SKF Bearings

[David Marshall]

Bearings...bearings.  I think most points have been covered by now.  As there is not a common standard or coding system across brands or countries it is difficult to compare.  Just as well that bicycles are low tech machines so that just about any commercial bearing of the right size will work..

 

As for codes the numbers and letters on the bearing will indicate type, size and material of balls, races, seals and the type of lube.  Again codes not the same across suppliers.

 

The ABEC (American) system measures tolerances - not contents - of the bearing.  The higher the number the tighter the tolerance.  ABEC 3 is considered adequate for bicycles.  Skate boarders would argue for ABEC 5 or 7.  Enduro supply three grades of bearing.  ABEC3, ABEC5 and ABEC3MAXED.  The maxed bearings have larger balls and heavy grease and are meant for suspension and headset applications.

 

Loose balls are graded by measuring the imperfections on the ball surface.  Shimano have G25 balls, that is the largest imperfection measures 25 microns or less, or G5 which is smoother. The cheap caged bearings that you get probably measure 100 or more.  If you spin the wheel on a new supermarket bike you will feel the difference.  You will not feel the difference between G25 and G5 balls - but your mind will know!

 

Bearings are like seals.  They do fail, even the market leading brands.  I treat with caution anecdotal slating of brands, even the inexpensive, ones because there are so many variables that come into play.  I remember the DT hubs that were common in the 9 speed era.  6000 or 6001 bearings that lasted from one Sani to the next.  Put that next to the 6802 bearing in the light hubs of today and you can't compare bearing life.  

 

The position of the bearing on the axle and the type of freehub also effects the life of the bearing.  So hub design also plays a big part.

 

As for ceramic bearings.... next instalment.

[brad890]

Thanks for the replies everyone.

 

Just got the bearings today. SKF was not available but got NTN which are apparently also good with the LLU seals.

 

Will update in a few months. 

[Skylark]

Just make sure the bearings are Japanese brand/made in Japan, Skf and bearing man also sell Chinese bearings for many of the sizes they stock, Chinese bearings worked perfectly in my hope hubs others bearly lasted a month in my pivot bearings, considering the savings from using non manufacturer branded bearings and the amount of labour fitting them its best just to always use the Japanese brand bearings.

 

Also seeing they have removable rubber covers its wise to fill the bearing with waterproof grease, definitely helps with durability in the long run.

 

Bearings come with a tiny amount of factory grease because if it's used in a high rpm installation, say in like a power tool, centrifugal forces will throw most of it out again, they leave it up to the end user to add grease as needed for the intended application.

[BaGearA]

Desperately need to replace the bearings in my front wheel 6805

 

so went to a shop today 

 

chinese bearing 25 bucks each ( nope )

 

NTN high quality japanese bearing r125 each    ouch f0k 

 

took them anyway as i expect them to probably last the life time of the wheel 

 

anyone have suggestions for cheaper shops tho ? Centurion/pretoria area 

[BaGearA]

also another question , is it better to leave the good seals in the bearing and leave them alone or risk damaging them a bit to put in new grease every now and then ?

[Larry King]

 

This guy explains some interesting facts about bearings.... hes pretty sharp.

[Skylark]

also another question , is it better to leave the good seals in the bearing and leave them alone or risk damaging them a bit to put in new grease every now and then ?

Open them up, factory grease in bearings is minimal, for an Mtb ideally you want them packed near fill with waterproof grease, especially pivot bearings. If you are careful the seals don't get damaged, I've yet to damage one, fabricate a little flat edged hook with a 90 degree bend to flip them out.