Dramatically different spoke tension with tire on and off rim?
I’am measuring spoke tension with a Park TM-1. With the tire and tube off the rim the average spoke tension reads around an average 22 degree deflection which is around 111 (kgf). All of the spokes fall well within the 20 percent variation. The wheel is also true both laterally, vertically as well as dished properly. When I put the wheel together and pump up the tube (100 psi) the average spoke tension changes dramatically. The average is now around a 18-19 deflection which is around 72-80 (kgf) (Most of the spokes are still tensioned proportionally the same but, one of the spokes is reading around a 15 degree deflection which is around 54 (kgf)). Is this normal?
Rebuild of lightly used rim. New spokes and hub, Original rim. I have put around 30 miles on this wheel before noticing this.
I have also been looking for the proper tension for a Matrix IS0 C-II rim, but since no luck so far I’am using what I think was the original tension 110- 115 (kgf). Since this rim does not have eyelets I wouldn’t think the tension should be any more than this?
3 Cross spoke pattern
Matrix IS0 C-II 700C 13mm internal dimension, So should fit 18-25 (Sheldon Browns Guide)
Shimano HB 5501 Front Hub
Spokes stainless steel 14 gage 2.0mm -1.8mm -2.0mm
Tire WBT Camino sport Casing 23/20 700C steel bead (Rated to 100 psi)
Tube continental Race 700