When replacing headset (i.e. fork, or steerer bearings), removing fork cone can be problematic. Especially if the fork crown is wider than the cone, so it can’t be punched off from the bottom. This post will explain the short and simple procedure and note the needed toos.
1. Tools for the job
- Scalpel blade
- Small hammer
- Small, medium and large flat bladed screwdriver
- Flat file
- Protective gloves
- Pliers, or, better, a vice
Put the fork on a wooden plank/surface, so it doesn’t get scratched, or damaged. Old towel can be added beneath – just in case.
Place a scalpel blade between the fork crown and the cone, with the sharp, cutting part towards the fork. It can usually be placed to get stuck with just hand force.
Carefully hold the blade in place with one hand, then gently knock it in with a hammer. Make it go in just for about 1 mm, so it can easily be removed with hands.
Rotate the fork by 1/8 of a circle (some 45 degrees), then repeat the process. In this first go around, don’t try to force the blade all the way in – just by about 1 mm.
Once the full circle is finished, make another round, knocking the blade a bit further in. About 2 – 3 mm is enough.
Also do the whole round. Rotating the fork by 1/8 of the circle. Work slowly and gently, without much force so the steerer tube doesn’t get cut, or damaged.
After finishing the round, check whether a small thin flat bladed screwdriver can fit between the fork and the crown. If it can’t, then use a flat file to blunt the scalpel blade, in order to minimize the chance of damaging the sterrer tube. Be careful not to cut yourself. Use protective gloves and pliers, or a vice. The blade is brittle, so work gently. Either place the blade with the “back” (dull side) resting on the wooden plank, holding it with pliers, or place it in a vice. Then gently blunt the blade with the flat file.
Now make a third round, knocking the blade for another 1 mm. Don’t use force if it won’t go, so you don’t damage the steerer tube. After this “round”, there should be enough room to place a small flat bladed screwdriver.
Place a small flat bladed screwdriver between the crown and the cone and turn it gently by about 1/16 of a circle (about 20 degrees). Repeat this all the way around, making the full circle in 8 to 10 “pokes”.
When rotating the screwdriver, the cone should be lifted by far less than 1 mm. Go gently, patiently. The goal is to lift the cone as parallely to the crown as possible, by small increments. After there is enough room to use a larger screwdriver, repeat the proces going around with a larger flat bladed screwdriver. Again, lift by just a little, at 8 to 10 different places all around the fork.
Finally, the cone should get unstuck – enabling removal with bare hands. Before placing a new cone, smear some copper, or aluminium mounting paste (i.e. “copper grease”) on the crown, so the new cone doesn’t get galvanically welded to the fork crown in time.
Mounting new headset will be explained in a separate article. Now, just a note: after placing a new fork cone, clean all the excess mounting paste – it will not mix well with bearing grease.