IS Disc Mount Torque Arm, Clamping Optional

[dmwahl]

I'm working on a KMX eTrike, and have the majority of the parts purchased. The one remaining item before I can ride confidently is a rear torque arm. Since the motor I'm using should be capable of 100Nm, I wanted something fairly heavy duty. I considered the doctorbass torque arm (epoxied on) but don't want to deal with the epoxy. There are a few other designs floating around the forum, but none are quite what I'm looking for or don't seem available anymore so I designed my own. It will bolt onto the rear disc mount and has flats to drill a hole for a clamping bolt (M6). The clamping hole will NOT be drilled, as I'm not convinced it's necessary, but some people may want the option so I figured I would at least make it easy to add.

I'm tweaking a few dimensions to get the fit just right, but after I'm confident with the dimensions I'll have a small batch made. Material will be 3/8" (9.5mm) stainless and I'd expect to sell them for somewhere in the $30 range shipped in the US. It is tailored for the KMX frame, but should work on many other frames as well. This is not a sale thread, just one to document the design and gather feedback.

[EDIT] Sale thread here

View attachment 1

Here is the profile of the design, can be used to verify fit on a given frame. Print it out at actual size and try it out. Warning: The paper version will not prevent frame, dropout, or axle damage.


[EDIT] Installed TA photos here

 

[dogman dan]

I give it a thumbs up.

 

[teslanv]

Similar to the one I had made for my Kona FS Bike.

http://endless-sphere.com/forums/viewtopic.php?f=3&t=60712

 

[dmwahl]

I like the polish on yours, might have to find my polishing wheels once the parts get here. Any issues so far?

 

[dmwahl]

I ordered a trial batch of them, we'll see how things go.

 

[Ykick]

Do you intend for the squeeze bolt to be threaded into one side of the clamp or simple pass-through and bring your own nut/bolt?

Please post up a For Sale - new thread if/when you're ready.

 

[cal3thousand]

Since this is not a for sale thread, I don't think I'm breaking any conventions, but mod can remove if I am:

Crossbreak has an affordable alternative currently for sale:

http://endless-sphere.com/forums/viewtopic.php?f=31&t=68835

 

[dmwahl]

Do you intend for the squeeze bolt to be threaded into one side of the clamp or simple pass-through and bring your own nut/bolt?

Please post up a For Sale - new thread if/when you're ready.

The intent is that one side is threaded and the other is a clearance hole. The distance between flats is 30mm, so a standard M6x30 will fit. There's no reason a 35mm bolt and nut wouldn't work though. Assuming it works as I hope, and I've checked it with a 3d printed copy so it should, I'll post in the for sale section. Not something I'll get rich off of, but if there's interest it's easy enough to buy in bulk and resell. I plan to use it myself without clamping, but I know some people want extra security and it's easy enough to add. The width is slightly below 10mm, so depending on the axle width it may need a little filing.

Since this is not a for sale thread, I don't think I'm breaking any conventions, but mod can remove if I am:

Crossbreak has an affordable alternative currently for sale:

http://endless-sphere.com/forums/viewtopic.php?f=31&t=68835

Fine by me. I saw crossbreaks version but it wasn't quite what I wanted since it looks like it requires filing the frame. Mine is bolt on, no frame modifications, otherwise I'd consider buying his. It's far easier and cheaper to buy one than design your own

 

[dmwahl]

Torque arms arrived last night and I got one installed. Took a few minutes with a file to get the fit just right, but after that it fits perfect. I applied some anti-seize to the axle threads and tightened the nuts down to 50ft-lb (~68N-m). Now I can finally turn the controller up to 11 and have some fun I will post the remaining arms in the for sale section this weekend and put a link here as well.

 

[littleskull99]

Does this mean you cannot use the disc mounts for a caliper with the ta installed? Thanks.

 

[dbaker]

calipers mount to the inside of the frame ears. His TA mounts to the outside. You can use with disc caliper.

 

[littleskull99]

Thanks dbaker.

 

[dmwahl]

Yep, that was the idea. You just need 10mm longer screws and everything else should be unaffected. I don't have rear discs on this bike, but wanted the option to add them later.

 

[dmwahl]

They're now posted in the for sale section here

 

[dbaker]

You rock! Click on link, click, click and done

 

[dmwahl]

You rock! Click on link, click, click and done

Thanks I didn't expect these to go so quickly, only 1 left! Ordering more now.

 

[teslanv]

The only thing I would caution about with the IS Disc brake Mount standard is that even though the geometry of the two M6 Holes is relative to the Rear Axle, the rotation of the drop-out is NOT. This is what I discovered when making a TA for my Kona King Kikapu. That TA fit on the Kona just fine, but not on another bike I had. On a round axle, this is a non-issue. It is only with the flattened axles we ebikers deal with, where it is an issue.

 

[dmwahl]

The only thing I would caution about with the IS Disc brake Mount standard is that even though the geometry of the two M6 Holes is relative to the Rear Axle, the rotation of the drop-out is NOT. This is what I discovered when making a TA for my Kona King Kikapu. That TA fit on the Kona just fine, but not on another bike I had. On a round axle, this is a non-issue. It is only with the flattened axles we ebikers deal with, where it is an issue.

Yep, that's why I have the PDF for people to print and test fit their own frame and also stated that it's originally designed for my KMX trike frame.

 

[dmwahl]

Drilled and tapped one this weekend to make it a clamping version, photos here: https://endless-sphere.com/forums/viewtopic.php?f=31&t=69073&p=1220325#p1220325