I took an EC90SL in from a customer.


The customer mentioned the rear hub rotation was gritty,
but a re-greasing of the rear hub should take care of that.
Actually, the front hub is the one that's really gritty and needs bearing replacement.
It's an R4SL hub with ceramic bearing spec,
so I asked the customer whether they'd prefer steel or ceramic balls for the replacement,
and they chose ceramic, so that's what we'll go with.


Pulled the bearings out.
There's some difference between left and right in terms of wear, but even the better side is a bit gritty,
so replacing both sides at once will give a cleaner result than just swapping the worse one.



Went with Tni ceramic bearings.



Cleaned out the rear hub.


↑Right is the freewheel side, left is the non-freewheel side bearing seal interior.
The non-freewheel side grease looks clean, but the freewheel side is dirty.
After cleaning out both, I applied ceramic bearing-specific grease.

Inspection shows the wheel is perfectly centered with virtually no runout.
If we'd only been doing a wheel truing, I barely would've needed to do anything.