Anyone install a TSDZ2 without the securing plate?

[colinh]

I'm installing a Tongsheng motor on a 2022 full suspension StumpJumper for my wife. It has a 73mm bottom bracket, and needs some shimming on the drive side to push the motor out to miss the wide chainstay on the drive side. There is enough thread left on the non-drive side of the motor bottom bracket axle IF I don't use the triangular securing plate, but not enough if I do need the plate.

I've spoken to eco-cycles who were very helpful and said they have bottom bracket extensions available; these increase the bottom bracket axle to ~100mm, so must add around 25mm. This pushes the triangular securing plate out, increasing the distance between the plate and the motor housing. Because of the much bigger gap, the extension kit comes with MUCH longer bolts and long tubes to replace the original washers. (See the pics at https://cycles.eco/products/tsdz2-upgrade-bottom-bracket-axle-extension-in-92mm-100mm-120mm.) I see that when the bolts are short and the plate close to the motor housing they would help hold the motor in place, but when the plate and motor are a long way away and the bolts really long do they really offer much resistance to twisting and rotating of the motor?

Since I suspect with the extension the plate/bolts don't do much, and since I only need the extension to accommodate the plate I'm tempted to forget the extension and leave off the plate. My wife is light (~120lbs), a casual rider not a speed demon. I figure if the motor casing on the drive side gets deformed I'll use her TSDZ2 as spares for mine, and fit a CYC motor to her bike.

Does this make any sense? Any thoughts? Thanks!

 

[Sturmey]

Don't underestimate the torque force. A 80nm motor exerts 80 newtons pressure at 1 meter. However the motor center (and torque clamps etc) is about 70mm from center, so the potential force (tangential twisting force of the whole assembly) will be approx 15 times 80 newtons which is approx 1200 newtons or equivalent to 120kg in weight. I dont think that aluminium housing will be strong enough to hold the unsupported motor when this is taken into account.

 

[Nealh]

I'm using my tsdz on my cargo bike until it breaks then I will likely fit fit another Bafang G370 to the front wheel as I have doen so on to the Road rat. My Ute has no way of the supprt bracket to be utilised and hanging by a cable tie will be no good.

 

[Sturmey]

Attached picture. Just to clarify, I take it this is what you mean by the 'securing plate' that you intend not fitting.

 

[peter.c]

With out that washer / plate the load is all on the face of the big nut and is a problem to keep tight ,
Remade a thinner version in stainless steel see pic the replacement bbs01 in a specialized camber
The 100mm/120mm version of tsdz2 will snap the main shaft at the circlip which has happened to me twice , now both run bafang without a problem

 

[colinh]

Thanks for the thoughts. I notice two documented instances online of the motor housing cracking, so I take seriously the comments about the forces involved. I filed a whisker off the motor housing where it contacts the chainstay (actually what touched was one of the protrusions housing the bolts that secure the drive side "plate" that covers the torque sensor), and this allows for less shimming and more bottom bracket thread protrusion on the non-drive side. I think this may now be enough to accommodate a thinner stainless steel plate to replace the mild steel original (thanks peter.c for the idea), providing some support to the non-drive side of the motor.

sturmey, yes, that is the plate I'm referring to.

 

[mr_ed]

There are some great sites offering to do laser cutting of small pieces for a reasonable price.