I've taken apart my old rear wheel as it's time for a rebuild.

I'm going to buy some DT Swiss spokes, but unsure of the length I need 264mm or 262mm!

I've measured my old spokes (drive side and non drive side are the same length), which I think are actually 263. Where do you measure from? Is it from the top of the eyelet or the centre of the eyelet to the threaded end?

Or is 2mm not going to make any difference???

Any help greatly appreciated.

try spoke calculator

although 1mm is unlikley to make a huge difference either way 2 might mean you run out of thread on the spoke.

It's measured from the center of the eyelet, and unless the originals were too short or too long, 1mm either side is not a huge deal. I would go for the longer size if the original spokes were not protruding out of the nipples; if the old spokes were protruding, I would opt for the shorter ones. You should also consider whether your new spokes might come with longer nipples (e.g., CRC only sell 14mm nipples with DT Swiss spokes, but most commonly used nipple size is 12mm, and the extra 2mm could be a problem if you get spokes that are too long). All in all, you might want verify your choice with the DT Swisss spoke length calculator before order.

why not nip down to your local lbs

they'll have onme of those park rulers with the spoke hole that will allow you to measure the length correctly and then they can sell you some spokes

http://www.wheelpro.co.uk has a great calculator and if you know rim / hun combo does 99 % of the work too

simples

why rebuild?