Wisper spokes

[allen-uk]

My 3rd broken spoke today.

1st at 300 miles, 2nd at about 800, 3rd at about 1100.

Flecc reckoned it could (in part) be the slightly disproportionate pedalling action caused by the one plastic leg - obviously although I PUSH with the left leg, the lack of calf muscles etc. means that it gets less power than the right-hand side.

Anyway, that's one theory. Are rear-hub ebikes particularly prone to popping spokes? Or is it Wispers? Or is it my weight (at 115kg its way over the recommended rider-weight, even though David at Wisper claims to out-rank me in this respect).

My bike shop, who repair the spokes for a nominal fee, is old and trusted, and checks and adjusts the whole wheel, of course, as well as the broken item. Would it help if I 'pinged' each spoke once a fortnight, listening for any dull-sounding ones?


A.

 

[steveindenmark]

I watched a video on Youtube recently where a top wheel guy in the USA said using the sound of a spoke to gauge the correct tension is nonesense. A bit like kicking a car tyre.

Even he used a tool to measure the tension of the spokes.

An interesting thought.

Steve

 

[Oxygen Bicycles]

My 3rd broken spoke today.

1st at 300 miles, 2nd at about 800, 3rd at about 1100.

Flecc reckoned it could (in part) be the slightly disproportionate pedalling action caused by the one plastic leg - obviously although I PUSH with the left leg, the lack of calf muscles etc. means that it gets less power than the right-hand side.

Anyway, that's one theory. Are rear-hub ebikes particularly prone to popping spokes? Or is it Wispers? Or is it my weight (at 115kg its way over the recommended rider-weight, even though David at Wisper claims to out-rank me in this respect).

My bike shop, who repair the spokes for a nominal fee, is old and trusted, and checks and adjusts the whole wheel, of course, as well as the broken item. Would it help if I 'pinged' each spoke once a fortnight, listening for any dull-sounding ones?


A.

Hi Allen,

David is using a decent quality thick 13G stainless spokes on his bikes so at the weight of 115kg it shouldn't be a problem really. Can I ask you where do they break, is it at the nipple side or by the hub flange?

all the best
Andrew

 

[allen-uk]

Steve: tak for tip.

Andrew: first two at the nipple end, this one at the hub (which might make it easier to replace!)

Allen

 

[Oxygen Bicycles]

Hi Allen,

One more question? On which side of the flange did they break, freewheel side or other flange or maybe both?

 

[Mussels]

I'm pretty hard on spokes and have managed to knacker a few rear wheels, Wisper have been working hard to combat the problem and their wheels have improved a lot. Incidentally I've also knackered the rear wheel on my Alpino and the motor is in the front.
I had a lot of problems with my 905 which lead to lots if research, the more reading I did the more complicated it became, a few things affect spokes breaking. Some are:
Spoke material.
Spoke thickness. (thicker is not always better)
Rim strength.
Tyre pressure.
Construction method.
Change one of those and it affects the others. I've had newly built wheels break in a few miles and a well used bike break soon after I start using it. The only reliable wheels I've had have been built by SJS Cycles using rhino rims, they also noted the SB hubs aren't great to start with.
Recently I bought a bike from a bike mechanic, he was a keen cyclist and had used good parts, after thirty miles of my riding the back wheel sounded like it was going to fall apart.

 

[allen-uk]

Andrew: this is the first 'flange' break, and it's on the same side as the gears.


Mussels: thanks for those ideas. Not sure where to start, but the only one I can really control is tyre pressures, where I am a bit lax (I let them go down a fair way before pumping them back up to 70-ish).

A.

 

[JuicyBike]

3 spokes breaking is not significant Allen, but annoying indeed.
Pinging is valid, unless you have another means of gauging tension.
Hub motors are more prone to breaking spokes, especially if ridden with"pulses"of assist.
On your bike, is it possible to alter the responsiveness of the pedal crank sensor? On our bikes moving the sensor disk towards the pickup can make the motor cut in and out more frequently. This could put more percussive loading into the spokes.
If you can reduce the responsiveness of your pedal sensor it may help... But really, I think you have simply been incredibly unlucky.

 

[allen-uk]

Thanks for the sympathy, Bob!

