Spoke threads - 12mm or 16mm nipple length

Unicycles and Equipment
1

Please excuse the newbie question.
I am thinking about building a 26" fatty wheel, to use in an Oregon Frame.
The hubs with spindle mounted disc brakes are offset by 18mm.
The spoke calculator has the spokes at 3mm different lengths on each side of the wheel.

My question is:

  • will a 16mm spoke nipple have the threads all the way through,
  • or will there be 10mm of threads at the bottom, and 6mm empty sleeve at the top.

I need to accommodate a 3mm difference, and want to use the 16mm threads to take up the slack between the extra width on the non disc side (100mm equivalent)
and the 64mm equivalent on the disc side (3mm shorter spokes)

Unicycle (UK) dot com have the Impulse hubs available at the moment.

2

I have heard of long nipples with more threads but the majority of the ones that I have used just had a longer smooth sleeve. The threads are at the rim end.

Unless you already have the spokes I would order two different lengths. Being 1mm off either way is perfectly fine, more than that and you start to run into problems.

Thinking about it more 3mm seems like too much of a difference between sides, maybe you should put the numbers in another calculator and see if they agree with what you already have. Remember to factor in the offset holes in the rim as well. I use freespoke which has given me accurate results in the past.

3

Thanks Jack,
I was going to get the spokes from Ebay, and the nipples from UDC.
The spokes come in packs of 36.

It might be a good idea for me to call into UDC UK when I am passing by to discuss the options (12 or 16mm).
The spoke lengths available are limited unless I get them cut down to size and re-threaded.
This will double the cost, and the build is supposed to be on a £300 budget all in, brakes and all.

I will try the freespoke calculator when the rim arrives, and I can measure the effective rim diameter and offset properly.

4

PS - I may take your advice and get 2x cheap packs of 36 spokes at the correct lengths, and only use half of them.

Or try to get the correct lengths from UDC.
36x 30p = £10.80p / or 36x 60p = £21.60p

5

Post #4 says that sapim 14mm nipples have different length of threaded section.

In one wheel of mine, I’m using 2 extra #8 brass washers under each disc-side nipple since the spokes are too long.

I have recorded 36 washers weighing 11.9g, not sure if those were brass or steel, but it’s not that much weight.

3mm is quite a bit and would need 3 or 4 extra washers, which at that point I would also go with different length spokes.

6

Oh, also, if you use 3 or more washers on the disc side, the flat section of the nipple might not stick out enough to use a spoke wrench.

7

Thanks guys.
I didn’t realise that the internal threads would bottom out on the base of the spoke threads.

My theory was:
There are 10mm of threads at the end of the spokes.
These will be located within 16mm of threads inside the longer / heavier nipples.
Which should give me 6mm of wiggle room, without resorting to washers or spacers.

I need to speak to UDC when I call in for the first batch of parts.
A £25 threading machine is making more sense at the moment to take away some of the guess work.

8

If there were 16mm of thread on a nipple, and 10mm on a spoke, you can only thread it in 10mm before it binds.

If you use a longer-threaded section nipple instead of a standard nipple:

If the spoke was too short, you’d be able to thread it on more times, but it won’t reach the nipple head.

If the spoke is too long, it’ll bottom out faster.
However, if you use a normal nipple and it bottoms out and you need ~1 more millimeter, you can use nipple washers to move the nipple further out.

Hope that helps.

9

I don’t know about UK suppliers, but you may do better ordering the number you need of the different lengths rather than buying 36 spoke lots.

The problem is that if your spokes don’t pass the shoulder of the nipple you are putting all of your faith in the nipple which is not generally a good idea. In this situation the shoulder becomes a stress riser.

All things being equal a little more spent on the outset will mean a much stronger wheel that doesn’t need as much work later on. Also, if you have the right sizes of spokes the wheel will be much easier to build.

So, as Eric said, triple check your length, and order the two different sizes. In the end you will be much happier.

10

Thank you for the advice,
The £25 wheel building package offered by UDC could be the best way forward for me.

I thought there would be a few millimetre of threads to play with.
But the 1mm tolerance at each end of a 550-ish diameter rim is less than 0.4%
Trial and error is less appealing now when the odds of success are so low.

Once the rim is ordered, I will measure up and decide which way to go.
Thanks all.