torque arm picture thread

[John in CR]

My only issue with some of the 2 bolt clamping dropouts is that they rely on BOTH bolts, and if one gets loose then both are. I know how I am about checking things, so I prefer the dropout/torque arm to be made from a single piece and a bolt to clamp it. Then even if the bolt fell all the way off, the axle would still be held in place on that side by what is effectively an extremely thick dropout.

 

[Arlo1]

I belive in a pinch bolt for hi power apps with regen!

 

[John in CR]

I belive in a pinch bolt for hi power apps with regen!

Nice long slots like that even give you a range of adjustment to align the wheel or tighten the chain just like your BMX in stock form. I'd like to go thicker with my clamping bolts too, but I don't trust my welding quite enough to rely on a small weld to do it your way. The 6mm grade 9 bolts I use have worked fine so far. Do you think I should go with 2 bolts in line with the slot at the end to clamp each U slot closed just to be extra safe, or is 6mm thick grade 9 sufficient along with loctite on the nut?

 

[Arlo1]

I belive in a pinch bolt for hi power apps with regen!

Nice long slots like that even give you a range of adjustment to align the wheel or tighten the chain just like your BMX in stock form. I'd like to go thicker with my clamping bolts too, but I don't trust my welding quite enough to rely on a small weld to do it your way. The 6mm grade 9 bolts I use have worked fine so far. Do you think I should go with 2 bolts in line with the slot at the end to clamp each U slot closed just to be extra safe, or is 6mm thick grade 9 sufficient along with loctite on the nut?

I think my bolts are 8mm grade 9 or 10 they are tough as nails. But I might remove the washer and bend a think piece of steal and have it welded across more area to make sure its strong. I don't think a 6mm is enough it will strip over time. 8 or 10mm is what you want. Even 2x 6mm is not very tough for trying to close thick steal up like this.

 

[John in CR]

So it's the threads that will give? If so, then I should go back to tapping threads in the bottom half of the dropout, but still use a long enough bolt to add a nut for extra security giving me threaded contact with over .5" of softer steel plus the hardened steel nut.

 

[Arlo1]

So it's the threads that will give? If so, then I should go back to tapping threads in the bottom half of the dropout, but still use a long enough bolt to add a nut for extra security giving me threaded contact with over .5" of softer steel plus the hardened steel nut.

Yeh a 6 mm bolt might brake but a grade 9 will be close. I would use 2 6mm bolts on each side and nuts as well or just one 8mm bolt. But in the end anything is better then nothing. What power are you going to run? Regen?

 

[John in CR]

I just checked and I was wrong about the 6mm. I used grade 9 in a 5/16ths size, which is essentially 8mm, so I'm ok. Thanks for the feedback though.

 

[auraslip]

I wasn't going to use hose clamps - I was thinking U - Bolts

The reason I did it as two pieces is because there is hardly any room for derailleur clearance. If it was one piece, the back side would have to be tiny.

 

[spinningmagnets]

From comradegerry

http://endless-sphere.com/forums/viewtopic.php?f=28&t=25973&start=30#p447138

 

[Spacey]

I belive in a pinch bolt for hi power apps with regen!

Love your pinch bolt idea of welding the nut onto the frame, I take it the weld holds up just fine?

Also those holes in your motor, I might do the same to my HS3540 not for cooling but for the UK rainy weather in the winter...and the summer grrrr

 

[Arlo1]

I belive in a pinch bolt for hi power apps with regen!

Love your pinch bolt idea of welding the nut onto the frame, I take it the weld holds up just fine?

Also those holes in your motor, I might do the same to my HS3540 not for cooling but for the UK rainy weather in the winter...and the summer grrrr

I live on vancouver island in a rain forest! I ride in the rain all the time the heat in you motor keeps it dry inside! Yeh I get some pretty good torque on the pinch bolts and if you can't weld a nut then just get a peice of steal with a hole in it to weld to the frame.

 

[dogman dan]

I would think water in the motor would be pretty harmless compared to the dry sugar sand I have rooster tailing from my rear tire.

I see your point John, about the two bolt setup I use. That's why I have the second nut on there, locknuting both bolts. Coming up on a year's use now, and never had it work loose. I torque it pretty good, using grade 8 bolts that can take it, then romp down the locknut. My idea is only going to work well with a bike like the mongoose, that has a huge flat steel plate for a dropout.

 

[Arlo1]

My idea is only going to work well with a bike like the mongoose, that has a huge flat steel plate for a dropout.

Thats why I welded 1/4 inch steal to the drop outs!

 

[John in CR]

My idea is only going to work well with a bike like the mongoose, that has a huge flat steel plate for a dropout.

Thats why I welded 1/4 inch steal to the drop outs!

+1 on the 1/4 plate for dropouts. That's all I use and then since I like at least double that at the axle, I use much smaller pieces to thicken at the dropouts.

 

[TonyReynolds]

Thanks!

 

[auraslip]

Ok I've re-thought this torque arm situation. I want it to be simple. Meaning I can do it with hardware store parts. It also needs to be relatively easy to remove for tire changes (not that it's really an issue with the right precautions)

The main problem for me was derailleur clearance. It dawned on my that if I could spin the axle 90" then it wouldn't be an issue, so I filed my drop outs so that the flats of the axle would be horizontal. And now I have lots of room!



