How do you measure tension with Sapim Xrays?

[Kontact]

I normally use DT Aerolites for builds, but have a Sapim build to do. But no one has a conversion to make my DT or Wheelsmith tensiometers useful, and Sapim doesn't make a tensiometers for its spokes.

One has only to look at the DT manual to see that spoke shape has a huge impact on how tension is read on a tensiometer. How are other pro wheelbuilders measuring tension?

Really appreciate any help or guidance. We've called most of the usual suspects already, and have a few more to try today, but it isn't looking good. It's hard to believe Sapim could have the rep it does with people just guessing the tension.

[GregL]

http://www.parktool.com/blog/repair-help/wheel-tension-measurement

About halfway down the page, it references the CX-Ray. With this info, perhaps you can derive a conversion for your DT or Wheelsmith tensiometer.

- Greg

[echelon_john]

CX-Ray is 2.1mm x 1mm

on the Park tensionometer, for 2.1x1mm:

12=89
13=98
14=108
15=119
16=133
17=148
18=165

[Kontact]

The problem then becomes converting the Park chart into useful numbers by comparing it to the DT chart, which they only have the DT New Aero in common.

At least we could buy the Park tool. The only weirdness is that the DT CxRays measure 10% different than what Park says they measure, which isn't very reassuring.

Thanks for the idea, guys.

[echelon_john]

on the park chart, the range for those numbers is 2.0-2.2mm x 1mm, so you should be in the ballpark.

[ergott]

The FSA tensiomenter doesn't use a conversion chart. I find the readouts far more consistent than the Park I replaced.

http://wheelfanatyk.blogspot.com/2008/04/tension-gauge-in-news.html

[Kontact]

The FSA tensiomenter doesn't use a conversion chart. I find the readouts far more consistent than the Park I replaced.

http://wheelfanatyk.blogspot.com/2008/04/tension-gauge-in-news.html

Does it come with the deflection to tension conversion for CX-Rays?

[Kontact]

.....

[oldpotatoe]

.....

Use DT

[Kontact]

Use DT

We are building prototype wheels for a large supplier for testing at different tensions. The customer gets what they want on a contract like this, and since it is also R&D, we need repeatable tension data to make it worthwhile.

But if it wasn't for that we could use DT, or zinc plated Huffy spokes. Lots of possibilities.