What's the deal with frequently broken spokes?

[technopedler]

As I understand it, broken spokes is quite a common problem for e-bikes with hub motors. Do you get the same issue with motors that are in the pedal crank like Bosch? I've been using a non-electric bike for years in Central London for commuting and never had a single broken spoken. I don't want the hassle of a wheeling a bike home/work when it's a 10 mile commute.

Thoughts on this?

TIA

 

[anotherkiwi]

3600 km without a broken spoke on my Chinese built Mxus wheel. I put that down to tightening them before riding then checking after 100 km, 2 or 3 were quite loose so got re-tightened.

 

[Rohloffboy]

When I first had my Rohloff igh built into a 26" Wheel back in 2004, the advice given was to use Plain Gauge Spokes as they would be stronger for my Touring Bike.
This proved to be totally wrong, as on my first tour that year, a couple of Spokes broke, in fact one even broke when the bike was not being used overnight!

Luckily I had a few spare Spokes stored inside the handlebars, like you do!

Anyway upon return from the tour, I had the Plain Gauge Spokes, replaced with Double Butted Spokes, and the problem has never returned.

The Stress on the Spokes from a electric hub motor will be quite great due to the increased torque, although diminished slightly with a larger wheel, say 27.5" instead of 26".

You can get Rims that are drilled specifically for IGH's my thinking is that such rims would be better suited to Ebike's with Hub motor as well, and maybe they are used in anycase.

At the end of the day, whether it be IGH or electric Hub motor, the Spokes are going to be shorter that that of a regular derrailure gear bicycle, a longer Spoke will have more give, even more so if Double Butted.

I don't think that you would have any problems with Spokes on an Ebike with a Hub motor, providing the right choice in Spokes and Rims has been made in the first place.

 

[technopedler]

When I first had my Rohloff igh built into a 26" Wheel back in 2004, the advice given was to use Plain Gauge Spokes as they would be stronger for my Touring Bike.
This proved to be totally wrong, as on my first tour that year, a couple of Spokes broke, in fact one even broke when the bike was not being used overnight!

Luckily I had a few spare Spokes stored inside the handlebars, like you do!

Anyway upon return from the tour, I had the Plain Gauge Spokes, replaced with Double Butted Spokes, and the problem has never returned.

The Stress on the Spokes from a electric hub motor will be quite great due to the increased torque, although diminished slightly with a larger wheel, say 27.5" instead of 26".

You can get Rims that are drilled specifically for IGH's my thinking is that such rims would be better suited to Ebike's with Hub motor as well, and maybe they are used in anycase.

At the end of the day, whether it be IGH or electric Hub motor, the Spokes are going to be shorter that that of a regular derrailure gear bicycle, a longer Spoke will have more give, even more so if Double Butted.

I don't think that you would have any problems with Spokes on an Ebike with a Hub motor, providing the right choice in Spokes and Rims has been made in the first place.

I've had my custom built e-bike for a couple of months (not used for all of that time). The hub motor is pretty big so it uses quite small spokes that are 12 gauge. They are Plain Gauge variety. However, I've had 3 broken spokes in the space of that time. I'm loathed to pour extra money into this as I feel this custom e-bike isn't good value for money. Having read and spoken to people I hear that a crank motor is better and much less harsher on spokes. However, if it feels like I can get my problem sorted for not much extra hassle then I would certainly give that a try. I'm not that knowledgeable on spokes and wheels so please let me know exactly what brand of wheel and spokes I would need to improve the reliability.

Many thanks

 

[KTM Bike Industries UK]

Plain gauge spokes are cheaper and heavier, but not stronger or better. Double Butted will be better, they give a bit more stretch and therefore build a better wheel.

 

[Deleted member 4366]

After working with them for 7 years, I've come to this conclusion. The Chinese ebike producers use 13g spokes, i guess because they thought that they need to be stronger. Add to that the factory workers on piecework, so they have an incentive to bang the wheels out fast instead of right to get the problem where bikes are being sold with incorrectly tensioned spokes that are too inelastic to deal with that. The final nail in the coffin is that the bike owners don't know that they have to check their spoke tension, so the spokes come loose and break.

The overall situation is compounded a bit by the odd batch of dodgy spokes.

If you build your own wheel with properly tensioned 14g spokes, you won't get any problems. If you have a ready-made wheel with 13g spokes and you keep them properly tensioned, you probably won't get any problems.

Taking a step back, despite everything about breaking spokes, you're more likely to suffer a cassette, derailleur or chain break problem on a crank-drive bike, which would leave you stranded than you would be stranded by a spoke problem. There's other reliability issues with crank-drive bikes, like controllers packing up and gear failures in Bafang BBSxx motors and bearing failures on Bosch and Kalkhoff Impulse motors.

I'd always pick a hub-motor for commuting. Not only are they more reliable, but they give you a much more pleasant and relaxed ride. Keep your crank-drives for sporting use, which is their forte.

 

[Deleted member 4366]

I've had my custom built e-bike for a couple of months (not used for all of that time). The hub motor is pretty big so it uses quite small spokes that are 12 gauge. They are Plain Gauge variety. However, I've had 3 broken spokes in the space of that time. I'm loathed to pour extra money into this as I feel this custom e-bike isn't good value for money. Having read and spoken to people I hear that a crank motor is better and much less harsher on spokes. However, if it feels like I can get my problem sorted for not much extra hassle then I would certainly give that a try. I'm not that knowledgeable on spokes and wheels so please let me know exactly what brand of wheel and spokes I would need to improve the reliability.

Many thanks

You need to go down to 14g. It's counter-intuitive, but the solution to breaking spokes is to fit weaker ones, not stronger. 12g is too heavy for a bike rim.

