I break the rear fork...

New E-bike assembled, all unrefined, but operative, first test, drive 10 km to a nearby location, everything nice... ho look! a medieval bridge with absurd elevation and bumps, lets test the climbing power... brrrrr!! Pum!.... ho shit...

The rear wheel jump out, motor stop working and LCD displays error related to trottle, I guess the cables twisted inside... I hope I can open the thing and re-solder them. There's chunks of aluminium teared off, bike it's a not cheap Scott double conated alu alloy, guess it wasn't enough...

I have to walk the 10 km back to my house dragging the not light e-bike.

I manage to put back the wheel, but it's obvious that the fix lacks some material and its weakened, also imposible to found spares for a rear fork that don't cost more than the bike itself nowadays.

Should I just purchase another second hand bike made of heavy iron this time?

Can I patch up the bike with one of those reinforcement brackets?
They expect me to pay 60 bucks for this piece of shit:



I also have a 3D printer and I'm considering to print a double solid piece from the strongest shitty plastic I have, PETG with 100% infill and 3cm thick, I'm used to make high power slingshots from that material with just 3mm wall thickness and 20% infill, can a piece like that stands the 100NW of the motor in a climb? (PETG will flex before break)

Steel is real, now you know why. Aluminum is very popular for frames, probably cheaper and easier to shape and weld by robots in mass quantities. Also it’s lighter which is a great selling point but it is not good for Ebike frames that use hub motors. Also it’s a one crash or incident frame that is usually needs of replacing when an uh-oh happens. I don’t think the 3d printing will work for this twisting action and you may rip your wires out again. I use atomic carbon fiber infused PTEG and it will never snap just bend. It’s $50 a roll vs $20 for cheap PTEG that snaps even at 100% infill. You may be able to do a sister repair with a steel plate and bolts and not need the torque arm but your axel might not be long enough, 1/8” is sufficient if a tight fit.

Couple things here caught my attention:

Debunker said:

The rear wheel jump out, motor stop working and LCD displays error related to trottle, I guess the cables twisted inside... I hope I can open the thing and re-solder them. There's chunks of aluminium teared off, bike it's a not cheap Scott double conated alu alloy, guess it wasn't enough...

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Guessing you are running a rear dd motor without a reasonable torque arm? Some quick and easy searching on this forum shows you that is not recommended.

Debunker said:

Should I just purchase another second hand bike made of heavy iron this time?

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If you do, make sure to use a good torque arm even with a steel frame.

Debunker said:

Can I patch up the bike with one of those reinforcement brackets?
They expect me to pay 60 bucks for this piece of shit:

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Maybe, depends on how much damage on the dropout/swingarm. You should post some good photos so we can make better suggestions for you.

Debunker said:

this piece of shit

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That actually looks like a very good one. :thumb: Compared to some real shit (the cheap ones) that are out there. If you would have had that installed (correctly) you wouldn't have had this big problem.

Debunker said:

I also have a 3D printer and I'm considering to print a double solid piece from the strongest shitty plastic I have, PETG with 100% infill and 3cm thick, I'm used to make high power slingshots from that material with just 3mm wall thickness and 20% infill, can a piece like that stands the 100NW of the motor in a climb? (PETG will flex before break)

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Flex. You do not want it to flex; any rotational movement there is the problem. You want it to be as firm and rigid and stable as possible, to keep the axle from rotating at all when bolted to the dropout. Don't waste your time trying to make one out of plastic. :?

Debunker said:

Can I patch up the bike with one of those reinforcement brackets?
They expect me to pay 60 bucks for this piece of shit:

Click to expand...

Someone is looking for suckers, you can find this torque arm on aliexpress for $10, max.