Broken Spoke. Am I fat or do spokes age??

[georgefromvt]

Last year I purchased an R Martin Bike. No problems, it rode like a dream. This summer I have two broken spokes already. The bike has 800 plus miles, I do many hills and unfortunately, a few pot holes. The R Martin features a bracket mounted motor so it easily manages high graded hills. The broken spokes are on the rear wheel. Is it possible I am too heavy--210 lbs or do spokes age with wear and tear? Any suggestions/ help would be appreciated. Last year when the bike was new, no broken spokes. I do not think I gained that much weight nor do I ride any differently.
http://www.electricbikedistributor.com/r13-electric_bicycle.html

 

[neptronix]

Did you periodically get the wheels trued, particularly when you first bought it?

The better quality the spokes.. the better the true of the wheel.. the lower the possibility of spokes breaking.

 

[Thud]

Spokes break, fact of life.
especialy if you've encounters substantial shocks like a pot hole.

 

[Ykick]

eBikes are heavier and faster than pedal bikes so potholess and rough surface extract a heavy toll. Hub motors also need frequent truing and tension adjustments. At least until they bed-in and only then if they don't take any hard shots from speed, load and impact.

 

[REdiculous]

Yes you're kinda heavy - the average American male is 180lbs - and yes they do break from time to time. I'm only 135-ish pounds and I've broken spokes before, and on a non-motorized bike.

 

[Solcar]

I wouldn't doubt that stainless steel spokes might age badly.

I try to be careful with ss screws and bolts because metal fatigue breakage is much more likely than other fasteners that I have used. My SS wire requires caution during use, too. I can't be worked very much before it looses its strength and breaks.

It seems the metal in the manufacture of the spoke matters a lot. None of my bikes use stainless steel spokes and the spokes average about 30 years old, depending on the bike. On one of the bikes the spokes have surface rust on them. The two bikes I ride the most are Huffies, made in Ohio in the old days, and none of those spokes have ever broken, even the one that I ride most often that has the surface rust on its spokes.

 

[dogman dan]

I only weigh 180 or so, and still break lots of spokes on non suspension bikes. Seldom do on the bouncers, so I've become a fan of suspension bikes.

With any bike though, you do have to keep an eye on the spokes. Particualrly with a new wheel. Spokes definitely stretch, and strectch even more on the driven wheel, whether pedaled or motored. So keeping the spoke tensions even on a new wheel helps, so that there is not so much strain on any one spoke.
Even when kept nicely tuned though, we just hit the potholes going faster on ebikes. So do racers who ride 25mph plus all day, so they need new wheels and at least wheels trued constantly. It can be tempting to just keep tightening up spokes, but I've seen pics of spoke nipples pulled right through the rim.

When I have the most spoke trouble, is when the wheel is radically dished, or the rim is bent. Then you end up with overtight spokes on one side and loose ones on the other side.

 

[icecube57]

Im nearly double the weight of some of you guys and It takes about 3 spoke tension sessions to bed in a wheel. When i first started ebiking I broke spokes but they were in a non hub rear wheel. I went to full suspension and they stopped breaking. I got the Tidal Force which is a hard tail frame and an X5 and I had problem related to spoke squeaks and clicking. I would get the wheel trued and it needed retensioning a few rides later because they were clicky until I changed the lace pattern and told them to tighten the snot out of it and I stop having problems. I broke two 12G spokes on my X5 but im nearly double the weight and the torque and regen created by the motor was retarded. I recently had an ebikekit wheel that was clicky and it wasnt laterally strong. I would lean into some corners and there was enough deflection in the wheel to where the brakes were dragging on the rim. I tensioned it a few times and it still didnt fix the problem. The motor was spoked with all the elbows on the inside of the motor flange. I changed the spoke patter to where they alternated inside and outside of the motor flange and it crosses under the neighboring spoke. This made for a really stiff and solid wheel and after about 3 retensioning sessions its been problem free and I do street and sidewalk riding which is very bumpy.

 

[MadScientist]

Most spokes failures are due to stress at the elbow caused by unloading when the tire in the vicinity of the spoke pushes against the ground or an obstacle (e.g. pothole). Spoke nipples can loosen if the spoke becomes slack, effectively loosening the rest of the wheel and increasing the vulnerability of the remaining spokes. High quality wheel building practice reduced these risks by "stress relieving" spokes (momentarily pulling on them hard enough to stress the elbow past its elastic limit) and applying proper (high) tension to them.

Spokes do not generally stretch (undergo plastic deformation) in use. Normal wheels, even with what feels like high tension, have spokes at about 1/3 yield stress. This stress does not increase much when the wheel hits an obstacle (10% is the number that comes to mind - see Brandt's The Bicycle Wheel for more on this). Spokes that have not been stress relieved can loosen as the elbow bends to fit the shape of the hub flange. The nipple can unscrew, though not if the spoke remains in tension. Also very thin butted spokes can twist and deform when you turn the nipple, and will elongate at the same time.

