New wheel loose spoke

[Hooijer]

Hello cycling technology fan. Like you, I am a good amateur bicycle mechanic. I have experience in making and repairing bicycle wheels. Although I'm quite a perfectionist, a wheel is never perfect. A wheel that is completely balanced is, in a sense, unattainable. It is always a balance between a straight wheel and equal spoke tension. You can also say it differently. More importantly, a round wheel with uneven tension. Or a wheel with equal spoke tension and not completely straight. For me the second, but you always strive for both as an end result. Now my question that I would like to share with you. A few times I've repaired a machine-made wheel. These wheels were perfectly straight and round. The spoke tension was also almost balanced. However, one or two spokes were too loose. You probably feel the problem. When the loose spokes were tensioned, the wheel was no longer straight. I was therefore forced to remove the wheel and correct it in the wheel straightener. To straighten it I had to tighten the spokes opposite the problem spokes extra. Actually too tight compared to the rest on this side. Finally all spokes were tight and the 'problem' was solved. However, it is of course not a wheel where all spokes have the same spoke tension. Then I asked myself the question. The two weak spokes have been repaired, but the wheel is still out of balance. There are now spokes that are too tight. What is your view on this point? Afterwards I shouldn't have done anything. Or are some too-tight spokes better than some weak spokes? Another option is not to change the spoke tension, but to solder the single slack spoke to the crossing spoke. Finally, there is an option to loosen the entire wheel and restart the tensioning process. This is not an option for me! It was a new bicycle with one or two loose spokes. It is unnecessary and uneconomical to write off an otherwise good wheel. I'm curious how you view this situation and what you think is the best compromise. Thank you for your help and hopefully we will learn from each other. Kind regards, Ronald.

 

[BikeGremlin]

Hello cycling technology fan. Like you, I am a good amateur bicycle mechanic. I have experience in making and repairing bicycle wheels. Although I'm quite a perfectionist, a wheel is never perfect. A wheel that is completely balanced is, in a sense, unattainable. It is always a balance between a straight wheel and equal spoke tension. You can also say it differently. More importantly, a round wheel with uneven tension. Or a wheel with equal spoke tension and not completely straight. For me the second, but you always strive for both as an end result. Now my question that I would like to share with you. A few times I've repaired a machine-made wheel. These wheels were perfectly straight and round. The spoke tension was also almost balanced. However, one or two spokes were too loose. You probably feel the problem. When the loose spokes were tensioned, the wheel was no longer straight. I was therefore forced to remove the wheel and correct it in the wheel straightener. To straighten it I had to tighten the spokes opposite the problem spokes extra. Actually too tight compared to the rest on this side. Finally all spokes were tight and the 'problem' was solved. However, it is of course not a wheel where all spokes have the same spoke tension. Then I asked myself the question. The two weak spokes have been repaired, but the wheel is still out of balance. There are now spokes that are too tight. What is your view on this point? Afterwards I shouldn't have done anything. Or are some too-tight spokes better than some weak spokes? Another option is not to change the spoke tension, but to solder the single slack spoke to the crossing spoke. Finally, there is an option to loosen the entire wheel and restart the tensioning process. This is not an option for me! It was a new bicycle with one or two loose spokes. It is unnecessary and uneconomical to write off an otherwise good wheel. I'm curious how you view this situation and what you think is the best compromise. Thank you for your help and hopefully we will learn from each other. Kind regards, Ronald.

Hi Ronald,

That is a good, reasonable question that I too have wondered about. Here, I'll try to give a full answer, but feel free to post a reply if I don't manage to explain it clearly enough on my first attempt, since English is not my native.

1. Briefly put​

• There are acceptable tollerances within which a wheel should be built to last long and work well.
• Sometimes it is faster to loosen all the spokes and start from "zero."

2. Longer explanation​

Being a perfectionist, I came to a hard realization that wheels are not perfect. That may seem obvious and logical, but to me it was a bit frustrating. I had to at least see what the acceptable tollerances are, to know I've hit the goal. So, this is my list:

2.1. Acceptable tolerances​

Acceptable trueness, and spoke tension tolerances
That link leads to my wheelbuilding article. Keeping and updating information on one place guarantees that all the info gets updated (backups are a different matter).
For convenience, I will copy/paste the criteria here, but the website article version is the one I keep up-to-date in case of any changes or new knowledge:

• Spoke tension uniformity (between spokes on the same side): up to +- 10% tension variation among the spokes (on the same side). Ideally +- 5%, so that the maximum tension difference between the tightest and the most loose spoke is up to 10%.
• Radial trueness: up to +- 0.5 mm deviation.
• Lateral trueness: up to +- 0.25 mm deviation.
• Rim dish trueness: up to 0.5 mm left-right deviation (dish gauge will always show the deviation as doubled!)

