BB30 bottom bracket systems, ﬁrst developed by Cannondale, have very large bearings that press straight into the frame. They've been followed by the Shimano Press-Fit system, loosely referred to as ‘BB90’, and both are appearing on bikes around the £1,500 mark. They’re effective and seem reliable so far.
Both designs are fairly easy to fit and maintain. There aren’t many budget aftermarket tools to service them yet, but you might as well get familiar with the ones there are as this system’s here to stay. If you’ve ever ridden BMX bikes and fixed them yourself, you can dust off your hammer and blocks of 2x4.
- Allen keys up to 10/12mm
- Resin and rubber mallet
- Torque wrench
- Budget option: Wood blocks and drifts, plus a hammer
- Professional option: BB30 tool (eg. Park Tool BBT-39, £59.99) or Press-Fit cup drift (eg. Park Tool BBT-90, £24.99), depending on bottom bracket type, plus headset bearing press (eg. Park Tool HHP-2, £149.99)
1 Diagnosis and removal
To spot problems with press-fit bottom brackets, drop the chain out of the way to one side or the other 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. More than about 1mm, combined with roughness, means it’s time to replace the bearings. Begin by removing the left arm, which on SRAM/Truvativ or FSA will usually require a 10mm or 12mm Allen key and possibly an extension bar. 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, simply loosen the two 5mm pinch bolts, lift the safety latch and unscrew the retaining bolt.
2 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 mallet. Remove any dust caps, spacers or wavy washers and keep them in their correct order of position. With Shimano, pretty much the same method applies as with SRAM/ Truvativ or FSA BB30s, although on some models the right-side crank arm and chainset unit comes off rather than the left. Hold onto the crank as it’s being driven out to prevent it from dropping and getting damaged. BB30 cranks might require a bit more force and a sharper blow for removal than BB90, which should normally just slide out with ﬁrm pressure.
3 Remove bearings – without special tools
There are two ways to remove BB30 and BB90 bearings. This step describes the budget option. If you've invested in the proper tools, skip to step 4 (BB30) or 5 (BB90).
Because of the current scarcity of speciﬁc tooling available for this job, the methods used are no different than those for BMX bearing and one-piece crank removal; they seem somewhat primitive but they’re an effective way of getting the job done. Knock out the bearing with 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, assuming both are needing replacement. 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 driven out.
4 Remove BB30 bearings – with special tools
These special tools still basically rely on brute force and impact to get the job done. 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 Remove BB90 bearings – with special tools
Park Tool have a special tool for Shimano bearings, the BBT-90, which is a smaller version of their headset cup remover; it’s just an expanding 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 job. The bottom picture shows the inner workings: there’s 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 assembly. The Shimano cups end up with a nominal width of around 90mm, thus the new (non-ofﬁcial but widely accepted) name of BB90; 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. Drilling a drain hole in the bottom bracket shell is a worthwhile step – although it's probably frowned upon by manufacturers. Now prepare to reassemble or install new bearings. 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 them.
7 Reinstall bearings
There are two ways to reinstall BB30 and BB90 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 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 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 Press in bearings
If you're fortunate enough to have some quality tools, such as the Park Tool HHP-2 headset press, 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, as pictured (top). Grease the splined area of the spindle and reinstall the left crank arm, remembering the spacers. On SRAM/Truvativ and FSA, tighten up to about 40Nm. With Shimano, tighten the plastic cap into the left crank arm until it can no longer move inwards (it requires a light torque of just 0.7-1.5Nm). Allow it to settle between efforts. Replace the safety catch, then tighten the 5mm Allen pinch bolts gradually and evenly, remembering that when one is tightened, the other loosens. Finish to a torque of 12-14Nm each (about twice as ﬁrm as your stem/steerer clamp bolts).
10 Test and readjust
Recheck the front derailleur adjustment – with some cranks this can change slightly. Check that the outer and inner stop screws allow correct shifting without chain drop-off. Now get on your bike, hammer through the gears and put some weight through the cranks by standing on the pedals and swinging the bike through the down strokes. This will bed everything down correctly, and there could be a little bit of play in the bearings after this test run. Recheck the crank arm bolt on SRAM/Truvativ and FSA, and don’t be afraid to put some power into it to keep it from loosening over your next long ride. On Shimano, if play has developed, loosen the two 5mm clamp bolts, tighten the draw bolt a bit further then retighten the two 5mm bolts.