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I understand how and why tire pressure causes circumferential rim compression and resultant reduction in spoke tension, but I was surprised to learn how much.
I just built a wheel with a 32h PowerTap SL+ hub and Velocity A23 rim, 2x with DT Comps and brass nipples. This is a fairly light rim (435g) and I weigh 180 lb, so I didn't want to go too high on the max spoke tension. However, due to the flange spacing, the tension ratio is pretty poor. I'm running a Hutchinson Intensive Tubeless tire, now, but may also run a 28mm slick or 33mm cross tire on it.
I greased the spoke holes in the rim and used WS Spoke Prep on the threads. I stress-relieve by squeezing parallel spokes, and remove any windup by pushing down on the rim with the wheel laying on its side. Using a Park Tensiometer, I started with about 125-130 kgf DS tension, and had some NDS spokes loosen on the first ride (55miles with 4,500' of climbing).
After re-tensioning/balancing, and measuring a few spokes, I currently get the following aproximate tensions:
At 20psi: 125kgf DS, 70kgf NDS
At 90psi: 100kgf DS, 60kgf NDS
If I continue to have NDS spokes loosen, I may increase the tension some more, or try some Loctite on the NDS nipples. Lacing the DS radial or 1x heads in, and OSB rim, or lighter NDS spokes might have helped, Any other observations or suggestions?
I just built a wheel with a 32h PowerTap SL+ hub and Velocity A23 rim, 2x with DT Comps and brass nipples. This is a fairly light rim (435g) and I weigh 180 lb, so I didn't want to go too high on the max spoke tension. However, due to the flange spacing, the tension ratio is pretty poor. I'm running a Hutchinson Intensive Tubeless tire, now, but may also run a 28mm slick or 33mm cross tire on it.
I greased the spoke holes in the rim and used WS Spoke Prep on the threads. I stress-relieve by squeezing parallel spokes, and remove any windup by pushing down on the rim with the wheel laying on its side. Using a Park Tensiometer, I started with about 125-130 kgf DS tension, and had some NDS spokes loosen on the first ride (55miles with 4,500' of climbing).
After re-tensioning/balancing, and measuring a few spokes, I currently get the following aproximate tensions:
At 20psi: 125kgf DS, 70kgf NDS
At 90psi: 100kgf DS, 60kgf NDS
If I continue to have NDS spokes loosen, I may increase the tension some more, or try some Loctite on the NDS nipples. Lacing the DS radial or 1x heads in, and OSB rim, or lighter NDS spokes might have helped, Any other observations or suggestions?