2 cone wrenches, usually 13mm for front hubs
open-ended wrench for the locknuts, usually 17 mm
flat headed screwdriver, preferably magnetized
rags
bicycle specific hub grease.
Two Cone Wrenches, Open End Wrench, and Axle Vise
Front Bike Hub
If your hub has play when you move your wheel laterally, or if it is too tight to rotate freely and smoothly, it must be adjusted immediately. Riding a bike with a poorly adjusted hub will ruin your hub and probably cost you a new wheel or at least hub overhaul.
Front Hub Adjustment
Tools to adjust a bicycle hub are:
two cone wrenches, usually 13 mm for front hubs (cone wrenches must be thinner than ordinary wrenches)
open-ended wrench for the locknuts, usually 17 mm.
The steps to adjust a front hub are:
1. Read the introduction to bicycle hubs and see a photo of a disassembled front hub.
2. Take the wheel off the bike. Remove the quick release device or axle nuts.
3. Remove any rubber dust covers from the outside of the locknuts.
4. Clean everything you can reach.
5. Examine the hub and axle to try to diagnose the problem. Are the locknuts loose? (They should be tight.) Does the axle wiggle when you move it? (It should not. You will need to tighten the cones.) Will the axle rotate freely without grinding or catching? (It should. You will need to loosen the cones.) Is the axle bent or broken? (You will need to replace it.) Does it feel dry or gritty? Has it been submerged in a creek crossing, washed with a pressure hose, or engulfed in mud or sand? (It probably needs an overhaul.)
6. Make sure one side of the locknut-cone connection is tight (Later we refer to this as the "first-tightened side.") (You will make the fine adjustments on the other side):
a. If both locknuts are loose against the cone, tighten one side. Note that both the cone and locknut thread on to the axle clockwise. You will tighten the locknut down (clockwise) against the cone. Hold the cone wrench on the flats of the cone and the open-ended wrench on the locknut. Rotate the cone counterclockwise and the locknut clockwise. Tighten them very snugly. Be sure to keep the same spacing from the outside of the locknut to the end of the axle.
b. If only one side is loose, make sure the tight side is indeed tight with the procedure detailed above.
c. If both sides are tight, pick one side and make sure it is very tight, and then do the fine adjustments on the other side.
7. Make the fine adjustments on just one side:
a. Loosen the locknut from the cone. Hold the cone still with the cone wrench, and with the open-ended wrench rotate the locknut counterclockwise. Once separated, you can usually move the cone with your fingers, but use the cone wrench if necessary. Loosen the cone by rotating it counterclockwise. Inspect inside the hub. Is the grease ok? Is anything bent or broken? Is grit or sand present? Can you see pits on the cone or ball bearings? If yes, overhaul the hub.
b. Be careful not to over-tighten the cone on to the ball bearings. This could score the races or bearings, ruining your hub or some parts.
With your fingers, tighten the cone until it contacts the bearings. While adjusting the cone's pressure on the bearings, rotate the axle until it feels smooth and snug. Bring the locknut down to contact with the cone. Tighten the cone against the locknut: hold the cone wrench on the flats of the cone and the open-ended wrench on the locknut. Keep the cone still--exactly where it is adjusted correctly, but hold it securely with the cone wrench. Tighten the locknut down (clockwise) on to the cone. Is the cone still perfectly adjusted? Probably not--this is hard to do even with a lot of practice. Repeat this procedure until you have it perfect.
Very fine adjustments can be made by (1) holding first-tightened side cone secure with a cone wrench and (2) to make the hub snugger--tightening the fine-adjustment side locknut or (3) to make the hub looser--loosening the fine-adjustment side cone.
When the fine-adjustment side is perfect, retighten the cone against the locknut, this time applying considerable pressure. Get the locknuts tight. Recheck the adjustment.
Don't be discouraged if it seems impossible. You can do it, and if you keep trying you will.
8. Install the wheel and check brake adjustments.
Front Hub Overhaul
A hub overhaul is very similar to a hub adjustment. You just take almost everything apart, inspect, lubricate, and reinstall it.
Tools needed for a hub overhaul are:
2 cone wrenches, usually 13mm for front hubs
open-ended wrench for the locknuts, usually 17 mm
flat headed screwdriver, preferably magnetized
rags
bicycle specific hub grease.
Two Cone Wrenches, Open End Wrench, and Axle Vise
The procedure to overhaul a front hub is:
1. Read the introduction to bicycle hubs.
2. Take the wheel off the bike and remove the quick release device or axle nuts.
3. Remove any rubber dust covers from the outside of the locknuts.
4. Clean everything you can reach.
5. You will leave the locknut and cone intact on one side and take the other side off, so choose which side to leave on.
6. Remove the locknut, cone, and spacers (if any) from one side of the hub. Hold the cone still with a cone wrench and rotate the locknut counterclockwise to break the lock. If the cone and locknut do not come off easily, the axle threads may be damaged, or the axle may be bent, requiring an axle replacement.
Remember the order the components come off, because they have to go back the same way they were.
7. Carefully remove the axle half way through the hub. Keep the axle in the hub enough to prevent the ball bearings on the other side from falling out.
Count the ball bearings in the exposed side of the hub, and remember the number.
Watch out for the ball bearings--they may pop out and roll away. Keep a rag under your work to catch escaping bearings. When I'm pulling the axle, I run my finger in after it to hold the bearings on the race until I'm sure the grease will keep them in. Try to keep the bearings in place until you count them. Then you can let them escape.
8. Remove the axle all the way from the hub. Corral the bearings. Both sides will have the same number of bearings.
9. Most front hubs have a metal seal or dust cap pressed into the hub over the bearings. It is not necessary to take these off. But if they come out easily with no danger of bending them, take them out. Do not risk bending the dust caps--you can clean the hub with them in.
10. Remove all the bearings and clean them. If they are not in perfect condition, replace them. Take the bearings to your bike shop--they come in several sizes and they have to be measured. Buy extras in case you drop some.
11. Clean the axle, cones, locknuts, and spacers (if any). Put the axle on a flat surface to test if it is bent, and notice if its threads are damaged (and therefore must be replaced.). If a cone is pitted it must be replaced. Take the cone and axle to the shop for comparison--they come in may shapes and sizes. Remember, you leave one side's cone and locknut tightened together. (This preserves the spacing.)
12. Clean the inside of the hub. Inspect the races on the inside of the hub. If they are pitted, you have to replace the hub or buy a new wheel.
13. Wash your hands--no use cleaning the machinery and polluting it with your dirty paws.
14. Begin reinstallation by filling one of the races in the hub with bicycle specific hub grease. We use Park Polylube. Do not glob it in--too much gets in the way.
15. Insert the right number of clean bearings on to the race. The grease should hold them in. This is where a magnetized flat head screw driver is useful.
16. Insert the axle side with the fixed cone and locknut.
17. Flip the wheel over while carefully holding in the axle, and load the other race with grease.
18. Insert the right number of bearings. You may need to retract the axle some for clearance--be careful that the other side's bearings don't fall out.
19. Install the cone, locknut, and spacers (if any), and continue with step 7. b. for adjusting hubs.