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this is the first time trying to lace a wheel. I have ben using the internet for instructions, and have done this wheel three times and have the same problem each time. when I am done I have two spokes tight and then two loose repeated all the way around the rim.
The rims are schwinn S2, the spokes are 10 5/8 long .120 dia. I am using a 4 cross pattern. I have ben using lacing videos from online as a guide when I am done and snug up the spokes every two spokes are loose and the next two are tight,then 2 loose all the way around the rim. I cant seem to figure how to post a picture.

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  • Welcome to the site - we might have to ask a few things to clarifty the problem here.
    – Criggie
    Dec 6, 2023 at 1:15
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    What wheel lacing pattern are you using? Are they normal J bend spokes with nipples in the rim?
    – Criggie
    Dec 6, 2023 at 1:16
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    Are the loose spokes all on the same side? or do they alternate?
    – Criggie
    Dec 6, 2023 at 1:16
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    Is this a front wheel (where all spokes are even length) or a rear wheel, which has shorter spokes on the drive side ?
    – Criggie
    Dec 6, 2023 at 1:17
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    Can you use edit to add a photo of the wheel ? Might add some context too.
    – Criggie
    Dec 6, 2023 at 1:19

2 Answers 2

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This is one of those issues in wheelbuilding that unfortunately, many of the guides and texts gloss over or ignore because it gets into the weeds fast and comes up more on build types other than the really mainstream ones that the writers of those documents get the most reps in with (i.e. common road and mountain wheels).

Presumably you are encountering this after the wheel is first laced but either before or you are doing much else to it, or you are finding that in the early stages of tensioning, one pair of spokes is getting very tight while the next remain loose, and so on.

If so, the usual reason for that is there is a difference between reality and the way spoke lengths are usually calculated, which is a formula like the following that models the wheel as a bunch of triangles and circles:

enter image description here

The way most calculators do it is they expect an F value based on measuring to the center of each flange, and then this formula is run for each side of the hub. A left and right length are output.

In reality flanges have thickness and so for a wheel where, like most, the spokes alternate between heads-in and heads-out on each side, there are actually 4 different theoretically perfect spoke lengths needed.

Usually the difference in ideal length is just noise, which is why most people don't think or know about this effect. But, there are exceptions:

  • If the flanges are very thick, and particularly on wheels that need very short spokes. The effect you're seeing comes up much more frequently on BMX and motor hub wheels, for example. The solution here can be either offset your initial engagement a little if that can work without ultimately causing thread engagement problems in either direction, or just use the 4 different lengths.
  • If the spokes chosen are borderline too short, such that the heads-in spokes get tight while the heads-out spokes (shorter distance to the rim) are still slack, starting from equal thread engagement. Theoretically some degree of this "problem" can always be observed on any wheel with alternating heads-in, heads-out spokes, starting from equal engagement and applying equal rounds of tension.
  • If the spokes chosen are too long, such that the effect of flange thickness on ideal length causes the heads-out spokes to run out of thread engagement and remain slack while the heads-in ones are able to tighten. There is always a hypothetical length where this can happen on any wheel with alternating heads-in, heads-out spokes, again starting with equal thread engagement and given even rounds of tension.

A very easy way to wind up with spokes that are too long or too short is if the rim diameter (ERD) you've done the calculation with is off. There is little margin for error and it's always good to just take the measurement firsthand.

Additionally, many very old bikes like the one in question have steel hub shells. Steel hub shells are typically much thinner than aluminum, and sometimes you have to address this when putting modern spokes through them. I can only profess limited experience here (maybe 6-8 such hubs with modern rims and spokes). When the j-bend is sized for a thicker flange than the one you're working with, the elbow hangs in space and is not properly supported by the flange. I don't know that I've seen this cause the problem you're describing, but I can imagine it being possible that this results in the elbow of the heads-out spokes opening up as tension is applied, since the heads-out spokes again run in a more direct line to the rim, while the heads-in spokes do not due to the way they have to wrap around the flange. This in turn could cause the effective length of the spoke to increase and at best will mean that turning the nipple doesn't add tension like you want. If this is happening (and in most cases just on general principle when working with steel flange hubs), solve it by using DT spoke head washers, enough of them under the head to make each spoke fit neatly around the flange.

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I've been lacing wheels for a while, and a few websites have really stood out as more clear in their instructions than others.

This is a good way to measure your hub: https://leonard.io/edd/howtomeasure This is a great tool to figure out spoke length: https://www.prowheelbuilder.com/spokelengthcalculator This is a great way to measure ERD: https://www.parktool.com/en-us/blog/calvins-corner/measuring-effective-rim-diameter And finally, the Park wheel building Video is great

Good luck and keep us informed!

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