How Do Torque Arms Work? (+ How To Design Your Own Torque Arm!)
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- เผยแพร่เมื่อ 20 ก.ค. 2024
- In this video I explain the basic principles behind your hub motor propelling your ebike forwards and how this translates into the requirement of a torque arm (or two) on your build!
Designing and building your own torque arm is simpler than you think! A few simple tools to get started and you should be able to accurately measure your bike and get a basic design started. A caliper and something to measure angles are going to get you most of the way there. Draw your design on google sketch up and print it to scale on printer paper. Cut it out and test fit! If you have a 3D printer, print it and test fit! Make any small changes you need to and move on to the final product by sending it to your local laser cutting / water jet cutting shop!
If you aren't up for building your own, these actually seem like pretty stout universal torque arms. As an Amazon Associate may I earn from qualifying purchases (at no extra cost to you):
Rear Torque Arm:
► amzn.to/3vM76hw
Front Torque Arm:
► amzn.to/3PbA3Kq
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Fully immersive, amazing explanation, if anyone asks me for a deep dive into t-arms I will link this video - I am only running a 350w rear geared hub at 16 amp but I have always had a t-arm, I have a perfect multi angle version but could not for the life of me get to fit to a standard cheap Taiwan made European/UK MTB not mention the fact I would have to fit it with hose clips, however I did fashion a cheap version with a few high tensile nuts and bolts mainly just to close the dropout off. In 3 years of low wattage ebiking I have had not one problem but still I worry about the t-arm fitting - Subscribed - checking out your other content!
Thanks for the kind words! Happy to have another subscriber, I really hope you enjoy my other content! Check out my recent video about my ebike lighting setup since you're a fellow ebiker :)
I installed a 350 watt front wheel hub motor onto a steel frame old bike, the tabs on the fork were thin and weak (since as a push bike they were plenty good enough with no torque). The kit I bought did not include a torque arm. Over time (1000 miles) the tabs spread apart and the shaft rotated in the fork, the wires wrapped and the bike stopped instantly, and it hurt. I fixed it by fabricating small plates from 1.5 x 0.25 inch plate, sawing and then hand filing the slots to precision, then welding the plates to the outside of the fork. I was amazed that the wires suffered no permanent damage. It is solid now, better than ever, however it took me a while to go full speed again, ha ha. My advice to go rear wheel drive and use a torque arm or weld reinforcing plates (if you have a steel frame).
this was a really good video,super helpful✌in going to try grind one out of some plate steel i have laying around
I'm sure you can get it to work!
There is a simple solution , just buy the normal torque arm and add Mountain bike disk break converter , these convertors have a secure ring clamp to attach to your fork body and the convertor has 2 holes that you can use to mount the arm of the torque arm. Problem solved. It is very secure as it is supposed to be able to support disk break. Hope this helps.
Great vid, thanks for the tips!
Thanks for watching, glad you enjoyed!
In fairness, you would think with the cost of a hub conversion kit of whatever power, they would throw in a set of universal torque arms or at least make you aware considering what will happen if it all goes bad at 20 or 30 km per hour. Great video.
Yeah you would think... but they really do penny pinch in these Chinese conversions...
@@EmbraceMaking People wanting the cheapest price does that.
I wish I would have known about torque arms yesterday.
This morning I was on my commute to work on my DIY 500W front drive ebike and the the front fork dropouts simply fell off while I was going uphill at full power and 30 km/h. Fell flat on my face and bruised my hands and elbows.
Nice video. I'm currently designing something similar to the one you mounted on your brake caliper mount, but for a front fork instead. My goal is to safely run a bafang g311 on a magnesium suspension fork. Since the motor itself has a 10mm axle, instead of a flattened 12 or 14mm axle it should not be stressing the dropouts in theory, and the torque arm and brake caliper mount should easily take the maximum of 600w I can do with my motor controller. Will post some pictures when it's finished. Im currently doing prototypes with my 3D printer, and will then get it CNC'd from 5mm thick tool steel
Great video. Thank you
What about hardening the steel after working it in shape? Necessary?
Bolt choice could be an issue too. Hardware store common bolt may snap if not a hardened.
