Installing new forks is a manageable job for anyone with the correct tools. Before you begin you will need to remove your front brake caliper, stem and front wheel. Allen keys and possibly crown race tools are all the equipment that will be required. If you are installing a threaded fork you will possibly need headset spanners and a spanner for a quill stem.
- 4mm Allen key
- 5mm Allen key
- 6mm Allen key
- Star nut fitting tool
- crown race remover
- crown race fitting tool
- Headset spanners
- Using a bike repair stand may help. If you can, enlist a friend to prevent dropping parts during assembly and disassembly. The first task is to remove the front brake caliper from the fork then the wheel. Move the caliper out the way and give it to your friend to hold or cable-tie it to the top tube with the bars when removed. If you have cable pull brakes you may be able to easily disconnect the cable at this stage instead. This is good practice as it will stop them interfering while you work or potentially kinking your cables and brake hose.
- Remove the forks by loosening the stem pinch bolts then the top cap compression bolt. The stem bolts should be loosened half a turn at a time to avoid damage to the threads. If the forks are not resting on the ground they may fall out which should be avoided so it’s time to enlist your friend again! The stem and bar combo should be lifted off first then the spacers and the individual elements that make up the headset. Care should be taken at this stage to keep track of the order they come out. Line them up on the bench as they come off and clean everything. Finally remove the fork from the head tube, the lower cartridge bearing and crown race. If the crown race doesn’t come off by hand easily and have a split in it you will need a crown race pulling tool. It’s probably time to pop into Perlie Rides where it will be a quick cheap job.
- Clean and inspect all the parts you have removed as well as the headset cups still in the frame. Check for cracks, abrasions, pitting of bearings and any imperfections. Do the same for any new parts you are going to install. Insure the crown of the new fork is clean of all paint and has been prepared with a crown milling tool. It is essential that all parts are clean and milled to avoid binding and creaking when assembled and adjusted.
- Installing new forks. Slide the crown race onto the crown of the new fork. If required use crown race installation tools. Place the cartridge or caged bearings in the cups with a small amount of grease. Installing new forks, slide the steerer tube through the head tube of the frame and commence replacing the layers of headset.
- Place spacers on the steerer tube until the remainder of the protruding tube is between three and five millimeters less than the stack height of the stem. This is crucial when installing new forks. If the steerer tube emerges above the stem, load cannot be applied to the bearings. If there is insufficient tube to clamp onto, the stem or steerer may crack due to stress. If there is more tube than desired, the entire fork assembly can be removed again at this point and shortened with a hack saw. Remember measure
twicethrice, cut once.
- Before refitting the new forks, the star nut needs to be installed.
- Install new forks and all the headset parts in the same order they were removed finishing with the compression cap. Tighten the compression cap until snug. The torque will be approximately 2.5 newton meters. For those that don’t have access to a torque wrench, 2.5nm is equivalent to the force required to snap a twig. Our goal is to leave it loose enough so the forks spin with none to minimal resistance. However it needs to be tight enough to eliminate all play. (Lateral bearing movement) Play is the nemesis of headsets. Loose bearings will destroy themselves in a short time. Prolonged neglect will flare your headtube, resulting in a damaged frame.
- Align the handlebars with the fork and tighten the stem bolts. Alternate top bottom again to avoid stressing the threads. Bear in mind stem bolts are not usually tightened too much especially if you have a carbon steerer tube. 5nm is typical with modern ‘ahead’ stems. Always check the manufacturers installation guidelines for torque settings.
- Check your handiwork by turning the bars 90 degrees and pulling and pushing against the frames top tube. Alternatively you can pull the front brake when reinstalled and rock the bike back and forth. If all went well then it will be silent and smooth. A problem will result in creaks, cracks and clunks.
- Finish up by refitting the brake caliper and front wheel. With your weight on the bike pull the front brake lever and rock back and forth to check for play again. Keep inspecting regularly while the components compress and wear in with use. Adjust when necessary.