Buying spokes

Now that I've got my spoke sizes (266 mm and 268 mm).  It's time to look at buying.  I'm looking for stainless steel spokes (in silver) that are double butted with an elbow.  The standard (according again to Musson's book) is 2 mm - 1.8 mm - 2 mm.

Web sites for searching on spokes are a mess.  You've got to be careful about names, sizing, and whether it comes with nipples.  For example, the DT Swiss Competition seems to be the standard double butted stainless steel spoke in their line - but it is available in several configurations, including straight pull, 2.0/1.8/2.0 and 2.0/1.5/2.0 - and of course in black or silver (looks like some other colors as well. To make matters worse some vendors use the SWG (standard wire gage) measure and call these 14/15/14.  And that's not all, some vendors leave off the 3rd number, so when you see 2.0/1.8 (or 14/15) you cannot tell if the spoke is actually double butted or single butted without clicking on the item.  Sometimes you see these written as 2.0/1.8 DB.  I've found that virtually all the DT Swiss Competition spokes listed as 2.0/1.8 are actually the double butted (perhaps they don't make a single butted spoke).

I looked also Sapim spokes - their standard is the Sapim Race double butted (2.0/1.8/2.0).  Their lightweight spoke is the Sapim Laser, which has a 1.5 mm center section.  My thought is that the narrow center is probably too light for touring.

Pricing is all over the place - depending on packaging.  Bought as singles, the DT Swiss spokes tend to be in the range of $1.00 to $1.30 (with nipples).  Best deals are in boxes of 100 (or 72), which seem to get you down to about $0.75 per spoke. All the better deals seem to be without nipples. At their cheapest (a box of 100), brass nipples seem to run about $0.12 each - so you've got to factor that into the cheaper spokes.

Here's some of the deals
Outside Outfitters
- DT Swiss Competition Box of 100 with nipples at $0.82 each.
- Wheelsmith bag of 50 without nipples at $0.74 each + 0.12 per nipple = $0.84 each

Thor USA
- Sapim without nipples $0.50 each + 0.10 per nipple = 0.60 each

The Thor looks like the best deal - but shipping is $10, so for 80 spokes I'm adding another $0.125 per spoke to get a total of $0.725 including nipples (delivered).  I've bought 40 of 266 mm and 40 of 268 mm along with 80 Sapim 12 mm silver nipples.

UPDATE (April 13,2016)
Working on the 2nd bike.  ThorUSA is still the best deal.

Spoke size

Effective Rim Diameter
I created a measuring device for Effective Rim Diameter (ERD) following Roger Musson's book. The only thing I didn't do was glue/crimp one of the nipples onto one of the spokes.  If you glue/crimp then your elastic bands must be able to fit through the holes in the rim.  The bungee cord that I used was a bit thick, so I had to screw both nipples on/off for each measurement, which doubles the uncertainty associated with adjusting the nipple on only one end. I took 5 measurements on each rim.

Measurements for the first rim: 148 , 148, 149, 149, 149 mm; average = 148.6 mm

For the second rim: 148, 149, 149, 149, 148 mm; average = 148.6 mm.

Adding the 400 mm for the two spokes in the measuring device and we get an ERD of 548.6 mm, which is within my measurement precision of the official ERD of 549 mm (see http://sun-ringle.com/wp-content/uploads/2012/10/SUN_website_rim_chart_2012.pdf )

Front hub dimensions
The web site for Shimano has the following data on the HB-M8000 front hub (http://bike.shimano.com/content/sac-bike/en/home/components11/mountain/deore-xt-m8000/hb-m8000.html)

• Axle length 100 mm
• Axle diameter 14 mm
• Center to Flange Right 41 mm
• Center to Flange Left  44 mm

I checked the measurement between opposite holes on the flange. The distance between opposite spoke holes on the brake side of the hub is 44 mm, whereas the similar measurement on the non-break side is 41 mm, so this appears to be what they are calling the "Center to Flange" distances (which seems odd to me).  Measuring the hub using the nomenclature on Musson, pg 56 - with the brake side being A and the gear side B.

• A = 44 mm (left brake side)
• B = 41 mm
• F = 53.6 mm
• Z + Z = 99.6  so  Z = 49.8
• X = 29 mm
• Y = 16.5 mm
• C = Z - X = 20.8 mm
• D = Z - Y = 33.3 mm

However, with the above C+D = 54.1, which is 0.5 mm longer than F (the flange to flange measurement). Given my set of calipers, the measured F is likely correct, but the X and Y are likely too short.  If we distribute the error with 0.3 mm on X and 0.2 mm on Y, we have the modified set

• A = 44 mm (left brake side)
• B = 41 mm
• X = 29.3 mm
• Y = 16.7 mm
• C = Z - X = 20.5 mm
• D = Z - Y = 33.1 mm

And C + D = 53.6 mm = F, which is what we wanted.

Going to the spoke calculator at http://www.wheelpro.co.uk/spokecalc/ , and here's the result

So for a 3-cross (which is my plan), I need 16 spokes that are 266 mm and 16 spokes that are 268 mm (or 267 mm) for the front wheel.

Now for the rear wheel.

Rear hub dimensions
The web site for Shimano has the following data on the FH-M8000 rear hub
http://bike.shimano.com/content/sac-bike/en/home/mtb1/wheels---hubs/rear-hubs/fh-m8000.html

• Axle length 146 mm
• Axle diameter 15 mm
• Center to Flange Right 45 mm
• Center to Flange Left  44 mm

Taking measurements - here my measuring gage couldn't reach then entire Z+Z length, so I've used a ruler for this measurement

• A = 44 mm (left brake side)
• B = 45 mm (right gear side)
• F = 50.0 mm
• Z + Z = 135 mm  so  Z = 67.5 mm
• X = 35.5 mm
• Y = 48.5 mm
• C = Z - X = 32 mm
• D = Z - Y = 19 mm

So we have C+D = 51, which is 1 mm to large from the F measurement. Splitting the difference on both X and Y provides

• A = 44 mm (left brake side)
• B = 45 mm (right gear side)
• F = 50.0 mm
• Z + Z = 135 mm  so  Z = 67.5 mm
• X = 36 mm
• Y = 49 mm
• C = Z - X = 31.5 mm
• D = Z - Y = 18.5 mm

which gives us C+D = 50 mm = F.

So back to the spoke computer:

Again doing a 3 cross, I'll need 16 spokes of 267 mm (or 268 mm) and 16 spokes of 266 mm for the rear.

Buying plan:

• 32 x 266 mm spokes
• 32 x 268 mm (or 267 mm) spokes

Let's make it an even 40 of each so that I have spares.

UPDATE (April 13, 2016):
I bought Sun RhynoLite rims, which are a little bit wider as I decided I wanted 1.75" tires on my touring bike, and will use the 1.5" tires on my spouse's.  The online ERD for the RhynoLite is 549 mm, which checks against my measurements.  I'm going with the same hubs, so everything is pretty much the same as above and I can use the same spokes as on the CR18 rims.