Tuesday, January 15, 2008

How to replace your Cartridge Bearings

In this post I'm going to detail the steps necessary to replace the cartridge bearings in your sealed hub. If you don't have sealed bearings, this doesn't apply to you.

How do you know if your cartridge bearings need replacement?

Well, for one, they will not spin as well and you will hear them. Secondly, they may develop side to side play even with the lock nuts tight. Thirdly, the seal may be wrecked, and they might be dribbling rust down your pretty high flange hub.

Supplies needed:
-2x new bearings (I'm using Nachi 6000RS2)
-Soft faced mallet
-Block of wood with 11mm hole drilled in it
-Cone nut wrenches (My hubs take 14mm and 17mm, yours may differ)
-Paper towel or rag
->500grit sandpaper or emery cloth


1)Using the cone nut wrenches, undo the two lock nuts on each side of the hub. I hesitate to say 'cone nuts' here because the inner one is NOT cone shaped like on a loose ball hub. It simply shoulders up to the inner race of the cartridge bearing, stopping it from moving laterally.

2)Once all four lock nuts have been removed from the hub, there is nothing holding the axle and bearings in place other than friction. You may now strike the end of the axle with the soft faced mallet in order to coax it out the other side. Be sure to strike the axle dead on the end, so that the force pushes the bearing straight out. What should happen, is that the shoulder on the axle should push the inner race of one bearing outwards. If the bearings are not COMPLETELY destroyed, the rest of the bearing will come out along with it.
(If this blows the bearing apart, don't worry we'll cover that scenario in a second)

3)At this point you should have the axle separated from the hub shell, with one bearing on it. You SHOULD be able to pull the bearing off the axle at this point.
(If not, insert the axle into the block of wood, and tap the bearing off)

4)Reinsert the axle and flip the hub over. Now use the mallet to strike the end of the axle and tap out the cartridge bearing on the other side.

5)If any of your bearings have blown apart, you will have a serious mess on your hands. Skip this step if your bearing came out in tact. You then need to use a flathead screwdriver from inside the hub shell, to get the outer race out. This may be difficult, but try to catch the screwdriver tip on the inner edge of the outer bearing race before tapping. Then work your way around the circumference of the outer race, coaxing it from the hub shell.

6)You should now be left with these unhappy little fellows:

Look at how gross that one on the left is!

7)Its time to clean things up. I was able to just wipe the rust off my axle with a rag, but the hub shell wasn't so easy. You wouldn't think that rust would adhere to aluminum that well, but mine was pretty stuck on.

8)Here I've used some 600grit sandpaper to clean the outer race shoulder of the hub shell. This is a step that not a lot of bike shops will spend time on, but I like to know that my bearing is not butted up against rust.

9)Lets take a closer look at the axle:

This is a thing of beauty. What's so interesting about it you ask?

Its made of hollow hardened stainless steel, with shoulders to hold the bearings the correct distance apart. Also, its machined to a very precise tolerance. The bearing seat is exactly 9.96mm in diameter.

The inner race of the bearing is exactly 10.00mm in diameter. This is on purpose, and is the reason why you were able to pull the bearings from the axle. If this tolerance was any tighter than 4 one hundredths of a millimeter, you would have had a much tougher time removing that bearing in step 3.

10)Its time to put it all back together. I like to apply a small coat of grease to the bearing seats in the hub shell, and the bearing seat on the axle. This is just a small step in preventing rust from adhering to them in the future, and it eases the installation of the new bearing.

11)The most important thing to remember when installing cartridge bearings, is to apply the force to the race you are trying to seat.

What I mean, is that if you are pressing the bearing into the hub shell, the OUTER race is the one that has friction, so you should apply the force there. If you apply the force to the INNER race, you can prematurely damage the bearing through lateral loading.

12)What I do to seat the first bearing, is use a second bearing (old or new) butted up against the outer race.

This allows me to lightly tap the bearing into place accurately. Be sure to take your time, working your way around the circumference of the bearing so that it goes in straight. You should rotate the hub around and eyeball it as you go so that you know it is not seating crooked. You will know when it is seated all the way by the sound it makes as you tap it. The sound will turn from a dull 'thud' to a 'ping' as the spokes resonate more once it has seated.

13) Now flip the hub over and insert the axle.

14)This is where the block of wood comes in really handy. You can now seat the second bearing in place by hand to align it, then use the mallet and block to drive it in place. Once again, take your time and make sure it goes in straight. Once the bearing is MOST of the way in place, you will need to add another bearing onto the axle, in order to drive the outer race all the way down on the bearing seat of the hub shell.

