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snottyotter
@M_V
How does everyone measure erd?
I've been using two spokes with nipples screwed down hard on the threads and cut at 200mm from the nipple shoulder. (Insert the spokes in opposing holes and measure the gap or overlap and add that to or subtract it from 400mm to get the erd)
This seems to work, I'm usually pretty happy with where the spoke ends end up once the wheel is built up.
I saw another method recently where you take a full spoke of known length, put two of them in opposing holes on the rim and screw nipples down to where you'd want them to end up and then use a caliper to measure between the bends as per this image and add that to 2 x the spoke length,
I tried my usual way tonight and got 600mm then this other way and got 606mm, 6mm difference on a 700c rim. Would equate to a 2-3mm difference in spoke length!
I kind of like my way because I'm measuring the actual spoke bed where the shoulder of the nipple is going to sit.
I've seen lots of people saying round down on spoke lengths in this thread which isn't what I do. I've kinda thought I rounded up because I was paranoid about having spokes too short and nipples snapping and figured that since I pretty much never built single wall rims then if it was a choice between too short or too long then too long was the better way to go but I guess it works better with my method of measurement too.
@arup you mentioned that you've written your own calculator, does it apply any sort of correction to account for you not wanting the spoke to actually end at the nipple seat or do you just account for it with your measurement method? Does that even make sense?