Round spoke length up?

Everything about building wheels, glueing tubs, etc.
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Joined: Wed Feb 18, 2009 12:02 pm
Location: Seattle

by jever98


apologies for a basic question that has probably been answered many a time - but it's difficult to search for: I get a recommendation for 269mm spokes from the DT Swiss calculator, but only 268mm or 270mm are available.

Am I right in thinking I should round up by a mm, rather than down?

No longer in the industry

by Weenie

Posts: 678
Joined: Sun Jun 24, 2018 8:10 am

by Jugi

I wouldn't say rounding up is categorically the right answer. Do another calculation for example with this tool. As it most likely returns something else than 269,0mm exactly, go for which ever is closer.

If the calculation is returns exactly 269mm, I would most likely go with 268mm to account for spoke stretch and hub's spoke holes slightly giving into the spoke pull when tensioned.

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by alcatraz

Too short spokes can be just as bad as too long. Better use 2-3 calculators to narrow it down. Remember that your choice of nipples can change the spoke length.

After you build the wheel you will know which calculator worked the best.

Spoke stretch is very small. I wouldn't obsess over it.

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Joined: Thu Jun 06, 2019 1:10 pm

by alanyu

I will choose 268mm spokes. Around 1mm shorter is reasonable.

Spokes will be elongated at a certain kgf (elastic deformation), for example:

Besides, spokes will also be stretched slowly as the time goes (creep). When you need to true your wheel after a long mileage (not a sudden crash, etc), you need to tighten (not loosen) the nipples again.

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