15)We're almost done. The axle and bearings are now friction fit together, and you can try turning the hub in your hands. The new bearings should feel ultra smooth compared to the crap you pulled out of there. The last step is to tighen the lock nuts into place. If you've driven the bearings in all the way with the mallet, the inner lock nut should lock into place without moving the bearing.

(Think back to Step 11, where I said that the force should be applied to the OUTER race. Its not the end of the world if the inner lock nut pushes the bearing in further, but its not exactly great for the bearing.)

Tightening the inner lock nut should NOT stop the bearing from turning smoothly on a hub that takes standard 6000 series bearings

16)The very last step is to put the outer lock nuts on, and tighten them in place. They don't have to be super tight, just snug. Thats it! Now get out for a ride and enjoy your newly serviced hub =D

If you enjoyed this How To, found it helpful, or think I'm a fucking idiot and I'm doing it wrong, please leave a comment. If you want to read another interesting DIY, check out what Simon is doing to keep his turtles cozy.


midnightsimon said...

Seriously quality tutorial, Lyle.

How would you feel about leading a mechanical workshop of some type at our space next month?

morgman said...

Good writeup. I like the numbered steps, it makes it easier to follow.

Now that you've done cartridge bearings, you can move on to the more challenging task of changing a flat!

mander said...

Nice one Lyle. I will follow this next time I have to change bearings. paying lbs guys to do it was getting very expensive.

bestonline323 said...

can i replace my ball bearings to sealed bearings on my bicycle rims? i was told to Take the sproket out and pull the ring with the bearings out. If your wanting to replace all of them it is easier to replace the whole ring. If you need to replace 1 or 2, the metal on the ring is real thin. You can bend it with your hand. Bend it and place the bearing in the place where it goes and bend the ring back into place. If you pull them out it is a good time to repack your bearings. That means clean them with some type of degreaser and put axle grease back on them. Make sure you put enough where they roll good.

but i would really like to get your opinion


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Tom said...

google found your article for me - and saved me from going and rebuilding my rim on a new hub. THANK YOU ;)

Serge said...

any idea how to change them if you just have a simple axle? as in one threaded from one end to the other.

Captain B said...

I had to work this out myself about 10 years ago when I was using sealed bearing hubs on my BMX. Good to see a decent tutorial - especially the part about applying force to the correct part of the bearing.

However, I'm not quite sure how you manage to install the second bearing with only one old bearing on top of it. Do you just gently tap the edges, working your way around in a circle to keep the bearing straight?

I use a stack of about 6 old bearings duck-taped together, so that when placed over the axle they protrude much further than the axle. I can then give the end of the stack a good hard bang with a mallet, knowing that bearing number two is going to go in perfectly straight.

chris said...

I was just changing my axle and didn't have any old bearings to pound the new ones in, nor did I have a block of wood so I found another sweet bearing tool:

A deep 3/4" socket in 1/4" drive. Sits right on the edges of the bearing and the 1/4" drive has enough room in the middle for the axle.

Mark said...

Rather than use a block of wood to fit the second bearing you could fit a nut and large washer to the side of the axle that has the bearing already in place then place a large washer over the second bearing, fit the nut and slowly tighten the nut until the bearing is seated?

morgman said...

We'll have to get Lyle to field the questions...

((lyledriver)) said...

Providing your washer is large enough to cover the outside race, but not so large as to get stuck in any bearing recession, this is fine.

If you look at any professional bearing press kit, the actual pieces have a protruding ring that seats against the outer race, while the body of the tool is just under the outer diameter of the bearing.

kesgegs said...

Really useful man, thanks so much.

Jonathan said...

Great explanation, just changed my bearings following your instructions without any problems. Thank you very much.

Formular said...

Great instructions. Just replaced my bearings.
One tip - I put my freewheel and remover back on the wheel once I had removed the locknuts. I was then able to slowly unwind the bearings from the hub using a tracknut on the freewheel side, holding the axle still by putting a pair of locknuts back on the other side of the axle. Once done, I put the freewheel and remover on the other side and unwould the bearing on the other side.

mace said...

Hi, thanks a lot for this. I went to a retailer today to buy a pair of new hub bearing cartridges and he gave me a cool tip regarding installation; put the new bearings in a freezer for a while, that will shrink them a little bit and make them easier to install. An eloquent tip, i will see later today if it works :)

Karam said...

Thanks a lot for sharing! Sintered bearings are best to use as these last long and even reliable. So no hassle of changing it again and again.

Billy Ripper said...

I used this tutorial several times, due to my bad memory. Now I wanted to use it again, again due to my bad memory, but I see the pictures aren't working anymore.
This tutorial deserves to live on, so I'd like to re-post it, but need pictures to do so. Can someone help me with this, preferably the master himself?

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