Never fitted a mid drive - do you need to protect the frame in case the motor twists under torque?

[maxwolfie]

Concerned about the downtube and chainstays - would think that the chainstays are actually more at risk though due to the direction of rotation?

Do people roll the motor housing hard up against the downtube without any frame protection (spare tube?)

 

[docw009]

I've installed four mid drives, two bafang and two tong sheng. What I learned on both is that the fasteners often loosen after the initial install and really need to be tight. There are cheap flat wrenches available for both, which often need some help with a hammer. Would be nice to have a socket tool that fits over the BB nuts used on these motors,

I've seen pictures on forums where owners have had their downtubes dented by loose motors. You have to be out having a really good time to ignore that kind of clunking in your motor. You also have to be clueless about mechanicals if you do an install that sloppy.

The Tong Sheng has a secondary brace that will inhibit the motor rotating into the downtube, if it is installed properly, I had to cut off a lot of metal on the last one to make it fit. Love my sawzall.

 

[Mongo]

All of my builds had/have bottle bosses on the bottom of the downtube, which are handy to use as motor stops and to secure the main harness (via a cable clamp) out of harm's way. I don't use the stamped wrenches to tighten the motors down - instead, I use the appropriate socket and a breaker bar. Not once have I had a motor come loose or change position.

You could mimic having a bottle boss stop by installing a metal band clamp. There are also several aftermarket secondary braces available for (at least) the Bafang motors.

 

[beemac]

Just make sure it can't move and you should be good - speaking from experience with only the tsdz2. If you're installing on a fsr or something unusual that doesn't allow you to clamp it to the chainstays you might need to make brackets. I made one that fixed to the seat-tube to keep the motor wedged against the downtube. Check pics 4/5 in this post. Motor hasn't moved a millimetre, it's still rock solid.

 

[caleb7]

In my case, maybe interestingly, the motor moved because I put a piece of inner tube there to protect the frame. And this caused BBSHD's ring teeth to dent the bottom bracket more than it's supposed to (probably because it twisted in tiny movements thanks to rubber) . And this means motor has a mm or so to twist under torque.

Now the motor stays in place since more than a year via a 'turnbuckle'. Which is a good method I think.

I didn't need that piece of rubber, but this is a fat bike, I don't know for others.

 

[2old]

The motor on my BBS02-equipped hardtail loosened once years ago, but since I tightened the nut with a Hozan bottom bracket wrench (spanner) and hammer, it's been tight for about the last seven years of off road activity. I used a thin (one or two mm) section of rubber to protect the frame.