Last part of the Allez rebuild is the overhauling or upgrading of the wheel set. The Mavic Ksyrium SLRs. Of course I will go for ceramic bearings but which one? Three of the big ceramic high-end bearing manufactures are ceramcispeed, c-bears and enduro. The quality is nearly the same but the price is gaping a lot. I would say ceramicspeed is on the first place, after that enduro and c-bears.

I decided to go with the enduro zer0 ceramic bearings because of performance/price. Another plus: they are doubled sealed (vv) and need no service.

Post as guidance? No warranty in ANY case of damage!

Lesson in Bearings

Hub bearings are not standardized. Each Manufacturer use different sizes and qualities of bearings in its hubs and wheel sets. A lot of Manufactures do not name their bearings in size, like Mavic. They sell just a replacement kit with the “correct” bearings.  To dissolve the  correct bearing measurement is the key. Often a bearing is named after  its data (inner diameter, outer diameter and width). The seals are also described in different ways e.g. 2RS1 or VV. Both descriptions provided a double sided seal.

As always there are a few exceptions: Multiple descriptions pointing to the same bearing as well as manufacturer self-described sizes or other standards.

This time first, the “special” Mavic parts need for this exercise: free hub body seal, new pawns with springs and the free wheel body oil.

I recommend those original parts during a service. They cost nothing but supporting a long lifetime of the free wheel. Especially the oil is indispensable. A lot of people use degrease to “sound-up” the free wheel. This is more than stupid because it will run dry and take damage over the time.

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First will be the front wheel. I put it on a squared timber to protect the hub. To open the hub the mavic QRM+ tool and a 5mm allen is needed. Everything done on the left side. Just unscrew the hub so the bearings are freed.

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As you can see there is nothing on the bearing which will name it… only after the extracting it can be named exactly.

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To extract the old bearings an inner bearing puller is needed as well as a sledge hammer. The inner diameter is 12mm so the bearing puller should have a snug fit. The extracting itslef looks rough but nothing to worry about – hammer it out.

After both bearings are redounded each bearing seat can be cleaned so the new bearings will fit like the first time.

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Now we a have both bearings in hand we can identify them. The measurement says they are 6901.

Front HUB Data, Mavic Ksyrium SLR

Measurements of the bearings in mm (INNER x OUTER x WIDTH): 12x24x6 
Industrial description (size) of this bearing:  6901, 61901
Sealing description: 2RS1, VV 
Additional identifier for bearing play: CN

Mavic OEM Part: M40078 (2x 6901 2RS1 CN)
Enduro part: 2x C0 6901 VV C-N

The bearing weight is nearly the same. The two new 6901 are at 20 gram (oem 19,9 gram).

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Time to insert the new bearings. For the best and smooth insertion adapters are needed. The 6901 have an inner guide which will perfect align with the inner diameter of 12mm. This will be a dry fir so no grease of something is needed. The bearing seat must be clean as well.

One side after the other. The first bearing  will be also installed with both 6901 adapters. On the “empty side” it will fit perfect into the empty bearing seat as a guide. Just slowly screw the bearing inside it’s seat until there is a noticeable resistance. After that same on the other side.

Do NOT overload the press. This will damage the bearing and maybe the bearing seat! 

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Now it is time to reassemble the hub but first cleaning up =)

Keep in mind that the allen insert is on the left side. For the first tightening you should “feel” the bearing. Then clip the adapters back in place, insert the spanner and mount the front wheel to adjust the correct bearing play. 

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After the wheel is installed the adjustment will be done with the QRM+ tool. This is a “feeling adjustment” – the bearing must be slightly touched. When you feel it it is the correct adjustment… and the front wheel is done.

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On the rear wheel the cassette needs to be deinstalled, first. Then the rear hub extraction itself. This is done with a spanner and the allen on the drive side. After that the hub can be extracted as well as the free hub body.

During the free hub body remove it is important to look for the pawls, they can easily drop-off! Also keep an eye for the washer between the free hub body and the hub shaft. Do not loose it!