General question: when 'PINGING' spokes, what are they supposed to sound like? And more to the point, what does a DUFF one sound like?

I've just pinged a few at random, and most are similar, but one responds with a dull 'clumph' sound. Is that the next broken one?

I've just checked Sheldon Brown on adjusting spokes, and his advice is Don't, at least Don't do what I had in mind, which was to only adjust the possibly loose ones. He talks about taking the wheel off, tyre off, all that guff, then working your way carefully around. Sounds like too much for the likes of me.

Allen.

 

[Mussels]

I'd agree that three isn't a lot, at the peak if my problems I was getting daily spoke breakages. How many miles do you get between breaks?

 

[flecc]

I've just pinged a few at random, and most are similar, but one responds with a dull 'clumph' sound. Is that the next broken one?

That's a slack one, the least likely to break.

A perfectly balanced wheel build has all the spokes evenly tensioned and no breaks are experienced.

Many builds though are imperfect, some spokes overtensioned in an effort to correct tension distribution errors at an earlier stage of the build. It's those overtightened ones that snap.

There are also other factors like the build pattern, spokes radial, 2 cross, 3 cross etc., and these are more relevant with disc brakes and hub motors which transmit twist relative to the rim.
.

 

[allen-uk]

Mussels:

1st at 300 miles, 2nd at about 800, 3rd at about 1100.

Any ideas on the 'pinging' question (just above your answer)?

Flecc:

does that mean I should be listening for a much HIGHER-pitched ping when I do my pinging tests, then?

A.

 

[flecc]

Yes, but not too high. Obviously that's difficult to express in writing, but a spoke should not be so rigidly tensioned that it has almost no side movement when you ping it. The aim is that they should all feel and sound the same.

Sheldon's right of course, just tightening odd spokes can never be satisfactory. Altering one or two spokes can mean either having the tensions correct and the wheel out of true, or over-tightening to maintain trueness.

To date your three broken spokes isn't serious though as others have remarked. The wheel can increasingly settle after replacements, breaking frequency then dropping and even stopping, so best be patient for a while yet.
.

 

[allen-uk]

Fair enough, flecc; I'm good at patience.

I supposed what I'm trying to avoid is the inconvenience - as I said earlier, my bike shop only asks £15 a time, but it's getting the bike to him, leaving it there, getting a cab home, etc., etc., which is a pain in the bum.

I shall try and develop my pinging skills in the meantime.


A.

 

[Oxygen Bicycles]

That's a slack one, the least likely to break.

A perfectly balanced wheel build has all the spokes evenly tensioned and no breaks are experienced.

Many builds though are imperfect, some spokes overtensioned in an effort to correct tension distribution errors at an earlier stage of the build. It's those overtightened ones that snap.

There are also other factors like the build pattern, spokes radial, 2 cross, 3 cross etc., and these are more relevant with disc brakes and hub motors which transmit twist relative to the rim.
.

and I agree with Flecc here, the built pattern is very important and has to be carefully selected. i.e on the rear hub motor and the 26'' rim there should be only 2 or 1 cross pattern. With hub motors and the 3 cross pattern the spoke ends are too bent and do not fit straight into the nipple causing the higher tension on the threaded part of the spoke (which is the weakest point of the spoke). Normally 3 cross pattern is the strongest and most recommended for use with disc brakes and hubs that have a ''fairly standard size hub diameter'' but it doesn't work well with hub motors which have a larger diameter of the hub shell.

Apart from the above there might be other factors too like one side of the spokes being tight up more than the other side. (Usually spokes on the cassette, freewheel side have higher tension) This is why the spokes on the gear side are more likely to break.

And lastly with use of disc brakes all braking power goes through the spokes what means that they are all ''pulled'' and then higher the rider's weight the more pressure goes on the spokes, too much of me now

all the best

Andrew
Oxygen Bicycles

 

[allen-uk]

Thanks Andrew.

I'm coming to the conclusion that it's largely down to luck on my part, as I haven't seen other Wisper owners reporting broken spokes (and my 905 doesn't have rear disc brakes).

A

 

[Oxygen Bicycles]

yeap Allen,

If you don't have a discs then you are probably being unlucky. See how it goes in further mileage.

all the best

Andrew
Oxygen Bicycles