Dave S wrote:
: Last night, I built a new rear wheel for cross riding using a Record
: 36 hole hubs, a Ritchey OCR Comp rim (called Trekking on web site) and
: DT 14/15 spokes.

: In doing the research, I noticed that Ritchey's web site gave the ERD
: as 596 mm whereas Damon Rinard's Spocalc gave it as 605 mm. Perhaps
: Ritchey has redesigned the rims?

: At any rate, I called Ritchey and the rep talked to a wheel builder
: who gave the ERD 599. Hmm... Right between the two values...

: I plugged the 599 value in Spocalc and built the wheel using 290's on
: the left and 288's on the right. At this point, I've tensioned them
: to 70 kg on the left and 115 on the right.

: On inspection, I noticed that the left side as 2-3 threads exposed all
: around whereas the right side has 5-6 threads exposed. I'm comcerned
: that the spokes are too short and I don't have enough threads embedded
: in the brass nipples.

I also had less than ideal results with an OCR rim. I just built a wheel
with a Ritchey Aero Road OCR rim that spocalc lists as 606mm, and I ended
up with about 1mm protruding out the back end of the nipples. Looking at
spocalc again, it has in parentheses "ERD is nipple contact dia + 3mm for
nipples". Does that comment mean I needed to make some adjustment to the
numbers before plugging them into the calculator? I know I had the right
hub dimensions, because I verified them calipers. Anyone have a good
technique for measuring ERD?

- mark