snapping spokes

Geege33708

100 µW
Joined
Jul 11, 2017
Messages
9
Location
St Petersburg, Florida
I am new to this form but was directed here bt a tech from ebikekit.com I have tandem Terra Trike and it is a bad ass ride for my wife and I. Seniors, also a little heavy.I encountered a major problem and need advice on how to proceed. I was a block away from my house and heard a strange noise and upon checking it out I noticed a broken spoke on my e hub. I limped home at 2 mph and by the time I reached home a total of 10 spokes were broken. I purchased the heavy duty wheel package which is rated at 600 lbs (?). We are well below that and I am wondering if there maybe another solution such as a mag wheel or welding steel bars on the wheel. Any solutions would be greatly appreciated. I was told that someone has a trike that you used a moped wheel and heavy duty spokes. Can you enlighten me? Thanks, Geege33708
 
That's exactly how my spokes have turned to sphaghetti. One goes, then another, and a couple more, then a bunch = taco salad. Happens quick.
On the other hand, when I was pedal only I could go for weeks with 1 or 2 broken, twisted spokes. Ebike weight and speeds seem to magnify spoke problems in a hurry, to the point of having to replace the rim also being the norm. :x
 
Welcome to my world, Broken Spokes.

Normally you can go with a handful of spokes snapped or broken and be fine.

The key is not 10, 11 or 12 guage spokes, but the key is to have double butted spokes of 13G/14G where on one end of the spoke is 13G and on the other end of the spoke is 14G. It does need to flex, thats why the 13/14G is good. Too stiff a rim is no good.

Then to have a bullet proof wheel setup, a motorcycle rim is great to have. Holmes Hobby sells them specifically for ebikes. A moto 17" is equal to 20" bicycle, while a 19" moto rim is equal to 24" which I can only assume a 20" or 21" moto is equal to 26" bicycle. Its good to have with the larger hub motors because of the moto rims angled nipple seat.

Spinning Magnets did an article on it.
https://www.electricbike.com/moped-rims-tires-hubmotors/
 
FWIW, his wheel is 20", with an E-bikekit direct drive motor. so he's got the short radial spokes.

My experience has been that its harder to keep that kind of wheel tuned, so none of the spokes get overtight, at some point as the wheel rotates under a heavy load. I sent him here, so he could see the many ways that others who ride hard cope with wheel problems.

The EBK wheel mechanic talked to his bike shop tech, and it was determined that his tandem trike could accept a 24" rear wheel. This will allow a single cross build, which should be a bit easier to keep in tune, and a tad more forgiving when its not in perfect spoke adjustment. I hope that we have found a solution, that will at least require much less maintenance, and be more able to limp home if he does pop one spoke.

The ultimate solution for heavier loads might still be a moped rim and spokes. But trying a 24" rim will be cheaper.
 
Two solutions. Lace 12G ss radial spokes, or go to a 16" moped rim with angled spoke holes so you can lace a crossing pattern. You don't want weak ass spokes for radial lacing, and you want them very tight to lesson the snap pressure on them when you hit the throttle. 12G spokes would be the cheapest solution, but a moped rim with crossing spoke pattern would be the best solution imo. I'd guess 90% of spokes break because they aren't tight enough. Didn't take long to figure this out. And contrary to what many here will tell you, thinner spokes are not stronger than thicker spokes.
 
Over years, I have encountered 3 principal causes of broken spokes.
1. Radical spoke angle
Remedies:
Custom drilled spoke holes to get angle over 80 degrees (a 2-hour DIY job)
Assymetrically drilled rims (moto rims or Ryde Andra bicycle rims)
- loose spoke elbow at hub flange
Remedy: insert brass washer(s) between spoke head and hub flange
- loose spokes
Remedy: Build wheels with equal spoke tension on both sides (if possible). Use heavier butted spokes and/or spring washers under nipples where tension is too high. Regularly inspect spoke tension.
 
Radial is sh*t to lace a motor, no matter how big or good are the spokes. Then, lacing single cross in a 20" rim is hell of a job unless the rim is moped or motorcycle. If you can fit a 24" wheel, that would make it much easier.
 
