I have calculated my spoke lengths I need. I would appreciate is someone would confirm I've done it right.

Question I have is, based on them calculations do i round up or down the spoke in mm? Sapim only seem to do 182 and 184mm.

As we all love nipple talk, what length should i be looking at? My velocity aeroheat rim has around 3mm of metal.

Thanks,
Damo

I'd probably use 182 & 184 but would much prefer 183 & 185.

I use the 12mm nipples for just about all builds. The decision to round up or down depends on two main factors. The first is knowing the bias of the calculator program and where the spoke is projected to end in the nipple. If the bias is to the short side, or the projected spoke end is below the nipple slot, then go up. OTOH if the spoke is estimated to end above the slot, then your upside may be limited, which brings in the 2nd consideration.

The amount of possible overrun above the top of the nipple varies with spoke & nipple thread length. I use nipples with 7-8mm internal thread, which allows overrun of 2-3mm with standard 10mm spoke thread length. However some nipples have more thread length and will not allow much overrun if any at all. That would argue for rounding down.

I round down and use nipple washers, which increase ERD 1.5mm, because Lasers (1.5mm) stretch 1-2 mm.

velocity said 12mm on all there in-house builds, got a email replied.

The one I used was the spocalc on the sheldon brown website. And just used his other one and got same result.

Trippled by edd's spoke calculator.

I have no experience with these calculators, and if anyone has one they know is reliable, and which way to round it?

DT swiss calculator rounds it up and down like you would normally in maths.

Sure. Buy your rims. Put two spokes in opposite holes with nipples threaded on to your target depth. Measure across the elbows with calipers and add twice the spoke length to get ERD. Do the same 90 degrees away. If that produces a different number measure on the diagonals too and take the average of the 4 measurements.

1.5mm spokes stretch about 0.7mm at 100kgf, 1.8mm 0.5mm. Account for that.

You get about 1mm below the slot below you risk nipple breakage and 2.5mm beyond it before you run out of thread with DT 12mm nipples. Round in the safer direction.

If you observe variations in ERD between rims you might have spokes cut to the correct 1mm increment so you'll be less likely to have problems putting a new "identical" rim on in the future.

I was planning on using sapim 2mm stainless spokes, so based on your stretching figures, I should round it up and not down as it wouldn't stretch enough.

Your figures based on a 20" or a 29" wheel?

260mm spokes. Stretch in longer and shorter spokes would be proportional to length.