Thanks Mark,
It's all good :^) I will go for 100-110Kgf'ish and see how the left side feels...
Doug Van Cleve Chandler, AZ
On 5/5/06, Mark Bulgier <Mark@bulgier.net> wrote:
>
> Hmm, no one's tackling this? Ok here goes nothin'
>
> Doug Van Cleve writes:
> > I am retensioning/truing a set of Campy high
> > flange/Nisi-Evian tubular wheels [snip] I typically shoot
> > for 110-120 KgF on the rear drive side
> > (measured with my Park tensiometer). I am not sure an older
> > rim like this is up to that, but I also want a reliable
> > wheel. What tension should I strive for? Rims/hubs are 36
> > hole, spokes are 1.8/1.6 double butted.
>
> I usually go for somewhere between "nice and tight" and "really tight".
>
> I built a few at "wow that's tight" (especially at low spoke numbers -
> say 24 or 28 in the classic era) but had some problems of cracking the
> rim around the spoke holes, usually many miles down the road.
>
> Seriously though, 36 spokes is plenty for a racing bike, so load
> carrying capacity should be adequate as long as the spokes are "sorta
> tight". Tight enough that the left side spokes (sorry, "non-drive
> side") don't loosen up in use - that's the lower boundary. Not so tight
> as to cause cracking or taco-ing*. That's a pretty wide range, between
> those extremes -- and it's easy enough to be sure you're in that happy
> land without a spoke tensiometer, in my opinion. With some practice
> anyway, and you already have that much practice and more. Yes there is
> probably some optimal tension for a given wheel, but I don't think
> reliability falls off very rapidly with tension to either side of that.
>
> The longevity of wheels built between those extremes will be determined
> more by whether the spokes were properly stress-relieved, than by the
> tension number. If you're not sure what stress-relieving means (many
> people have incorrect or incomplete notions about this), read Jobst
> Brandt's book, or at least the paragraphs that describe
> stress-relieving, I think he gets it right. It does NOT mean releasing
> the residual twist in the spokes so the wheel doesn't make springing
> noises the first you ride it. That's nice to do too, but if you aren't
> putting gloves on to stress-relieve a new wheel, you may not be doing it
> right. Squeezing spokes that hard with bare hands kinda hurts.
>
> The guy who taught me how to stress-relieve in the early 70s did it the
> Jobst way. His explanation of why we do it was wrong, but his results
> were good - just about no broken spokes. He was an old Italian dude who
> learned in Italy and just always did it that way because that's how HE
> was taught. Wasn't until I read Jobst's book that I learned WHY it
> works. Hint: it's not because the spoke "beds in" - makes that little
> groove where it exits the hole in the hub flange. That might be a small
> part of it, but the real answer is all within the metal of the spoke.
>
> Wow all those words and I didn't even answer your question. I am very
> sorry about that.
>
> Mark Bulgier
> Seattle WA USA
>
> *On the West coast, wheels taco. In the East they pretzel, and I'm told
> they potato chip in the Midwest, though I have not experienced this
> first hand. ;)