First wheelbuild

[531colin]

With a straight rim, using a tension gauge (and a little experience) I expect to get tension variation down to 5%.

[phil parker]

Since I've been using a tension gauge (for about 6 years, now) I build my wheels in a slightly different manner in that once I've got some 'tension' in the spokes I have a quick check all around to eliminate any 'rogue' spokes (too low or too high tension) before I start to true. This almost certainly prevents uneven spoke tensions later on in the build.

Not that I suffered with that before, but I had to be more careful on how quickly I tensioned the spokes from slack doing it a step at a time. Whereas now I can use the electric screwdriver in two stages: down to one spoke thread at the base of the nipple; top of the spoke level with the screwdriver slot.

As Colin mentions: the key is having a 'true' rim to start off with - if you're correcting any considerable blemishes in the rim, you may have uneven spoke tensions in places, if not, I would expect the tensions to be within 5% which is far less than you can ascertain by 'feel'.

[Brucey]

re the musical note thing; despite the reams that have been written about this there are a few things that you need to know in a concise form. (skip to point 5 if you like...)

1. The pitch depends on length. 10% longer means 10% lower frequency.

2. The note depends (to a good approximation) on stress per unit area in the spoke, not tension per se. Thus if you believe that the stress in the spoke is more important that the absolute tension value, for spokes of the same length you can set the pitch the same for thin spokes as thick ones. Otherwise for constant tension, thin spokes need to be set to a higher note than thicker ones.

3. Frequency depends on the square root of tension (but spoke crossings muddy the issue considerably).

4. Musical notes are logarithmic in nature vs pitch, i.e. adjacent notes vary by a fixed percentage (a gnat's under 6%) from one another. An octave is a doubling of frequency.

5. If 3 and 4 (or indeed all the above) seem confusing don't worry. The bottom line is this; if you make the note the same as a similar known good wheel, it'll be fine. For uniformity purposes, a whole tone of note variation (like adjacent keys on a piano keyboard) is worth a little over 12% tension variation. Thus a semitone of note variation is about 6% variation in tension value, which would be a wheel with very uniform tension.

cheers

[531colin]

re the musical note thing; despite the reams that have been written about this there are a few things that you need to know in a concise form. (skip to point 5 if you like...)

1. The pitch depends on length. 10% longer means 10% lower frequency.

2. The note depends (to a good approximation) on stress per unit area in the spoke, not tension per se. Thus if you believe that the stress in the spoke is more important that the absolute tension value, for spokes of the same length you can set the pitch the same for thin spokes as thick ones. Otherwise for constant tension, thin spokes need to be set to a higher note than thicker ones.

3. Frequency depends on the square root of tension (but spoke crossings muddy the issue considerably).

4. Musical notes are logarithmic in nature vs pitch, i.e. adjacent notes vary by a fixed percentage (a gnat's under 6%) from one another. An octave is a doubling of frequency.

5. If 3 and 4 (or indeed all the above) seem confusing don't worry. The bottom line is this; if you make the note the same as a similar known good wheel, it'll be fine. For uniformity purposes, a whole tone of note variation (like adjacent keys on a piano keyboard) is worth a little over 12% tension variation. Thus a semitone of note variation is about 6% variation in tension value, which would be a wheel with very uniform tension.

cheers

As a young man I used to be jealous of people who could do things like this........despite repeated outbreaks of "Victor Meldrew syndrome" I am amused to find that to some extent, in some way, I must have mellowed a bit, because these days instead of being jealous I simply enjoy it.....like watching a buzzard catch a thermal.
So thanks for that, Brucey, its another miserable day, and I should be Polyfiller-ing the walls.....you gave me a bit of sunshine!

[Brucey]

So thanks for that, Brucey, its another miserable day, and I should be Polyfiller-ing the walls.....you gave me a bit of sunshine!

ah, I've done some good then....

If it is any consolation, it took a lot longer to figure all this out than it did to write it all down or then to read it; I started re-reading John Allen's article in the HPVA archives, and whilst it is fair enough (give or take) it isn't all that much use to anyone wanting a quick pointer on how to build a wheel with roughly the right spoke tension, or to ensure a uniform spoke tension.

My hope is that point #5 does this reasonably well, in a succinct fashion.

cheers