BB30 bottom bracket systems have very large bearings that press straight into the frame. They’ve been followed by the Shimano Press-Fit system, loosely referred to as BB86 or BB92, and both appear on a wide variety of both road and mountain bikes. Note that BB90 is a separate, Trek-specific standard which falls outside the scope of this article.
- Confused about different standards? Read our our complete guide to bottom brackets
- How to replace an external bottom bracket
Both designs are fairly easy to fit and maintain — though bikes built with poor tolerances are prone to all sorts of problems, but we won’t cover that here.
The tools required to service them have come down in price in recent years, but if you’re looking to service them on the cheap, a hammer and sturdy block of wood can also do the trick.
To be totally clear, the processes involved for servicing press fit bottom brackets vary slightly from standard to standard, so the steps described here may not necessarily apply to your bike. If you’re in any doubt, consult your local bike shop.
Tools required to service a BB30, BB86 or BB92 bottom bracket
- Budget option: Wood blocks and drifts, plus a hammer
- Professional option: BB30 tool (e.g. Park Tool BBT-39) or Press-Fit cup drift (e.g. Park Tool BBT-90) depending on bottom bracket type
- Headset bearing press (e.g. Park Tool HHP-2)
1. Diagnose problems and how to remove BB30 bottom brackets
To spot problems with press-fit bottom brackets, drop the chain out of the way so that it doesn’t rub against the chainrings.
Turn the cranks to feel for roughness or play; feel for sideways play at the pedal end of the arm. As a (very) rough guide, more than about 1mm of play combined with roughness means it’s time to replace the bearings.
Begin by removing the left arm, which on SRAM/Truvativ or FSA, and some others, will usually require a 10mm or 12mm Allen key and possibly an extension bar.
These can take a bit of hoofing to get off, so reinstall the chain onto the big ring to protect yourself in the event of a slip and work with the bike on the ground if necessary for better leverage.
With Shimano cranks, simply loosen the two 5mm pinch bolts, lift the safety latch and unscrew the retaining bolt.
2. How to remove crank
Drop your chain down off the inside ring; the whole right-side crank assembly might now simply push out. If not, give the protruding end of the spindle a decent tap with the rubber faced mallet. Remove any dust caps, spacers or wavy washers and keep them in their correct order of position.
Hold onto the crank as it’s being driven out to prevent it from dropping and getting damaged.
We’ve found that some BB30 cranks might require a bit more force and a sharper blow for removal than BB86/92, which should normally just slide out with ﬁrm pressure.
3. How to remove BB30 bearings without special tools
There are two ways to remove BB30 and BB86/92 bearings, and this step describes the budget option. If you’ve invested in the proper tools described above, skip to step 4 (BB30) or 5 (BB86/92).
The methods described here are essentially no different than those used for BMX bearing and one-piece crank removal. They seem somewhat primitive but they’re an effective way of getting the job done.
First, find a suitable drift. This can be a piece of narrow tubing or rod that ﬁts into the bearing aperture and allows you to strike the inner edge of the bearing cup for Shimano, or the inner race of a BB30 bearing. Whatever you choose, the edge of the drift should be square enough for a good purchase without slipping.
Angle it ﬁrst to one side, strike a sharp blow, then angle to the other side, strike a sharp blow, and repeat until the bearing has been driven out.
4. Remove BB30 bearings with Park BBT-39
These special tools still basically rely on brute force and impact to get the job done, but they differ from a piece of hardwood and mallet in that they offer a bit more control and precision over the process.
To use the Park Tool BBT-39, carefully angle it sideways in the bearing aperture to get the wide bit past the inner race as pictured on top. Insert it until it comes into contact and is squared up against the inside of the bearing, avoiding any circlips or internal frame ridges.
Now give it a couple of good sharp whacks with a resin mallet to dislodge the bearing. Make sure you position and protect your frame in such a way that it won’t fall over and damage vulnerable tubing or paint.
5. How to remove BB86/92 bearings with Park BBT-90
Park Tool has a special tool for Shimano bearings, the BBT-90, which is a smaller version of its headset cup remover; it’s just a slotted, splayed tube that you hit with a hammer. A drift made out of a length of alloy tubing or rod, ideally between 15 and 20mm in diameter, will also do the same job.
The bottom picture shows the inner workings — there’s really not much to it, other than possibly an internal ridge or circlip which you should be careful to avoid.
Note the sequence of crank, axle and cup disassembly. Once installed, they work just like the threaded versions.
Once removed, but before cleaning, spend some time giving the bearings and surfaces a good looking over to check for signs of wear or corrosion.
Notice the rust marks by the pointer. Water will most definitely work its way in and settle in a pool if it has no way out.
Now prepare to reassemble or install new bearings. Thoroughly clean the bottom bracket shell and make sure that the circlips are still correctly seated in their respective grooves, which are located just inboard about 1cm from the outer edges of the bottom bracket shell. There’s no need to remove these.
7. How to fit BB30 and BB86/92 bearings without proper tools
There are two ways to reinstall BB30 and BB86/92 bearings. This step describes the budget option. If you’ve invested in the proper tools, skip to step 8.
The BB30 inner shell and crank spindle are usually aluminium, while the bearing races are steel, so copious amounts of grease can and should be used.
If possible, support the bottom bracket on a wooden block while knocking in the bearings. Although not the ‘approved’ method, if done carefully while keeping them parallel they’ll go in just ﬁne. The Park BBT-39 presses make life easier, but an old bearing or pipe drift will do it in a pinch, as long as it measures 41.5mm in diameter.
Ensure that any wooden drift is properly ﬂat, so that the impact is spread evenly through the entire surface of the bearing, and primarily the outer race — this will also avoid damaging the seal. Never press or drift in a new cartridge bearing by the inner race only.
8. How to fit BB30 and BB86/92 bottom bracket with a headset press
If you’re fortunate enough to have a proper headset press, such as the Park Tool HHP-2, this can now be used in conjunction with the bearing press plates included in the BBT-39 toolset.
Position the headset press as pictured with the press plates up against the bearings and slowly tighten the press, ensuring it stays constantly aligned during the process. Press the bearings in until completely seated into the frame and bottomed out against the internal circlip stops. But don’t overdo it, as these can be damaged if forced.
With Shimano Press-Fit the process is identical, but more force will be needed. Tighten until you see grease oozing from between the edge of the cups and bottom bracket shell, ensuring there are no gaps left.
9. Reinstall arms and tighten
Generously grease the spindle and insert the right side. Tap in with a mallet but protect the finish with a bit of tape.
Grease the splined area of the spindle and reinstall the left crank arm, remembering the spacers, and tighten to spec.
Article last updated 15 January 2018