2.2. Spoke tension uniformness​

When I build wheels, I aim for the most uniform spoke tension that keeps the rim's trueness within the above-listed specifications (acceptable tolerances). In other words: whenever I have to choose between more uniform spoke tension, and 100% true wheel, I aim for the more uniform tension, as long as the rim is not out of the given acceptable trueness specifications.

Yes, with some poor quality rims I have to go with +-15% spoke tension difference (so a total of 30% difference between the most and least tight spoke on a given hub side). With high-quality rims, I can reach as good as +-5% or even better.

2.3. Absolute minimum, and maximum spoke tension​

Minimum tension:
In my experience, with swagged spokes ("butted"), as long as the tension is over 60 kgf, they won't start loosening. For straight, 2mm thick spokes, the min. tension is around 80 kgf.

Maximum tension:
With most rims and nipples, 130 kgf is the maximum safe tension (I would say that even with very strong rims, when using washers and 2mm wide spokes, 150 kgf is the absolute max. safe tension), beyond which something is likely to get damaged sooner or later (either threads, or the nipple-to-rim interface).

So, on highly dished rear wheels (Shimano 11-speed road hubs for example), I often deliberately make the dish trueness err to the left (up to 0.5 mm when using a dish gauge). This lets me get the looser, left hub flange spokes get above the minimum tension threshold, without the right hand side spoke tension being over the safe limit.

In other words, for cassette rear wheels, I make my dish tollerance to be from 0 to 0.5 mm to the left.

3. Starting from scratch​

Spoked wheels are a relatively complex pre-tensioned structure. Tightening one spoke moves the rim towards that hub flange, so it results with:

• The rim moves towards that flange (and closer to the hub/centre in that spot).
• Two adjacent spokes (coming from the opposite hub flange) also gain a bit of tension.
• Spokes on the opposite side of the rim gain a very, very slight amount of tension (as the rim tends to move away from the centre/hub at the opposite side - not really, if other spokes are tight, but the tension/tendency is there).
• 2nd adjacent spoke both left and right (so, the two adjacent spokes from the same hub flange) will lose a bit of tension (the tightened spoke has taken more load and pulled the rim).

With stiff, double-walled rims and tensioned spokes, these differences can't always be measured, but they are there. This makes fixing a wheel with many spokes tensioned unevenly very difficult (my video called "Wheel truing catches and gotchas" where I couldn't get it fixed without starting over).

When starting over, I make sure that all the nipples are evenly screwed in. For that, I use a "special" nipple driver - see 8:35 in my video called Bicycle wheelbuilding tools explained (the link should open the video at that time, but there are sections visible in the timeline).

​

4. Tips & tricks​

While I do always aim for the as-good-as-possible, it is fair to say that the following stuff is true based on my knowledge and experience so far:

Uniform spoke tension is overrated.
As long as spokes don't go under the minimum or maximum safe tension (see section 2.3), it will often be fine. This doesn't mean one should slack when building wheels, but when there is a situation where it's difficult to achieve a uniform tension (bad rim, damaged rim, very little time during a race or a standard bike shop in May etc.), just make sure to stay within the max. and min. tension limits and get the wheel to be straight.

Swagged (butted) spokes by Sapim and DT Swiss are very forgiving
I build a vast majority of wheels with the cheapest, "Chinese" straight 2mm spokes. They are not very strong, durable or of high quality, so any imperfection in the wheel building technique gets "punished" very quickly (within a 1000 km or even less). But, the high-quality spokes can let you get away with almost anything. Especially if paired with a strong double-walled rim.

Thinner spokes on the left for the highly dished wheels
A rather neat trick (patting myself on the back with one hand as I'm typing this ). If a rim is not strong enough to take high tension, and a cassette (hub) requires a highly dished wheel, then one could use thinner spokes on the left hub flange. Ideally swagged 1.8-1.5-1.8 spokes. Those spokes will elongate more, so they are a lot less likely to start loosening (nipples unwinding) even if their original tension is below 60 kgf. The right hand side spokes will get higher tension on dished wheels, so they can be 2mm thick.

