A customer brought in the rear wheel from a Nomu Lab Wheel No. 1.
The sprocket attached freewheel body was extremely eccentric, so
I immediately realized the hub axle was broken.
I've seen a few cases where the hub axle breaks on PowerTap rear hubs
at the outer end face of the right side bearing on the hub shell,
but this one failed in a different way.
The hub is a Tuni Evo hub, specifically Evo Hub I with a 10mm axle.
The Evo Hub II with a 15mm aluminum axle has
hub shell dimensions and compatible freewheels that are roughly the same as Evo Lite Hub,
but Evo Hub I has a narrow flange hub shell
and there's no Shimano 11-speed freewheel body available for it.
Originally, a different rear wheel was built with this rear hub,
but since the bike didn't need to be converted to 11-speed,
I reused the rear hub.
Independent of the customer's wishes (which I do respect),
I have a tendency to reuse parts when I can,
and this time it seems that habit backfired on me.
The hub axle didn't break flush with the outer end face of the hub bearing,
but shows marks where it was ground away by rotation.
When I removed the freewheel body, needle bearing rollers
scattered out like chocolate sprinkles.
↑ This bearing here is a needle bearing type,
and when it broke apart, the internal parts became like a file that ground away at the axle.
The matching front wheel is a WH-7801,
and the brake zone is quite worn.
When you touch it, you can feel the circular dents.
We have a 7900 front rim that catastrophically failed here at the shop,
and the brake zone wear on that rim
is actually in better condition than this one,
so I told the customer it was certain to fail the same way soon.
After weighing the cost and time involved in replacing and rebuilding the rear hub,
I decided to sell my personal Nomu Lab Wheel No. 1 front and rear wheels
to the customer at a good price (I don't have photos of those).
I have things I want to write about regarding the 7900 rim failure shown above,
but I still haven't been able to write about it.
It's not about why it happened, but rather about the manufacturer's warranty situation,
and the point that if we dealt with things that way, we wouldn't be able to sell wheels anymore.
The sprocket attached freewheel body was extremely eccentric, so
I immediately realized the hub axle was broken.
I've seen a few cases where the hub axle breaks on PowerTap rear hubs
at the outer end face of the right side bearing on the hub shell,
but this one failed in a different way.
The hub is a Tuni Evo hub, specifically Evo Hub I with a 10mm axle.
The Evo Hub II with a 15mm aluminum axle has
hub shell dimensions and compatible freewheels that are roughly the same as Evo Lite Hub,
but Evo Hub I has a narrow flange hub shell
and there's no Shimano 11-speed freewheel body available for it.
Originally, a different rear wheel was built with this rear hub,
but since the bike didn't need to be converted to 11-speed,
I reused the rear hub.
Independent of the customer's wishes (which I do respect),
I have a tendency to reuse parts when I can,
and this time it seems that habit backfired on me.
The hub axle didn't break flush with the outer end face of the hub bearing,
but shows marks where it was ground away by rotation.
When I removed the freewheel body, needle bearing rollers
scattered out like chocolate sprinkles.
↑ This bearing here is a needle bearing type,
and when it broke apart, the internal parts became like a file that ground away at the axle.
The matching front wheel is a WH-7801,
and the brake zone is quite worn.
When you touch it, you can feel the circular dents.
We have a 7900 front rim that catastrophically failed here at the shop,
and the brake zone wear on that rim
is actually in better condition than this one,
so I told the customer it was certain to fail the same way soon.
After weighing the cost and time involved in replacing and rebuilding the rear hub,
I decided to sell my personal Nomu Lab Wheel No. 1 front and rear wheels
to the customer at a good price (I don't have photos of those).
I have things I want to write about regarding the 7900 rim failure shown above,
but I still haven't been able to write about it.
It's not about why it happened, but rather about the manufacturer's warranty situation,
and the point that if we dealt with things that way, we wouldn't be able to sell wheels anymore.