I've experienced my fair share of busted spokes about 1 to every 400 miles now compared to 1 to every 200 miles because my cargo bike is a bit heavy and the local streets are need of repair. Because ebikes are heavier and traveling faster any bumps can cause you to break a spoke. A heavier gauge spokes will help and checking the tension, and for any corrosion. Also check the rim and check to see that the spoke nipple is straight. Once when I learned how get the tension right and keeping the spokes free of corrosion the number of busted spokes dropped. One recommendation is to buy extra spokes which will help so you will have them on hand when you need them. I bought a real nice bike that had a bent frame for $10 and ended up salvaging off of it like cables, shifters, spokes, metal pedals, etc. so I had plenty of replacement parts.
 
A 24" rim seems like the best solution. laced with quality spokes in a 1x pattern.
It will also help save the spokes to run a wider, larger tire that can soak up more shock.

Thicker spokes are not really an answer. Anything above 14g is going to be nearly impossible to get tensioned properly. To work properly, a spoke needs to be tensioned until it has stretched. A 12g spoke's strength is so high that getting the spoke tensioned that far is often more than a bicycle rim can survive, and you end up with a broken rim. A 12g spoke that isn't tensioned fully, but just "tight" will fatigue and fail. A thick 12g used this way will actually be much weaker than a thinner 14g spoke that has been properly tensioned.

The solution is to use lightweight moped rims. Moped and motorcycle rims are measured different. a 16" moped rim is the same size as a 20" Bicycle rim, and the tires are interchangeable. The Moped rim is stronger and can use thicker spokes, so if you opt for a moped rim, you could retain your wheel size and fit thicker spokes.

Another option is to use an 18" or 19" moped rim, allowing a 1x lace pattern along with the stronger spokes to be used, making an even stronger wheel.

If this was my bike, I would fit a 24" wide rim with a 2.4" tire like a CST cyclops. 2nd choice would be the 16" MC wheel with a CST 2.4" wheel.
 
I used to get the odd broken spoke, but since I went thinner to 14g, I've never had a problem.
 
Been wrestling' with a similar design issue in my new custom build,.... small diameter rim, large powerful hub motor, heavy bike/rider weight with disk brakes. Added factors include regen braking and wide rim/tire.

Most all 20" large hub motor/wheel assemblies are radial laced with 12ga due to extreme spoke angles of single cross lacing AND the 36h standard. They usually serve jus fine for typical bicycle use,.... but not for the NON-typical design needs of special applications, such as trail use, heavy bikes, tandems, and trikes with disk brakes and other "non-typical" factors to consider. These jus demand a cross pattern of lacing, AND,... a higher spoke count!

To overcome this issue and prevent the common problems often experienced, I've chosen to double the spoke count of both rim and hub. This will allow a single cross lacing with acceptable spoke angles, AND a more even distribution of stress and loads over the greater number of spokes. I'm also considering single butt 12/14ga as hub motors are typically drilled for 12ga. This matter may be reconsidered depending on rim drilling, and the fact that the greater number of short, 100mm or less, spokes will see little typical advantage or benefit of lighter gauges. The double-wall rim I've chosen can easily be "double-drilled", whereas typical rims may not be so accommodating.
 
yea well
ERD spoke calc
3X 237.6mm @ 65 degrees
2X 199mm @ 68 deg
1X 169.3mm @ 76 deg (1X is Ideal)

Chain Reaction Cycle has spokes for sale, plus Im putting in a $100 order (tubes, wire, housings, pads etc etc)
However....
240mm DT Swiss PG's
(3X is 2.4mm difference = not so bad) Also look at the degrees not much diff between 2X and 3X

194mm Colony BMX
(2X is 5mm difference = may be an issue)

So...
I've been searching to see how big of a difference can be tolerated.
Found this
https://sheldonbrown.com/wheelbuild.html

Generally, I round upward to the nearest available larger size. The length is not super-critical, but it is worse to have spokes a bit too long than a bit too short. If spokes are too long, they prevent you from using the screwddriver. Unless a rim has recessed spoke holes, you will have to file off protruding spoke ends to avoid their puncturing the inner tube. The right-side spokes of a dished rear wheel are ideally 1 or 2 mm shorter than the left-side spokes.

