint. These will allow you to heat the internal sleeve, and flow more brass into the joint.

Bicycle tubes prepared for splicing. Note the internal sleeve which
serves to align the tubes and strengthen the joint.

splice.jpg (7196 bytes)

Then you are ready to connect  the tubes. Slide the assembly together, cradling it in a length of steel angle stock so the spliced tube will be straight. Melt brass into the joint between the tubes and into the drilled holes. Heating the internal sleeve at the joint is easiest if you hold th join slightly open at first. Apply brass at the joint first, and then heat at each hole in turn. Build up the brass as necessary so it is everywhere above the level of the tubes' surface. Once the joint has cooled, file the brass down to the level of the tubes' surface.

You might also use an external sleeve, though this will not produce an invisible joint. An enternal sleeve is suitable for the tandem's bottom bracket assembly, where there is no expectation of a smooth joint.

To avoid splicing, you could use ready-made longer tubes. Good-quality Cro-Mo tubing from a steel supplier will save you time but cost you more. A low-cost option for 1 1/4 inch diameter tubing is antenna mast tubing, available at any Radio Shack store. It is not made of high-quality steel, but it should be adequate if a bit heavy.


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Contents 2001 John S. Allen

Last revised 3 February 2003