Spoke Lengths - + or -?

meagain

Best to round spoke lengths up or down?
Calcs give 287.4 for front and 286.8 for rear. Not sure whether to go 288 and 286 or just 286 all round?
Any views welcome!

lateralus

Sheldon says round up, and that length is not super critical:

http://sheldonbrown.com/wheelbuild.html#spokes

robbarker

Initial tensioning with the nipple driver is easier if you round up, not down. If your spokes are marginally too short, you can get into the game of nipple driving then having to back each spoke off a certain number of turns, which is a time consuming PITA. More than about 3mm too long will result in the threads bottoming out though, so get as close as you can.

Assuming you're building a conventional dished rear wheel, it's normal to have about a 2mm difference between drive and non-drive sides. This is good becasue the wheel pretty much dishes itself with initial tensioning if you get the spoke lengths right.

meagain

"Assuming you're building a conventional dished rear wheel" Nope, an old unused Campag L/F screw on respaced for 120 fixed rather than 126 geared!

My only doubt about rounding up is protruding spoke and inner tube interface - but this time I'll be using double wall rims so probably not the same issue as with old singles.

288 for front then I guess. But I think I'll go down to 286 for rear.

Thanks.

robbarker

I'd go 288 personally, particularly if you used the DT calculator which always seems to be a bit conservative.

aracer

Personally I always round down, since spoke calculators don't allow for spoke stretch, and hassle with nipple driving is a lot better than not being able to fully tension due to bottoming out.