Spoke Length
 

This is probably a long shot, but I'll ask anyway...

I was having some trouble with my back wheel going out of true every time I rode it, so I rebuilt it with double butted spokes for more tension, and it's working out perfectly.

My issue now is that I had to buy two boxes of 100 spokes, so I've got 168 spokes sitting on my bench feeling unloved. I thought it'd be cool to get some more hubs and rims and build a couple of spares (plus it'd be good practice).

Problem: I can't find the same hub except on a complete wheel. I suppose if I was serious, I'd buy the whole wheel and rebuild it with the double butted spokes, but I'm not that hardcore.

Finally to my question: does anyone know of a reverse-spoke-length-calculator? Something that could suggest a hub/rim combination for the length of spokes I have. Or should I just forget about it and buy more spokes...

Dont understand why you bought a box when u can buy just the number of spokes u need plus 2 just in case.

What size are the spokes u bought?? that could help.

http://www.mrrabbit.net/wheelsbyflemingapplications.php

Grab the spreadsheet...

You can use it in reverse...

=8-)

To my knowledge, there aren't reverse spoke calculators. but this might help. Spoke length changes by 1/2 the change difference in ERD. The hub calculation is different, and more complex, and depends on the amount of cross, so take a shot at what looks like a potential rim, then try a few flange diameters, and get a sense of how spoke length changes relative to the hub diameters for any cross.

Don't worry about flange to center measures, they change only about 1mm for every 10mm. When you get rim and hub you think will work, you'll recalculate the spoke length with each dimension accurately entered as a double check.

Also, if you find a combination that requires a spoke length about 2mm or 4mm shorter, you can build them up with 14mm or 16mm nipples (respectively). Barring that, just sell the leftovers on ebay and order exact quantities of spokes (Wheebuilder.com, Cambria Bike, Alchemy Bike Works, etc.) next time.

Thanks for the help guys. I think I'll just hold on to them in case I need spares later
(I'm a pack rat like that) and just start a fresh with the new wheels.

I didn't realize I could buy individual spokes. I took the spokes I had down to my LBS so I could be sure of getting the right lengths, and they'd only order them for me by the box. Now that I'm more familiar with the process, I think I'll use those websites you pointed out. Cheers!

Tgy... I would not come back to that LBS if they got you spokes by the box only.

Note that sometimes, I order spokes by the 100 box. See huskybicycles.com and how their Taiwanese stainless spokes 14g sell for just 23 cents each in the 100 box. And UCP spokes? Even cheaper. And my recent experience has been okay with these. So buying by the box isn't always bad. But that works best if you have lots of similar wheels/rims/hubs to maintain and build.

Funny how they are charged the same per piece in Taiwan regardless whether it is 254, 270, 282, or 292...yet they charge differently - to make an extra buck off someone they know is building a Velocity DeepV on a track hub.

Not very honest and straight-up...and if the picture is actually that of the spoke - that's a 7.0mm elbow that'll snap no matter how much tension is used whether thin steel flange or basic alloy hub.

I'm charged at the latest .0750 apiece for a 14g spoke in lengths of 200mm to 310mm - and I do not vary my wholesale or retail price likewise unless I cut and thread again.

=8-)

So why does the 7mm elbow fail? What is the reason? How much stress must you apply for it to fail? And how different is the fatigue stress at the elbow if it's just 6.2 mm or 7mm at the elbow? And why wouldn't proper tensioning alleviate and cold-set the spoke heads correctly to relieve the stress prior to cyclic loading and thus reduce long term fatigue? I don't disagree with prevailing theories on spoke line and elbow radius, but I believe it's a second order effect that is far smaller when compared to quality of steel and forging process to make the spoke.

But the price is attractive. Not many places offer that low of a cost for spokes.

1. Grab an alloy hub with standard 3.2mm flanges.
2. Grab a 14g spoke with a 7.0mm elbow. (Use calipers to enclose the spoke from the outside of the shank to the outermost face of the mushroom.)

- Some people will measure elbows differently such as inside of shank to face of mushroom...

3. Stick that in the hub and note the unsupported portion of the elbow that sticks out before the spoke transitions to a rim...
4. Do the same with a 6.2 or 6.3mm.
5. Grab an old DT with a 6.1mm elbow.

Then visualize what happens when torque is applied - and released - during the cyclic use of the wheel. What will happen irregardless of tension to the portion of spoke elbow that exists the flange BEFORE transitioning to the rim?

Also note how the 7.0mm elbows and heads rests in the flange holes in abuilt wheel. What stands out?

Assuming you are a retailer - you can get 14g stainless uncut for .18 apiece /w nipple and .23 apiece cut to length - right here in San Jose, CA.

..33 apiece if not.

=8-)

What kind of hub? Most of the Shimano hubs, for example, have similar dimensions.

That does bring up an interesting point. I have the ability to work through a local bike shop and buy spokes at wholesale prices. It's generally more economical for me however, to buy just the quantity that I need on the internet at retail prices.

Basic alloy hubs come with 3.2mm thick flanges...most Shimanos, Joytech's, Quandos, etc.

6.2mm elbows on 14g spokes are intended for those flanges thicknesses...

=8-)

Mrrabbit:

23 cent a piece cut to order in SJ? Cool! I'm game. No, I'm not a retailer. Just an enthusiast who donates a lot of time and personal money fixing bikes for bikes for local school kids, scouts, etc.

As for the visualization of 7.1mm coming out of a spoke hole and flexing, that would be an effect at the elbow point just where it exits the hole, and only if the stress and flex were plastic and not elastic. A properly tensioned wheel, neither too tight nor too loose, should never see fatigue stress because the deformation is all elastic. Yes, the bumps and thumps can shock it, but also it can relieve stress at the head. Which is why I say I agree with the premise that somewhere between 5.9 and 6.something is a good length for most spoke flanges. But think this is a second order effect. The cause of pre-mature spoke failure within, say a month or two of casual riding, and not after 2000km, is due more to cheap metal and the forging processes used by that company to bend the spokes that may be breaking the mushroom heads, which is where I'm seeing almost all my failures. I haven't seen any fail at the elbow on my wheels.

But don't get me wrong - if you know a supplier of 6.3mm offset spokes... I'm all for more ideal spokes at the same or lower costs!