WebreaderShopNewsletterTop dealers & workshops

Noise in the MTB bottom bracketHow to make your bike fit again

Robert Kühnen

 · 03.09.2019

Noise in the MTB bottom bracket: How to make your bike fit againPhoto: Robert Kühnen
How to eliminate the cracking in your bike's bottom bracket
Have you localised the source of the noise on your MTB or at least roughly narrowed it down? Is the bottom bracket creaking? Then it's time to get to work. We reveal the important steps here.

THE TREAD CENTRE

Rhythmic cracking in time with the leg work is often localised in the bottom bracket. However, all other parts through which forces flow are also possible causes. The frame transports and amplifies the noises. This makes it difficult to locate them by ear alone. On this page, we will show you the steps that can be taken around the pedalling centre of the bike. Observe the manufacturer's instructions on the torque values for the screw connections.

1 The crankset can generate noise in many different ways. In focus: the bearings and the mounting of the crankset - here a direct mount model from Sram. Photo: Robert Kühnen 1 The crankset can generate noise in many different ways. In focus: the bearings and the mounting of the crankset - here a direct mount model from Sram.
2 After dismantling a Sram crankset, remove the locking screws, loosen the blade and clean the contact zone. Tip: A dentist's tool is very useful here. Photo: Robert Kühnen 2 After dismantling a Sram crankset, remove the locking screws, loosen the blade and clean the contact zone. Tip: A dentist's tool is very useful here.

You can find more articles on the subject of eliminating noise on MTBs here:

>> Eliminate noises on the MTB: Handlebars, seat post and steering bearings <<

>> Eliminate noises on the MTB: Frame and wheels <<

>> How to eliminate noise from the frame and wheels <<

3 Coat the contact zone between the blade and crank with assembly grease, avoiding the threaded holes. Photo: Robert Kühnen 3 Coat the contact zone between the blade and crank with assembly grease, avoiding the threaded holes. Clean and degrease the 4 locking screws and reinsert with medium-strength threadlocker. Tighten to 8-9 Nm. Photo: Robert Kühnen Clean and degrease the 4 locking screws and reinsert with medium-strength threadlocker. Tighten to 8-9 Nm. 5 Pedals are often sound generators. Check whether the bearings have play or are running roughly. If in doubt, simply try a different pedal. Fit and tighten the pedals with plenty of assembly grease. Use washers for carbon cranks. Also oil the pedal mechanism and tighten the cleats under the shoes firmly with greased screws. Photo: Robert Kühnen 5 Pedals are often sound generators. Check whether the bearings have play or are running roughly. If in doubt, simply try a different pedal. Fit and tighten the pedals with plenty of assembly grease. Use washers for carbon cranks. Also oil the pedal mechanism and tighten the cleats under the shoes firmly with greased screws.

EXCEPTION PRESSFIT: DRY INSTALLATION

Almost all parts on the wheel are installed lubricated. Pressfit bearings are not. Martin Rosenbaum, design engineer at Bikeahead, advises: "Pressfit bottom brackets should be fitted dry. With assembly paste, the friction is too high, with grease it's easy for dirt to get into play and it cracks under higher loads." Sram and Shimano also recommend dry installation. Once you have reached the bearing, check whether the bearing rotates easily. Replace any jolting bearings. Photo: Robert Kühnen Almost all parts on the wheel are installed lubricated. Pressfit bearings are not. Martin Rosenbaum, design engineer at Bikeahead, advises: "Pressfit bottom brackets should be fitted dry. With assembly paste, the friction is too high, with grease it's easy for dirt to get into play and it cracks under higher loads." Sram and Shimano also recommend dry installation. Once you have reached the bearing, check whether the bearing rotates easily. Replace any jolting bearings.
How do you like this article?
Remove the bolted bearing shells, clean and refit with assembly grease. Tighten to 35 Nm. Photo: Robert Kühnen Remove the bolted bearing shells, clean and refit with assembly grease. Tighten to 35 Nm.
Home

Most read in category Workshop