Calculating spoke length

[the_duke]

Ok guys.

I have some lovely Araya RM20 rims and some 32 hole M900 hubs.

The hubs aren't with me yet but I want to get some spokes sorted before they arrive.

Can anyone tell me what length spokes I need for a 3 cross pattern or do I need to wait for the hubs to measure etc?

Cheers in advance,

Luke

 

[dbmtb]

Bet it's 260 drive 262 non-drive and 263 front.

 

[Andy B]

try this http://lenni.info/edd/

 

[the_duke]

try this http://lenni.info/edd/

Cool cheers, it doesnt have (or I cant find!) the front hub but rear is on there. It gives me the following,

Hub: Shimano XTR FH-M900, rear
Rim: Araya RM20
Number of spokes: 32
Crosses: 3
Spoke length left: 266.6
Spoke length right: 265.3

Now spokes seem to come in 264 and 266mm!

 

[jimo746]

I just had to calculate the spoke length for some wheels I'm about to build up and IMO you're better off waiting for the hub to turn up so you can take the measurements directly from it (vernier calipers are handy).
Several websites explain what to measure & how, just follow their instructions, I measured up and then input the info into a couple of the online spoke calculators and they all came back with the same spoke length.
IMO a 1mil difference won't make a vast difference to the build eg I got the results of 263mm/264mm for my front wheel (disc-side/non-disc side) but will go for 32 x 264mm spokes.

Oh, and measure twice, order once

 

[FluffyChicken]

front hub is the same as every other Shimano front hub at the time.
So 268 for the front with 12mm nipples (use XT-II/DX)
I'd go 267 if you could.
Which reminds me, if you find any wrong measurements on that site I might be able to get them changed. (if I can find my email again)

EDIT
I remember Araya put it in their docs for a standard hub and they say 267mm
267 would be none drive side then and 265 for drive side.

http://www.araya-kk.co.jp/rim/archive/1992/09-10.htm

 

[FluffyChicken]

and as you know it's 1mm less than RM395 you can use
http://www.retrobike.co.uk/forum/viewto ... ength+book
pictures and find the RM395/XTR and well take 1mm off

 

[the_duke]

front hub is the same as every other Shimano front hub at the time.
So 268 for the front with 12mm nipples (use XT-II/DX)
I'd go 267 if you could.
Which reminds me, if you find any wrong measurements on that site I might be able to get them changed. (if I can find my email again)

EDIT
I remember Araya put it in their docs for a standard hub and they say 267mm
267 would be none drive side then and 265 for drive side.

http://www.araya-kk.co.jp/rim/archive/1992/09-10.htm

Flipping heck now I am confused, this is getting beyond my skill set. Looks like I will be shelling out for an LBS to supply spokes and build

Was hoping to at least supply the parts to save a few quid.

 

[FluffyChicken]

What's confusing about 3 halves of 267mm and 1 half of 265.
Confirmed by 3 methods (website calc, Araya's own documents and a member here little black book)

 

[dbmtb]

Was hoping to at least supply the parts to save a few quid.

I think most shops would be understanding about wanting to do a retro wheel with rims/hubs they don't sell.

But I think it would be better form to actually buy the spokes from them.

If it was me - I'd just charge a bit extra for the labour so there might be no win in it for you. And if you bring the wrong spokes then you risk having to pay double.....

Alpina spokes are available in double butted 2,0 version, in 265. If your local shop can't get them, I can - and will be buying a box of 100 shortly for my Mavic Dakar/321CD front wheel. Can sell you them for 55p a spoke plus postage.