How to remove a bottom bracket, realize it's pooched, and replace it with a new one

So, when I brought my camera to Bike Sauce a couple weeks ago, I fully intended to write a tutorial on how to overhaul a bottom bracket.  However, I realized that it was pointless to overhaul this one, because I would just be postponing the inevitable.  So, I leave you with the revised tutorial:

Crank with dust cap

That is a crank with a dust cap on it.  The dust cap is the little plastic bit in the middle.

*NOTE: if you are currently thinking "Ilan you're crazy, there's no dust cap on my bike" and there's no bolt visible, you may have an external bottom bracket.  Many newer cranks use these.  There is a picture of a Truvativ (aka SRAM) one below.  If this looks like what you have, you are lucky and this will indeed be an easy task for you.  Scroll down to the bottom of this post for instructions.  If you have a BMX, dirt jump, fixed-gear freestyle, or other trick-type bike, and neither of the above applies to you, you might have an MID bottom bracket, and I can't help you. This video has a good explanation of how to install one of those, so that's where I'll refer you in that case.

You can get it off with a big flat-head screwdriver; however, if it doesn't come out fairly easily, put some lubricant, like Tri-Flow around the edges and give it a few minutes to seep in then try again.  Do not do what I did above and try to push harder because it should be easy.  I managed to still get the cap off, but if you really screw it up, try using a pair of needle-nose pliers to push the cap on its threads.  If that fails, you'll have to break it and remove it piece by piece.  In my humble opinion, stick with a screwdriver and lube, you'll save yourself a lot of time and aggravation.

No dust cap on this side!

This is what your crank should look like once you've removed that cap.

Crank puller threaded in

After you pull off your dust cap, you'll need to undo the bolts on the inside of the crank.  Usually, these are 14mm and will come off with a ratchet.  If you have a square-taper bottom bracket (you can look at the shape of the spindle on the inside, if it looks like a square, this means you) then you'll use a standard crank puller.  If your bike is older than about 1990 or was cheap, odds are that it's got a square-taper bb.  However, if you have an Octalink or Isis bottom bracket (the spindle is shaped like a star) you'll need a special crank puller that is specific to those designs.

Before you thread the crank puller in, I suggest you grease its threads to prevent any binding or damage.  The crank puller has two sets of threads, you'll need to roll the big nut to the end of the smaller spindle.  The big nut threads into your crank. DO THIS CAREFULLY, it is not difficult to strip these fine threads if you use unnecessary force to try and get it in.  Make sure that the tool is well lined up with the threads and turn it in. Once you have it in hand-tight, use a wrench to give it little tweak to make sure it wont come loose - again, DO NOT USE EXCESSIVE FORCE.

Now spin the tool around so the spindle screws into the bigger nut.  This is now pushing against your bottom bracket spindle and you'll notice the crank arm pulling away from the bike. Once the arm is mostly off the spindle, you can undo the big nut in your cranks and pull the tool out.

The spindle that lies beneath

 This is what the bottom bracket looks like installed in your frame.  Now you need to remove the lock ring on the adjustable side.  This is the non-drive (left) side on most bikes.  You'll need a bottom bracket spanner to take this off.  If you have a standard (English thread) bottom bracket, this will come off in the normal counter-clockwise direction.

To remove the cups, you will need a bottom bracket tool with the correct number of splines and a 32mm or 36mm flat wrench.  The non-drive side will thread out counter-clockwise and the drive side will thread out clockwise for a standard bottom bracket.  If you have an Italian or a French bike, both cups may thread out counter-clockwise (there is an explanation of different threadings on this page of Sheldon Brown's fantastic reference website under bottom bracket.)

Disgusting bottom bracket

 Once you've pulled all the parts out, you'll want to give them a thorough clean with some degreaser and a rag to get all of the old grease off.

Normally, the next step would be to regrease everything and reinstall the bottom bracket and cranks just like you remove them.  However, before this overhaul, my bb had been experiencing some significant creaking on a bike tour and a few longish rides.  Also, judging from how disgusting that grease was, I would guess it had been last serviced sometime in the 90s.  After cleaning, I noticed some rather large wear lines in the cups and the spindle.

Disgusting wear marks next to disgusting hand

Those big white circles on the spindle where it forms cones?  Yeah, those shouldn't be there.  I can't get my camera to take a very good picture of it, but there are also deeper pits in the cones and one of the ball bearings is completely flat on one side.  All of this stems from not taking good care of your bb and letting it go too long without an overhaul! You have been warned.

This is also one of the reasons you should properly clean anything you pull out of your bike before you put it back in, otherwise you can miss problems with it.  If your bottom bracket is very worn out

Luckily, I was at Bike Sauce, where we had plenty of barely used bottom brackets lying around, so I took one of them and decided to use that instead.  Unfortunately, in my excitement, I forgot to take a picture, but it's one of the newer style sealed cartridge units that are pretty prevalent these days. These install pretty much the same way as the other one came off, but use splined tools on both sides.  Also, you put in the lockring (the piece that comes off) first then the whole unit screws in the other side.  Remember to grease the threads on both sides before you install! Screw in the cartridge until it is quite tight (there might be a torque rating on the case of bb unit).

Installed sealed-cartridge bottom bracket

Re-attach your crank arms by tightening the bolts (After you grease them and the spindle arms!) on either side with your ratchet.  Again, there are torque ratings, but if you get them very tight - mountain bike spec: one quarter turn from stripping - they'll be good.  If they're not tight enough, they will creak and loosen which will damage the cranks, the bb, and your cool.

Installed cranks - finally

External bottom brackets: If you have one of these, you'll need this tool to take out the bottom bracket. Your crank arms will come off with an Allen wrench on the non-drive side (Shimano ones use a special tool).  This whole process takes about 30 seconds.  If you have an expensive bottom bracket, you can press out the bearings from their housings and press in new ones.  However, for most cases, it's much simpler and cheaper to just replace the whole unit for about 25 bucks.