P.S.
If it's of any help, here is my series of videos about wheel building (the link should open the playlist), and my wheel building article section.

Hope this helps.

Relja TheLongWinded Novović

 

[Hooijer]

Hello Relja, thank you for your response. I agree with you that it is good to start from scratch on a used rim where there is a lot of uneven spoke tension. In that case I would also recommend a new rim and spokes, because damage has probably already occurred in the materials. My example was slightly different and probably simpler. I had a new e-bike with a front wheel motor. Of the 36 spokes, one was completely loose and the other 35 were at the correct tension. I don't have a nice meter like you, but I do have a feeling for the right spoke tension. I have 30 years of experience in bicycle maintenance. As mentioned, I tightened the loose spoke and the result was quite a wobble. The bicycle has a V brake so the problem had to be remedied. This was also achieved by tensioning the adjacent spokes on the other side, although they did not actually need any extra tension. I also did it over a length to spread the tension a bit. All in all, I did what I could with this situation. The rim was probably not that stiff, so one loose spoke could have such an effect on the rest of a new wheel. I'm just curious if you would have handled it the same way or not? Although I have a lot of patience, I am still looking for the fastest and best way to tension one spoke without overstressing the adjacent one. greetings Ronald

 

[BikeGremlin]

Hello Relja, thank you for your response. I agree with you that it is good to start from scratch on a used rim where there is a lot of uneven spoke tension. In that case I would also recommend a new rim and spokes, because damage has probably already occurred in the materials. My example was slightly different and probably simpler. I had a new e-bike with a front wheel motor. Of the 36 spokes, one was completely loose and the other 35 were at the correct tension. I don't have a nice meter like you, but I do have a feeling for the right spoke tension. I have 30 years of experience in bicycle maintenance. As mentioned, I tightened the loose spoke and the result was quite a wobble. The bicycle has a V brake so the problem had to be remedied. This was also achieved by tensioning the adjacent spokes on the other side, although they did not actually need any extra tension. I also did it over a length to spread the tension a bit. All in all, I did what I could with this situation. The rim was probably not that stiff, so one loose spoke could have such an effect on the rest of a new wheel. I'm just curious if you would have handled it the same way or not? Although I have a lot of patience, I am still looking for the fastest and best way to tension one spoke without overstressing the adjacent one. greetings Ronald

Probably, yes. I.e: if tightening one spoke brings the wheel out of true, I would try to compensate by sligthly loosening the adjacent same-flange-side spokes, and slightly tightening the adjacent opposite-flange-side spokes. To keep their tension as uniform as possible (so 2 spokes to the left and to the right of it).

Though, it depends on the particular rim. For example: do I know that the rim is straight (the only way to really know is to see if it's straight when all the spokes are loose)? If I started with a good rim and didn't get any problems after hitting a bump, I would expect it to be straight and what you did sounds reasonable. If I suspected a faulty rim, I would fist check to see if it is bent with loose spokes, and if so, see to replace it (or try to "gently" "persuade" it to straighten ).

A bit more info - if it helps:

Old spokes and nipples are OK to reuse. They should be replaced if more than two spokes break on a wheel, especially if the tension has been all over the place. But if none broke, and all but one or two had good tension, then the spokes are probably good (any factory defect spokes break, so the used ones are at least "battle tested" - at least that's my logic ).

Rims should be replaced when damaged or worn (worn rim-brake rim - short video).

I'm sure you did a good job on the tension. You can do without a tension meter.

• A guitar pluck is good enough to test the relative tension (i.e. if the tension is uniform).
• A well-built strong wheel is good enough to get the "feel" of what the ballpark optimal tension is.
• If a rim goes out of true after spoke stress relieving, then the overall tension was too high for the rim.

Tension meter makes things faster and removes trial-error guesswork, but I've built good wheels without one (I recommend using one, but never let not having it stop you from building good wheels).

If the rim tension is uniform enough (and not too low for any spoke), the wheel might work just fine.

Relja

 

[VlPo]

I.e: if tightening one spoke brings the wheel out of true, I would try to compensate by sligthly loosening the adjacent same-flange-side spokes, and slightly tightening the adjacent opposite-flange-side spokes. To keep their tension as uniform as possible (so 2 spokes to the left and to the right of it).