Originally Posted by
El Cid
.. ... I don't even know what those numbers mean...
Originally Posted by
El Cid
.. ..The Surly website says that my rim is compatible with 32 hole hubs..
Means your rims have 32 spoke nipple holes.
Originally Posted by
El Cid
..The SRAM hub has a QR......
QR AKA q/r is short for quick-release, as opposed to a nutted axle. The axle is short, not protruding through the dropouts and hollow to take a skewer with an acorn nut at one end and a lever at the other.
Originally Posted by
El Cid
..and a 100mm o.l.d. .....
O.L.D. = Over-Locknut-Distance. this is how wide your fork needs to be between the inside faces of the dropouts/fork ends.
Originally Posted by
El Cid
..they appear to be the same on both hubs. .....
Not all of them.
According to here:
Spoke Calculation Info | Spews | The Information Hole | Surly Bikes
your current front hub has a 58 mm flange diameter on both sides.
This MIGHT be misleading.
It's listed under "spoke calculation info", but the relevant fact would be the hub's spoke hole circle diameter.
Maybe Surly are calling spoke hole circle diameter for flange diameter, I can't tell from here.
What's obvious is that Sp-Dynamo doesn't, they list something they call "spoke P.C.D." AND flange diameter.
And comparing the two, it's quite obvious which is which.
Either way, the SP has one side 52 and the other 58 mm, so even if Surly's posted "flange diameter" is their spoke circle diameter, you still won't be able to reuse half your spokes.
Maybe if you do different number of crosses. If your current is 58 mm@3X, you might have enough spoke to do 52mm@2X.
Then there is center-to-flange.
SP use a symmetric 25 mm while Surly use a lopsided 22.5 and 32 mm. This isn't as important as the 52/58 mm though.