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Evlkneevljr
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199 Posts
Discussion Starter · #1 ·
....Enough to help a brotha out? I built up a front wheel with 258mm Wheelsmith 14DB spokes, 12mm alloy nipples, Stans flow rims, and Hadley 20mm front hub. For some reason, the spokes are shorter than I think they should be (threads just barely disappear into the nipple all tensioned up - both sides). Is this safe? Anyone bored enough to check my calcs to see if I did something wrong?
 

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Evlkneevljr
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199 Posts
Discussion Starter · #3 ·
I used the one on the rim and on the site (same). I also did some snooping around the FAQ board on his site and that erd was given. I Ordered the spokes and measured those, maybe I should have done that with the rim; I just figured there was so much info saying that is the correct ERD and Mr Stan himself answering the FAQ on ERD for that rim.
 

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Registered
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Unfortunately, not all rim manufacturers measure ERD in the same manner. It is always best to measure ERD on your own, to the same point on the rim the spoke calculator you are using specifies.

Alternatively, when building with ZTR rims you can ask them what spoke length to use with your hubs.

If you want to have some fun, and not be so bored, call Stans for their spoke length recommendations for your hubs and rims, and then vary the ERD number in your spoke calculator until you get the same lengths (you may still have to do some rounding).
 

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transmitter~receiver
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9,334 Posts
There's nothing wrong with your math. My guess is that the published ERD of that rim, like every Stan's rim I've measured, is ~1.5mm too small.
Roger Musson's instructions on measuring ERD (here) follow the correct interpretation of the geometry (to the ends of the spokes threaded to the ideal spot in the nipple).
I doubt you will have a catastrophic failure of the wheel. Part of the reason there is still confusion about ERD is that spoke length is relatively tolerant of variation. A buddy of mine has a 29er wheelset with Mavic rims that, due to their ridiculous practice of reporting SSD without giving instructions on how to convert it to ERD (which their own calculator does internally) and a shop employee calculating spoke length that didn't know better, ended up with 2-3 threads showing on every nipple. ~3 years and no problems yet, though he doesn't ride his mountain bike that often or very hard.
 

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Evlkneevljr
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199 Posts
Discussion Starter · #6 ·
I guess I learned a new lesson - measure it yourself. I appreciate the info! I am also helping a friend rebuild some Sun Ringle rims with Ringle hubs. last year, when we tried to true them, they seemed to be locked up. Now that I'm pulling them apart to re-lace, I see the spokes were at the end of their threads.

I'm taking advice from both of you - it turns out the factory build on his Sun singletracks used the wrong length spoke! Sun's website has 2 ERD's for that rim, so, I measured it. The smaller one of the two was right. I called Sun and they said use the tech doc (larger of the two) because that's what the engineers put together....well looks like the engineers goofed on the doc and manufacturing has been using too long of spokes.

With my ERD measurement, it would be a 2mm shorter spoke than what they used. Looking at all the spokes all the way around, all are sticking out about 2mm beyond the nipple......Looks like I'll be taking my own measurements from now on....
 

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transmitter~receiver
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9,334 Posts
daverach2478 said:
I guess I learned a new lesson - measure it yourself.
:thumbsup:
daverach2478 said:
I'm taking advice from both of you - it turns out the factory build on his Sun singletracks used the wrong length spoke! Sun's website has 2 ERD's for that rim, so, I measured it. The smaller one of the two was right. I called Sun and they said use the tech doc (larger of the two) because that's what the engineers put together....well looks like the engineers goofed on the doc and manufacturing has been using too long of spokes.
people throw the term "engineer" around pretty liberally.
if you understand the spoke length calculation, the meaning of ERD (and thus the measurement to take) is very clear.
whoever had their hands on the spoke wrench and could see the protruding spokes should have raised a red flag.
it's a little disconcerting that a company that produces wheelsets could have this much confusion internally. :skep:
daverach2478 said:
Looks like I'll be taking my own measurements from now on....
Can't go wrong there. :thumbsup:
 
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