Fig.1

Bottom Bracket Removal/Installation and Overhaul

Pre Adjustment Inspection

Fig. 2

Check the distance between both crank arms and the chainstays. If the distance is different, the crank arms may be bent. Visually check the crank arms.

Fig. 3

The other possibility is that the bottom bracket spindle is the wrong length, or installed the wrong way. (The left and right sides of the spindle are often different lengths.)

Fig. 4

Check the distance between the crank arm and the bottom bracket cups. There should be more than 1mm between the two.

If there is 1mm or less of space between the crank arm and bottom bracket cup, then the crank arm may run into the bottom bracket cup when it is reinstalled at the end of this procedure.

If this is the case, it may be necessary to install a different crank set, or bottom bracket.

Remove Crank Bolts

Fig. 5

Shift the front derailleur to the smallest chainring, and the rear derailleur to the smallest gear.

Fig. 6

Remove dustcaps over crank bolts, if present, using a screwdriver, or other appropriate tool.

Hex wrench shown in picture.

Fig. 7

Using 14mm socket wrench or 8mm hex wrench, unscrew the crank bolt or nut counterclockwise.

Technique shown below.

Fig. 8

It may take a lot of force to break free the crank bolt.

The most effective way to break free the crank bolt is to hold the wrench handle and crank arm close together as shown in the picture.

Squeeze the two together with both hands.

Fig. 9

Unscrew the bolt or nut and remove it along with any washers that may have been under the crank bolt.

Repeat with the opposite crank arm.

Extract Crank Arms

Fig. 10

Park tools square taper crank arm extractor shown. This tool is only for use with square taper bottom brackets (most common type).

Some bottom brackets have splined spindles, and require a crank arm extractor with a larger diameter plunger.

It is very important to only use the tool designed for your bottom bracket.

Fig. 11

Back the plunger all the way out of the outer body by turning counterclockwise.

Grease the threads on the plunger and the outer body of the crank arm extractor.

Fig. 12

By hand, thread the outer body of the extractor into the threads of the crank arm.

It should thread in smoothly, and most of the threads should be buried in the crank arm.

If it does not thread in smoothly, or it does not thread in very far, remove it and visually check both sets of threads for damage.

Fig. 13

Thread the plunger into the outer body of the crank arm extractor, turning it clockwise.

Fig. 14

Once the plunger contacts the bottom bracket spindle, grab the crank arm in one hand and the handle of the extractor tool in the other, and continue turning the plunger clockwise.

Fig. 15

It should take a lot of force to free the crank arm from the bottom bracket spindle, but once it is loose, it should easily slide off.

As you pull the crank arm off of the spindle, lift the chain off of the smallest chainring and let it hang down resting on the front derailleur cage.

Fig. 16

Unscrew the outer body of the extractor from the crank arm.

Repeat the extraction procedure with the opposite crank arm.

Remove Bottom Bracket

Fig. 17

First, identify the style of bottom bracket.

Some bottom brackets are threaded differently than shown in these instructions.

The fixed cup of the bottom bracket is generally on the drive side (right side) of the bicycle, as shown in the picture.

Fig. 18

The adjustable cup has a lockring.
(shown at left with lockring hook spanner)

Attach the appropriate lockring spanner to the lockring on the adjustable cup.

Fig. 19

Turn the lockring spanner counterclockwise to loosen the lockring.

Fig. 20

Remove the lockring by hand or with the spanner.

Fig. 21

Either by hand, or using the appropriate tool, slowely remove the adjustable cup, turning counterclockwise.

Fig. 22

When you remove the adjustable cup, the bearings may fall out of the cup.

Set aside the adjustable cup with its bearings.

Fig. 23

Most bottom bracket spindles have different right and left sides, the right side is usually longer.

There is usually writing, or some type of marking on the middle section of the spindle that will allow you to remember its orientation.

Fig. 24

Pull the spindle most of the way out of the bottom bracket shell, and look for writing on it.

If there is writing, compare the writing to the orientation of the spindle in the bike.

The spindle shown at left has writing that is read while facing the front of the bike.

Remember this orientation so that the spindle can be installed in the direction that it came out.

Once you have determined its orientation, pull it out of the bottom bracket shell and set aside.

Fig. 25

The drive side (right side of bike) bottom bracket cup is usually the "fixed" cup.

This means that it is very tight against the bottom bracket shell so as to not come loose.

Also, the fixed cup is usually left hand threaded, meaning that you turn it counterclockwise to tighten. This is the opposite of "normal" threading.

With a 36mm wrench, or a large adjustable wrench, turn the fixed cup clockwise to break it loose from the bottom bracket shell.

If the fixed cup is very tight, it may be necessary to use a "cheater bar", which is a piece of pipe inserted over the end of the wrench to get more leverage.

Fig. 26

By hand, or with the wrench, remove the fixed cup turning clockwise, and set aside.

Clean and Inspect Parts

Fig. 27

Visually inspect the threads of both bottom bracket cups, as well as those on the bottom bracket shell.

If the either bottom bracket cup did not unthread smoothly, look closely at the threads for damage.

Fig. 28

Clean both cups as well as the bearings and bottom bracket spindle, using solvent if necessary.

Be sure to remember the orientation of the spindle.

Fig. 29

Visually inspect the bearing surfaces of both cups, and the spindle.

The bearings generally wear a straight line around the bearing surface.

If this line is crooked, or bigger in some spots than others, it may be an indication of a worn out bottom bracket.

