Regaring possible damage to hubs caused by chopping out fully-tensioned spokes, Sheldon Brown wrote:
I don't believe this is a real-world problem. I have never known of any hub being damaged by this.
Sheldon "Chopper" Brown
Sheldon,
This is really a tough one to gauge. I think we can agree that rims can be damaged by cutting down fully -tensioned spokes, but I also think it can cause problems for hubs. I say this because I have had three hubs fail at the flange, and as I recall at least two of these failures came right after the wheel was rebuilt. I see two possible reasons that the failure may not have been a direct result of cutting the spokes:
1) The damage came as a result of overtensioning the new build. 2) The damage came as a result of the cut-down process, but only because the old build was wildly over-tensioned.
The first two flange failures I had were on the frot and rear of a pair of Miche hubs. They were pretty soft and the flanges just bulged out. Back when I was using those hubs, I tended to overtension my wheels. I would pull in all the high spots to get the wheel round, with little attention to the ever-increasing tension. I figured tighter was better. I got better after a little practice. The later failure was on a Record hub, a great big crack. At that point I knew how to build wheels, and I got the tension to a reasonable level. On that wheel, I had cut the hub from an old wheel, and it was possibly quite tight. In any event, when I called Campy to get a warranty replacement, the first thing the guy asked is how I removed the hub from the old wheel. Maybe it was just one of their ways of avoiding giving out new hubs, but I found it interesting that he asked this question. After that, I was not a chopper.... on my own wheels. In the shop, it would depend on the available time, the quality of the hub, existing spoke tension, etc.
Tom Dalton Bethlehem, PA, USA
Sheldon Brown <CaptBike@sheldonbrown.com> wrote:
Tom Dalton wrote:
> At least in a shop setting, this practice is frowned upon because
>it takes more time. It's hard enough to get people to pay a fair
>price for wheel builds, and I suspect that the whole "never reuse
>spokes" thing was started by shops that had no interest in trying to
>pry another ten bucks out of a customer for the time required to
>unthread all the spokes. Even if this time is paid for, once it is
>done there are still so many problems. If the spokes are old an
>fatigued and one breaks in the first 1,000 miles it will be "the
>shop's fault." If the spokes are the wrong length for the new rim
>you need to call the customer with disappointing news. Or, maybe
>they were the wrong length to begin with, but the kid doing the
>service writing is clueless about the whole matter.
That's all correct.
I'll add that it's also possible that sometime in the past a spoke or two may have broken and been replaced. The replacement spoke might be a slightly different length than the original. That could cause significant hassles in building up the wheel.
Also, it's not unusual for old wheels to have frozen or damaged
nipples. It's just a big potential hassle, too big to deal with at
shop labor rates.
> ...In fact, proper disassembly of a wheel requires letting out the
>tension evenly, maybe a half turn at a time, all the way around.
>Only at that point should you cut away the old spokes, and by then
>it's not much harder to completely unscrew the nipples (particularly
>if you use an electric drill). Unfortunatley, many (most?) shop
>mechanics take the quick route by cutting down fully tensioned
>wheels. This really puts a lot of stress on the hub flange...
I don't believe this is a real-world problem. I have never known of any hub being damaged by this.
Sheldon "Chopper" Brown +-------------------------------------------------------+ | Le beau est aussi utile que l'utile --Victor Hugo | | (The beautiful is as useful as the useful) | +-------------------------------------------------------+ -- Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com Useful articles about bicycles and cycling http://sheldonbrown.com
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