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So built my first 29 wheel last weekend, using a park tools tension meter I normally try to get to around 18-20 on the gauge which seems to work well for the last 3 26 wheelsets I've built. For this build it gets really difficult to tighten past 15 without getting close to rounding the nipples.
Initially I thought I might be running out of thread but that's not the case, which made me think, does the gauge read the same on longer spokes? Is there more flex in a longer spoke therefore it will read lower and will be more difficult to tighten to the same reading as a shorter spoke? Should I stop worrying and just ride the wheel and see how it feels flex wise?
(And yep I know to distress the spokes when tightening the wheel)
I,m sure some of the engineer types can explain it better!
Sounds about right
The tool provides three points of contact with the spoke so it's measuring flex between two set points. Length of the spoke doesn't matter. However, diameter of the spoke does. What gauge are they? Are you comparing apples to oranges or apples to apples?
Also, don't take the numbers on the park tool as an absolute. Calibration is often way off. I use one for building but I gauge it against a known good wheel and then use it check balance and consistency. For a 1.8mm round spoke, I know mine is right when spokes on the high tension side are 25 +/- 0.25. It works for my park tool, but your may be different.
They are rev spokes, thinking about I think the last lot were comps so not tapered. Agree the tool may not be calibrated well but still useful for relative tension. Even if not calibrated perfect it should always be out by the same amount per spoke I would have thought. 15 seems very low though. Any other ideas? I can use a bit more brute force, but I've already got a blister from using the spoke key and the spokes make that creaking sound when tightened
Actually he sounds right! Revs are narrower so they will flex more at the same tension.
Maybe even by the ratio of their respective guages.
Just ride them as is
The size of the wheel makes no difference but the spoke cross-section does.
You need to have a look at this table from Park:
The Rev is only 1.5mm whereas the Comp is 1.8mm
From the table you can see that for 100kg of force on the spoke the Park Tensiometer will show about 16 for the Revs and about 20 for the Comps. Pretty much where you're at now.
Ah that makes sense I had taken into account the spoke is narrower. Thanks guys.
Now I just want dry day to test them