PowerTap problem/suggestions

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dgasmd
Posts: 1953
Joined: Sun Apr 15, 2007 5:10 am
Location: South Florida

by dgasmd

Final update:
So the wheel went back to saris for calibration and bearing change. They also replaced the internal/electronics, so in essence I got a brand new G3 hub. To say I'm impressed and hold a high level of respect for the commitment to customer service is a gross understatement!! Have gone on a few rides already and it's sweet as it gets again!!!

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WMW
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by WMW

fio wrote:Yes, we have had issues with the bearings in the past. A couple hundred miles is not typical for our old bearings though.


Hi Michael. IMO this has nothing to do with bearing quality and everything to do with the design.

The SL series (and probably others) have spacers that constrain the inner bearing races laterally. That works fine if the tolerances are perfect, and the user applies just the right amount of QR pressure, but that is hard to achieve. When it isn't achieved, then the bearings are preloaded and wear out quickly. The NDS hub bearing is only a wimpy 6802, and suffers the further injustice of an NDS axle cap that is a loose internal fit (via o-rings). The QR pressure is the only thing keeping that cap aligned and pressed against the bearing's inner race. Even if everything is perfect, this bearing doesn't last long.

The G3 seems to be different, though I haven't disassembled one to find out exactly what has been changed. The ones I've seen had a touch of lateral play in the hub and the freehub both, indicating that the bearing inner races are no longer laterally constrained throughout. If you can explain the details on that or point me to a diagram, I'd appreciate it.
formerly rruff...

Butcher
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by Butcher

I mentioned this preload issue when I had my problems with my SL+ [bearings would not last 200 miles without some problems and be destroyed in 500 miles]. They insisted there are no issues and it was a fluke thing. They eventually replaced the entire hub, but only after the 4th time the bearings failed.

I always believed the service department was top notched in helping, but had their head in the sand when they refused to acknowledge their preload issue.

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WMW
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by WMW

Preload is what kills most bearings.

Probably the most idiot proof no-preload hub design is the White Industries. Axle is totally free in the bearing races, and you use a collar with set screw (on the axle, not the end cap) to keep it all together.

Got an H3 back for a rebuild that had >30k miles on it. Ridden in rain and crap, hub never serviced, bearings were silky smooth. They use cheap bearings but large and with decent seals.
formerly rruff...

eric
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by eric

I like the White hubs a lot but the preload is not idiot proof. The preload adjustment tends to back off and it's not immediately apparent how to fix it. I've instructed a couple friends on how to set it. However when it goes out of adjustment the preload gets loose instead of tight. When this happens the hub will develop play but it wont' destroy the bearings.

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