Wheel building Q – spoke calcs for rims with offset holes

Bear with me – I’ve got a history of ordering the wrong spokes, so I’m half asking, half thinking aloud.

I’m building on a Stans Hugo. Holes are 5mm either side of centre. I’ve been reading about offset rims and it seems the issue is confused because there’s 2 types of offset – there’s the holes being drilled either side of a centre line, and holes drilled either side of an off-centre line. Or even 3 – frames built offset to match wheels built with equal spoke tensions but unsymmetrical hub measurements.

Stans Hugos are offset 5mm either side of centre, which, as far as I can think, has the same effect as reducing the centre – flange distances by the same amount. Assuming the spokes go from the hub to nearest set of holes in the rim?

Spoke calcs with the actual centre to flange measurements give 264.8mm and 266.4mm. Calcs with actuals minus 5mm give 264.5 and 265.9. So it doesn’t really matter anyway.

As long as the bit in bold is correct?

I always go with the DT Swiss spoke calculator and never had a problem, either with offset spoke bed or 0 offset. You don’t say what spoke pattern you’re building (I’m reading in iPhone in middle of dog walk so may have missed it), but if you’re building straight pull the DT calculator allows you to enter an offset value.

[edited due to uncertainty creeping in]

It’s all triangles with the calculations so it may well be that shortening the flange to hub centre measurement will have the same effect as entering the offset. Spokecalc allows you to enter an offset in any event I think?

but I don’t know which offset they’re asking for – the centre of rim to the mid-line of spoke holes (for non-symmetrical patterns), or the spoke holes to centre line (for symmetrical patterns).

I suppose it’s easy enough to find out. hang on…

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Edit: it’s for asymmetric rims. Is on the Wheelpro one anyway. This is what the summary underneath the calcs says if you put “5” in the offset box:

Hub diameters Left = 56 Right = 54
Flange distance Left = 20 (25) Right = 33 (28)

Calcs use an amended flange distance – in brackets. One increased, the other decreased.

I took off 5mm for each hub flange distance, built up perfectly at the weekend. Though bugger all difference in spoke length – just put me into round up/round down decisions where I wasn’t before.

Most pleasurable wheel building experience I’ve ever had (7th go at it). No frustrations, went through the steps quickly and easily. 😀

Probably made easier by the stiffness of the rim (there was some necessary wobble correction, though) and maybe the fact that it resonates better – the different tones which come out when you pluck (natural, 3rds 5ths etc) were a lot easier to distinguish than I remember from last time. Although last time I was trying to have an argument at the same time!