This is how I serviced my SLX hub, It was last serviced in December so has gone roughly 3 months without coming undone or causing any problems, If you have any tips/suggestions feel free to add 🙂

This is written as a guide only.

Servicing Shimano 20 maxle hub, I have the SLX hub HB-M667 hub. The XT HB-M776 and Saint HB-M810 look similar in design so this guide should also apply to them.

What you will need:

28mm Shimano cone spanner

32mm spanner – I use my forks to hold the axle in place when servicing, therefore an adjustable spanner is too large to use, as it can’t fit in the gap between the fork leg and the wheel.

Grease. I use White lightning Crystal grease, Shimano grease is also good. Silkolene RG2 grease (motor cycle grease) is also an option. I would avoid white lithium grease, as it dries up and becomes a crumbly mess. Also park tools polylube 1000 isn’t that great seems to liquefy and dribble past the seals.

If the bearings are worn you will need 36 (18 in each side) 3/16 inch bearings at grade 25 – although grade 40 will suffice [more on bearing grades see end of post.] I get mine from SJS cycles

Kitchen towels or rags to wipe away old grease

BB tool

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First remove the maxle and then the wheel form the bicycle.

Then grab your BB tool and undo the centrelock, remove it and the disc rotor

Grab your 28mm spanner and 32mm to undone the cone and lock nut. Place the wheel on your lap insert the 28mm first then the 32mm onto the lock nut, turn the 28mm clockwise whilst the 32mm anti clockwise.

If only the locknut breaks free, but the cone stays in place (or vice versa). Insert wheel back into the fork and tighten the maxle, this will hold the axle in place whilst you undo the cone (or locknut).

Remove the axle from the hub; take care as bearings may start to fall out.

Wipe away old grease and dirt from the axle and cones. Make sure the threads are clean too.

Remove the bearings from the hub, wiping grease off the bearings will make it easier for them to fall out (I shake and tap the hub to make them fall out) A magnet will make things easier.

If the bearings are shiny then they should be fine for further use, if they are dull they will need replacing.

Wipe away as much of the old grease as you can.

There are plastic bearing retaining rings inside the hub, these rings make it hard to remove the old grease.
My method is to use a 4mm alley (the ones with rounded ends are best, anything similar will also do) with some folded over kitchen roll over the end; I insert the end into a hole in the plastic ring and rotate round. I do this a couple of times and wipe away any grease/muck.

Although not done this myself – you could maybe use degreaser to properly clean it if you wish.

Now everything is nice and clean, time to reassemble:

Put grease into the plastic retaining rings, filling the holes, a dualco grease gun is awesome for this but a finger works just as well – just not as fun.

Place the bearings into the plastic rings 18 each side, if the bearings are falling back out – you need more grease.

Put grease onto the cones and a little onto the thread.

Insert the axle carefully to not knock any bearings out; from the non-drive side (disc rotor side) might need a bit of a push at the end to push the axle past the seals.

Install cone and locknut on the drive side, do them up by hand and then with spanners.

Install the wheel into the fork, do up the maxle (tight).

Adjust the cone and locknut with the spanners so that there is no play but the wheel spins smoothly. Taking the wheel out and turning the axle with your hand will give you a better feel on how smooth your adjustment is, before final tightening. Bear in mind it will slacken off a bit when you finally tighten down.

Now finally to tighten: Using the spanners, with the wheel in the fork with the maxle done tight.

Turn the 32mm (locknut) clockwise and the 28mm (cone) anti clockwise. Use most of the force on the 28mm since you are basically tightening the cone against the locknut.

Do it up tight, bit less than you would for bottom bracket, when the 28mm spanner starts to dig into your hand a fair bit, that’s should be enough.

Remove the wheel and reinstall the rotor and centrelock, and then install the wheel again.

You’re done; now go out for a test ride. 8)

Bearings: The smaller the number the higher quality the bearing is. Bearing grade refers to how accurate the bearings are. So at grade 1000 the bearings are less round and there is more variation in the size/shape (deviation from a perfect sphere).

Shimano use grade 25 bearings in XT and upwards and grade 40 in everything below.

Grade 100 bearing are acceptable.

Grade 1000 should not be used, these are those weldtite ones sold in bike shops.

My rear hub felt much smoother when I changed from grade 1000 bearings to grade 25.