Note

On spoked wheels, weights are attached to the spokes (Figure 26). On cast wheels, weights are attached to the rim (Figure 27).

Spoke Inspection and Replacement

Spokes loosen with use and should be checked periodically. The "tuning fork" method for checking spoke tightness is simple and works well. Tap the center of each spoke with a spoke wrench (Figure 28) or the shank of a screwdriver and listen for a tone. Atightened spoke will emit a clear, ringing tone and a loose spoke will sound flat or dull. All the spokes in a correctly tightened wheel will emit tones of similar pitch but not necessarily the same precise tone. The tension of the spokes does not determine wheel balance.

Bent, stripped or broken spokes should be replaced as soon as they are detected, as they can destroy an expensive hub.

Unscrew the nipple from the spoke and depress the nipple into the rim far enough to free the end of the spoke; take care not to push the nipple all the way in. Remove the damaged spoke from the hub and use it to match a new spoke of identical length. If necessary, trim the new spoke to match the original and dress the end of the thread with a thread die. Install the new spoke in the hub and screw on the nipple; tighten it until the spoke's tone is similar to the tone of the other spokes in the wheel. Periodically check the new spoke; it will stretch and must be retightened several times before it takes a final seat.

Spoke Adjustment

If all spokes appear loose, tighten all on one side of the hub, then tighten all on the other side. One-half to one turn should be sufficient; do not overtighten.

After tightening the spokes, check rim runout to be sure you haven't pulled the rim out of shape.

One way to check rim runout is to mount a dial indicator on the front fork or swing arm, so that it bears against the rim.

If you don't have a dial indicator, improvise one as shown in Figure 29. Adjust the position of the bolt until it just clears the rim. Rotate the rim and note whether the clearance increases or decreases. Mark the tire with chalk or light crayon at areas that produce significantly large or small clearances. Clearance must not change by more than 0.08 in. (2.03 mm).

To pull the rim out, tighten spokes which terminate on the same side of the hub and loosen spokes which terminate on the opposite side of the hub (Figure 30). In most cases, only a slight amount of adjustment is necessary to true a rim. After adjustment, rotate the rim and make sure another area has not been pulled out of true. Continue adjustment and checking until runout is less than 0.08 in. (2.03 mm).

If the spokes are not bent or damaged also, they may be reused. This procedure describes how to replace the rim without removing the spokes.

1. Remove the tire as described in this chapter.

2. Securely fasten the spokes together with wire, string or tape at each point where they cross.

3. Place the replacement rim on top of the old rim and align the nipple holes of both rims. This is to make sure the replacement rim is the correct one. When the rims are aligned correctly, mark one spoke and its corresponding nipple hole on the new rim.

4. Remove the nipples from the spokes using a spoke wrench. If they are coated with dirt or rust, clean them in solvent and allow to dry. Then check the nipples for signs of cracking or other damage. Spoke nipples in this condition can strip when the wheel is later trued. Replace all nipples as necessary.

5. Lift the hub and spokes out of the old rim, making sure not to knock the spokes out of alignment.

6. Position the hub and spokes into the new rim, making sure to align the marks made in Step 3. Then insert the spokes into the rim until they are all in place.

7. Place a drop of oil onto the threaded end of each spoke and install the nipples. Thread the nipples halfway onto the spokes and stop them before they make contact with the rim.

8. Lift the wheel and stand it up on the workbench. Check the hub to make sure it is centered in the rim. If not, reposition it by hand.

9. With the hub centered in the rim, thread the nipples until they just seat against the rim. True the

Rim Replacement

If the rim becomes bent or damaged, it should be replaced. A bent or dented wheel can cause serious handling problems.

1. Bracket to fit fender brace

2. Wheel rim

3. Nuts

4. Bolt wheel as described under Spoke Adjustment in this chapter.

Seating Spokes

When spokes loosen or when installing new spokes, the head of the spoke should be checked for proper seating in the hub. If it is not seated correctly, it can loosen further and may cause severe damage to the hub. If one or more spokes require reseating, hit the head of each spoke with a punch. True the wheel as described under Spoke Adjustment in this chapter.

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