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directset explanation
Traditional headsets have aluminum cups that press fit into the head tube and then cartridge bearings that fit into the aluminum cups. A Directset eliminates the aluminum cups and instead has bearings that press directly into the head tube, eliminating unnecessary weight, reducing stack height, and minimizing the number of parts.
headset and frame compatibility:
Directsets can be used with frames and forks intended to be used with 1 1/8 inch Aheadsets (threadless headsets). Directsets are incompatible with frames designed for traditional threaded headsets. Frame head tubes must be made with a specific bore diameter.
preparing frame and fork for headset installation:
1. Use a head tube reaming and facing tool to prepare the top and bottom of the frame's head tube. Often, even very expensive frames have head tubes that have not been properly reamed and faced. Be sure to use the correct reamer diameter corresponding to the Directset being installed. For a 1 1/8 inch Directset, the head tube bore size should be a diameter of 33.90mm to 33.95mm, and for 1.5 inch Directset, the head tube bore size should be 49.57 to 49.612.
2. Use a crown race cutting tool to turn and face the crown race seat of the fork. Be sure to use the correct cutter diameter corresponding to the Directset being installed.
Note: it is imperative to complete these steps to ensure a smooth operating Directset. If these steps are not completed or done improperly, the Directset may be rough in turning or may tend to "stick" to one side or the other. This applies to ALL frames and forks, new or used, painted or unpainted.
cutting your fork steer tube:
There are 2 possible methods for determining the required fork steer tube length: Calculation method or Assembly Method. We prefer the Assembly method. Both are listed below. Before you cut the steer tube, read this important note: In some frame/fork combinations, the fork shock adjustment knobs could hit the bottom of the bike frame during extreme turning. If this happens, and if desired, a thicker crown race is available from crankbrothers.
calculation method:
 Determine the Directset stack height by adding the following measurements
a. 10.3mm (Bottom of the large diameter portion of the upper bearing and shield.)
b. 10.0mm (Crown race bottom to the top of the lower bearing.)
c. Measure the head tube length.
d. Measure the total height of any stem spacers used.
4. Measure the height of the clamp portion of the handlebar stem.
5. Add the above dimensions and subtract 3mm for adjustment clearance.
ii. assembly method (preferred):
1. Install the bearings as instructed in the section below.
2. Install the crown race as instructed in the section below.
3. Assemble the Directset as instructed in the section below.
4. Tighten 1 stem clamp bolt enough to hold the assembly in place.
5. Mark the steer tube at the top of the stem.
6. Disassemble the stem, spacers, and shield.
7. The required fork steer tube length will be 3mm below the marking from step 5.
Once you have determined the required fork steer tube length, you’re ready to cut. Cut the fork steer tube carefully in the correct location, as determined above, using a tubing cutter, hacksaw or other appropriate cutting tool. Use a file to remove any burrs from the area of the cut.
cutting fork steerer tube:
1. Carefully cut the fork steerer tube in the correct location,
as determined from step B, using a tubing cutter, hacksaw
or other appropriate cutting tool. Important: see note below
in step F about crown race thickness before cutting the steerer
tube.
2. Use a file to remove any burrs from the area of the cut.
installing upper and lower bearings:
1. For most Directset models, the upper and lower bearings are identical. For Iodine Directsets, use the bearing marked "34" for the lower bearing, and "28" for the upper bearing. For Ti Directsets, the bearing that weighs less is the upper bearing.
2. Reminder: ream the head tube before installing the bearings.
Lower bearing: Press the lower bearing in using a good quality headset press. It is important that the bearing be installed straight, or the bearing could break during installation. If the bearing is not going in straight, remove it and start again. We recommend installing the bearings using the stepped cones of the headset press, even though this applies pressure to the inner race and ball bearings during installation, because this makes it easiest to install the bearings straight and does not damage the bearing. Remove the stepped cone before any final hard pushes (for making sure the bearing is fully seated). Regardless of installation method, pay close attention that the bearing is installing straight, rather than at an angle.
3. Important! Remove the aluminum shield and the aluminum split ring from the upper bearing before installing upper bearing into head tube.
4. Upper bearing: See 3 above. Press the upper bearing in similarly to the lower bearing, being careful to press the bearing in straight.
installing crown race:
 1. Press the fork crown race onto the fork with an appropriate crown race installation tool until the flat back face is flush against the fork crown. Note: the crown race should fit with a press fit. Important: In some frame/fork combinations, the fork shock adjustment knobs could hit the bottom of the bike frame during extreme turning. If this happens, and if desired, a thicker crown race is available from crankbrothers.
installing star nut into fork steerer tube:
 1. Position the star nut with the concave end facing upward over the top of the steer tube.
2. Press the star nut into the steer tube to a point 10 to 15mm below the top. This should preferably be done using a star nut installation tool. If this tool is unavailable, thread the compression bolt into the star nut and light tap the assembly into position with a deadweight mallet or similar tool. Ensure that the threads of the star nut are aligned with the steer tube. Note: when replacing a fork, it is necessary to use a new star nut.
assembling Directset.
 1. Place the lower seal over the fork steer tube and onto the crown race, ensuring that it is seated properly on the crown race.
2. Insert the fork steer tube into the head tube, holding it while completing the steps below.
3. Slide the split ring over the steer tube and into the upper bearing.
4. Slide the aluminum shield over the steer tube until it touches the split ring.
5. Install the stem height adjustment spacers (if used) and then the stem onto the steer tube. Using spacers is a personal choice.
6. Seat the steer tube firmly upward in the head tube and the stem firmly downward against the spacer (or aluminum shield if spacers are not used), leaving the stem clamp bolts loose.
Caution: the top of the steer tube must be 3mm below the top of the stem before the compression bolt is tightened. If the steer tube is too long, sufficient compression may not be possible and the Directset will remain loose, risking rapid headset wear and possible damage to the frame. If the steer tube is too short, the stem may not have sufficient clamping surface against the steer tube to be used safely.
tightening/preloading Directset assembly:
1. Lubricate the compression bolt.
2. Insert the compression bolt through the recess in the top cap and begin threading the bolt into the star nut, while seating the top cap into the top of the stem.
3. Tighten the compression bolt with a 5mm hex wrench to preload the bearings. Apply only enough torque to remove all play from the Directset while ensuring it still rotates freely. CAUTION: insufficient preload will result in a loose headset. Excessive preload will result in the headset binding. Either condition will cause rapid Directset wear and could adversely affect the steering characteristics of the bicycle.
4. With the stem aligned with the fork, secure the stem to the steer tube and lock in the bearing preload by tightening the stem clamp bolt/s. These should be tightened to the torque recommended by the stem manufacturer. WARNING: make sure the stem clamp bolts are sufficiently tight to prevent the stem and handlebars from turning relative to the steer tube. A loose stem can result in damage to the bike, loss of control, and severe injury or death to the rider.
5. If the Directset needs readjusting after the initial break-in period: loosen the stem clamp bolt/s, reset the preload with the compression bolt (step 3 above) and retighten the stem clamp bolts (step 4 above).
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