Sealed Bearing Service

Sealed bearings are designed to retain the lubrication inside, keep dirt and water out. Meaning lower maintenance.

Sealed Bearing Service 

What about sealed bearings running more smoothly and why don't these so-called "sealed bearing" last longer?

Bontrager rear wheel bearing
Bontrager rear wheel bearing. Note: This bearing does have an outer seal.
Lack of any type of maintenance.

Sealed bearings are known as Cartridge bearings.

The other system "Cup and cone" that run ball bearings are usually easily disassembled and serviced by cleaning the races, replacing the bearing balls, re-greasing, and reassembling. Also, individual bearing balls are quite cheap to replace. As used mainly by Shimano

Whilst bicycle bearings have a seal "sealed bearings" they are not airtight!

Notorious BB 30
Notorious BB 30 Bottom Bracket bearings New and worn out - This bearing has been running with no lubricant and the bearing cage has collapsed, making a very wobbly crankset. Note the corrosion!

When water enters the bearing during a ride or washing, then you store your bike especially in a dry or heated environment for a short period, this will speed up corrosion then using your bike every day!

Note: Use branded bearings only that are made of better quality and tolerances.  

Reasons why BB30 bearings fail:
  • Fatigue - From not being installed correctly, meaning any miss-alignment will cause the bearings to wear much quicker than they wear designed for. The extra load on bearings from spinning faster will also shorten the life. 
  • Installation - Using the correct tools and correct process to install correctly. When the BB30 bearing does not have a good interference fit 'too tight' in the frame, the bearing is having too much load applied and to 'lose' and the bearing will move in the housing, both causing rapid wear. 
  • Contamination - From water ingress, will wash the lubrication out. Grit and dirt entering the bearing will add to the wear. 
  • Lubrication - Lack of lubrication will add load and heat to the bearing. 

Many bike manufacturers have now upgraded the BB30 to an external fitting system or a modified BB. 

Read: Noisy Or Creaking BB30 Bottom Bracket Bearings

The question I hear a lot "How long should sealed bearings last?"
A: "Not as long as you think. Most bearings wear from water ingress and lack of any maintenance. But don't overlook rapid wear by over pre-loading bearings"

Moden bicycle are mainly fitted with sealed bearings, as its cheaper to assemble, these bearings can also be cheaply poorly made and don't last very long. 

Poor fitting, usually using brute force, accounts for a high number of premature bearing failures When replacing any bearing, it's good practice to fit using the correct tools and procedure recommended by the manufacturer. This may mean cleaning, measuring and machining before installation. If unsure contact your local Cycle Technician.
Its good practice to have a follow-up adjustment of headsets to adjust pre-load after 300 miles. 

The seal is to protect the bearing from contaminants, it is important to keep the new bearing clean when you take it out of the packaging so you don’t contaminate it just by handling it.
The seal fitted to the bearing rub's on the inner ring of the bearing, increasing the friction in the bearing. So it’s not going to be as free rotating as it could be without a seal.
A bicycle wheel, for example, you would want that bearing to be as free spinning as possible. So manufacturers come up with different designs, balancing between having a good seal and running free, the cost can also have an impact on the quality of the bearing.
Bearings used in many bicycles do leak a small amount of grease, to help keep the seal lubricated, this has a downside that water can seep into the bearing by a capillary action.
The better designs have a second seal "a type of dust cover" known as an outer seal fitted over the cartridge bearing when it's installed.

Even well-sealed bearings (of any type) can be contaminated if exposed to pressurised water when you spray your hubs with water as you clean your bike. as can happen in heavy rain, if the bearings become submerged.

Some manufacturers even on high-end bikes do not fit an outer seal to the lower headset bearing. This area is prone to dirt and water and replacing the lower headset bearing in less than 6 months of use is inevitable.

Headset lower bearing. Specialized carbon fork
Headset lower bearing. Specialized carbon fork, note no outer seal fitted

Service guide:

As a guide only: Replace cartridge bearings before every 6000* miles or as soon as there is a rough feeling or noise when you spin the bearings or any side to side play in the center casing.

We are replacing bearings a lot sooner, from a combination of cheaply made bearings and from the British weather.

"Do not continue to ride your bike with worn bearings as you can damage the frame"

*In-between replacing cartridge bearings. Every 2000 miles (or after being submerged in mud or water) Maintenance inspections are required as the following:
  • Headset - Remove bearings, clean the outer surface, the cups, crown race and seals. - Inspect bearings for any roughness, dry noise, corrosion, any sign of water entry or any inner cage side movement. If unsure replace. When replacing smear grease on to bearing surface and refit, coat a drop of oil on seals. When reassembled wipe of any lubricant. 
  • Bottom Bracket - Depending on type: Remove crack arm and axel. Wipe bearings and housing (use a de-greaser) Inspect axle for any wear, bearings for any roughness, dry noise, corrosion, any sign of water entry or any inner cage side movement. If unsure replace. When replacing smear grease on to bearing surface, axle, and refit. wipe of any lubricant. 
  • Wheel hubs - Before removing wheels from frame spin for rough noise and feel for any side play. Remove wheels and spin axels and freehub body for rough feeling or dry noise. Remove dust covers and wipe clean bearings, inspect for any sign of water entry, corrosion. Replace any bearings that feel rough. 
"Fitting mudguards helps to protect the life of components"

Video How To - Campagnolo Ultra-Torque bottom bracket removal showing inspection of worn bearings.

In this video view - Worn bearing side to side movement and rough dry noise when spun. Also rusty grime due to not being maintained. 

Video How To - replacing Shimano Hollow Tech 2 bottom bracket.

In this video view - Water in the frame and rusty grime due to not being maintained.

  • “Good practice” after replacing headset bearings - require a follow up to be re-preloaded between 4 - 6 weeks
  • Use less grease or any oil if you ride in a gritty or sandy area as this will become a grinding paste and wear out the connected components.
  • Stop riding if there is a noise or play coming from the headset, crank or wheel hubs as you could make things worse and make a costly repair or do un-repairable damage to the frame.
  • As with different types of bearing design, fitting and types of lubrication always see manufacturers recommendations.
All hubs, bottom brackets and headsets need cleaning, regressing and servicing regularly, especially if you are riding in extreme conditions and If you have hubs that cost over £200.00 it makes sense that you need to service your hub after every ride that consists of riding knee high in mud and water, and not just putting your bike in the shed after every ride and hope it's going to run as smooth as when it was new next time you take it out for a ride! And if you think washing your bike with a power hose is going to do the job and save time, you are making a big costly mistake. Unless you are a team rider who has a mechanic do this for you after every ride, you are going to have to learn to do it your self or pay a mechanic. 

Some of the best quality BB and headsets I have worked on or installed are made by Hope Technology. They can cost 3 times more than an originally fitted bearing, but will last 5 times longer as they use superior bearings and good quality outer seals, Note: also when replacing with a Hope system you don't need to replace as a complete unit, just the bearing, and outer seals saving you money over the long-term.

See more about: Bearings and bearing numbers explained

You May Like To Read: 

No comments:

Post a Comment

Please leave a review to help others and for us to continue to improve our service to you.
you can leave a comment by posting a review of our service and rate your mechanic.