Brandt recommends very high tension: tightening spokes to the point that the rim begins to deform, then backing off only a little. Cheap or ultralight rims (the race rims dogman mentioned?) might be too weak for this approach, but quality rims designed for durability will take high tension without a problem. If in doubt, the rim manufacturer should have a recommended maximum spoke tension, though it can be hard to track down.

I rarely have any trouble with my wheels - they stay true from the first ride and I can count the number of spokes I have broken on one hand, despite a good deal of hard mountain bike riding in the pre-suspension days. I attribute this to conservative choices in parts (durable rims, 32 or more high quality spokes) and careful wheelbuilding or checking (stress relieving, plus retruing and tensioning if necessary) of factory wheelsets.

That said, I don't own any hub motors. Of course the shorter spokes are less springy, making them more likely to go slack and cause problems. I also have to wonder whether poor quality spokes are used in some hub wheels. Even with the challenges of hub wheels (weight and less spoke springiness), I have to assume that most spoke failures are due to poor materials or build quality.

 

[Joseph C.]

.

 

[jimw1960]

Weird that so many have problems with broken spokes. I probably have logged over 100k miles on bikes in my life over road and mountain trails and never broken a spoke. I've busted rims, but never a spoke.

 

[chrisvw]

I've broken quite a few spokes - both on the front hub motor and on the rear wheel. The number one rule as mentioned above is to keep spokes tensioned. If they get loose, they'll definitely break much sooner. I weigh about 200 lbs but carry my work stuff in a pannier so am probably loading my bike similar to you. I have to check spoke tension every 2-3 months. When I didn't, I'd have the same problem.

I doubt this applies to you. There's a known issue with some of the Crystalyte hubs (I think mostly the 5000 series) where the spoke holes were not radiused properly, so spokes would break right at the hub motor. People used 12 Guage spokes or put little washers in to fight this problem.

 

[Recumbent Bicycle Source]

A properly trued wheel with each spoke tensioned correctly will be very strong an durable. There seems to be so little attention paid to wheel truing and spokes from the Chinese Manufacturers. Wheel building is art and science in the cycling world. The best builders have a "feel" for what is best. I've never broken a spoke on any of my bikes, but I'm pretty anal about maintenance and wheel selection, truing.

You should also take a look at the tires you are running an the pressure in those tires. I guess in the ebike world I'll learn a lot more about wheel differences under load and torque and how that differs from just plain old human pedal power.

 

[johnrobholmes]

Most spokes failures are due to stress at the elbow caused by unloading when the tire in the vicinity of the spoke pushes against the ground or an obstacle (e.g. pothole). Spoke nipples can loosen if the spoke becomes slack, effectively loosening the rest of the wheel and increasing the vulnerability of the remaining spokes. High quality wheel building practice reduced these risks by "stress relieving" spokes (momentarily pulling on them hard enough to stress the elbow past its elastic limit) and applying proper (high) tension to them.

Spokes do not generally stretch (undergo plastic deformation) in use. Normal wheels, even with what feels like high tension, have spokes at about 1/3 yield stress. This stress does not increase much when the wheel hits an obstacle (10% is the number that comes to mind - see Brandt's The Bicycle Wheel for more on this). Spokes that have not been stress relieved can loosen as the elbow bends to fit the shape of the hub flange. The nipple can unscrew, though not if the spoke remains in tension. Also very thin butted spokes can twist and deform when you turn the nipple, and will elongate at the same time.

Brandt recommends very high tension: tightening spokes to the point that the rim begins to deform, then backing off only a little. Cheap or ultralight rims (the race rims dogman mentioned?) might be too weak for this approach, but quality rims designed for durability will take high tension without a problem. If in doubt, the rim manufacturer should have a recommended maximum spoke tension, though it can be hard to track down.

I rarely have any trouble with my wheels - they stay true from the first ride and I can count the number of spokes I have broken on one hand, despite a good deal of hard mountain bike riding in the pre-suspension days. I attribute this to conservative choices in parts (durable rims, 32 or more high quality spokes) and careful wheelbuilding or checking (stress relieving, plus retruing and tensioning if necessary) of factory wheelsets.

That said, I don't own any hub motors. Of course the shorter spokes are less springy, making them more likely to go slack and cause problems. I also have to wonder whether poor quality spokes are used in some hub wheels. Even with the challenges of hub wheels (weight and less spoke springiness), I have to assume that most spoke failures are due to poor materials or build quality.

All good info here. A wheel shouldn't break in if built properly.

 

[liveforphysics]

If you want a look at how much abuse a spoked wheel can handle, watch around the 10sec mark of this video. I hit the pause button about 10 times between 9sec to 11sec, and you can watch the wheel wad-up, unload, deflect into an oval, then bend to the side, then straighten out.

425ft-lbs of torque at that rear wheel, and it still has a hub left in it after loads of abuse (though it has needed half a dozen new spokes since I've owned it).

http://vimeo.com/23752461

 

[Stevil_Knevil]

I wonder, does the amount of spoke flex determine how f a r the shoe will be thrown?

