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5.10 Frame Building Part 3: Steerer Tube Prep




Description

This article is from the Misc Bicycles FAQs, by various authors.

5.10 Frame Building Part 3: Steerer Tube Prep

One of the last parts of finishing off the frame is to face the steerer
tube. The steerer tube was left a little long to provide some area for
brazing. This extra tube needs to be cut off and the lugs faced,
meaning providing a smooth, parallel surface for headset crowns. The
excess tubing is cut off with a hacksaw. To face the tubes, a process
similar to the facing of the fork crown race is done. The one big
difference is that the cutting head has three blades - a reamer to
smooth the interior surface, and then a double blade facing the lug, the
second blade providing a little lip. The cutting tool is fit in, a
graduated cylinder is placed in the opposite end of the steerer tube to
square the cutting tool, then a spring, spaces, and finally a bolt to
provide tension in the spring. Again the tool is cut with by turning a
handle clockwise until you have a smooth surface. This process is done
on both ends of the steerer tube.

The seat tube is also reamed is a similar manner to what was done to the
steerer tube and for the same reasons. They have several different
reamers for this for different size seatposts.


 

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