Spokes and me

[allen-uk]

When I broke a spoke on my Wisper 905 last autumn, members predicted that it wouldn't be the last.

It wasn't.

Two things. One, when I was riding along familiar roads/hills in the half-hour BEFORE the spoke went, I was very conscious of reduced power. Then the spoke went, I took it to the bike shop for repair, and picked it up the next day. And the power (no, the battery hadn't been charged at all) was back to normal.

So is that usual, i.e. that duff spokes will give reduced power?

Two, why me, why me? Is it Wispers in general, me being heavy (115kg), or the rotten roads around NW London? What does for me spokes? The man in the bike shop said he thought it was torque, and that having more spokes might help.


Allen.

 

[Mussels]

I've had both (905 & 906) back wheels rebuilt by SJS with Rhyno rims and had no problems since. The spokes are much better now than they were when I got my 905 but are still a weak point.
I don't think it's anything to do with the motor as the 906 has the motor in the front and I've had no problem with the front wheels on either bike.
As for the power being affected I think that's just a coincidence.

 

[flecc]

I think there may be more than one contributory factor here Allen.

First your weight as you mention, though that will only play a part if there are other factors at work.

Second, the motor torque as well as rider's, all on the same wheel.

Third, the wheel build pattern influences spoke failure (see below*).

Fourth, the nature of your disability giving an uneven and possibly arrhythmic pattern of forces.

I've known of a number of cases where some owners of certain e-bikes have regular spoke failures while others don't, even where weights and usages are similar. Frequently a wheel rebuild solves or greatly reduces the problem for the afflicted owners, indicating an original flaw in the build.

* Member JamesC drew attention to the way in which the build pattern can affect the spoke failures. The eZee Torq 1 wheel was particularly prone to spoke failure on certain owners bikes but never on others and was the subject of a long post by him.

N.B. Post crossed with Mussels.

 

[allen-uk]

Thanks for the ideas. The imbalanced pedalling might not help - hadn't thought of that. I DO pedal with my plastic leg, but without a calf muscle it obviously isn't as powerful as my proper leg, and I do have a crank shortener fitted on the plastic side, so again even I was pushing as hard, the rotation would be more on the right than left. Interesting thought!

My bike shop man said that although he thought more spokes would help, he couldn't fit them as the motor/hub was one unit, and had a set number of spoke holes. Any (easy) way round this?

Allen.

 

[flecc]

I don't think more spokes would help and it wouldn't be practical to add any. Other e-bikes have 36 spokes on their motor wheels, includig the Wispers that aren't giving trouble. Even with the factors mentioned, the wheel should not give trouble.

A skilled rebuild of the wheel is much more likely to provide a solution as owners of other troublesome wheels can confirm. Even with the best make e-bikes and much effort put into quality control, factory wheel builds often fall a bit short and need correction.
.

 

[stevebills]

I think Tag wheels are the answer and what a shame they went bust

They’ve stood up to everything that we’ve thrown at them so far. The broad rim and thick lip mean we’ve haven’t had any pinch flats yet, even when we’ve run double wall tyres down to 15psi. You can still whip tyres on and off them OK though.

They come in full range of axle types and widths and the DT Star Ratchet freehub picks up really quickly too. The downside is that these things are tremendously heavy – 4.157kg/9.16lbs to be exact (1.952kg/4.3lb front and 2.205kg/4.86lb rear). That’s 1.25kg (2.75lbs) heavier than a conventional crush proof wheelset like Halo’s 48 spoke SAS set and means they totally dominate the bike.

 

[Wisper Bikes]

When I broke a spoke on my Wisper 905 last autumn, members predicted that it wouldn't be the last.

It wasn't.

Two things. One, when I was riding along familiar roads/hills in the half-hour BEFORE the spoke went, I was very conscious of reduced power. Then the spoke went, I took it to the bike shop for repair, and picked it up the next day. And the power (no, the battery hadn't been charged at all) was back to normal.

So is that usual, i.e. that duff spokes will give reduced power?

Two, why me, why me? Is it Wispers in general, me being heavy (115kg), or the rotten roads around NW London? What does for me spokes? The man in the bike shop said he thought it was torque, and that having more spokes might help.


Allen.

Hi Allen we don't seem to have as many broken spokes since we changed to a better grade of spoke about two years ago.

I regularly ride my XC tourer and have never had one go (I am 125KG). I do have my bike serviced regularly when the spoke tensions are adjusted, this may be helping. Our dealers offer a free spoke service after 300 miles, I am sure this makes a difference too.

A single broken spoke should not make any noticeable difference to power

Have you had many go?

All the best

David

 

[allen-uk]

Hello David.

Two. One after about 400 miles, one last week (after about 800).

My bike shop has serviced the bike twice (new brake pads etc!) and tensions the spokes - maybe he's over-tightening them.


Allen