A customer brought in a Cosmic Carbon 40 for service.
It's a tubular setup.
The customer wanted the hub bearings upgraded to ceramic, but
CeramicSpeed is a bit pricey, so
we decided to swap in Tni bearings instead.
↑Removed them.
↑Installed them.
For the bearings I swapped in,
this wheel uses 5 total across 2 different sizes.
Front hub left and right, and rear hub left are "6901,"
rear hub right and freehub body are "608-9."
Except for the fact that the FTS-L freehub body uses 608-9 bearings,
bearing sizes vary by wheel, so research beforehand is essential.
According to bearing standards, 6901 is
defined as outer diameter 24 / inner diameter 12 / width 6 (in mm).
Similarly, 608 is defined as outer diameter 22 / inner diameter 8 / width 7,
but Mavic apparently decided that a rear hub axle
with an 8mm outer diameter wouldn't have sufficient strength,
so they adopted a custom non-standard size of
"608 size with a 9mm inner diameter."
This is generally difficult to source,
but Tni offers "608-9" bearings
which is exactly what fits, so that's a real help.
All three 6901s were made by NSK (Japan) at their Japanese factory.
Of the 608-9 bearings (as Tni calls this size), one
was from SKF, the venerable Swedish bearing giant.
It has a black seal.
It says ITALY on it, so it's probably from their Italian factory.
The other one is from NSK's Indonesian factory.
The NSK bearing with the brown-colored seal
has a D at the end, so it's definitely contact-type,
but I can't tell much about the lip seal characteristics of the SKF bearing.
Mavic prioritizes dust and water resistance
and intentionally uses contact-type bearings despite their slightly lower rolling efficiency,
but the rear hub right bearing that had the SKF
is the location among the five least prone to water ingress, so
maybe they had their reasons for changing the bearing characteristics there only.
Bonus
First-generation Shimano Hollowtech II bottom bracket for road,
but it has a warning that says "do not disassemble."
However, it's not impossible to remove
the double or triple seals and replace the bearings.
The bearings here are size "6805," with
dimensions of outer diameter 37 / inner diameter 25 / width 7.
There is no standard size other than 6805 with
outer diameter 37 / inner diameter 25
that has a width other than 7.
(The other sizes with outer diameter 37 are
6301 at outer diameter 37 / inner diameter 12 / width 12, and
6904 at outer diameter 37 / inner diameter 20 / width 9.)
However, the bearing on Campagnolo's Ultra-Torque cranks
is a non-standard size: outer diameter 37 / inner diameter 25 / width 6.
The design wouldn't work unless the bearing is 1mm thinner,
and there's no other standard size that fits just right.
This "1mm thinner 6805" is also generally hard to find.
But Tni's ceramic bearings have it in stock.
However, it's not labeled "6805-6" or anything like that—
instead it's labeled 6805 (Shimano), 6805 (Campagnolo), so
you need to be careful when ordering.
It's a tubular setup.
The customer wanted the hub bearings upgraded to ceramic, but
CeramicSpeed is a bit pricey, so
we decided to swap in Tni bearings instead.
↑Removed them.
↑Installed them.
For the bearings I swapped in,
this wheel uses 5 total across 2 different sizes.
Front hub left and right, and rear hub left are "6901,"
rear hub right and freehub body are "608-9."
Except for the fact that the FTS-L freehub body uses 608-9 bearings,
bearing sizes vary by wheel, so research beforehand is essential.
According to bearing standards, 6901 is
defined as outer diameter 24 / inner diameter 12 / width 6 (in mm).
Similarly, 608 is defined as outer diameter 22 / inner diameter 8 / width 7,
but Mavic apparently decided that a rear hub axle
with an 8mm outer diameter wouldn't have sufficient strength,
so they adopted a custom non-standard size of
"608 size with a 9mm inner diameter."
This is generally difficult to source,
but Tni offers "608-9" bearings
which is exactly what fits, so that's a real help.
All three 6901s were made by NSK (Japan) at their Japanese factory.
Of the 608-9 bearings (as Tni calls this size), one
was from SKF, the venerable Swedish bearing giant.
It has a black seal.
It says ITALY on it, so it's probably from their Italian factory.
The other one is from NSK's Indonesian factory.
The NSK bearing with the brown-colored seal
has a D at the end, so it's definitely contact-type,
but I can't tell much about the lip seal characteristics of the SKF bearing.
Mavic prioritizes dust and water resistance
and intentionally uses contact-type bearings despite their slightly lower rolling efficiency,
but the rear hub right bearing that had the SKF
is the location among the five least prone to water ingress, so
maybe they had their reasons for changing the bearing characteristics there only.
Bonus
First-generation Shimano Hollowtech II bottom bracket for road,
but it has a warning that says "do not disassemble."
However, it's not impossible to remove
the double or triple seals and replace the bearings.
The bearings here are size "6805," with
dimensions of outer diameter 37 / inner diameter 25 / width 7.
There is no standard size other than 6805 with
outer diameter 37 / inner diameter 25
that has a width other than 7.
(The other sizes with outer diameter 37 are
6301 at outer diameter 37 / inner diameter 12 / width 12, and
6904 at outer diameter 37 / inner diameter 20 / width 9.)
However, the bearing on Campagnolo's Ultra-Torque cranks
is a non-standard size: outer diameter 37 / inner diameter 25 / width 6.
The design wouldn't work unless the bearing is 1mm thinner,
and there's no other standard size that fits just right.
This "1mm thinner 6805" is also generally hard to find.
But Tni's ceramic bearings have it in stock.
However, it's not labeled "6805-6" or anything like that—
instead it's labeled 6805 (Shimano), 6805 (Campagnolo), so
you need to be careful when ordering.