I don't have firm numbers off the top of my head - but I'd bet you want to go about 10-20% less than on a modern rim. Really isn't so much less when you realize that if doing a build with older parts you probably are going for 5 or 6sp - which implies that the non-drive side due to less dish on it will end up with more tension on it than doing a 8,9,10sp build.
When you've built a bunch of wheels, you will start to recognize the "witching point" of a rim - the tension at which the rim starts being quite naughty (where just a slight change in the tension of a couple of spokes can really cause the rim to move all over the place). If you get to that point, you've got to back off the overall tension of the wheel.
Some older rims can be more fussy too. I've seen some strong yet brittle rims such as Fiamme ergals actually blow apart from too much tension - such rims will crack at the eyelets if you tension them as you would a modern rim.
In general, uniform tension is more important than the actual tension. Within reason. Go way too low and ugly things can happen.
In the old days folks weren't using tensionometers like they do know (I did know of folks in the day who would pluck the spokes to check for uniformity of pitch). In general, building 5-6sp wheels is a let easier than building modern high-dish wheels. But using the current techniques on older parts generally is quite useful.
Use of the tensionometer really is quite helpful. Unlike those who doubt the system, I've found that it really is possible to use the tensionometer to more equally distrubute the wheel's tension. Sure, you may not be able to get it perfectly even, but you can get close. And yes, you can make tension uniform without it - the number of increadible wheels built by folks on this list without a tensionometer or spoke prep is probably in the tens of thousands. But for someone getting into it, the tensionometer is quite helpful (and is helpful for the best wheelbuilders too in many cases).
Spoke prep is also another area where using the modern methods is helpful. The wheelsmith stuff is great but a tad time intensive. Linseed oil works really well as a substitute, but read the warning lable on the container regarding spontaneous combustion of rags soaked in the stuff.
And finally, double butted spokes are generally always better than straight guage. Straight guage can work fine, but double butted spokes seem to be more spring-like which is good. But as a trick, you can use straight guage on drive side rears and double butted on the non-drive side rear. That takes stress off the drive side! Of course, the best is to use a lighter double butted spoke on the non-drive and a heavier butted on the drive. Not at all necessary for old wheels, but this trick works wonders on off topic modern high-dish stuff.
Anyway, have fun! In reality you can build wheels all sorts of ways and have great results. Look at all my babbling on this and I'm just one opinion.
Mike Kone in Boulder CO
> Ahoy !
\r?\n>
\r?\n> I am of the understanding that rim manufacturers state recommended spoke
\r?\n> tension. Easy enough for current production - pick up the telephone, poke-out
\r?\n> an e-mail to the tech. dept.
\r?\n> Ah, but how does the CR Lister determine this type of recommended/optimal/safe
\r?\n> spoke tension ? No Signor Fiamme nor Monsieur Super Champion to contact.
\r?\n>
\r?\n> Alloy rim, steel rim, tubulare, clincher, galvanized, stainless, straight
\r?\n> gauge, butted - the head spins.
\r?\n>
\r?\n> I am a novice at the Right and Proper technique of wheel building and, as
\r?\n> such, I am observing "textbook" instructions and recommendations as part of a
\r?\n> training regime. Need the rules to condition sensibility.
\r?\n>
\r?\n> Thank you
\r?\n>
\r?\n> Richard Cielec
\r?\n> Chicago, Illinois; U.S.A.
\r?\n>
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\r?\n> ---------------------------------
\r?\n> Get your own web address for just $1.99/1st yr. We'll help. Yahoo! Small
\r?\n> Business.