If the holes in the motor are too big, you might need to use spoke washers to stop the nipples from pulling through, though I've never needed to use them.

 

[technopedler]

You need to go down to 14g. It's counter-intuitive, but the solution to breaking spokes is to fit weaker ones, not stronger. 12g is too heavy for a bike rim.

If the holes in the motor are too big, you might need to use spoke washers to stop the nipples from pulling through, though I've never needed to use them.

That is interesting. I shall ask my local bike shop to fit 14g double butted spokes to the entire wheel. Any particular brand or shop to buy them from? I could ask my cycle shop to supply but I'd rather go for quality ones myself.

 

[KTM Bike Industries UK]

That is interesting. I shall ask my local bike shop to fit 14g double butted spokes to the entire wheel. Any particular brand or shop to buy them from? I could ask my cycle shop to supply but I'd rather go for quality ones myself.

DT or Sapim. Don't bother with anything else.

 

[technopedler]

DT or Sapim. Don't bother with anything else.

Something like this? https://www.jejamescycles.com/sapim-race-double-butted-14-16g-spokes-silver.html?gclid=CjwKCAiA693RBRAwEiwALCc3u4gcFMXW1R2K1WYepMWo6UIlz1ctRTGVd_8XUn48vmx-MxuuS9C70hoCTroQAvD_BwE

The double butted one has two ratings 14G and 16G. Assuming the 14G is for the ends and the 16G is for the middle. Is this the correct type of spoke?

 

[KTM Bike Industries UK]

Something like this? https://www.jejamescycles.com/sapim-race-double-butted-14-16g-spokes-silver.html?gclid=CjwKCAiA693RBRAwEiwALCc3u4gcFMXW1R2K1WYepMWo6UIlz1ctRTGVd_8XUn48vmx-MxuuS9C70hoCTroQAvD_BwE

The double butted one has two ratings 14G and 16G. Assuming the 14G is for the ends and the 16G is for the middle. Is this the correct type of spoke?

Yes, that's correct. Just make sure you get the correct length and remember a well build wheel with bad components, is better than a badly built wheel with good components.

Ideal is a well built, evenly tensioned wheel, built with good components.

 

[Ocsid]

Why is it believed the torque on a hub drive will be greater than on a crank drive; the same torque is needed for the bike to have the same performance. [given same size wheels masses etc]
If hub drive spokes fail more frequently my suspicions would be it is that the spokes here are shorter so less elastic?

 

[technopedler]

Yes, that's correct. Just make sure you get the correct length and remember a well build wheel with bad components, is better than a badly built wheel with good components.

Ideal is a well built, evenly tensioned wheel, built with good components.

I'm not sure what length I need so I can measure the old spoke. Where do I measure from and do I include the end bit that unscrews? This is what my spokes look like: http://www.ebikespokes.com/images/Spokes/Spokes_ebike_G10_1.JPG

Why is it believed the torque on a hub drive will be greater than on a crank drive; the same torque is needed for the bike to have the same performance. [given same size wheels masses etc]
If hub drive spokes fail more frequently my suspicions would be it is that the spokes here are shorter so less elastic?

To be fair, I'm no expert. It's just what I've read from my Googling. It feels as though a hub motor is applying more force on the spokes as it is directly attached to the spokes rather than the force on the spokes if it was torque applied via a chain (via a crank motor). I'm only guessing (with a little bit of logic).

 

[anotherkiwi]

Extra un-sprung weight on spokes that are not at correct tension. IGH bikes break spokes too if they aren't tight.

Torque figures for 250 W crank drives are almost always given as higher than torque for 250 W hub motors. Whatever the number it has to go through the hub, motor or other, to be applied to the road.

 

[KTM Bike Industries UK]

I'm not sure what length I need so I can measure the old spoke. Where do I measure from and do I include the end bit that unscrews? This is what my spokes look like: http://www.ebikespokes.com/images/Spokes/Spokes_ebike_G10_1.JPG

https://www.sheldonbrown.com/spoke-length.html

and remember if you wheel is dished (which is probably is) you'll need 2mm shorter on the drive side than on the non drive side.

If you're worried about snapping spokes, pay someone to build the wheel.

 

[BornAgainCyclist]

DT swiss alpine 3 are serving me well with a Q128C and 535 700 rim if looking for the same. The dishing advice ties into my experiences as well.

 

[technopedler]

Okay, so I've measured the spoke length and it's 176mm. I've looked everywhere for Sapim double butted 176mm spokes but it doesn't seem like the do these. I've looked for other brands but 176mm seems to be very much shorter than what is generally available. The only ones I've found are generic ones that are plain gauge. And thus they might not be any better than what I have right now.

I need 36 spokes in total. Any recommendations? I've included a picture of the back wheel to help show what I'm working with. TIA

 

[BornAgainCyclist]

Rose bikes? Dt swiss alpine 3? How many crosses?

 

[Deleted member 4366]

Whilst those spokes might be better quality. I've always used the cheapest plain 14g ones that I can find, and I never had any problems.

 

[anotherkiwi]

Okay, so I've measured the spoke length and it's 176mm. I've looked everywhere for Sapim double butted 176mm spokes but it doesn't seem like the do these. I've looked for other brands but 176mm seems to be very much shorter than what is generally available. The only ones I've found are generic ones that are plain gauge. And thus they might not be any better than what I have right now.

I need 36 spokes in total. Any recommendations? I've included a picture of the back wheel to help show what I'm working with. TIA

View attachment 22543

https://www.ginkgo-veloteile.de/ginkgoshop/en/Wheel-Accessories/Spokes-and-Nipples/butted-spokes/Sapim-Strong-silver-60-151mm-J-bend.html