Three piece front hub failure – hazardous design

Hey folks, recently customer came with his 2017 mountainbike on Mavic Crossride wheels for a checkup. We discovered an unusual cracking noise coming from the front hub area, ruling out one possible cause after another, the hub itself remained as the sole possible explanation.

We overhauled the hub and noticed its unusual three piece design (see photo below). Putting it in a vice we finally found out what was causing the noise – one of the cup simply separated itself from the rest of the hub. It was possible to disassemble by bare hands.

I’m wondering, have you ever seen such design? When I look at the cheapest shimano or novatec (aliexpress) hub they are made from one piece.

I’m not an engineer but I see this failure as very hazardous for the rider, potentially ending up in a front wheel failure if it were to be ridden in this condition for a longer time – I believe failure of the one side would lead to failure of the other and after that the tension of the spokes wouldn’t be enough to hold the hub in one piece. What are your thoughts on that?

Cheers from Czech Republic

1 Like

My first reaction without doing any real analysis would be that the clamping force of the axle would probably keep things together. The bearings are pressed in the outers, any lateral force trying to pull the ends of the hub shell off the center should be countered by the bearing and cone assembly holding the hubshell ends in compression.

As to why this construction, Mavic was really big on the 3-piece hubshell with a carbon center section. Of course they advertised reduced weight, but IMO it was more for the visual than anything else. I’m guessing since they had tooling to make the outer sections for those hubs, a cheaper option for an all-alloy hub was to just machine a center section and use the outers, rather than have a one-piece construction.

3 Likes

it’s only a ‘hazardous design’ if it’s not manufactured properly. just sayin’.

1 Like

If it’s a front, rim brake wheel, there’s not much torque difference between the two flanges, so not much risk of unequal tension breaking a spoke. And as mentioned, it’s not like the flanges we’re going to fall off.

A torque situation- driving wheel or disc brakes- would do well with more spokes.

2 Likes

Mavic and Tune are two of the most know users of this design for more than 15 years. Pretty much problem less on the Mavic ones (tune had issues with flanges supporting radial lacing… but not really linked to 3 pieces design).

Phil Wood used thread-on flanges for many years before changing to a one piece design in the recent past.