Great video! I just wanted to share my experience with using a cheaper torque arm. I built my own electric scooter with a 48v 7570watt hub motor, I got this motor and the swing arm from an old electric scooter and I reused the same torque arm that I got from my donor scooter. The torque arm was of bad quality and was not able to hold up 1 hour of continues regen braking and full throttle. It resulted in the axle spinning and the wires spinning w the axle ripping all my connections, however, I could reconnect it and get it working again. I highly suggest for those using regen braking to make their own strong torque arm.
Good advice! Yes, regen and high torque motors should have a proper solution!
the broken torque arm rip your cables, lesson learned : dont install torque arm at all
48v is way too low
I was told to get a 1/4 inch thick torque arm. I’m just wondering if I’m supposed to use the torque and the spacers on the axle. Also if they’ll all fit with the bolt on the axle. ???
I have a 26" beach cruiser that i have a 27.5 48v 1000w front electric hub on it, i put 4 toque arms on it 1 on each side of the front and 1 on each side of the back of the forks and its been holding really good, i love this beach cruiser electric bike, it's actually a real Budweiser beach cruiser, love it but make sure that u have the battery peddle assist first so that it isnt only adjusted to your throttle are you won't get that distance as you would when you had pedal-assist my beach cruiser does not have pedal assist but my battery already been tuned in for it and im getting between 25 30 mile range witch is pretty good for thumb throttle only ,
I have a stealth.bomber type e-bike that only has the thumb throttle and key with voltage monitor on it very basic setup. I noticed its not getting the range I expected is that because I don't have any kind of pedal assist on it? Or any kind of battery tune? Can you explain a bit more what you did to your battery to get better range??
@@lightseek88
my kit is 48v 1000w but my battery is 52v 1200w , my bike is DIY build, my blue bike is 48v 1500w and I use a 52v 1600w battery on it, and it's DIY also,I'm not sure about the answer to your question, I'm only DIY build, I wont do store manufactured built bikes,
Do you install a torque arm in front of behind the fork to dissipate front motor torque?
Great video . But im still trying to find out how to cut a hole with 2 flat sides for the axle from thick steel ?
You'll need to drill two outside holes then drill another dead centre in the middle to remove the partition. Then it's out with a small flat file to create the sides. To be fair, without a vice and/or drill press, it would be difficult to do properly. Have you got sorted yet?
how about the downside for regen braking?
i am wonderin if an iphone camera can create a scan of the frame whwere mounting a custom torque arm and that scan can be used for creating the cusom torque arm design.
I haven't tried it, but I have heard that the new iphones can do a pretty good job of 3D scanning... could work!
It's not that hard to fabricate your own torque arm even if you have no tools. You already have the template for the axle hole, just use the washer/spacer that came with the kit. The hole dimensions is typically 14mm (16mm for 5000w+ enduro-type motors) x 10mm. Take a credit card and trace the washer hole outline with a sharpie. Then carve the overall shape with a knife or scissors. When you're happy with the template then take that to a water-jet equipped machine shop and have them cut it for you.
Can you post a template of the hole shape (for the Axel)? I could then print it out and verify if it is the same as my axel. That would be a lot easier for me as I am not very techy with software. As long as I have a template of the hole, I definately have the skill and tools necessary to create the torq arm. Its' funny because you seem like the design/engineering type of person while I am more the manufacturing type. I always regret that I never got the education necessary to become and engineer. Oh well, next life maybe.
Most torque arms do not fit the axle tightly, and allow for some axle movement inside of the torque arm. Usually the axle will rotate to where it wants to be forward motion, but if you are using regenerative breaking the axle will rock back when you applied the break. This will cause forward and backward motion within the torque arm, that is concerning and may possibly cause the axle to get more sloppy overtime.
I really only need one torque arm the Axel is solid all the way through redundancy just as weight and complications
Redundancy is a safety feature in itself. I don't mind the extra few grams when my e-bike hits 60km/h ...
@@EmbraceMaking exactly, not to mention the extra peace of mind knowing that your wheel is extra secure at a high speed
is it bad to use a torque arm with a torque washer at the same time?
I can't think of a reason why it would be a problem.
is torque arm needed for a 500w motor on an Specialized A1 SL Premium Aluminum frame? Thanks
Probably not but it's still recommended for any aluminum frame. If you're overvolting to anything over 55v, definitely consider it.
