Big problem with nubuk (chosen) hub

[sguiom]

Hi,

I would like to share my experience with nubuk hubs (built by chosen).

I bought a complete 29er wheel set last year, just like this one :

http://www.nubuk-bikes.de/teile-parts/l ... t/a-32858/

Price is very competitive but … the rear hub is crap and nubuk company do not answer to its customers !


The freehub cannot support normal use. A deformation appears after a few hundreds of kilometres. When the deformation becomes too big, it makes contact with the axle and then the freehub becomes not “free” anymore. I precise that my weight is 68 kg and that I’m not very powerfull (climber, not sprinter).

Here is a picture of the failing freehub :



There is no doubt that after deformation there is failure just like what we can often see on tune’s freehub.

Surprisingly, nubuk sent me a new freehub the first time that this happen without any problem. However, it happens again and despite 10 e-mails and numerous phone calls, they do not answer me anymore. I have no answer to my problem. These freehubs are different from ZTR ones so I cannot find spare parts in my knowledge.

I am not sure that anybody could help me but at least I want to warn people to buy wheels with nubuk hubs, or even anything to this company, since they do not answer anymore when there is a problem.

[serum]

That's not a very convincing precision produced part; judging by the deformed material it suggests that the pressure is unevenly spread. One pawl engages before the others) this puts alle the stress on this one pawl, instead of spreading it evenly over all 3.

[sguiom]

I agree...

[Asymptotic]

Also agree that's extremely poor despite that specific area under the pawl being thin.

It might just be the picture, but is the suface unusually textured for aluminium or just badly anodised?

[serum]

that rough surface is not because of the anodizing;

It either indicates that the part is sand/glass blasted or tumbled after machining with a rough medium or that the part is molded in a sand-mold with a lost wax method. Judging by the overall quality/looks/country of origin, i suspect the latter.. (cheapest method, and while the quality of the used aluminum for this molding method can be topnotch, it usually is rather soft)

The pawls don't look like perfect machined precision either.

The relative cheap novatec hubs i'm using on my roady have got a better finish in this pawl-area than these chosen hubs.

[sguiom]

Yes, I would said like serum, its the molding that make this surface.

Morover, I can add that there is no bearing under the pawls on contrary to hope hubs for example. Thus there is a free space between the freehub and the axle here, and the alloy can be deform. I also think that the freehub can twist because of this lack of bearing since there are also scratches of the teeth on the freehub where there are no pawls.

[serum]

You could carefully tap the deformed material back, using an as large as possible rod and a hammer. (applying radial force) just make sure to support the freehub. Measure the pawls, just to be sure, and press in a steel or 7075 aluminum bushing to avoid the material from deforming any further. Good thing about pressing the material together actually makes it stronger in terms of hardness. How is the radial play on the body when it's in place?