After switching from a 7-speed freehub body to a 9-speed, I need to re-dish the wheel to center it.
I need to shift it a total of 5mm towards the cassette side, and my question is this:
Can it be accomplished using the same spokes?

Yes. The tension on the drive-side spokes will be substantially higher, but it's manageable.

IMO, if the wheel is going on a steel frame, I would rebuild the hub to 135mm width and spread the frame. I've had good success with 9-speed road wheels on 135mm width hubs, less so with 130mm width.

I'd like to know more about this recommendation. I have zero issues with 10 speed hubs spaced at 130mm width. I'm even running 11 speed on one bike. Are you encountering interference with the stays or something?

To the OP, you could measure your new hub dimensions with the extra 5mm and enter into a spoke calculator to see what difference it makes to "optimal" spoke length. I'm guessing it's minimal and that you're fine with the spokes you have.

I will be contrarian, a bit concerned the result will not live long.
With more info about the spoke count, rim brand and model and hub brand and model I might be persuaded.

Probably, as long as you don't run out of available DS threads.

Brad

My first thought was that 5mm seems a lot. Spoke length is probably not an issue; run some number though a spo0ke calculator (which I haven't had a chance to do yet) and you'll probably find less than 1mm change. DS tension could be a problem however.

I concur with the sentiments of this thread. Tell us more about spoke count, hub type, and proposed flange-to-center offset for each side of the wheel. You will run into tension problems before your run into spoke length issues.

If this is on a 126mm spacing, would it even be possible? 7-sp on a 126 is already pretty heavily dished, and on the wheels I've built, there is SIGNIFICANTLY more tension on the drive-side. Making an even MORE heavily-dished wheel may bring the drive-side spoke tension up quite a bit, maybe too much.

Spacing is already 130mm, and the hub is an Exage.
My LBS guy seems to think he can get the wheel centered on the frame by tweaking the axle spacers...so I hope he is successful.
Thanks for the replies and advice!

The aluminum Shimano hub itself is the same for 7 speed and 8/9/10 speed. The axle, freehub and other assorted small parts make up the difference. If you add a 8/9/10 freehub and go from 126 to 130 OLD you will have the same amount of dish as an 8 speed wheel and they seem to hold up just fine. I've done this several times, swapped in a 8/9/10 freehub and set spacing at 130 OLD, and not had any issues. Spoke length was never a problem. I did back off all the nipples several turns and worked my way back up, balancing spoke tension and checking dish as I went.

I'm a large person (6-foot-4, 240 pounds) and my rear wheels take a beating. I'd rather be riding than maintaining wheels, but my favorite frame is aluminum and has 130mm spacing. The tension difference allows the NDS spokes to loosen over time. A similar wheel on my wife's bike but with 135mm spacing doesn't have this problem. (She's also 85 pounds lighter than me...)

If it is a 130mm wheel, then you should be fine.

I had one wheel that the nipples bottomed out when re-dishing, so I took out all the DS nipples and added two nipple washers. Easier than trying to thread and cut the spokes.