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Now three bearings are shown: Outer left bearing (left side), outer right bearing (free hub shaft) and the free hub body bearing itself. I will start with the last one – the free hub body bearing.

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The free hub body bearing is not provided to change by Mavic. They say: “Buy a new free hub body, that’s fine. Here is the part number”. That is not the correct way in my opinion. I don’t want that because there is no wearout or something else after those thousand kilometers. 

To extract the bearing anyway it is necessary to open the outer body dust cap with an nut. After that the bearing can be pulled with the sledge hammer (9mm puller). After that the measurement to name the bearing. Data says:  MR9227

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Rear FREEHUB Data, Mavic Ksyrium SLR

Measurements of the >>freehub<< bearing in mm (INNER x OUTER x WIDTH): 9x22x7 
Industrial description (size) of this bearing: 608/1, 609, 9227, 92272, MR9227
Sealing description is: 2RS2, VV 
Additional identifier for bearing play: CN

Mavic OEM Part: 30871101 (complete free hub body, bearing is no provided to change)
Enduro part: 1x C0 MR9227 VV CN

The weight against each other is more noticeable as the previous one. OEM: 11,2 grams and the Enduro ceramic 9,9 grams.

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After the cleaning of the bearing seat it is time to install the new one in. To support the press in process of the new bearing a 6805 adapter will help from the free hub side. Same here, no anti seize, grease or lube. Stop when you feel any resistance.

Finally the dust cap needs to be installed. I use some grease on this to prevent dirt and grime to trespass. The torque is not documented. I install the cap a little more than hand tighten. Time for the other two bearings.

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Now I will go for the outer left bearing. Bearing puller and sledge hammer… nothing new. This one looks like the bearing on the front hub. Confirmed by the measurement data: 6901

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Rear HUB Data, Mavic Ksyrium SLR

Measurements of the >>outer left<< bearing in mm (INNER x OUTER x WIDTH): 12x24x6 
Industrial description (size) of this bearing: 6901, 61901
Sealing description is: 2RS1, VV 
Additional identifier for bearing play: CN

Mavic OEM Part: 33000001 (rear hub set: 1x 6901 + 1x 608/1)
Enduro part: 1x C0 6901 VV C-N

The installation process is the same. Just feel the resistance  during the press fit. Ah… and do not forget to clean the bearing seat =)

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At last the outer right bearing. This one looks in shape/size like the free hub body bearing. After the extraction with the 9mm puller this is already confirmed by measurement: MR9227

Measurements of the >>outer right<< bearing in mm (INNER x OUTER x WIDTH): 9x22x7 
Industrial description (size) of this bearing: 608/1, 609, 9227, 92272, MR9227
Sealing description is: 2RS2, VV 
Additional identifier for bearing play: CN

Mavic OEM Part: 33000001 (rear hub set: 1x 6901 + 1x 608/1)
Enduro part: 1x C0 MR9227 VV CN

For the installation I use the 6901 adapter on the right side. Just for a clean press fit.

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Now that all bearings are done it is time for the general parts that wear out. The free hub body seal and the pawls inside the free hub.

The change of the body seal is quite simple: Just strip it of, clean everything up and fit the new one in place. Just keep the seal direction in mind, it’s important!

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Now for the pawls. Thousands of kilometers without a mark? No, the pawls showed some wear… time for a new pair.  Important thing on this a small amount of the special Mavic free hub oil on each pawl seat. Just a drop, nothing more. Then just clip the pawls in place.

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Last step the final assembly of the rear hub. After a cleanup of the free hub body it is necessary to lube it up. Just five drops of the Mavic free hub body oil across the teeth inside the free hub body.

Remember the setup? Insert the hub on the left side, washer on the outer right bearing, swing in the pawls and slip over the free hub body in its place. Finally the nut secured with a torque of 10NM.

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Now it is time to install the cassette and adjust the bearing play. This is just a simple as it could: Grease up the free hub body, fit the cassette in place and torque it down to 40NM.

After the wheel is installed the same bearing-touch-feeling from the front adjustment is needed to find the correct bearing play. After that all work is done =D

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