Spoke length query

step83

Building a wheel for the bike as you do. Spoke lengths have me confused though. Worked out I need 260mm for the non drive side and 259mm for the drive side.
Would I be best off getting 260's for the drive side rather than going down to 258s?.

cooldad

Yes. But 1mm is unlikely to make any difference one way of the other.

The Rookie

Well 259 could be anywhere between 258.5 (use 258mm) and 259.49 (use 260mm)... If you use the DTSwiss calculator it tells you what spoke length to buy anyway!

step83

Exact numbers came out as
Left spoke length: 260.3
Right spoke length: 259.3

Thats using a 3 cross lacing. I initially ordered a pile of 260mm spokes which going by my maths were right. May just build it up using 260's an see what happens worst case ill have to re lace the right/drive side with 258's if they wont tighten down.

The Rookie

I'd use 260's for both those nominal lengths anyway.

cycleclinic

I always round down. You might get away with rounding up but you risk getting some spoke wind up which is av
oided with sapim race or dt comps by having the right spoke lengths. Also dishing the wheel is alot easier.

The Rookie

None of the wheel building guides I've read suggest always rounding down....

cycleclinic

I dont do guides i do what my experience tells me works. Rounding up has always caused more problems than rounding down, today for example i had spoke length for the ds rear of 279.8mm. I was using cx rays and rounded to 280mm. One spoke ran out of thread and started To twist. It was o.k. as the twist started to happen at full tension but still its annoying. rounding down to 278mm is what i will try next time. Ideally 279 and 285mm would have been the lengths i would have used expect cx rays are not imported in those lengths so i tried 280 amd 284mm And it worked just. Morral is i should listen to my own advise!

Rounding down is generally better than rounding up If you want to avoid running out of threads. what you have to account for is spoke stretch when under tension even sapim race stretch abit which you notice if you squeeze pairs of spoke hard you get a significant tension drop. Round down if you can. If you cant only round up by 0.2mM. Sapim race spokes in silver come in mm lengths from 257mm to 266mm so no problem there.

I hope that explains it.

The Rookie

For it to run out of thread at .2mm long the calculation was wrong in the first place, simple.

Also says you were economical with the truth when you said you always round down!

I trust guides written by those who appear consistent and know what they are doing than someone's experienced who has clearly got something wrong and is inconsistent in what they say.

step83

I built them fine on 260's once id corrected the spoke layout. Like Rookie said, every guide ive read says to round up even speaking to a wheel builder at my LBS he said the same thing its within a millimetre which is liveable.
Built it up fine, dished nicely too just needs some tensioning and a bit of truing up. Surprisingly found it very relaxing to do.

SonDa5

What spoke are you going to use? Hub front or rear? HUB make and model?

ugo.santalucia

The Rookie wrote:

I'd use 260's for both those nominal lengths anyway.

+1