Shimano Hollowtech II crank and bottom bracket: removal and installation

How to tell which crank and bottom bracket you have

Start with the crank's model number, for example FC-M6100 or FC-R7100. The steps on this page follow Shimano's dealer's manuals DM-MAFC002 for mountain bike cranks and DM-RAFC010 for road cranks.

The left arm. Look at the left arm around the axle. If it has a cap screwed into the end of the axle and two pinch bolts across a slot in the arm, it uses the method on this page. Shimano calls this the standard type, and FC-M6100 is one of them. The FC-M9100, FC-M9120, FC-M9125 and FC-M9130 cranks are different: their left arm has an adjustment nut and a single mounting screw torqued to 45–55 N·m. Do not use the steps below on those.

The bottom bracket. A threaded Hollowtech II bottom bracket has two cups that screw into the frame. The FC-M6100 exploded view lists SM-BB52 cups with the crank. BB-MT501 is another threaded Shimano bottom bracket made for the same thread. Both are marked B.C.1.37" x 24T, which is English thread. If there is no thread in your frame and the cups are pressed in, you have a press-fit bottom bracket instead.

Thread direction. On an English-thread bottom bracket, the left cup is normal right-hand thread and the drive-side (right) cup is left-hand thread. The one exception Shimano lists is a road bottom bracket for a 70 mm shell with M36 thread: on that one the right cup is also right-hand thread and tightens clockwise.

Crank arm spacers. Some mountain bike cranks need a spacer on the axle. FC-M6100 needs none. FC-M8120, FC-M7120, FC-M6120 and FC-MT610-B2 need a 3 mm spacer. FC-M8130, FC-M7130 and FC-M6130 need a 4.5 mm spacer. Fit it with the rubber side facing inward.

Shell widths and bottom bracket spacers

Measure your bottom bracket shell across its faces before you fit the cups. The number of spacers depends on the shell width.

A 1.8 mm spacer plus a 0.7 mm spacer can be used in place of one 2.5 mm spacer. The BB-MT501 table comes from DM-MAFC010, which is written for the newer FC-M6200 cranks. For an FC-M6100 with its SM-BB52 cups, use the DM-MAFC002 rows.

Torque figures

The cap figure is very low on purpose. The cap only pulls the arm in far enough to take out play. The pinch bolts are what hold the arm on.

Remove the left crank arm

Before you start: loosen both pinch bolts first, then the cap. Keep the cap, stopper plate and bolts together; they go back on the same arm.

1. Loosen the two pinch bolts on the left arm with a 5 mm hex wrench.

2. Unscrew the cap from the end of the axle with a TL-FC16 or TL-FC18.

3. Lift the stopper plate in the slot of the arm so it no longer locks the arm in place.

4. Pull the left arm off the axle splines.

   From DM-MAFC002, crank (removal is the reverse of installation)

Pull the drive-side arm and axle

1. With the left arm off, pull the drive-side arm out from the drive side. The axle comes out with it.

2. If your crank had a 3 mm or 4.5 mm crank spacer on the axle, keep it with the crank so it goes back on.

3. Wipe the old grease off the axle and splines. If the bottom bracket bearings have play, replace the bottom bracket.

   From DM-MAFC002, crank and safety notes

Remove threaded bottom bracket cups

Before you start: remember the drive-side cup is left-hand thread. Turning it the wrong way tightens it.

1. Fit the cup tool for your bottom bracket (see the tools list). For SM-BB52 cups, Shimano's FC-M6100 exploded view lists TL-FC36.

2. Turn the drive-side cup clockwise to loosen it.

3. Turn the left cup counterclockwise to loosen it.

   From DM-MAFC002, bottom bracket

4. Note how many spacers came off each side and their thicknesses, so you can check them against the spacer table.

Install threaded bottom bracket cups

1. Measure the shell width (68 mm or 73 mm) and lay out the spacers for your bottom bracket from the spacer table.

2. Grease the threads of both cups with Shimano Premium Grease (Y04110000).

3. Fit the inner cover between the cups. Shimano warns that leaving it out lets more water in.

4. Thread the drive-side cup in counterclockwise, with its spacers, by hand.

5. Thread the left cup in clockwise, with its spacer if your table calls for one, by hand.

6. Tighten both cups to 35–50 N·m with a torque wrench and the right cup tool.

   From DM-MAFC002 and DM-MAFC010, bottom bracket

Road threaded bottom brackets (BB-RS500, BB-RS501, SM-BBR60, BB-R9100) go in the same way and take the same 35–50 N·m, apart from the 70 mm M36 exception in thread direction.

Two notes from Shimano on the tools. TL-FC24 and TL-FC25 adapters wear with repeated use. When you fit one into a TL-FC32, check which positions it can be used in. With a TL-FC33 or TL-FC36, any position works.

Remove and install a press-fit bottom bracket

Before you start: press-fit cups that have been removed must not be reused. Have a new bottom bracket ready before you knock the old one out.

