There’s a bit of joke in the online forums, that if you think you know better than the “little japanese guy that designed your bike”, “you should not be here asking questions”. I keep running into this. Those guys know/knew their stuff. I didn’t know what butted spokes were…
But let me back up a bit. I’ve got two rear wheels with missing spokes, and James has been giving me the gears about wobbly wheels. That said, I haven’t tried to true them, they don’t look far out when I spin them on the bike.
No big deal, a spoke can’t cost much, get one from the dealer.!? The dealer only sells the whole set of 36. $100 US for the 400E spokes, $60 for the S, $80 for the SM, plus exchange, plus shipping or dealer markup.
But there are places (e.g. buchananspokes.com) that make spokes and will sell you whatever you want… and there is the catch.
Take the 400SM, as far as I can tell, it has 4 different types of spokes in it, longer ones on the sprocket side, and 4mm (8 gauge) spokes that are in tension on braking, and 3.6mm (9 gauge) spokes for the ones under tension on accelleration. Buchanan lists different bend angles and different “throats” for the long (7/16 throat, 24 degree bend) and short (3/8 through, 30 degree bent)… but they’re just offering me the thicker spokes.
The 400S appears to be the simplest, straight 4mm spokes, 7 1/2″ rotor side, 7 5/8″ sprocket side. Buchanan’s description adds a 26 degree bend, and 0.320″ (8.2mm) round body nipples.
The 400E (and kickstart) are the same as the 400S, but using double butted spokes to save weight (8/9 gauge). This means the spokes are 3.6mm for most of their length, and 4mm at the ends.
The sprocket side spokes are longer because the wheels are dished toward the rotor side. For the SM wheels, you basically add dish until the rotor side of the hub is in-line with the rotor. For the 400E wheel, it appeared to be about 1/2″ off center. I didn’t lay it out accurately, but there was 60mm from the face of the sprocket, and 28 (?) from the face of the rotor. Now the sprocket is thicker than the rotor, and measurements should be coming off the hub, but there is no way the sprocket is 22mm thicker, so most of that difference is in the dishing of the wheel.
And then of course there are the wheel spacers. The “400E” I got for cheap is a real frankenstein, with KTM wheels and a 19″ rear rim… and the spacers seem a tich wide. Fortunately I seem to be close to getting a metal working lathe running, so I should be able to make my own spacers and possibly other things.