Even if its just one of those universal cheap torque arms, I would do it for a layer of safety just in case
Isn't it bad to mount it on the brake calliper mount because there is already torque from the brake which it absorbs
I don't see a problem with it because it is not a summation of torque. They wouldn't be happening at the same time (acceleration / braking)
@@EmbraceMaking yeah you right, didnt think about that
My bike has 5mm steel drop outs and I am putting in a 1000w motor , is torque arm essential here or could I get away with it for at least till I get at till I sort one out?
I would put one in asap just to be sure... if you don't have one I would really limit how much you get on the throttle just in case!
@@EmbraceMaking thanks, wheel arrived today but waiting on battery so I've plenty of time to get a torque arm ordered.
@@FlyingFun. Make sure you put 2 on for 1000w
@@Poepad I have one on there, the other side has the washer with the lug on which is not much but better than nothing, I've been keeping an eye on it and it's all been fine so far, I think my 1000w motor does not have much torque and my frame is steel so fingers crossed.
Defo put 2 on if I up the power.
ThankS for video. On front hub motors should you mount the torque arm on back or front of the forks ? I've seen it both ways and lots of different opinions!
I'd have to revisit the research I did, but I think with sufficient strength of mounting points you should be okay either way... I think lol
I am using a 500w front hub motor the frobts forks are made of steel do i need torque arms?
You're probably fine... but maybe just do something super simple just to be sure. Even one of those generic ones with the hose clamps just so you have something to give you some cushion in case it ever wiggles loose.
@@EmbraceMaking can i use a 10mm wrench and hose clamps as diy torque arm?
Two bucks for a cusrom water-jet part? Where can I find a shop like that?
Tiny little pieces like this can be made from scrap when the fab shop runs a bigger job. Sometimes you have to wait until they are going to process a bigger job but if you ask nicely they can fit it on the bed for a few bucks.
Are you sure about your forces at 1:27? The axle is trying to spin the same direction as wheel. The force must be applied in opposite direction.
Just mentally hold the wheel steady and see what the bike does. The bike will turn in the opposite direction of course.
Great! - if you have access to a cnc milling machine
You can always ask your local shop nicely. Ask them to get it on the waterjet with a bigger job of the same material and thickness.
the best metal to use to make your own is the backing plate of a car disc break pad. thats what i would use .,
Seems pretty thin, how thick are the ones you're talking about?
Embrace Racing just some a shop had laying around in there scrap pile . They was off some kind of diesel truck
great vid !! i made my own as you did with cardboard ect then i cut and filed the 6 mm steel myself. im happy with it but i know i can do better but ..,a couple of bucks in a machine shop !!!???> is this true??
If the part is simple enough and very small, lots of machine shops can squeeze it in on their water jet machine or laser/plasma cutter when they run another bigger job. These arms can be small compared to bigger jobs and can often times fit on the waste material of big jobs they do. Ask around nicely and someone will help you out!
pro tip: you can watch movies on flixzone. I've been using them for watching all kinds of movies lately.
@Landyn Nathan yup, I've been using flixzone for months myself :)
Thanks very much!
Thank you for watching!
The problem I'm having is that I can't REMOVE my rear tire with hum motor from my Addmotor HITHOT 1 ebike! I lubed up both sides of axle at dropouts but the damn wheel doesn't budge! Even with a rubber hammer the axle isn't moving at all... It's like it's welded in there!!! I'm banging and pulling but it won't budge!!!
Did you get it out bro?
@@seetheanimal5867 I have had a similar dilemma. I have used the wood handle of a rubber hammer to lever between the motor drum surface and the frame to spread the gap between the two, which has allowed to get 1-5 mm spread enough to seat the axle in the frame slots. The idea is to use WOOD not steel as metal rods and surfaces will slip and slide very dramatically with lots of knuckle banging and swearing. I have also used short lengths of standard 1x2 pieces of soft pine wood to get the same leverage and enough friction on the paint and metal surfaces to grab and pry, without damaging or scratching the paint or metal surfaces. Also, very important technique: if wanting to pound on the threaded axle to get it in or out of the frame slots, hold a 1x2 or 2x4 piece against the threaded axle, THEN beat on THAT, carefully, to get the axle seated or unseated and not damage the threads. Good luck.
