nymtber

Ok, I have a wheel that came on a frame (er..bike) that I had purchased a few years ago. I bought it for the frame to put my good mountain bike parts on, as well as my good LX hub, CR-18 wheelset and mountain tires.

The bike came with some decent wheels on it, as well. Front is an LX hub laced to a Mavic 221 eyelet rim, the rear an XTR M590 laced to a WTB powerbeam rim. The problem is the powerbeam rim is worn out on the braking surface, enough so it is quite concave in profile (I work in optics...concave/convex fit into my everyday talk now...haha) and I dont want it to mess with the brake pads. I want to put some different tires (more rated for trail/path than off-road) on this spare set, so I decided to order an Alex Adventurer 32hole 26" rim and replace it myself (I have the tools needed to build a wheel). Its worth it to me to put the money into it, as that is one heck of a quality hub, no reason to let it go to waste

SO, to my main question....

I did some calculations using the "spocalc.exe" on Sheldon Brown's web page, and used the values that were in spocalc for the XTR M590 hub, and an approximate ERD of 543, according to Alex Rims. I will measure ERD myself, but for now, close enough. I will have the rim in hand next week.

I get the following values for spoke length:

Left spokes: 265.0mm
Right spokes: 263.4mm

Does that sound right, using that approx. ERD? Can I trust the measurements for my hub that come with spocalc? I have 6" digital calipers, but I figured if Sheldon would have posted it, he would trust the values...

I plan on straight 2.0 Wheelsmith silver spokes and silver brass nipples. Where is a good place to order them from, where I can order only the quantity I want? (I will likely order a few extra of each size, JUST in case someday I break one. The wheel currently has wheelsmith double butted spokes, but drive side (right side) spokes look rough, and I dont know the history of the wheel, so even if the spokes were the right side, I am tossing them. Nipples appear to be anodized alum, so they will be tossed, as well.

Sorry to make it such a long post, This will be my first wheel build, Just asking for a little help, I want to make sure I figure out things correctly before I go order/buy spokes.


Thanks guys/gals

FBinNY 

Your results are definitely in the ballpark, but I can't tell you offhand if they're exact. Different spoke calculators tend to differ by a few millimeters even with the same input data. This is probably because of slight differences in how rim ERDs are measured and a difference of opinion in how far into the head of the nipple a spoke should end.

The good news is that each calculator is consistent, so if your first calculation comes up a millimeter short, probably all of them will. For example, when I use a the old Wheelsmith calculator, I consistently come up short by 2-3mm, partly because I insist that the spoke should end between the screwdriver slot and top of the nipple. I have a bias to the longer side of the "right" length, so I add 2-3mm to every Wheelsmith length, depending on the rounding, and/or to get to the next available stock length.

The best 2 bits of advice I can offer are to stay with the same calculator so that you'll know how to tweak the answers, and to keep a wheelbuilding log, including data like calculated length, actual length used, and the "perfect" length based on the length used plus/minus and difference you'd change next time. So if you use the suggested length and come up short 3mm, you'll at least learn for next time.

nymtber

hmm, anyone else? I checked another calculator online, results were exactly the same. So, once I get a chance to actually measure ERD (IE: Rim in hand, next week) I will plug in actual numbers. I plan on following the wheel building info that is on Sheldon Brown's site. His information seems to be fairly straight forward Too bad hes not still around, one of cycling's biggest losses.

Al1943

Try it on the DT Swiss calculator. It's never let me down.
Round down on the driveside rear to account for stretch.

Al

davidad

Lace it with double butted spokes, it will make a better wheel.
If the old spokes are not cut or kinked they would be ok. Get new brass nipples. The aluminium ones are silly and weak.

Al1943

Based on what?
DT Swiss aluminum alloy nipples are all that I have used for the last 8 years with not one failure.

When was the last time you saw a brass airplane?

nymtber

I will do that. I was actually looking into where to buy spokes, and seems I can only find single quantities at Cambriabike.com, and I might end up with DT swiss spokes. Brass nipples are an absolute for me, being a clyde. I need to lose weight long before worrying about a few grams from aluminum nipples! Gonna check a few bike shops just to see what their prices are on spokes. Cambria was $0.49 each for straight gauge spokes. The current spokes are not in the best shape, too bad because they are wheelsmith spokes.

How will double butted make a better wheel than straight gauge?