I have two rear wheels I keep swapping around on my main mountain bike
One has a wider rim, the other a faster engaging hub, Ideally I want the ‘best’ of both without too much hassle

I have (both originally merlin builds):
1 – Mavic XM719 disc (32h), DT comp, Shimano XT (6-bolt, 32h)
2 – Mavic XC717 disc (32h), ACI DB (apart from about 8 unknown ones after a partial rebuild, Hope XC (6-bolt, 32h)

What is the best way to go about getting a Hope XC hubbed XM719 rimmed wheel?
Will I need new spokes? Or will I get away with using the old ones? And which set of spokes will fit? if any? Is it the hub that determines spoke length? the rim? or both?

Should I send it to a shop to do?

Or should I have a go at loosely putting them together, and getting a shop to tension it up properly? In which case do I tape the ‘new’ rim to the ‘old’ wheel and swap spokes to the ‘new’ rim (so the ‘old’ hub eventually is worked onto the ‘new’ rim).
Will the wheel dishing not be out somewhat?

Or, in the long term, would I be better off having a shimano hub rather than a no-longer made hope one, albeit quicker engaging (I think 22 engagement points/rotation on the hope, 15 engagement points/revolution on the shimano)
I’ve not really had either that long, ie not long enough to replace the hope bearings, or either freehub, so I don’t really know if theres anything major that makes one lesser than the other in the long term

assuming both wheels are 3 cross, then its probable that the 719/XT has 255mm and 256mm spokes, and the 717/Hope has 262mm spokes. The hope in a 719 will need 257mm.

The pitch circle diameter of the hope is just that bit smaller than the XT.

I would say that your 255mm and 256mm spokes will be too short overall. Others might suggest you have a go and just leave some thread showing. I’d buy a box of 257mm myself.

Hmm, so not so straightforward then

So, what about the rebuilding of the now ‘outcast’ wheel, the XT/XC717 combo? It’d be useful on my spare/second bike, given the freehub on that is almost dead (a X139-N/comp disk? wheel (off of a 2003 marin)

So would the probable 262mm spokes work with the XC717 disc and XT hub? Or will they protrude too far, poking into the rimstrip?

the remaining “bastard” wheelbuild would now need 260mm and 261mm.

TBH if the rim profile is deep enough and you make sure you use a good cloth rim tape just in case, I reckon you might be OK reusing the 262mm and hope that you have enough thread, but again some people may more or less picky than me.

I built a wheel that should have needed 293 and 295 and I used 294 without any problems.

“and hope that you have enough thread”

Ah yes, I hadn’t thought about the spokes not having enough thread on them for the larger hub