Tech: Replacing Cartridge Bearings

The goal was to replace my bearings in my Zipp wheels, as you can see from this post, my bearings really needed some work. This is a lot more of a technical based post than I would normally do, but it was highly rewarding fixing the bearings myself (Warning, wheels are expensive and things easily break so do this at your own risk)

The basics here apply to any wheels with Cartridge bearings, but in this case, it’s a set of Zipp Wheels with 88/188 Hubs.

Why?
Well as you probably know things wear away the more you use them, and also riding in dirt and wet can accelerate the wear process. The wear is what causes your wheels to not turn smoothly (or at all, if its really bad). In most cases, your wheels will have cartridge bearings (unless you have Shimano wheels that use loose ball bearings and races). A cartridge bearing is a self-contained unit, think roller skate or skateboard bearing. The balls are contained in an inner and outer holder (called the race) then the unit pressed into your wheel. If you do a regular check on how easily your axles on you wheels turn you may find your bearings feel gritty or not so smooth. This natural wear and can be accelerated by riding in wet conditions and not servicing. Depending on when you find this wear, you can either regrease the bearings or have to replace the whole cartridge.

First off, you need to know the basics of your hubs, how they come apart and torque specs. It’s easy to take most hubs apart but I’m not going to go dive into details of the disassembly / assembly procedure. You can find most of the hub dismantling instructions at the manufacturer’s website.

Ceramic or Steel?
So my bearings are shot, broken caput. Since I will be spending time there replacing, my thought is to upgrade, so I got some 61803 Enduro Ceramic Zero bearings. These are a direct replacement for the steel bearings in the wheels and can be purchased from many places. Warning. Roadies love ceramic but it tends to be 2-3x the cost of normal steel bearings. Since Ceramic or Steel bearings are the same size, either can be used so you don’t have to be one of those hyper particular roadies.
Normal bearings are steel or stainless steel, ceramic bearings are a different material, thus have different surface properties. Ceramics can be used in place of steel for ball bearings. Their higher hardness means they are much less susceptible to wear and typically last for triple the lifetime of a steel part. They also deform less under load, meaning they have less contact with the bearing retainer walls and can roll faster. Ceramics are also more chemically resistant and can be used in wet environments where steel bearings would rust. Two drawbacks to ceramic bearings are a significantly higher cost and susceptibility to damage under shock loads, which is why installing them with proper tools is critical.

Steel : ~ $12 per bearing   Ceramic :~ $28 per bearing

In cycling, ceramic bearings have been proven to roll smoother, or use less power to rotate because the material to make the bearings form smoother surfaces. Ceramic bearings can be found for wheels, bottom brackets, and rear derailleur pulleys. Enduro ( a leading brand) also make KITS of bearings for popular wheels, the price is normally a better value.
https://www.endurobearings.com/wp-content/uploads//2011/12/bearingkitcatalog.pdf

Tools Needed:-

  • new bearings the right size – (this case 61803 / 6803)
  • grease (park)
  • hammer
  • punch with a flat face, a center punch will not work or a use a bearing extractor tool.
  • motor oil (to lube your zipp hub)
  • 2mm hex key
  • home made press tool or a Wheels Manufacturing sell a basic press for $35
  • home made bearing adapters or two 6803 Wheels Manufacturing adapters $7.50 each.
  • clean rags
  • ample time, no rushing, these wheels cost a fortune 🙂

Step 1
Have a clean workspace and take apart your hub (this example I am using rear hub), you need to remove the cassette first, then remove the preload adjuster, then the dust cap (note orientation) then slide out the axle, pop off the freehub body, and by pop I mean it will almost fall off! -Watch out here because as you remove the freehub body from the hub shell you will / should find a single washer, this is very important! do not lose. This washer sits between the inner freehub bearing and the outer hub shell bearing along the line of the axle. Then remove the dust cap from the freehub body (again noting orientation)

Step 2
Remove the old bearings from the freehub. There are 4 bearings in the rear wheel and 2 in the front. There are 2 bearings in the rear hub shell and 2 bearings in the freehub body that attaches to the shell. We will start with the Freehub body bearings. I managed to replace both bearings in the freehub body without removing pawls or the springs. The old bearings come out relatively easy, just a few moderate taps of the hammer using the punch. Slide the punch on the inside of the freehub wall down to the lip of the bearing then tap, moving the punch around the circumference of the bearing lip, ie at 12’oclock, 6, 3 and 9. After a few light taps the bearing will pop out! easy. You can support the freehub between two wood pieces or do what I do, I like to use several rags folded over and rest the freehub or hubshell on the rags. (see images under Step #4) Flip the freehub over and do the same thing to remove the other bearing.

Step 3
Thoroughly clean all the metal surfaces where the new bearing will sit by using a clean rag and make sure you get off the old dirt / grease. If you don’t do this you will mess up how the new bearing seats. Apply some fresh new grease to the bearing seat, push the new bearing into the hole lightly by fingers, try not to twist it, but if it goes in a little crooked don’t sweat it, as soon as you use the press it will straighten out. I noticed that the outermost bearing on the freehub as the easiest to install, I could almost get in all the way in with just my fingers.

Tech Tip : Only press on the outer metal race / ring of the bearing, pressing force on the inner ring while installing will irrepairably damage the bearing.

The order I used here was to install the outer bearing first (one closest to where cassette sits). Using my home made press, I put in the centering adapter to the pawl end, then I lined up the bearing press and tightened. Not much force was needed at all and I made sure the bearing was down all the way and seated. Now turning the freehub body around I pressed in the pawl side bearing, this time I used two bearing press adapters (not a centering adapter)

Note. This outer bearing is probably your most worn bearing as it is exposed to drive train dirt.

Step 4
This step I replace the bearings in the hub shell, that’s the part attached directly to the spokes of the wheel. Similar procedure. Remove old bearings with a punch, clean thoroughly, apply a little grease, add bearing by hand then use the bearing press. On my wheel the bearings took a little more force to locate the new ones in place, but getting the old bearings out was as easy as the freehub body. One thing you want to do here, since you are dealing with the whole wheel is to be gentle and make sure things are setup well, not slipping. Accidentally smashing the wheel could mean broken or bent spokes and even worse carbon rims. After installing bearings check the flushness of the bearing face. Hi five yourself and move on to re-assembly.

Step 5
Put the wheel back together, clean and insert the freehub dustcap, place the axle through the freehub mount the freehub to the hub shell, don’t forget that washer!, at this point you need to make sure parts are clean and that you have some fresh oil in that pawl drive area. Check to make sure the pawls and springs are on properly before you mount. You can push the pawls in towards the axle with your fingers as you twist to make it seat in the shell, take special care to make sure the rubber seal is not twisted or captured, you might need a small knife edge to straighten out, but be sure not to cut or tear, this light seal is your dirt friend. Clean and put the dust cap on the non-drive side (correct orientation), spin on the preload adjuster ring, adjust preload, tighten 2mm set hex.

Step 6
Adjust preload. I use tight then back off 1/8th of a turn. Tighten 2mm set hex. Feel the bearings on a spin, buttery right? – mount the cassette, done!

This is a lot of stuff right? So questions, just type em in the comments box and I will get back to you.

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