mainstreetexile 

I'm planning to replace the spokes on an existing wheelset I have that has had some strange spoke rust / breaking issues. This is my first time buying bulk spokes and replacing the spokes on an entire wheel, and I'm looking for some confirmation on the right spoke length before I place an order.

I used the Edd spoke calculator, which already had the specs for my hubs (Shimano M590) and rims (Mavic XC717). The rims are double wall. The calculator suggests the following:

Front wheel: 264.7mm
Rear wheel: L 264.4mm / R 262.6mm

For simplifying things, would it be reasonable to just buy a load of 264mm spokes for these?

Are there any concerns replacing DT plain gauge J bend 14g spokes with the equivalent spokes from Sapim, or are the bends where they leave the hub pretty standard?

SkyDog75

Since you've already got the wheelset, why not remove some spokes and measure them? There's no way to be more certain than that.

(Getting it right) > (Convenience)

You really don't want them too long or too short, and there's not much wiggle room. I'd personally recommend ordering as precisely as you can.

No concerns at all. You can use DT, Sapim, Wheelsmith, or whatever floats your boat. I've used Sapim for my last few wheels because Dan's Comp sells 'em at great prices. 14g stainless, including brass nipple, for a quarter each. Double butted, including brass nipple for 40 cents each. Cut to the exact length you specify, and in the quantity you need. The only catch, if you can call it that, is that they don't take spoke orders online so you need to phone in the order.

Drew Eckhardt 

No. Depending on your rims (there's some variation in ERD) and how some one else measured the values being used by your calculator (to the nipple slot or top) you may run out of threads on the rear drive side.

Usually you have about 1.5mm of thread left between the top of the nipple and the spoke bottoming and the slot is 1mm deep. 264mm spokes are 1.4mm longer than your calculator calls for on the rear drive side. If the person determining ERD measured with spokes at the nipple tops you'll probably run out of threads. If they aimed for the slot but your rim has a ERD 2mm smaller than expected (they replaced worn extrusion dies or otherwise changed things) you'll probably run out of threads.

Measure your existing spokes, adjust if they're long or short, and order replacements.

FBinNY 

You have a wheel with spokes. The SIMPLEST and MOST ACCURATE way to determine spoke length is look at them noting where they end with respect to the top of the nipple. Make a note of what you'd need to add or subtract to have the end between the slot depth and top of the nipple.

Now loosen and remove a sample spoke from each flange, measure it -- from the inside of the elbow to the end -- and add or subtract the adjustment, and you know EXACTLY the length(s) you'll need.

Andrew R Stewart 

After removing a spoke from each location (ft, rear lh and rear rh) to actually measure the lengths (and note where in the nipple the OEM spokes are then alter lengths as needed to have the new spokes end up where you want in the nipple), I'll add the unmentioned aspect of rim condition.


Reinstall the measured spokes to the full tension (pluck the others around and match the measured ones). Then go around each wheel and reduce the tensions evenly, a nipple turn at a time, until there's no tension left but the rim isn't flopping around on the spokes. Now the rim will attain whatever shape it naturally is. Spin the wheel and watch the rim for how round and flat it is. One hopes that the stresses of real life haven't flat spotted or bent the rim from the round and true shape it should have left it's factory with.


If the rim is nice and round and straight then go ahead and relace with new spokes with the confidence that the new spokes won't have to prod the rim into a shape you expect it to be. If the rim has flat portions, wiggles to the sides then rethink your choice as the wheel will end up with unevenly tensioned spokes as a result of their having to push and pull the rim into a round and flat shape. Andy.

FBinNY 

Andy makes a good point about checking the rim before you commit to rebuilding it. But, I think he got distracted and has the cart before the horse.

So BEFORE removing spokes to measure, asses the rim for alignment (spin it), and note whether the spokes all seem to come to similat heights within the nipples.

If the rim is reasonably true and the spokes similar in height, you're in like Flynn, and by doing this first, saved your some unneeded work.

Retro Grouch 

Yeah, and if the wheel is old enough to have produced "spoke rust," check the track where the brake shoes rub. If it feels concave, I wouldn't reuse the rim.

Also, Dan's Comp should pay me a commission. Sapin spokes, cut to the lengths you specify in the exact quantity you need. They are both quick and cheap too.

davidad

Since you are replacing them go with double butted spokes. Always makes for a stronger wheel.

SkyDog75

I understand and generally agree with the thinking, but there are a few exceptions to the rule. Some rims were actually made with concave brake tracks, like the Arayas on my daughter's '91 Bianchi Advantage. They're similar to the RM-17 shown HERE on Araya's web site.

dabac

If there is a considerable advantage to using a slightly long spoke its possible to add a washer to the nipple to kinda stretch the ERD a little.
Or to drill out a few turns of thread in the nipple to allow for more overshoot.

mainstreetexile 

Excellent advice, thanks everyone!

I"ll remove an existing spoke from each group to measure, check how the untensioned rims look, and order different size spokes as necessary.

Re: the spoke rust, the wheels are only a few years old, but I was having problems with the spokes breaking in unusual spots, and noticed some rust on some of the spokes. Not sure if it was a low/high tension issue that fatigued and caused cracks in the spokes letting rust in, or if it was some sort of manufacturing issue with the (DT) spokes that allowed rust to form.

They're not particularly high end hubs or rims, but the rims still look like they're in good shape so I figured I'd try buying spokes and rebuilding them for fun, practice, and to see if I can get some more use out of them.

I had seen the good deals on spokes at danscomp, and the low price was part of the reason I was thinking about buying new spokes and rebuilding them in the first place, glad to hear other people have had good experiences with them as a retailer.