Chapter Six - The Front Triangle

STEP VI-8: Before the head tube is reamed and faced, it must be thoroughly cleaned. All of the sanding and grinding have left a coating of tiny abrasive particles inside and outside of the tube. These abrasive particles can quickly dull cutting tools. Cleaning can be done with mineral spirits and a bottle brush. (I have silver brazed a tiny wire wheel to a 6" piece of 5/16" tubing. Mounting this extended wire wheel in a hand held drill allows me to clean thoroughly all the way through the head tube.) If there is a large burr around the inside of the end of the head lug, run a half round file inside the head tube to break off the burr. A deburring tool sold by many tool companies works fine also. Head tube facer/reamers are made by several companies. Campagnolo, Gipiemme, Sylva, And Cobra again are completely interchangeable. Zeus, VAR, and Bicycle Research also make head tube facer/reamers. Most of these companies make a reamer size that conforms to the Italian standard, that is, a press fit I.D. of 30.2 mm. Japanese frames come with the Japanese standard of 30.0. This is kind of handy because Japanese frames can always be reamed to the Italian standard if necessary. VAR manufactures three different sizes for their tool as well as the new oversized cutters for 1-1/8" and1-1/4" steering columns. Oversized 1-1/8" cutters are also available from Cobra and Tioga. (During the 80's and 90's, 1-1/4" steering columns were becoming popular for mountain bikes. At the time an excellent cutter that would slide onto the Campagnolo #733 tool was available from Fisher Mountain Bikes. I don't know if these are still available.) Use of these oversized steering columns, at this time, is reserved exclusively to lugless construction and can be found on several off road bikes. Use of oversized steering columns is also recommended for tandem construction. (I have built a number of tandem frames with 1-1/4" steering columns. It's an excellent size for tandems, but an overkill for mountain bikes.)

FIGURE 6-33: Examples of riffler files

FIGURE 6-34: #733 set up to do the top of the head tube first

Essentially, all of the head tube reamer/facers on the market work the same except that some of them double as head set presses with the use of a few extra parts. For that reason I will cover only the Campagnolo #733 tool. Place the frame in the Park stand with the head tube in a horizontal position; this will keep the cutting oil from running off the tool as fast as if it were positioned vertically. It is recommended to face the poorer of the two ends first. That would be the top, since the bottom should be a factory finished end if you followed directions properly. This allows the centering cone of the tool to locate on a factory end instead of a rough cut end. Figure 6-34 shows the #733 assembled in the head tube and ready to cut the top of the head tube. The Campagnolo #733 is turned in a clockwise direction when looking down at the handles. Pressure is applied to the tool by turning the large nut at the threaded end. Moderate pressure is recommended. This should be enough pressure to peel off a paper thin curl of metal as the tool is turned. Mill until a smooth surface appears all the way around the end of the head tube and lug. Use plenty of cutting oil and turn the tool only in the forward direction; turning it backward will dull the cutters quickly. Never turn reamers or facers backward! After the surface is smooth all the way around, the spring tension can be reduced for a finishing cut. Simply keep turning the tool in the same direction for a finishing cut. The tool can be disassembled at any time to check for a uniformly smooth surface. Remove the tool from the head tube, clean out the chips, and insert it from the other end to mill the bottom end of the head tube. Again, mill until a smooth surface is obtained. Use plenty of cutting oil and keep the spring tension set to medium pressure. Milling too much off the bottom head lug can alter front end geometry slightly as well as shave the ring of the lug thin so it looks rather unsightly. Figure 6-35 shows the bottom of the head tube being faced and reamed.

FIGURE 6-35: Reaming and facing the bottom of the head tube

FIGURE 6-36: Use of the "GO-NO GO" Gauge to test for press fit

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