I’m building a new pair of wheels for my cross bike using Superstar hubs & DT Swiss rims. I’ve done the spoke calcs and for the front wheel they came out at 289.2 left and 290.5 right. I’m using Sapim Race spokes which are only available in 2mm increments so I went for 290mm. I’ve laced up the front wheel and, having equal length spokes, the dish is way out – probably about 10mm.

My question is, am I likely to be able to take that much dish out or should I replace the disc rotor side spokes with 288mm ?

Just take your time with the dish and it will come right.
10mm seems a lot but if you have very little tension on it will all come good.
As a rough rule, i would get the dish about right which would bring on a bit of tension, then focus on the hoop a little, then the true, all the time you are bringing the tension on. the repeat.

For the record faced with the spoke lengths you have i would have gone for 290mm. but don’t check your nipple length (insert joke)
A lot of calculators use 12mm and CRC only sell 14mm, that trips a few people up.

If it’s not upto tension yet just add 2 turns to the disk side and see if it moves over, keep going untill either the threads bottom out or the spokes poke through far enough to cause punctures. If it is upto tension then add a turn/remove a turn on each side.

I’d always round down anyway, spokes (normal double butted 1.8mm spokes) stretch about 2mm as you tension them

I’ve only laced it up so far and not actually put any tension in to the spokes. Having read the appropriate section in Roger Musson’s about dish, I’m not so bothered now. Having thought about it, using equal length spokes on a disc front hub will always produce a big dish offset. Good job I re-read it cos he advises to remove the dish error before starting to tension.

I’m sure it will all come out in the wash. Thanks for the advice people.

you’ll be fine.