Hi folks,
I’d like to build a new wheel based on an old one. I’ve just removed the old rim that has to be replaced - a big, old, drilled 29er KH rim. The hub is a KH Moment. I measured the spokes to be ~296mm.
So, now is the question: how does this work while UDC spoke length calculator tells they should be 287mm?
I’d like to reuse these spokes to lace my new rim - a 29 H522 DT Swiss rim - but the spokes look way too long. 
Maybe it was laced with 4 spoke crosses. You can select this in the spoke calculator and get 296mm.
Addditionally you should check the ERD of your rim.
That’s clever. I have not checked before taking the wheel apart. Here is the single picture I have of it:
@Vogelfrei80 > That’s a uni you sold me ~2 years ago. Do you remember whether you laced it with 4 crosses? 
That looks like 3 cross to me.
I’d too say that his looks like 3 cross.
Your rim is not the rim you selected on the calculator.
The KH Freeride rim you’ve selected is likely this one:
https://www.unicycle.co.uk/unicycle-parts/rims/rims/29-kris-holm-freeride-rim.html
You’d probably be best off calculating the ERD of the rim you’ve got yourself with two spokes and digital calipers if you want to use that rim again in the future.
I’ve also got one of those rims but I can’t off the top of my head remember the ERD I came up with for it.
Doing a spoke calculation with the rim you want to use, you get 289 (3 cross) or 298 (4 cross).
I’d consider that too far off to get away with. UDC UK say you can typically get away with +1 to -2mm, which fits with my experiences.
I’m not sure at all of the rim I selected, but I’m pretty sure the one you linked is the 2017 version. So my rim is either the Freeride I selected or the XC one. But none of these works with my spokes, according to UDC calculator.
Yes, it is curious that neither work, however there’s no guarantees that a) your wheel was built with the ideal length spokes in the first place, or b) the UDC spoke calculator has the correct BSD measurement for your rim.