And spokes come in 2mm increments.

I remember watching a video Barrent did with his wheel lacer.
https://www.youtube.com/watch?v=CZ3Ji72-qM4
Nothing on how much of a difference is tolerable. 1mm is fine obviously, 2mm should be ok as well.
 
Lacing 72 spokes is a good solution for a small diameter wheel. It does let you lace single cross neatly, and makes a good wheel.

I never could find 12-14 butted spokes. I make custom flange washers out of alu pop rivet heads, and oval angled nipple washers out of plain brass washers. When you order a motor direct from a manufacturer, they will custom drill the flange to your spec.
 
d8veh said:
I used to get the odd broken spoke, but since I went thinner to 14g, I've never had a problem.

Agreed. Meanwhile, continue to buy common bicycle parts, at bicycle prices, working with bicycle tools, so on, so forth....
 
DRMousseau said:
To overcome this issue and prevent the common problems often experienced, I've chosen to double the spoke count of both rim and hub.
Doubling the number of spokes on existing wheel does not work. Tripleing does.
Think about alternating left/right holes in the rim, also the valve hole location.
And the holes in one hub flange should be between the ones in the opposite flange.
So if you really want to do this, go for 108 spokes.
 
I am from now on only going 24" on my motors. Stronger rim over all. Shorter spokes, say in the 145mm instead of 170mm. So aint no CRC, Niagara, JensonUSA going to be stocking them. Closest I've seen at CRC is 180-188mm, so 27.5" tire. But to go a larger diameter tire, is unCOOL in my books. 24" is COOL. Motor COOL that is :)
 
MadRhino said:
Lacing 72 spokes is a good solution for a small diameter wheel. It does let you lace single cross neatly, and makes a good wheel.

Better in this case might be to lace a 36 hole rim "radially" to a hub drilled for 72, with the hub laced interrupted (lace two, skip two). That would give the benefits of cross lacing without the oblique insertion angles.
 
markz said:
Shorter spokes, say in the 145mm instead of 170mm. So aint no CRC, Niagara, JensonUSA going to be stocking them.

Dan's Competition cuts to order; I've gotten spokes from the 100mm range on up to the 300mm range. Sapim 14ga stainless for $0.25, double butted for $0.40 (they stock different lengths of butted blanks) and they can usually furnish 13-14ga and 14-17ga for a little bit more.
 
silence said:
Doubling the number of spokes on existing wheel does not work. Tripleing does.
Think about alternating left/right holes in the rim, also the valve hole location.
And the holes in one hub flange should be between the ones in the opposite flange.
So if you really want to do this, go for 108 spokes.

This is assuming the use of "typical" rims with little room to work around. I'll be using a 20x100mm rim and have greater concerns of left and right hole offset, which may require cross swap. Valve hole is typically centered between the wide offset and no real concern.

Chalo said:
MadRhino said:
Lacing 72 spokes is a good solution for a small diameter wheel. It does let you lace single cross neatly, and makes a good wheel.

Better in this case might be to lace a 36 hole rim "radially" to a hub drilled for 72, with the hub laced interrupted (lace two, skip two). That would give the benefits of cross lacing without the oblique insertion angles.

This and other patterns have been considered for my particular purpose,... a typical 20x100mm 36h double-wall rim, to large 2000W hub-motor, on a rather heavy-weight frame and assembly. Any kind of "radial" or nearly so, jus doesn't seem to be the best alternative to a solid single cross lace, and doubling to a 72count should. My greatest current concern though, is the rather narrow flange spacing in relation to the rather wide hole spacing of the rim. But if I were to use a typical rim with little hole offset, your suggested lacing would probably be best.
 
When you notice one spoke loose or busted thats when to stop and tighten them to the same feel, and true it again.
I let 2 of mine go and it was a snow ball affect.
 
I think I solved my problem. I got a whole new motor and rim from Golden Motors. A 20" aluminum cast rim and motor. So far I have put about 25 miles on it and other than a little stiff, it seems to be OK!!!
 
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