Fig. 30

Also look for "pitting", which is little dents or gouges in the bearing surface.

Look at the bearings. If any of them is broken, or has pitting, they are destroyed and need to be replace.

If any part of the bottom bracket assemby is worn out or broken, then it is likely that other components of the bottom bracket are worn out as well.

Bottom Bracket Assembly

Fig. 31

Apply a thick layer of grease to the bearing surfaces on the bottom bracket cups.

Also, lightly grease the threads on the cup.

Fig. 32

Insert the drive side bearings into the fixed cup (drive side bottom bracket cup).

Fig. 33

If the bearings have a retainer ring (as shown in picture), be sure to insert them so that the retainer ring will not contact either the cup or the spindle.

Fig. 34

Thread the fixed cup into the right side of the bottom bracket shell, turning counterclockwise by hand.

If it is very difficult to turn the cup, remove it and inspect all of the threads for damage.

The threads are very fine on the bottom bracket shell, so it is easy to cross thread them.

Be careful and make sure that the cup is going in straight.

Fig. 35

With a 36mm wrench, or a large adjustable wrench, tighten the fixed cup against the bottom bracket shell.

The fixed cup needs to be very tight. Minimum torque is 300 in. lbs

Sometime, the wrench will have a tendency to slip off of the wrench flats on the fixed cup. If this happens before the fixed cup is properly tightened, then it will be necessary to use a different tool to tighten the fixed cup.

Fig. 36

Insert the drive side (right side) of the bottom bracket spindle into the bottom bracket shell.

Be careful to insert the spindle in the right direction, because it's right and left sides may be different.

Fig. 37

The square taper should be sticking out of the fixed cup on the right side.

Fig. 38

Insert the left side bearings into the adjustable cup, making sure they are well greased.

Fig. 39

Slide the adjustable cup over the spindle and thread it into the bottom bracket shell, turning clockwise.

Fig. 40

Turn the adjustable cup until it contacts the bearings. Do not over tighten the adjustable cup as you could damage the bearings.

Fig. 41

Grease the threads on the lockring, and thread it onto the adjustable cup, turning clockwise. Do not tighten the lockring against the bottom bracket shell.

Install Drive Side Crank Arm

Fig. 42

The square tapers on the bottom bracket spindle, as well as those on the crank arm, should be clean and dry before the crank arm is installed.

If there is any grease on the tapers when the crank arm is installed, then it may slide too far onto the spindle damaging the crank arm.

It is also possible that the crank arm could slide all the way into the bottom bracket cup.

Clean the square tapers on the drive side of the spindle.

Fig. 43

Also clean the square tapers on the drive side crank arm.

Fig. 44

Slide the drive side crank arm over the drive side of the spindle.

Fig. 45

Grease the threads on the crank bolt or nut.

Fig. 46

Install any washers, then thread the crank bolt or nut into the threads on the bottom bracket spindle.

Fig. 47

With a 14mm socket wrench, tighten the crank bolt to 250-300 in. lbs, turning clockwise.

Do not over tighten the crank bolt, as this may damage the crank arm tapers.

Adjust Bottom Bracket

Fig. 48

Turn the crank arm slowely by hand, feeling for rough spots and tightness.

Holding the crank arm next to the seat stay, seat post, then chain stay, rock the crank arm towards and away from the bike, feeling for play.

Fig. 49

If the bottom bracket is loose, and rocks back and forth, then the adjustable cups needs to be tightened by turning it clockwise.

If the bottom bracket is tight, and feels rough or slow, then the adjustable cup needs to be loosened by turning it counterclockwise.

Fig. 50

Once you have obtained a smooth adjustment, use the pin spanner or other tool to hold the adjustable cup still, and tighten the lockring with the lockring spanner until it is snug.

In the picture, an adjustable wrench is holding the adjustable cup still.

show both tools turning

Fig. 51

Once again, check your adjustment as described above, rocking the crank arm back and forth.

If necessary, tighten or loosen the adjustable cup for a better adjustment, then tighten the lockring more.

It is more important for the bottom bracket to have no play, than for it to be perfectly smooth.

Some roughness in the bottom bracket will go away as it wears in.

But if the bottom bracket is loose, it will destroy itself very quickly.

Fig. 52

Repeat the process of adjusting the adjustable cup, and tightening the lockring, until you have a smooth adjustment, there is no play, and the lockring is tight.

Recheck the adjustment, looking for smooth movement, and checking for play with the crank arm at different locations.

Install Left Crank Arm

Clean the square tapers on the non-drive side crank arm and bottom bracket spindle with solvent. There should be no grease on these parts when they go together.

Fig. 53

Slide the non-drive side crank arm onto the non-drive side spindle, being sure to line it up 180 degrees opposite the drive side crank arm.

Grease the threads on the crank bolt, and using a washer if necessary, thread the crank bolt into the spindle.

Fig. 54

Tighten the crank bolt to 250-300in. lbs with a 14mm socket wrench or 8mm hex wrench. Do not overtighten the crank bolt as you can damage the crank arm.

Fig. 55

If there are dustcaps, install these in the threads of the crank arms over the crank bolts on both crank arms.

The dustcaps only need to be snug, not tight, because they are usually weak plastic.

Final Adjustment Check

Fig. 56

Now that both crank arms are installed, recheck your bottom bracket adjustment one more time.

The crank arms should spin smoothly, and there should be no play when rocked back and forth.