This is about as good as I can come up with. I haven't worked out the actual hardware, but I'm thinking 1/8" width by 1" wide L bracket for the top, and 1/4" steel plating on the bottom. Since they'll be pressed right against the original drop outs and the chain stay protrudes out a bit, the L bracket will have to have the bottom leg removed and both torque arms will have to be trimmed to clear the chain stays.

It will be secured to the drop out with bolts and to the chainstay with a U-bolts. I'll apply the pinch bolts first, and then the U-bolt, and then FINALLY drill into the dropouts. This way the chainstay will see most of the torque, rather than the weaker aluminum drop outs.

John says the big problem with this design is the complete reliance on bolts to produce the pinching force, and I agree. However, it would be easy to modify this quick drawing by using a larger L bracket to incorporate 4 bolts rather than just 2. This would spread the clamping force out along the axle. The devil is in the details, so if any of you have any suggestions I'd love to hear them. I believe this design is solid because it's based on KISS principles. It should work for most bikes, is simple to remove, and is easy to do correctly; All you need to make it is the hardware, a hack saw, and a drill. A tap would be superior than just using nuts, but is not totally necessary.

 

[John in CR]

I wouldn't call bolts a big problem at all. I just know how I am about preventive maintenance and pre-flight safety checklists, so reliance on bolts is a bad idea for my own bikes.

 

[Kingfish]

Still working for me after 3-1/2 months
~KF

New and improved!

I thought that I would update this information. The ghetto front torque arm was replaced after 7 flawless months in July with my custom designed and professionally machined assembly. Mounted as a pair, they survived 2500 miles On the Road to California and back without any issues. The 2WD eBike had regen on the front hub only. I was grateful that this was one of the least problematic items on my trip and remained tight the whole time

Chief features are:

• new EBike-Kit hub motor with disc brake option
• enabled the disc brake, and
• designed a 2-link and clamp assembly.

The keyed torque arm is crafted from 1/4" thick stainless steel, whereas the link and clamp are from aluminum. Stainless steel fasteners were used to attach the pieces, and Blue Loctite was used all threads - including the M14 nut.

Cheers, KF

 

[auraslip]

Nice KF - I'd like to know more about that. Where you got it made, etc etc.

I have that same fork BTW. Right down to the gold speckled "fishing lure" paint job.

Do you have anymore pics of your bike ? I wanna see a cross country riding 2 wheel driving bike!

 

[Kingfish]

Nice KF - I'd like to know more about that. Where you got it made, etc etc.

I have that same fork BTW. Right down to the gold speckled "fishing lure" paint job.

Do you have anymore pics of your bike ? I wanna see a cross country riding 2 wheel driving bike!

"fishing lure" paint job: hehe - yeah it reminds me of that too :lol:

The trip is in my sig The last 3 pages of the thread provide a good concise brief of each day and there are plenty of pics in the backfilled stories. Page 27 has several pics as well.

The design is mine; I used AutoCAD to draw it up, and I had it made locally. There are essentially four parts: linkage (arm and link) and clamp (2 halves). It's a pretty straight up design that works around the disc brake mounting. My machinist prefers anonymity. It has crossed my mind to do a production run. The big question is matching the diameter of the fork.

If there is enough interest and commitment I can make these available to ES folks.
Best, KF

 

[Diamondback]

id be interested in a pair of these if you do decide to make a production run.

Jason.

 

[Kingfish]

id be interested in a pair of these if you do decide to make a production run.

Jason.

Cool! I need to collect a bit of data to ensure a proper fit. Here’s what I would like to see:

• Take a close-up pic of the fork where the axle passes through – with the M14 nut removed, and/or provide the year make and model of the fork.
• Also it would be helpful to measure the fork diameter where the clamp will go: Take the measurement from the axle equal to the radius of the hub motor – just above where the disc brake mounts as displayed in the image of mine. Suspension Forks are often egg-shaped or oval instead of perfectly round, therefore we need to take this diameter measurement in two directions: Front to back, and from the inside to outside. I use digital micrometers and the preferred units are in millimeters, although I can convert inches to mm easy enough. Make sense?

If we get enough people to commit and if the fork diameters are close enough then a production run is feasible at a reasonable cost.
Best, KF

 

[Diamondback]

sounds good.

ill have to get some measurements made.

gives me the excuse to go buy a set of digital verniers.
been wanting a set for a few years, now i have a good reason to go buy a set

Jason.

 

[jhinshel]

Hi,
I am after a cad (or similar file) for a torque arm. I appreciate that I would have to adapt this, but this would serve as a good starting point for me.
I would be grateful if someone could make one of these available.
justin

 

[John in CR]

Hi,
I am after a cad (or similar file) for a torque arm. I appreciate that I would have to adapt this, but this would serve as a good starting point for me.
I would be grateful if someone could make one of these available.
justin

Justin,
They're so easy, how about you try to come up with an even better design? An ideal torque arm that will fit any bike has been elusive. Ideal includes simple, as little steel as practical (for those who erroneously think ounces matter on even such a critical part of an ebike), but with a broad surface that clamps firmly to the axle.