Determining Spoke length with DT spokes

Unicycles and Equipment
1

I’m going to be building a 24" wheel using a Nimbus 36H ISIS hub and a Halo SAS rim (ERD 488 mm). The spoke calculator on UDC gives me a spoke length of 232.27 mm for a 3-cross build. So, for example I might use a DT Champion 14 ga. spoke that is 232 mm long

But here’s my question…in the “tips” section down below the calculator it reads:

If you use DT spokes and nipples (these nipples are about half as long as normal) add 1 to 1.5mm to the calculated spoke length.

This is really confusing me because standard DT nipples are listed as 2x12mm long and standard Wheelsmith nipples are also listed as 2x12mm long…I don’t see any difference? I wanted to use DT spokes/nipples but I’m not sure if I should add 2 mm to the length (next size up is 234 mm) or not…I don’t want them to be too long!

Can anyone clear up my confusion on this “tip”?

2

It is a bit misleading

If you use the DT swis calculator (rember to halv the flange spacing as it wants a left and right from the center of the hub rather than UDC total width) you will see teh figures with the DT calc set with a 12mm nipple to be virtually identical to the UDC one.

Ignore that tip and just remember that the spoke measurement is with 12mm niples on both, and that 14mm nipples need 1 mm shorter spkes and 16mm need 2 mm shorter spokes as the threads are placed that much further out. This is handy if you can’t get teh exact spokes you need you can use longer nipples to tailor for shorter spokes.

Anotehr warning when you buy spokes with nipples they don’t allways tell you what length nipples come with them so ask don’t assume as I have been screwed over several times with that one :stuck_out_tongue:

You have a bit of spoke length play in the 10mm of nipple thread but ideally you want it as close to running out of thread as possible to maximise the number ofthread turns into the nipple for maximum strength. It is sole destroying if you bottom the spokes out before reaching your final desired tension so round down is normaly the best thing.

This is all part of the “fun” of wheel building :stuck_out_tongue:

Hope that helps

4

It helps a lot! Thanks!

6

Is known to be wrong. For DT spokes use the DT spoke calculator.
(I was successful in reverse-engineering their formula).

7

DT calculator gives 233 mm, UDC calculator gives 232 mm. I’ll round down and get the 232.

8

The DT one adjusts more accurately for spoke hole sizes etc while the UDC one is a little more simple

Normally they are both the same and only the DT swiss “corrected” length is sometimes different.

9

Yes, the DT one is targeted at DT nipples.
But NO; both use a different approach in calculating, and so not exact the same formula. They are essentially different. Play around with digits and compare to see for yourself.

Also note: BOTH are not fully 100% perfect(!).
But almost aways the DT approach is giving more accurate of fully accurate results. While I’ve seen multiple complaints about the other.

10

Fair enough I use those two and another wheel building site one (I forget which) and have yet to have any real difference in the sizes quoted, but I go for the DT measurement normally.

Dodgy thread length in nipples have caught me out before and not just with the different 12/14/16 but between the same sizes (maybe the DT nipple effect?).

The other thing I have found is a lot of places don’t ship DT nipples with their DT spokes to confuse things even more :stuck_out_tongue:

I have a mass of different size nipples and spokes through various issues and having to bulk buy odd sizes so I normally aim short so I can adjust with different nipple lengths, but even then it can still not always pan out.

The fun of wheel building :stuck_out_tongue: