Bolt failure - damage

Hi there - first time post so please be gentle.

I am looking for a bit of advice before I start to sort a problem. I did not build but bought as a new bike.

The bike has only done 62 road miles and is built around a "cloned QS205" and "Sabvoton 72060 Controller". However soemthing has failed resulting in a lose bolt which has caused the cable damage in the photo. The bike clearly no longer operates.

The bolt that has caused the damage is loose and just moves in and out freely but will not come out completely so may have a nut or some other retainer behind.

Any suggestions on what has caused this? Is this a major repair?

Several of the other bolts were loose so is this a build problem.

Thanks for any help or sugegstions.

https://endless-sphere.com/forums/download/file.php?mode=view&id=255169

Hi David
The bolt looks like a rotor bolt... Usually they are just threaded into the side plate of the motor, ie. into the aluminium around the hub. If it's loose but won't come out, it sounds like the threads are damaged, it might come out with a bit of force. Not too much mind you I could be wrong!
As for the cable damage, there is definitely a severed phase wire, but there may be hall sensor wires that are broken as well. If you have enough cable to play with, then some cable splicing should fix it up, fiddly but easy.
If however if it is very close to the axle and there is not enough wire to play with, then this is a much bigger job a you will have to open up the motor, pull all the cable out, then pull the fresh cable through and resolder it all up. Quite the ordeal for a nicked wire. More pics might help.
K

Thanks K

The bolt just pulled out this morning. He are some more photos.

The bolt is covered in alloy which suggests the threads have been destroyed. It also looks like some spacers have been used which may not be up to the task as there is a lot of movement in the disc now with just one bolt removed.

There should be six rotor bolts. With one removed, the disk should still feel pretty secure. Since it is wobbling, it is likely that all of the bolts are loose which suggests that they and weren't tightened down properly to begin with and also weren't installed with thread locking compound. I don't see any on that bent bolt. You are going to have to remove the motor to fix the wiring and so forth. When you do that, you will need to inspect the other five bolt holes to see if they can properly secure the remaining five bolts. If so, you should tighten them down and use thread locking compound. You should also look into repairing the threads in the hole where the one bolt came completely out. If you don't repair that bolt, I'd make it a point to re-check the remaining five bolts a bit more regularly than normal.

Hi David, this is quite a common issue, brake rotor bolts loosening and then freying you cables.
As said above ... Get some threadlock, such as a loctite medium strength.
You will have to remove the wheel to re-atached all your wires.
There maybe enough exposed wire coming out of the motor to be able to crimp the wires back together using a crimping tool and a few different size 'crimping butt connectors'. Crimping tools are cheap and so are the butt connectors that you will crimp. This removes the pain of try to solder everything back together that i would not recommend due to the short wire lengths and tricky location.
If you are worried anout removing the wheel, photograph each side of the axle and dropout areas of the bike so you know where each spacer goes when reassembling. Obviously make sure there are no exposed wires and everything has been insulated once crimped. Most people would use shrink tubing which can be slid onto a wire before you crimp the wire back together. I often forget to put the shrink tube in place , so i prefer to use 'self amalgamating tape'. Its a rubber tape that bonds to itself. You have to stretch it to twice its length before wrapping it around the exposed wires/crimps. It is waterproof if wrapped tightly and of course electrically insulating. Its also not sticky and easy to remove with scissors.

This kind of thing is a right of passage in the ebike world. I hope this helps you.

Thanks all - rite of passage well and truly taken!

Even more annoying as only done 60 miles over the last couple of months and the builder has basically said not his issue as I should have checked the bolts. Great customer service....not!

I could attempt myself but there was a electric transport shop 6 miles away so just dropped off there. The technician thinks he can repair and hopefully no damage to the motor or controller. He also expressed surprise and concern that there was no thread lock on the bolts especially as it is a 40+ mph off roader!

As you say lesson learned.....the hard way although tempted to send the repair bill to the builder with an appropriately worded letter. I will certainly not drop it if there is more damage than just the bolt and cable.

A couple of things to keep in mind during the repair/reassembly. The extra silver spacers used in this set up subject the bolts to different forces that without them (bending rather than shearing). You should replace them with decent quality bolts. Also, it looks like one of the axle spacer washers, the one against the axle nut, should be on the inside of the dropout to protect the frame, instead of being on that side of the torque washer.

What kind of motor is it? Maybe the builder had to add spacers, etc. to get it to fit into the fat frame, and cable clearance got impacted.

davidmt said:

Even more annoying as only done 60 miles over the last couple of months and the builder has basically said not his issue as I should have checked the bolts. Great customer service....not!

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Yes, you should have checked them. But no, they shouldn't have come loose. The reason you check the bolts is because it's a safety issue and it isn't worth risking that other people don't do their job correctly - and clearly they did not.

If you are going 40+ mph, you should probably have a regular safety checklist. That said, even slower 25-ish mph riders like myself should do regular safety checking. It is easy to get complacent.

It looks to me like the bolts weren't long enough and came loose because not enough threads were engaged into the hub motor shell. With all those spacers you may need longer bolts. They should be screwed into the hub about 1/2". You should be able to use that loose bolt to check that. If the builder used bolts that were too short, I'd push back on him about who is responsible.

If I were you I'd add some spacers to the disk brake caliper and remove one of the hub spacers.

www.recumbents.com said:

It looks to me like the bolts weren't long enough and came loose because not enough threads were engaged into the hub motor shell. With all those spacers you may need longer bolts. They should be screwed into the hub about 1/2". You should be able to use that loose bolt to check that. If the builder used bolts that were too short, I'd push back on him about who is responsible.

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Agreed on all points perhaps excepting that I still think that the lack of thread locker is contributory to the loosening. But yes, given how thick those spacers are, those bolts may be shorter than they should be.

I think otherwise: maybe they are too long, and were forced stripping the thread because they would't sit on the rotor.

MadRhino said:

I think otherwise: maybe they are too long, and were forced stripping the thread because they would't sit on the rotor.

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Eyeballing it, I don't think so. But eyeballing it isn't a very good method. Measuring is better. :^)

I agree that it is something that should be checked. Too long certainly could be the ultimate cause.

The worst is when the bolt breaks off and some is still left inside the hole.
I got a rack mount thats like that on the rear dropout.

EZ-outs when they break off. They're aren't so easy to use but will work.

Thanks all for the feedback. I have challenged the original builder over the comments about no thread lock and length of bolts etc and he has actually admitted that he just installed the complete unit from his Chinese supplier without checking and was a little hasty in refusing warranty .

Probably not something I would have admitted on email but basically unless he covers the full repair costs I will be taking further action. He is now saying I should not have given it to another builder!!

I have shared some of the comments and suggestions from this thread with the technician current doing the repair who has suggested he will rewire and install titanium bolts with thread lock - he was confident he could repair so thank again for all your input. He will also be giving the bike a good going over!

Ps - this is the bike!

I see no point in using titanium bolts. High tensile steel bolts would be as strong or stronger. No need for the weight savings and added expense of titanium in this application.

I'd be checking the front rotor as well (then every other connection)

Once he refused warranty, he effectively gave up his right to complain about you going to someone else. Good luck extracting a refund or payment for repairs. Someone willing to do sloppy work on a bike like this obviously intended for more than tooling around the neighborhood and picking up groceries is clearly not conscientious.

davidmt,

What happened to you is the reason I now only buy Shimano Rotors .
( no rotor bolts coming loose on any of my 3 conversions )

When buying a new Shimano Rotor it comes with the following ...'

1) Rotor Bolts that have Quality Locktite

2) A thin metal strip with a tab on it that helps keep the Bolt in place and not loosen up, it fits under the bolts , there are three of them.

I would ... install a New Shimano Rotor before riding your bike again .

I've learned along the way just to loctite everything i work on.... As long as its metal against metal

Standard torx rotor screws are pre/locktite. Screwed to proper torque spec, they never fail nor get loose. I never had a loose rotor in 20+ yrs riding DH bikes very hard.

I have now had the technician's report which is not good!

Besides the obviously failure and damage which you have seen he has confirmed that the rear motor and axle is much larger than the bike frame was designed for.

The dropouts on the frame have been designed for a standard 9mm quick-release axle this means that the anti rotation washers that have to be fitted to the rear hub will not fit into the frame. This in turn will mean that the axle is free to spin which will pull and damage the control cables beyond repair and could result in the rear wheel coming loose from the frame.

The frame is a standard fat bike frame imported from China that was not designed to be fitted with this style of motor in which the frame has had no reinforcement in the dropouts, disk brake mounts and or the headtube all of which is woefully under the specifications for an E-Bike.

They are of the opinion that this bike is unfit/unsafe to be used as a bicycle and any of the points raised could cause serious injury to the person/s using it and even the people that maybe around the bike when the failure happens.

I am not sure how easy it would be to uprate and correct the failings noted above but they certainly should not be down to me to resolve.

I have therefore rejected the bike and requested a full refund - disappointingly the builder has gone very quiet!

I will start naming and shaming and commence legal action unless he sorts this mess out!!

Thanks again.

I would have expected that the rear dropouts would have been been augmented by the addition of torque arms - especially since the frame appears to be aluminum and you are running the motor at a fairly high power level.

I don't have enough experience/knowledge to say anything about the headtube or disk brake mounts..