@@richardjordan9712 actually that is wrong … the axle is likely twisted (rotated) into the frame axle inserts .. simply grabbing the flat sides of the axle with a wrench and rotating the axle till the damn thing pops out easy peasy
@@seetheanimal5867 I find your reply offensive..
@@richardjordan9712 I found your reply incorrect
I’m going to fabricate and weld my own torque arms..we have a waterjet cutter at work but the guy who ran it got furloughed.
Best of luck, hope it turns out well for you!
I have the GrinTech V4 torque arm, and a knock off chinese one like you mentioned.
The chinese ones are bad and no one should use them. I use it on the chain side because I already have a V4 on my drive side.
And it's sinched down flush with the frame pushing up against the frame with 3 hose clamps.
So the knockoff just works as a 2ndary brace but not a primary load distributor.
No one should be using those chinese ones as a standard, they're prone to fail.
Agreed... this video is like another PSA for that advice!
damn.. looks like i’ll be laboring with drilling, grinding for a while
It will be worth it!
@@EmbraceMaking 1/4 inch steel does not work for high power motors. my mxus 5k turbo motor tore clean through the plate and nearly broke it in half except it fell off before it could do that, and then proceeded to throw the axle nuts and jump out of the bike almost completely
if u only got a 1kw or less motor u dont need a torque arm as long its a steel dropout ,if its aluminium its maybe ok but just dont go full throttle ASAP, build the revs gradually , torque is highest at acceleration not high speed
Aluminum for sure, steel it's a nice redundant feature.
Do retail ebikes need torque arms--I looked at a few premade AWD ebikes and I do not see torque arms on them. I have a 1000 watt hub motor I want to put on my ebike--I have a mountainbike and the ebike seems much more durable.I also looked at a part number for the front forks of an AWD ebike and it was the same part they used on their RWD--all it looks like they did was install a front hub motor to their already rear drive ebike--if this is even semi common in frames breaking or parts failing--why would they not put a 10 to 25 dollar part on a 3k to 4k bike.
I would imagine a retail ebike has the proper reinforcement right from the factory. This video was geared more towards the DIY ebike builds such as mine.
@@EmbraceMaking All good retail ebikes are made more durable and thicker.I would never put anything above a 500 on a normal bike frame--you are creating a "bomb on wheels". The 1000 front hub motor on mine can not even be used under about 10 mph or it will spin the front tire.
i dont have local machine shop
Time to get resourceful.. if you have an angle grinder/cut off wheel and a drill press you can get by ;)
Or just buy a universal kit
@@doomtomb3 I did and it was not fitting on the fork so I ended up drilling more space
Have aluminum bike. Made mistake of no torque arm. Ruined a brand new kit.
Frustrating :/ but hopefully you can salvage some parts?
So basically I need to buy a 3D printer and learn how to use it and print plastic versions of torque arm designs and then take them to a metal fabricating shop. There are two I know of near me. One minimum charge is 350 and another one is 500. Both metal fabricating shops look like they make great stuff.
I think there is no such as a Rear Hub Universal Torque Arm. The one from Grin Tech made my wheels come off and they make good stuff. Front universal ones that exist definitely don't work on every bike. There could be universal front ones but they would need to consider more bikes.
Hi Chris, the 3D printer is a nice to have but before they existed people used cardboard and paper templates. I've designed many automotive adapter brackets using cardboard over the years lol. If your design is just a flat profile, ask a shop to laser or water jet cut them... for such a small bracket they should not charge you that much. Likely they are quoting you for machining / milling which requires expensive setup for one part.
I just bought a set for £10 but thanks anyway.
Has anyone successfully transformed an aluminum bike to ebike with a high wattage over 1000 w motor and torque arms that has lasted for a significant amount of time
Define significant amount of time... mine is 1500W... Id have to check my mileage on it but no issues yet.
As in years 2 years or high amount of miles as in 3000 5000 miles
A couple bucks? You sure about that ?
universal arms are trash, absolutely useless ,they are held together by a tiny bolt in the adjustable pivot ,no way that will resist the torque, i however did ave one and one it was set in position i cold welded the mid joint so it cannot spin or move if any torque slip does happen
I agree they aren't great, but I suppose for someone who doesn't weld or have access to fabrication tools it might be better than nothing.