‘Aheadsets’ (now an almost generic term, like Hoover instead of vacuum cleaner) have become ubiquitous on mountain bikes these days — all be it in a number of different guises — but before Dia-Compe introduced and patented the Aheadset design in ’91, steerer tubes were threaded and stems fitted via an internal quill. The introduction of the threadless system had the welcome benefit of lopping around half a pound in weight from the set up, and simplified adjustment. Gone were the days of needing huge 32 or 36mm spanners to tweak a loose headset.
Whether you have a standard threadless headset with separate cups, a semi-integrated headset with cups hidden inside a large-diameter head tube, or an integrated headset with internal ridges on the head tube forming the bearing seats, adjustment and servicing is pretty much standard.
Cleaning the bearing seats and rebuilding will be the major differences. Rather than the cup-and-cone set-up shown, higher spec headsets will instead have cartridge bearings. Pulling these out as a whole and spinning them with your fingers will indicate their internal state. If they feel graunchy when spun, they’ll need repacking or replacing, depending on how easy it is to remove the seals and clean inside. Any major scratches or pits in the cleaned bearing surfaces will mean extra outlay, as a pitted headset will always feel awful when put to the test on the trails.
TOOLS FOR THE JOB:
Rags or tissues, bearing grease, degreaser or cleaning product, rubber mallet, tape (a zip-tie, elastic band, or old toe-strap would suffice), Allen keys as required for your brakes and stem bolts, knife (or pick) for prising off seals.
1 Remove the front wheel.
2 Remove the brakes. V-brakes can simply have the cable slipped from the brake lever, leaving the calipers on the fork. Disc brakes will need removing at the caliper end, or if you have a split lever clamp, remove the lever.
3 Remove the 5mm top cap with an Allen key.
4 Loosen the stem-clamp bolts, but do not totally remove them.
Slide stem and spacers off — remember to take note of their order.
5 If the fork is tight, a tap with a rubber mallet will loosen the tapered loading washer and allow the fork to drop out. Slide the bearing cover and tapered washer off, along with any seals (remembering their orientation). Take note of their order.
6 Slide fork out.
7 Remove the bearings (they may be in a cartridge rather than loose as shown, inset) and place them on a rag in the order they came out. This will make reassembly a much simpler process.
8 Spray cleaner on the bearing surfaces. Wipe off dirt and grease. The bearing seat should be gleaming.
9 Clean all bearings and internal parts — not forgetting the crown race.
10 Regrease the cup and now clean bearing. Replace seals.
11 Spread a thin film of grease on the crown race. Spread a similar amount where the tapered loading washer contacts the bearing, and slide fork back through the headset. Replacing the tapered washer and bearing cover should keep the fork in place.
12 Wipe off any grease on the steerer tube. If using a degreaser, spray a rag and wipe as this will prevent the newly packed headset being contaminated.
13 Slot spacers and stem back onto steerer tube, making sure the spacers are in the correct position.
14 Replace the top cap with a 5mm Allen key, doing it up finger tight. To adjust the headset, pull the front brake and rock the bike backwards and forwards, checking for play at the bearing.
Small adjustments are best. You don’t want to over-tighten the headset. It should spin freely with no rocking. If it binds and still rocks, check any fork bushings — they may be causing the play.
15 Straighten the stem, tighten the bolts and you’re away.
Like caliper bolts, keeping spacers, top cap and washers on the steerer will prevent any losses.
Attaching the bars to the frame keeps them out of the way during the adjustments and cleaning.