Getting proper spoke tension on a 9c clone hub motor/ wheel assembly

MarkJohnston

10 kW
Joined
Mar 25, 2021
Messages
620
Helllo,

I have a really skinny long Brushless DD hub motor. n any case the wheel didn't come today well built and the other day I checked and lots of spokes we're loose.

I put the wheel in the truing stand by wound up not putting enough tension and equal tension in the wheel. Spokes are still coming loose all the time and I keep tightening them, but on my day off I am going to have to take off the motor again and redo. :(

It's extremely difficult to get the spoke tension just right. Especially with a rear wheel + freewheel because one side has a bit less tension. I'm not sure how to feel for that exactly with my hands. That is, im not sure how to feel the exact slight difference between drive vs non. It's very difficult. I don't feel like buying a spoke tension meter. Seems dumb. But I hate spokes coming loose. Any ideas how to restore this wheel?

I basically screwed up and just made way too many adhustments on the first true since I'm new to this. It's quite a frustrating process especially with my crappy truing stand that isn't calibrated.
 
AHicks said:
I wouldn't try it without a proper tension meter.

You don't need a tension meter, but you do need to know how a good tightly spoked wheel feels. When I worked in bike shops in the early '90s, almost nobody used a tensiometer. The only one I ever saw was a Wheelsmith tool that seemed inaccurate and awkward. Yet we built good strong wheels then.

Even today, I only use a tensiometer at the end of a build, to confirm my impression that it's tight enough.
 
MarkJohnston said:
I have a really skinny long Brushless DD hub motor. n any case the wheel didn't come today well built and the other day I checked and lots of spokes we're loose.

I put the wheel in the truing stand by wound up not putting enough tension and equal tension in the wheel. Spokes are still coming loose all the time and I keep tightening them,

In good bright light (direct sunlight, for instance), closely inspect, with magnification, the area around the nipple holes in the rim. When spokes keep loosening even without riding it, it may mean the rim is deformed and/or cracked around at least some of those holes. It's very common in OEM hubmotor wheels that have spoke loosening problems. This image search shows a bunch of rims with these problems (from various causes, not just the one suspected here)
https://www.google.com/search?q=+amberwolf+rim+spokes+crack&tbm=isch
Here's one of mine that specifically broke from too-thick spokes:
file.php


Sometimes it's not the rim that breaks, but the spokes, usually at the elbow (j-bend).
file.php



Beyond the ability of the rim to handle the spoke tension (like for commonly-used 12g spokes), this means the tighter the spokes, the more that area deforms, eventually breaking, with cracking becoming easily visible. With each deformation, the formerly-tight spoke is now looser. Once it cracks it pretty much can't be tightened, the crack will just spread wider and let the nipple come thru it further, instead of pushing back on the nipple and keeping the spoke tensioned.

Sometimes an eyeletted rim will take the abuse of the too-thick spokes well enough to work where a non-eyeletted rim can't, but the best solution is to use spokes thin enough to tension properly without exceeding the rim strength.

Alternately, a rim designed specifically for the gauge of spokes being used (or rather for the tension that will be required for those spokes) will also work. But since most sellers have none of that info available (they may not even have basic info like ERD, etc), it's much easier to pick a rim that is designed for the load and usage the bike is going to use, then use standard spoke sizes typical for that type of rim--for bicycle rims that's usually going to be 14g or 15g spokes. Or butted or double butted spokes, like 14-15 or 14-15-14, etc.

For more details on how this all works, you can look up "spoke" or "spokes" in Chalo's posts, or mine, here on the forum, or places like Sheldon Brown's bicycle info site, or books like Jobst Brandt's on wheelbuilding, etc. (I have not read this book, but it has been recommended to me).
 
Chalo said:
AHicks said:
I wouldn't try it without a proper tension meter.

You don't need a tension meter, but you do need to know how a good tightly spoked wheel feels. When I worked in bike shops in the early '90s, almost nobody used a tensiometer. The only one I ever saw was a Wheelsmith tool that seemed inaccurate and awkward. Yet we built good strong wheels then.

Even today, I only use a tensiometer at the end of a build, to confirm my impression that it's tight enough.

But the fact remains, you DO use a tension meter right? So why would you tell a rookie you don't need one?

I don't claim to be a pro, but I have built several wheels after teaching myself how not long ago. My belief is I'll have a lot more confidence in the end result, KNOWING, beyond any doubt, that spoke tensions are correct, and uniform. If done right the first time, using quality components, there is no more screwing around. I don't think a rookie builder can achieve that without a tension meter.
 
