I ruined the rim from my rear wheel and have just got hold of a replcaement rim. Am i ok to use the spokes from the old wheel build or should I get new spokes? (both rims are dt 4.2ds)

if they're quality spokes with no visible damage and yo trusted the original build, it should be okay.

i've re-used spokes in the past and built perfectly fine wheels. It's more faff though.

And… you may find it a PITA to undo the nipples on the current wheel – if they're old/well used wheels, the nipples may be seized onto the spoke… solution – cut the spoke…

I've re-used spokes many times with no problems. If the nipples have seized a bit of WD-40 or similar normally gets them moving.

If you are replacing a like for like rim, then the best way is to place the new rim next to the old one, wrap some tape around them at 3 or 4 points, then just transfer over the nipples and spokes one by one to the new rim – saves having to lace the spokes or anything. Easy 😀 just down to tensioning then.

Cheers guys. Well I decided to reuse them. Wheel now laced but I think it may go to the LBS for tensioning and truing (plus for them to check my lacing 🙂 )

have a go yourself. If you're not too sure, get the wheelpro book. Last set of wheels I had shop built, I checked with a park guage. Drive side tension varied from 17 to 23! When I did it myself, it ranged from 23-24

Guess which one will remain true the longest.

Ditto – do it yourself – it's easy really – just use (for example) the Sheldon Brown guide

http://www.sheldonbrown.com/wheelbuild.html