Wheelbuilding / Wheel Building / Wheel build help

Rounding up by 3mm?
😅😅😅😅😅😅😅😅

No.

You'll probably find one side is ok and one side is about 2mm too long.

some other online folk suggest elsewhere that spoke length doesn't have to be suuuuuuper accurate.

It's true, you can nearly always get away with ±1mm 🙂

Maybe you can get away with it, but if for whatever reason the calculator is 1-2mm off you may find yourself with spokes 5mm bigger in one side.

Cool, thanks for the kind replies 😎

I’d recommend doing your own measurements (definitely for ERD, but also hubs if there is any doubt) and using this.

Genuinely thank you for that second link Svendsvin. That’s a short spoke Nirvana! 🙏🏻

Thanks! Now we're talking... that calculator says 260.5 and 261.5 due to factoring in the rim thickness (which spocalc doesn't seem to). so maybe these cheap DT competitions in 261 are gonna be ok after all. Think I'm gonna risk it. They're so cheap I'd only lose time.

I'm struggling with excessively imbalanced spoke tension. How imbalanced should they be for a modern rear wheel?

Rim: 24h Light Bicycle R35 (35mm carbon rim)
Hub: Bitex RAR9 rear w/ 11sp freehub
Spokes: Sapim D-Light - DS: 272mm, NDS: 278mm
Two cross

DS spoke tension: Quite high indeed, only slight movement with squeezed, average note of C above middle C when plucked
NDS spoke tension: Quite low, does move a lot when squeezed, average note of middle C

Dishing is still off, needs to go still 4mm+ towards DS.

I do feel slightly silly quoting musical spoke pitches on this thread... time to buy a spoke tension meter?

could it be that your spoke calculations were a little off and the DS spokes are too short? I put your specs in a spoke calc. and the lenghts it provided were: NDS 279mm and DS 275mm... and 3 mm are a massive difference in spoke lenght

Nice of you to have a go at my spoke calcs! What was the calculator that you used? I used the Sapim spoke calc.

Oh I should have said it's a 2 cross wheel, but you must have already guessed that.

aah good that u say it, what is your spoke count? I did calc it with the standard 32 holes, so I wouln't trust my above numbers too much.
I used this german site: https://speichenrechner.de/index.php

24h, should have mentioned. I have edited my post with that info now.

I measured the hub carefully with calipers and the ERD with a tape measure, and even the rim bed thickness with the prong on the calipers.

How imbalanced should they be for a modern rear wheel?

The tension ratio for a wheel with the same number of spokes each side is the ratio between the flange offsets from the spoke holes, i.e. after allowing for offset or stagger. On a non-offset rim to a road rear, that can easily be 2:1, which would give a frequency difference of half an octave since frequency is a function of the square root of tension.

could it be that your spoke calculations were a little off and the DS spokes are too short

Spoke lengths won't affect the spoke tension as long as the spokes are threaded into the nipples and haven't bottomed out.

How imbalanced should they be for a modern rear wheel?

Very imbalanced, hence 2:1 triplet lacing patterns. It's not unusual for the NDS spokes to be only 60% of the tension of the DS spokes with the same lacing patterns on both sides and the same spokes. You don't really have all that many options - the wheel needs to be dished properly, and once that's done the spoke tensions are what they are.

ok, with your updated numbers, I calced DS 272 mm and NDS 277mm , only 1 mm diff. to your NDS spokes , so the spokes seem to be okay... looking at the hardware, we have a nonsymmetrical hub with different flanges, DS is heavily dished and the NDS is less dished... I think the design and combined parts add themselves up to create this difference....

@gbj_tester you beauty

The rim is non-offset. The spoke holes are not staggered.

The flange offsets from the spoke holes are 16.2 mm (DS) and 37.8 mm (NDS). That's a ratio of 2.33, i.e. DS spokes should be at 2.33x the tension of NDS spokes.
Square root of 2.33 is 1.53. Therefore DS spokes should ring at 1.53x the frequency of NDS spokes. But they currently ring at twice the frequency (an octave higher) and need to go higher still to correct the dishing.

So I think I've confirmed that something is going wrong (possibly incorrect spoke lengths?). What shall I change?

@HK_Berlin and @Brommers thanks for your inputs also.

I should perhaps just get the thing dished properly and see what tensions I end up with. Am I likely to break something in the process though?

I might be looking at a 16:8 hub if this doesn't work.

You'll also get better ERD measurements using a couple of spokes with nipples threaded to where you want them to end, through opposite spoke holes on the rim and measuring the gap between them, ideally in a couple of places.

So I think I've confirmed that something is going wrong (possibly incorrect spoke lengths?).

Spoke lengths won't alter spoke tension. Build it up so the DS spokes are tight, and the NDS are tight enough to centre the rim. After that, there's nothing else you can do without changing parts. And there's no reason why those parts can't be built into a functioning wheel.

there's no reason why those parts can't be built into a functioning wheel.

Although it would have been better to have started with the 8/16 version 🙂

Definitely a lesson learned there.

So if I just correct this dishing and my DS tension is then >4x my NDS tension.... firey death?

Are you using a tensionmeter?

Edit: ah just read you aren’t, sorry. I’d like to know roughly what tension you’re building each side to that’s why I asked.

if I just correct this dishing and my DS tension is then >4x my NDS tension...

It won't be, the geometry cannot be gamed. As you wind on the DS to move the rim to the right, the length of the NDS spokes necessarily grows, and since they're made of rubber, that means their tension rises even though you haven't turned the nipples.