Modded Dropouts Or Naw?

So it would go on the back side, eliminating the need to tap/drill a hole through the existing dropouts.
No, you still need to attach the plates to the dropout as you had described, and would look like your mock up, but with a pinching bolt a the end. Per the examples posted by 99t4, drilling a small hole and slot allows the bolt to pinch the axle.
 
I'm just really nervous about doing this, I'm only 15 and I don't want to die when my custom dropout fails at 35mph.
Good for you for going the DIY route. The bikes of choice around here for 15 year olds are the 20" fat tire folders. They ride around in groups of 3 or 4. They do ok on flat ground, but they're pedaling hard to get up the hills around here. You'd fly right past them with the bike you're planning on.
 
No, you still need to attach the plates to the dropout as you had described, and would look like your mock up, but with a pinching bolt a the end. Per the examples posted by 99t4, drilling a small hole and slot allows the bolt to pinch the axle.
Alright, thanks for the info. With the added plates the axel will never come out. I plan to ride this bike up some pretty steep hills, flat out. I think it will work!
 
Thought I’d post pics of a couple of Norco MTBs dropped off to me last night for repair (sic), and the culprit motor and controller.

The owner destroyed one after the other in exactly the same way.

The grey “storm” frame appears to use cast dropouts, judging by the grain in the aluminium.
 

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Thought I’d post pics of a couple of Norco MTBs dropped off to me last night for repair (sic), and the culprit motor and controller.

The owner destroyed one after the other in exactly the same way.

The grey “storm” frame appears to use cast dropouts, judging by the grain in the aluminium.
I'm not running 3000w at 72v, just 1500w at 48v. Did the owner not run any torque arms or reinforced dropouts?
 
I wasn’t posting as a comment on your setup.

Just seemed like relevant subject matter.
 
Yep, twice lucky.

The cast dropout sheared, didn’t round out.

The forks on the bikes were cheapo suntour and rockshox judy. If it were a front motor will installation …
 
Yep, twice lucky.

The cast dropout sheared, didn’t round out.

The forks on the bikes were cheapo suntour and rockshox judy. If it were a front motor will installation …
.. he probably would not have dropped the bikes off.
 
Grin makes clamping torque arms, too, if it's helpful.

1695956736154.png1695956784055.png
 
Poor choice for many reasons talked about here (TorqArm_V1 section):

"While this design did work and was an improvement over no arm, we ran into failures from the hose clamp in cases where a motor controller had shorted mosfets. The curved hose clamp slot in this design put stress concentration points on the clamp which facilitated the hose clamp tearing in half. As well the contact point to the fork was prone to sliding downwards. As a result we discontinued manufacturing this model in 2010 and do not recommend its usage. There are of course now countless Chinese clones of this bad design being sold by clueless people all over the world. "

-and-

"I see many sites still selling the original universal torque arm, what's up with that?

TorqueArm_China_Clone.jpg

Unfortunately somebody sent a sample of our first universal torque arm design to China in order to have it made cheaply. This happened shortly before we discontinued this model in lieu of the improved Rev2 and Rev3 arm designs. We've since seen this cloned copy proliferate among many China kit suppliers and traders, in ever declining quality, and have with some bemusement had those companies try to sell it right back to us."


It's a poorly excecuted clone of a poorly designed GrinTech product TorqArm_V1 / DISCONTINUED long ago.

In addition to the deficiencies GrinTech describes above, these clones also (MOST importantly) do not have close tolerances necessary to adequately grip the axle without any play. They are a loose sloppy fit on the axle and ANY play there will only increase over time until axle spin results.

My advice? Return it and get GrinTech TorqArm_V4, 5, 6, or 7, whichever one best fits your frame. (I think they have an Amazon presence). They updated their original design for important reasons. You want in to the 35mph club? Sure, but don't take stupid chances.
 
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Here are the modded dropouts complete! How does it look?
 

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That torque arm will not keep the axle from spinning. The hose clamp will allow the arm to slide. I don't feel the little bolt will hold up under use.

I might be wrong but good luck anyway.
It is epoxied using JB Weld Steel as well so it should be fine. Here is a better photo: IMG_20231012_200423.jpg
 
forget the hose clamp. drill a hole in the arm that matches up with the lower brake caliper mounting bolt. you may need to go to the hardware store a buy a longer bolt and possibly a few washers.
Could I bolt it directly to the frame and drill a hole there?
 
Pretty smoothly.
Should be a near interference fit. Best case is too tight to fit without a few light passes with a file to get it to go on. Throw all of your other cautions out the window if your torque arms aren't tight. I have a less than ideal fit on one side with my Grin torque arms so I jam a small piece of straight razor blade in between the axle and torque arm as a shim which has worked well.
 
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