1. To remove, put the Shimano removal tool in from the opposite side to the cup you want out. Press the tip so its flaps open and the collar catches the edge of the cup.

2. Tap the tool with a soft face mallet until the cup comes out. Repeat from the other side.

3. To install, set the spacers for your shell (89.5 mm: one 2.5 mm spacer; 92 mm: none), fit the inner cover and line up the cups.

4. Press the cups in with the Shimano press tool until there is no gap and the face of each cup sits parallel to the face of the shell.

   From DM-MAFC002 and DM-RAFC010, bottom bracket

Shimano lists TL-BB12 and TL-BB13 for its press-fit bottom brackets, including SM-BB92-41B, SM-BB72-41B and BB-RS500-PB. Road press-fit shells need a bottom bracket made for 86.5 mm.

Install the crank

Before you start: do not fully tighten one pinch bolt and then the other. Tighten them in turns, a bit at a time.

1. Fit the crank spacer if your model needs one (see crank arm spacers). FC-M6100 has none.

2. Slide the drive-side arm and axle in from the drive side until the arm touches the bottom bracket.

3. Grease the axle with Premium Grease.

4. Push the left arm onto the axle with its wide spline tooth lined up with the wide spline on the axle. The two arms should point in exactly opposite directions.

5. Grease the cap thread, screw it in with TL-FC16 or TL-FC18 and tighten it to 0.7–1.5 N·m. This only takes out the play.

6. Push the stopper plate in, in the direction shown in the manual, and check that its pin is fully seated.

7. Tighten the two pinch bolts with a 5 mm hex, a little at a time and swapping between them, until both reach 12–14 N·m on a torque wrench.

   From DM-MAFC002, crank

Road cranks covered by DM-RAFC010 go on the same way: drive side in, grease the axle, line up the wide splines, cap to 0.7–1.5 N·m, seat the stopper plate, then the two pinch bolts in turns to 12–14 N·m.

Shimano says to check the pinch bolt torque again with a torque wrench after about 100 km (60 miles), then now and then after that, and after any hard crash. A left arm with loose bolts can come off while you ride.

Check for play

1. Look at the gap between the left arm and the bottom bracket. There should be none.

2. Hold both crank arms and push them side to side. You should feel no knock or movement.

3. If there is a gap or play, loosen the pinch bolts, retighten the cap to 0.7–1.5 N·m and do the pinch bolts again in turns.

   From DM-MAFC002, crank

4. If the play is still there with the cap set correctly, the bearings are worn. Replace the bottom bracket.

If you are worried about the crank itself

This page covers removal and installation only. If you think your crank is damaged, use Shimano's crankset inspection page (DM-RAFC012) and take the bike to a Shimano dealer before you ride it again.

Parts and consumables

Tools

• 5 mm hex wrench for the pinch bolts
• TL-FC16 or TL-FC18 for the left arm cap
• Torque wrench covering 0.7 N·m to 50 N·m (you may need two)
• Cup tool for SM-BB52: TL-FC36 (Y13098000), as listed in the FC-M6100-1 exploded view
• Cup tool for BB-MT501: TL-FC32 (Y13009210), TL-FC33 (Y13009230) or TL-FC36 (Y13098000)
• Cup tool for BB-MT800 and BB-MT801: TL-FC25 with TL-FC32, TL-FC33 or TL-FC36; or TL-FC37 (use TL-FC37 with an impact wrench)
• Cup tool for SM-BB93: TL-FC24 with TL-FC32, TL-FC33 or TL-FC36; or TL-FC34 (use TL-FC34 with an impact wrench)
• Road cup tools: BB-RS500 and BB-RS501 take TL-FC32, TL-FC33 or TL-FC36; SM-BBR60 takes TL-FC25 with TL-FC32, TL-FC33 or TL-FC36, or TL-FC37; BB-R9100 takes TL-FC24 combinations or TL-FC34
• Press-fit: TL-BB12 and TL-BB13, plus a soft face mallet for removal

DM-MAFC002's full tool list also includes 8 mm hex, 17 mm and 32 mm wrenches, TL-FC41 and a hexalobular [#30] driver for other models and jobs in that manual.

Troubleshooting by symptom

Creaking from the left arm

Take the left arm off, grease the axle and splines, and refit it to the correct torque as in installing the crank.

Crank knocks or moves side to side

Reset the cap and pinch bolts as in checking for play. If the play is in the bearings, replace the bottom bracket.

Left arm pinch bolts keep coming loose

Check the cap and stopper plate are seated, then tighten the bolts in turns to 12–14 N·m. Recheck them after about 100 km (60 miles).

Shifting got worse after a bottom bracket change

Shimano lists bottom bracket shell faces that are not parallel as a cause of poor shifting. Check the spacer count against the spacer table, and have the shell faces checked if the spacers are right.

Bearings noisy after washing

Water in the bearings causes noise. Do not pressure-wash around the bottom bracket; clean it with a neutral detergent.

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