When my life was all about being a custom bicycle builder I laced up hundreds of wheels.
A few motorcycle wheels and a hand-full of E-motor wheels.
This is my technique ...
1) Before assembly measure across the rim in several places to check for roundness.
If the rim shows a bunch of oval or egg shape take a pipe clamp (or two) and squeeze the high spot to force it round.
Trying to tune an out of round rim by spoke tension is a loosing game.
2) After the spokes are in place the first step to building the wheel is adjusting for roundness.
Think of this as the up and down. This is the core of the build so it's important to adjust as close as possible.
At this point the spokes just need to be snug with none too loose or too tight.
It's kind of a tug of war where sometimes one quadrant of the circle will need to loosen while the other quadrant tightens.
3) Once the up and down looks good it's time to focus on the side to side.
This is adjusting not final tension. If needed, loosen one side tighten the other.
4) After the side to side looks good check the dish.
3 glasses on a table is an excellent dish tool.
To reveal an off-center dish, place the wheel on the glasses, measure the distance to the axle nut, turn the wheel over, measure again. When both sides measure the same it's centered.
If it's off center a bunch then it may require all the spokes on one side to loosen a full turn or two to allow the other side to tighten enough to tug the the hub to center.
dish tool.jpeg
5) Once all 3 adjusting procedures are done and look good it's time to tension.
Start at the valve hole and adjust each nipple the same amount ... about 1/4 turn.
Check tension by feel ... not tight enough ? Go around the wheel again and turn each nipple the same 1/4 turn.
Once the tension feels close tap the spokes with a small wrench and listen for a bright musical tone.
Sounds dull ? Not tight enough.
For the final tension, to reduce the chance of rounding the corners of the nipples a four side spoke wrench is best.
6) One more task once a tone is found.
Any spoke on the outside of the flange really wants the head to be more then 90 degrees.
Force the the spoke head to bend by taking a small hammer and punch and striking the spoke.
When that is done you'll will likely find the spokes will need to be tensioned again. Often it will require as much as a 1/2 turn.
Tap with small wrench and listen for bright, ringing tone.
bend spoke head.jpeg
That's my method
As Always ...
Your Results May Vary

Edit ... before the build de-burr all holes in the rim. Use quality spokes. DT Swiss or Wheelsmith.
 
Well good advice but not exactly what I was looking for.

My question again is

How do I get the tension just right in a wheel with one side with a steep bracing angle? Like on a rear wheel with freewheel or disc brake wheel?

There are suppose to be slightly less tension on the side with the longer spokes, non drive or disc side.

So just plucking them and listening for a ting sound is enough?
 
MarkJohnston said:
Well good advice but not exactly what I was looking for.

My question again is

How do I get the tension just right in a wheel with one side with a steep bracing angle? Like on a rear wheel with freewheel or disc brake wheel?

There are suppose to be slightly less tension on the side with the longer spokes, non drive or disc side.

So just plucking them and listening for a ting sound is enough?

Correct ... keeping in mind the tone will be slightly different on each side.
All spokes on each side should be roughly the same tone. ( right side verse left side )
My understanding of the history of the bicycle is the original tension wheel (wire spokes) were derived from music wire.

Damon Rinard's spoke calculator shows the expected tension amounts per side.
If you wanted to get all science about it ...
Knowing the spoke diameter and length combined with the tension knowledge the exact pitch could be calculated.

What your probably experiencing is the spokes are settling, the spoke is seeking the straightest path which can be helped along with the hammer and punch trick, the nipples are finding their sweet spot pushing the rim burrs out of the way etc.
A common phenomenon.
 
MarkJohnston said:
How do I get the tension just right in a wheel with one side with a steep bracing angle? Like on a rear wheel with freewheel or disc brake wheel?

There are suppose to be slightly less tension on the side with the longer spokes, non drive or disc side.
There's no "supposed to be" about it. You want the tensions to be as equal as possible. But the only way to get different bracing angle between one side and the other is to make the flatter side tighter than the more conical side.

If you use cross-1 lacing, you can put all the flatter side spokes outside the flange for more bracing angle, and all the looser side spokes inside the flange for less bracing angle. This really helps when the flanges are too close together, as with most hub motors.

So just plucking them and listening for a ting sound is enough?

That's a great method for determining how uniform the spokes' tension is, but it won't tell you how tight they are. You can use it to compare against a known good wheel, but when the spokes have different lengths or thicknesses, they'll ring different notes at the same tension.
 
One more "gotcha" that effects spoke tension, and this is rim dependent, sometimes when the tire is inflated to it's proper pressure the spoke tension decreases.
This usually only happens to light weight rims and high pressure tires.

A couple more pre-build items that help with achieving high quality results :
Use a belt sander to deburr the spoke end at the first thread, this reduces the chance of messing up the nipple thread.
Lube the spoke threads so the nipple can spin as freely as possible.
White lithium grease is common workshop staple.
A tiny dab of grease on the nipple head where it contacts the rim too.
All this grease does make a mess which must be removed before rim tape can be applied.

Tension meters need enough spoke length to function so doesn't work for every wheel build.
That's when practicing "tension by tone" pays off.
 
Ok there is actually no bracing angle because the free wheel is built into the hub motor. I got the tension up and I think it is working. Just did a 16 Mile ride and wheel is still true. Knock on wood spokes don't unwind again
 
MarkJohnston said:
Ok there is actually no bracing angle because the free wheel is built into the hub motor.
Bracing angle has nothing to do with where the freewheel is, or even if there is one.

It refers to the spoke flange holes vs the rim's nipple holes, and the angle between them, vs being completely vertical.

Random choice of google results for "spoke bracing angle":
https://shop.torzc.com/bracing-angle/
 

Attachments

  • TORZC-lab-bracing-angle[1].jpg
    TORZC-lab-bracing-angle[1].jpg
    20.8 KB · Views: 646
Idk. It's a bit complicated, but the spokes are still holding. I'm going to attempt my first wheel build soon. It's not important to understand all the terminology and technique. I just need to do it
 
Yeah with the tension higher it seems the spokes don't unwind. IT's a beefy rim so hopefully it's not over tensioned.
 
Back
Top