Odd spoke sizes - move up or down in size?

[VK2GOM]

Hi all,

I have calculated the spoke sizes required for my new Mavic / Hope 2 rear wheel build for a 3x crossing lacing, they are 259mm left, 258.2mm right.

Now the snag - it seems I can only obtain spokes here in Oz in even sizes, so it's 258mm or 260mm.

Any advice on mixing 258 (for the 258.2) and 260 (for the 259), or do them all in 258 or do them all in 260 and hope the extra 1.8mm on the right side won't cause problems? I see the places I've found that will sell you spokes are in packs to suit, eg. 32 all of one size.

Tempting just to throw the rim and hub into a bike shop and have them build it for me and examine their result before I hand over the dollars

Any musings welcome.

Cheers - Rob

 

[Ryder321]

I'm not sure if this is true or not but i think you can just twist the hub more, so the spokes come out on different angle. but i don't think it would work in your situation due to them being different from what they should be on each side. I don't know much about building rims but i would probably just get the shop to do it.

 

[125PHIL]

i would run 258, and 260 if i was lacing my own wheels, but when in doubt when it lands on a odd number i generally round up, you get a bit of adjustment out of the nipples.

cheers

 

[b_S]

I'd buy 258 for both sides, and if you need longer (highly doubt it) then run longer nipples on that side.
Have always found inaccuracies in spokes calculators anyway, be prepared to buy new spokes regardless

 

[VK2GOM]

Thanks for the info guys. Roger Musson's wheelbuild book says don't worry about +/- 1mm, but my engineering background wants to get it right! I think I'll try and get hold of 16 at 258, and 16 at 260 and see how I go.

Cheers - Rob

 

[F1234K]

From my experience what you choose to do here will only effect how much you have to correct the dishing later.

Generally when I build a wheel I tension all the spokes the same amount to start with (most likely just so you don't see any more thread on the spokes).

From this point your dishing will be out slightly but you cannot correct that yet till you have gotten most of the trueing done (since the wheel will be too wonky still).

Once the trueing is done you will find if you choose 258 for both that the side that wanted 259 will be pulling more and you will need to tighten the other side to compensate.

The opposite is true if you choose 258 and 260 since you now have a little more on the 260 side and it will be pulling to the 258 side and you will need to tighten the 260 side a bit more.

1mm isn't a big deal and almost all wheels built out there will have had this same issue.

In your case I would go 258 both sides for the following reason:
the diff from 258.2 to 258 is 0.2mm. The diff from 259 to either 258 or 260 is 1mm, BUT you are loosing 0.2mm on the right side. So by going to 260 you create a difference of 1.2mm. Going to 258 you create a difference of 0.8mm.

I would go with 258 both sides because the difference is smaller and you will need to do less dishing later...

my 2 cents

 

[b_S]

Number nerding aside, from my vague experience with Pro2 hubs the rear builds to be fairly evenly dished on both sides - many (most?) newer rear disc hubs do so going for even spoke length is a good start.

And yeah, what you said is very valid too

 

[spiderman]

I agree totally with F1234K...... Build the wheel with 258mm....your thread length on the spoke is usually adequate to compensate for 3-4mm of measurement error and even if the spokes are too long and stick out the nipple approx a mm you can file them off so you don't get any punctures. you will still have plenty of thread in the nipple.....

I have built many a wheel where the spoke calc has made and error..

Best thing is to tell you LBS what hub and rim you have ...ask them to calculate the spoke length and then if it is wrong hit them up for the right length...then its not your fault