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I've been reading up on building my first set of wheels, and a lot of discussion here is on how different calcs (and different people on the same calculator) are getting different lengths for spokes for the same hub/rim combo. Seems to be endless conversation about 1mm differences. 5mm I can see, but 1?

I just removed a junk rim from a CK hub, the spokes had at least 3mm sticking out past the head of the nipple, each and every one. The wheel was straight and true, and served well till a broken derailleur trashed a couple spokes. If the wheelbuilder had calculated "correctly" he would've gone with 2-3mm shorter spokes all around and had 0-1mm past the nipple for "ideal" length.

With 2mm shorter spokes:
1-Would the wheel have been any stronger? (can't see how)
2-would he have run the risk of the spokes being too short? (possibly)
3-would that add noticeable weight? (I think not.)

What I'm trying to figure out, is do I need to have precisely sized spokes, or just pretty damned close?

I have a pair of CK ISO hubs to build, not decided on rims yet.
 

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Chris Bling
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2,594 Posts
Most spoke companies do not offer every single length of spoke. For example, Sapim offers certain spokes in even lengths only and others in odd lengths only. You have to use your judgement and previous experience to know what the particular spoke calculator is actually telling you. If a spoke calculator give me the lengths I need at 291 and 293 (lets say only even lengths are available), I am going to go with 290 and 292. At least with me, I find if I go with the shorter length it usually end up working out well.

That being said, don't jump from one calculator to the next and so forth. Stick with one and get familiar with it.

In answer to your questions above:
1. I believe it would have. There were hardly any spoke threads in contact with the nipple threads if they really were 3mm above the top of the nipple

2. No

3. No

And finally, you need to have close lengths. Dont underestimate by 2mm's but dont overestimate by 2mm's.
 

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~ B A D A S S ~
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3,238 Posts
I've been reading up on building my first set of wheels, and a lot of discussion here is on how different calcs (and different people on the same calculator) are getting different lengths for spokes for the same hub/rim combo. Seems to be endless conversation about 1mm differences. 5mm I can see, but 1?

I just removed a junk rim from a CK hub, the spokes had at least 3mm sticking out past the head of the nipple, each and every one. The wheel was straight and true, and served well till a broken derailleur trashed a couple spokes. If the wheelbuilder had calculated "correctly" he would've gone with 2-3mm shorter spokes all around and had 0-1mm past the nipple for "ideal" length.

With 2mm shorter spokes:
1-Would the wheel have been any stronger? (can't see how)
2-would he have run the risk of the spokes being too short? (possibly)
3-would that add noticeable weight? (I think not.)

What I'm trying to figure out, is do I need to have precisely sized spokes, or just pretty damned close?

I have a pair of CK ISO hubs to build, not decided on rims yet.
I used Spoke length calculator for wheel building (click rims for how to construct a rim measuring device), also the "help" section is worth reading.

I set my nipples so they were at the bottom of the little cutout, secured the threads with teflon thread tape, and after buildup the rim compression and spoke stretch gave me a spoke that ended flush with the cutout kinda. I used dt comps on 26 inch dt rims.

Post 5 is good here too for the lacing bit imho http://forums.mtbr.com/wheels-tires/wheelbuilding-resources-517093.html

Also read mike t's build guide.
 

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~ B A D A S S ~
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3,238 Posts
What i meant to say is that I used the measuring devices from that site, measured and filed the spokes to the 0,01mm of the longest even mm i could get them. Sat the nipples so the spokes were at the bottom of the slot, used the exact same nipples I intended to use on the build.

Measured my rim diameter (average) and then calculated everything with the calulator from that site. And the result was that the spokes ends were flush with the top of the nipples/nipples slot when torqued to max torque for the rims. And it was my first build!

I used molycoat on the nipple seats and in the threads if anyone is interested. I had no pinging or spoke windup. It was messy though.

I can really recommend the park tool tensiometer, it was really helpful.
 
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