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I'm currently building my first wheel and I've used prowheelbuilder.com to calculate what spokes I need to use, which is Left 275.8, Right 275.7 for the rear wheel, and Left and Right 275 for the front.

Would it be possible for me to use 272mm spokes since the shop that I'm buying the spokes from doesn't have a 275mm?

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    Go to a different shop.
    – MaplePanda
    Sep 7, 2021 at 3:56
  • Is that a yes or a no? I've tried asking other shops nearby but they don't sell spokes...
    – Ego
    Sep 7, 2021 at 4:02
  • I personally tried 3 different calculations, and I cut a wire to the same length and compared that with other bike wheels I had access to. You should consider double-checking your results with at least one other - that difference in rears feels a little small, unless you have a fancy hub.
    – Criggie
    Sep 7, 2021 at 6:28
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    Order online. Not Amazon or Aliexpress, but one of the several stores that specialize in bicycles.
    – ojs
    Sep 7, 2021 at 6:55
  • Thank you for the advices and I'll double check it on other wheel calculator and buying it from online shop.
    – Ego
    Sep 7, 2021 at 8:20

2 Answers 2

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I personally would be uncomfortable with spokes that are that far out. In a pinch, one shorter spoke with less thread engagement might be fine, but you're talking about all spokes on both wheels.

If your shop had 276mm spokes, that might be a better option, especially if your rim is deeper profile and the rim-tape doesn't touch the nipples.

Any good bike shop would have spokes in 2mm increments. That they don't suggests supply lines are difficult, and they don't have access to a spoke roller to hand-make spokes.

Try some other suppliers for the right length (once you've double checked the maths.) Spokes are expensive - you don't want to get the wrong length.

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  • Thank You Very Much and I think the shop I'm buying from sells a 276mm.
    – Ego
    Sep 7, 2021 at 8:22
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    That sounds like a bike shop that stocks a few spokes for odd repairs. A bike shop with a more regular wheel builder will stock more sizes, cut as required, or order in the right size for the build. These days you can easily mail order online to 2mm (or even 1mm) increments, though I'd seriously consider 276mm for everything for simplicity
    – Chris H
    Sep 7, 2021 at 11:10
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    Current DTs let the spokes poke out above the nipple by about 1-2mm. Some spoke/nipple combinations run out of thread at the top of the nipple. 276 will indeed probably work, but if you have the raw formula spitting out 275.00 and then you want to give it around 0.7mm for elongation/compression (which is about the safe amount for a 2.0/1.8), it's very possible for 276 to have you flirting with running out of threaded length once that wheel is approaching final tension. The limiting factor with rounding up is usually running of threaded length, not the point where the spoke pokes the tube. Sep 7, 2021 at 19:03
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    @NathanKnutson fair enough. I rounded up by 0.8 or 0.9 mm on my last build and had ore than enough, but that sort of amount is comparable to the tolerance in ERD
    – Chris H
    Sep 8, 2021 at 7:49
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This calculator purports itself to be based on the pure classic formula without fudging in any correction for spoke elongation or rim compression, as many online spoke calculators do. If the numbers input were accurate, here would be my verdict: short by 3mm is in the realm where you may get some threads showing with 12mm nipples and shouldn't do it with aluminum nipples because that's where you really want optimal thread engagement. Best would be go to 16mm brass nipples if you can stand it; they drop the start of the thread down a little and your thread engagement should be pretty good with them.

I will note that calculators of this sort where you choose the parts and trust their dimensions are really a leap of faith, particularly with rim measurements. I'm a firm believer in measuring the rim firsthand and doing it with the nipples you're going to use for that build. A measurement taken this way is what the classic formula expects to have plugged into it.

If you round up to 276, only do so with extreme prejudice against the risk of running out of threaded length once you're nearing final tension, because that can happen and then you will have to either start again or accept a sub-par result.

All the 270-276 lengths are mainstays of the 650b/27.5 era. In case it's unclear, they're all common lengths and a shop not having them suggests either simply being out or being a shop that doesn't really build wheels. If local availability is the challenge, I highly recommend just buying them online by the each or getting the Sapim 20-packs.

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