Sirocco CD battery rack sheared off, accident waiting to happen!

[Ash21014]

So the other day when my mate was riding my old sirocco CD the metal connectors on the battery rack sheared off, the weight of the battery rack presumably pulling all the wires out of the back which then caused it to fall back hitting the ground, pictures attached. How on earth does this happen? Metal fatigue? How can a solid piece of metal just break off?

 

[chris_n]

Judging by the state of the rest of the bike it has never had any maintenance carried out. One side must have been broken for a long time before the other side gave up having been subject to twice its original loading. If it had been a car it would have failed it's MOT a long time ago.

 

[Ash21014]

It's rarely used anymore so hasn't had tlc in a while, not sure what that has to do with the metal shearing though? He said to me that it started rattling a bit near the start of a ride which was around 100miles, but because the screws become loose and need tightening up periodically it was assumed to be that, but yes I'm assuming one side broke a little before the other.

 

[Deleted member 4366]

I reckon the off-side broke first from either an impact or metal fatigue and then the oscillating twisting force on the near-side broke the welds by fatigue. it's a shame that you never spotted it because the strut would have been easy to repair, but now the consequential damage is far worse.

You can fix the rack with a couple of pieces of steel tube. bash the ends flat and drill holes. You can fix them to the seatpost clamp by using a longer bolt.

It's possible that the electrics will work if you join the corresponding wires. If not, you can use any cheap controller - about £30.

 

[Kuorider]

The seat post looks a bit bent, has the bike had a heavy impact? This may account for the break as the battery would put a fair force on the mounts if the bike was jumped off an edge and landed hard enough to bend this part.

 

[Mike63]

The seat post looks a bit bent, has the bike had a heavy impact?

I had this model bike and the seat post sheared off where it looks like that one is about to shear too.
....before riding it again...change the seat post.

 

[chris_n]

It's rarely used anymore so hasn't had tlc in a while, not sure what that has to do with the metal shearing though? He said to me that it started rattling a bit near the start of a ride which was around 100miles, but because the screws become loose and need tightening up periodically it was assumed to be that, but yes I'm assuming one side broke a little before the other.

Doesn't have anything to do with the metal shearing but both sides didn't snap at the same time. If the bike had been cleaned and maintained it would have been spotted before it became a problem. Riding 100 miles with a bike that is rattling and has screws coming loose can hardly be described as an accident waiting to happen, more like an inevitable consequence of ignoring the obvious. Its like the car driver that needs new discs because he ignored the sound coming from his brakes and the rust all over the wheels.

 

[Ash21014]

The seat post looks a bit bent, has the bike had a heavy impact? This may account for the break as the battery would put a fair force on the mounts if the bike was jumped off an edge and landed hard enough to bend this part.

The bike has only been used on road. The only impact that I can possibly think of was when I received the bike back from Woosh after they had repaired the failed battery and pedal sensor. The end of the battery rack was bent downwards so I couldn't even remove the battery from the bike, which suggests that it was dropped on its back during the repair...

Doesn't have anything to do with the metal shearing but both sides didn't snap at the same time. If the bike had been cleaned and maintained it would have been spotted before it became a problem. Riding 100 miles with a bike that is rattling and has screws coming loose can hardly be described as an accident waiting to happen, more like an inevitable consequence of ignoring the obvious. Its like the car driver that needs new discs because he ignored the sound coming from his brakes and the rust all over the wheels.

Can you please explain how cleaning the bike of some cosmetic rust would have revealed microscopic metal fatigue and prevented the catastrophic failure of the first metal strut? Both sides presumably did not snap at the exact same moment, but clearly if one snapped due to fatigue the other one was already dangerously compromised and could have broken at any moment regardless.

Obviously a bike should be well maintained, however, any lack of maintenance does not excuse an unrelated manufacturing problem. The above poster saying their seat post sheared off suggests a materials issue common to this bike. After all there's no smoke without fire.

Furthermore this is not the only dangerous maintenance-unrelated failure I've experienced with this bike, the front disc brake had to be replaced after it failed without prior warning down a hill, and the throttle lever separated in two resulting in it detaching from the handlebar and me falling off the bike in the middle of the road. More evidence that points to a general lack of poor quality.

d8veh Thanks for your suggestions, but as this is my older backup ebike I will be selling it off for parts after this, I now consider it to be too dangerous to use and after having spent a couple hundred on replacement parts already, I feel spending more money and hours repairing it would be a fools errand. I guess the lesson learned here is, "buy cheap, buy twice".

 

[chris_n]

The bike has only been used on road. The only impact that I can possibly think of was when I received the bike back from Woosh after they had repaired the failed battery and pedal sensor. The end of the battery rack was bent downwards so I couldn't even remove the battery from the bike, which suggests that it was dropped on its back during the repair...

OK so now you are telling us that the rack has previously been bent which is a totally different scenario to what you initially told us. Still the point about maintenance holds as I am sure that if the bike was cleaned and checked regularly the cracks where the bracket was welded to the seat stay would have been visible. The fact that you didn't seem to notice the state of the seatpost suggests that spotting the issue with the rack was never going to happen.
How did the brake disc fail without prior warning? Did the disc shear, cable snap?
As far as a materials issue related the the whole bike goes all of these bikes are made with generic bought in parts, that same front brake and seatpost are on hundreds of other bikes of similar quality.
As you say at the end of your post "buy cheap buy twice"..
There are still far too many external influences to say this rack is an accident waiting to happen.

 

[trex]

How long have you been riding with a seat post like that?
I concur with d8veh's suggestion that the off-side arm broke, that would produce the rattle that your friend heard.
The damage is repairable, contact woosh support for advice.

 

[Ash21014]

OK so now you are telling us that the rack has previously been bent which is a totally different scenario to what you initially told us. Still the point about maintenance holds as I am sure that if the bike was cleaned and checked regularly the cracks where the bracket was welded to the seat stay would have been visible. The fact that you didn't seem to notice the state of the seatpost suggests that spotting the issue with the rack was never going to happen.
How did the brake disc fail without prior warning? Did the disc shear, cable snap?
As far as a materials issue related the the whole bike goes all of these bikes are made with generic bought in parts, that same front brake and seatpost are on hundreds of other bikes of similar quality.
As you say at the end of your post "buy cheap buy twice"..
There are still far too many external influences to say this rack is an accident waiting to happen.

The cable didn't snap and the disc didn't shear, when the brake lever was pressed the brake gave no stopping power at all. The cable moved normally and the calipers appeared to be contacting the disc as normal. Upon further testing I found that the issue was intermittent, sometimes the brake gave full stopping power and other times zero, I believe when this happened there was a bit of a clunking/clicking noise. Not having the expertise or desire to investigate what the failure was I decided the safest thing to do was replace it was a Shimano brake set.