 

[MadRhino]

I wonder, does the amount of spoke flex determine how f a r the shoe will be thrown?

Nope, only how hot the curry.

 

[Ykick]

Most spokes failures are due to stress at the elbow caused by unloading when the tire in the vicinity of the spoke pushes against the ground or an obstacle (e.g. pothole). Spoke nipples can loosen if the spoke becomes slack, effectively loosening the rest of the wheel and increasing the vulnerability of the remaining spokes. High quality wheel building practice reduced these risks by "stress relieving" spokes (momentarily pulling on them hard enough to stress the elbow past its elastic limit) and applying proper (high) tension to them.

Spokes do not generally stretch (undergo plastic deformation) in use. Normal wheels, even with what feels like high tension, have spokes at about 1/3 yield stress. This stress does not increase much when the wheel hits an obstacle (10% is the number that comes to mind - see Brandt's The Bicycle Wheel for more on this). Spokes that have not been stress relieved can loosen as the elbow bends to fit the shape of the hub flange. The nipple can unscrew, though not if the spoke remains in tension. Also very thin butted spokes can twist and deform when you turn the nipple, and will elongate at the same time.

Brandt recommends very high tension: tightening spokes to the point that the rim begins to deform, then backing off only a little. Cheap or ultralight rims (the race rims dogman mentioned?) might be too weak for this approach, but quality rims designed for durability will take high tension without a problem. If in doubt, the rim manufacturer should have a recommended maximum spoke tension, though it can be hard to track down.

I rarely have any trouble with my wheels - they stay true from the first ride and I can count the number of spokes I have broken on one hand, despite a good deal of hard mountain bike riding in the pre-suspension days. I attribute this to conservative choices in parts (durable rims, 32 or more high quality spokes) and careful wheelbuilding or checking (stress relieving, plus retruing and tensioning if necessary) of factory wheelsets.

That said, I don't own any hub motors. Of course the shorter spokes are less springy, making them more likely to go slack and cause problems. I also have to wonder whether poor quality spokes are used in some hub wheels. Even with the challenges of hub wheels (weight and less spoke springiness), I have to assume that most spoke failures are due to poor materials or build quality.

All good info here. A wheel shouldn't break in if built properly.

Isn't there some settling and/or alloy metal deformation that goes on with regard to the hub spoke holes and flange and where spoke nipples meet the rim?

Probably not on a well built eyeletted rim like you guys can produce - but the standard China Kit rims seem to need repeated tensioning for at least 'few hundred miles.

 

[johnrobholmes]

There shouldn't be any metal deformation at the nipple/ rim juncture. If there is, the deformation will continue indefinite until the metal fatigues or work hardens. Any deformation at the hub/ spoke would be due to crappy hubs (not common) or a wheel that wasn't built properly.


The common causes of spoke deformation are due to the spoke bending to the proper angle (when it is not set when the wheel is built), or the bend of the spoke giving way because the hub flange was too skinny and washers were not used. With proper spoke head shimming and cold setting, a wheel should last thousands of miles.

 

[ZOMGVTEK]

I'm nearing 2,000 miles on my Golden Motor hub, and I never trued the wheel or tightened the spokes. I smash into potholes all the time at 20-40 too.
I only have two broken spokes, but they're bent and pulled out of the wheel from a impact.

Its common to need to true the wheel often?

 

[ejonesss]

i was wondering if.

1. thicker spokes.

2. solid wheel instead of spokes (more expensive since either solid wheel or a filler slab has to be machined.

would work to prevent spoke breakage ?

 

[liveforphysics]

i was wondering if.

1. thicker spokes.

2. solid wheel instead of spokes (more expensive since either solid wheel or a filler slab has to be machined.

would work to prevent spoke breakage ?

Thinner spokes stretched tighter is the key to keeping a spoked wheel together IMHO.

 

[MadRhino]

i was wondering if.... solid wheel instead of spokes (more expensive since either solid wheel or a filler slab has to be machined.

would work to prevent spoke breakage ?

Of course, if you don't have any spokes, you are very unlikely to break one
Yet if you bend it, you are in deep sh*t truing it.

 

[liveforphysics]

I've got many flights of stairs and many unexpected single track rocks/logs hit with my tiny roadbike wheel laced to a hubmotor with these spokes laced and tightened to a point I think the wheel might just implode if you snipped a spoke.

http://www.sapim.be/spokes/butted/super-spokes

The wheel is staying dead-nuts true, dispite having a >200lbs rider on a rigid 4340 cromo fork in a rigid roadbike on tiny skinny tires at 100psi intentionally taking bigger impacts on a regular basis than many of you may ever take by accident.

Going to small spokes stretched very very tight was also what it took to finally make a rear wheel survive multiple races on deathbike.

 

[ejonesss]

the problem i am seeing is the spokes break off at the elbow and i think it is due to the back and forth torque of starting and stopping with disc brakes.

doing a lot of start and stop electric riding on dumpster rummaging scrap metal runs and yard sale runs and a spoke snaps once a week.