Grin Tech's Torque Arm V7 - Built for Regen

The Torque Arm V7 is a unique design that actively clamps the axle with tremendous force so that there is no play even with motors that do regen and have alternating torque. Hub motor systems with regenerative braking have been notoriously prone to nuts getting loose and axle spinout, even with a torque arm is present.
This V7 arm design works on both front forks and rear dropouts, and is compatible with motors that have M12 and M14 axles and 10mm flats to prevent rotation. It is the culmination of extensive lab testing at Grin and uses specially hardened 17-4 stainless steel and Grade 12 bolts right at their strength limit.
[Of course, the best solution is a motor that has the torque arm fully integrated with the axle and not as an afterthought. But if you've already got a Chinese hub motor that relies just on axle flats for torque transmission, this arm is as good as it gets.]
Here is Grin's general torque arm info page:
ebikes.ca/prod...
Here is the .pdf user manual:
ebikes.ca/amfi...
Here is where you can buy them from Grin directly:
ebikes.ca/shop...
And we also have an amazon listing for those who like to deal with the devil:
www.amazon.com...
Shot and Edited by Aaron Enevoldsen

[@SeaforgedArtifacts]

Always the best designed ebike gear from GrinTech

[@DatEbikeGuy]

Thanks for making E-Biking safe again. I’ve heard so many stories about Chinese torque arms failing and people ending up in the hospital. In the best-case scenario, only the cables are damaged.

[@GrinTechnologies]

In a perfect world, nobody would have to buy torque arms because every hub motor would have one built in. It used to be like this in the late 1990's and early 2000's, but then China came around and ruined it with axle flats and for whatever reason that terrible design standard became the norm for the past 20 years.

[@martinfromtirol3828]

just installed a grin torque arm on a rear hub motor, ROCK SOLID !

[@UWMailing]

We run a couple of Bullitt cargo bikes on our delivery fleet which I upgraded to this torque arm and I can definitely say it was a huge improvement. Clever design, as usual from the Grin Tech folks.

[@dilly69420]

This is the kind of overengineered that I love

[@GrinTechnologies]

Ha well in this case it's to compensate for a heavily under-engineered axle design (courtesy of China...)

[@dilly69420]

@@GrinTechnologies “F**k it, I’ll do it myself”

[@warlockboyburns]

On my bike I just tightened some hose clamps around the axel and through some holes that we conveniently already there so that axel can't fall out of the dropout. It doesn't look the cleanest but it works.

[@alexvonhoene1391]

It can't fall out, but could it spread the dropouts and spin in them? That's what a torque arm is there to prevent.

[@warlockboyburns]

@@alexvonhoene1391 Falling out is the only problem I've had. It wears away the opening when it spins as it's falling out but doesn't spin unless it comes out.

[@xmtxx]

I don't need this, as I already have the all axle motor, but that's the reason why I give you money.
Keep up improving the ebike world!
Yay!

[@thedon2703]

Amazing work 🫡

[@daniele_go]

I already have V6 torque arm, very happy with it!

[@swarbrickjesse]

Great product. Please make this for QS203 16MM axles. Id buy them up!

[@zoobiewa]

Yes exactly. Hear hear.

[@DeleteWorld]

How do you get high power regen? I have your Brompton kit with the 20A controller, will I get more regen with the Phaserunner? I'm hesitating to buy it ;)

[@GrinTechnologies]

If your reference point is with a Grinfineon 20A controller, then yes you will get way stronger regen braking if you upgrade to a Baserunner_Z9 controller instead. Is this a really old kit with anderson connectors or a less old kit that has the Z910 plug on it?

[@jasonlenfesty6459]

Nice production work. Did you use EDM for the spline machining?

[@davidhunternyc1]

Hello, I've been thinking about buying lightweight ebike but I don't know which one. I really like the Hummingbird ebike because it's featherweight and will be easy to fold and bring up and down stairs and on the subway. They use a 250 watt Zehus all in one motor/battery hub. It's super compact but the weight is entirely on the rear of the bike. Coupled with your body weight the bike isn't balanced. The benefit is that there is no external battery. What's your thoughts. Is there a way to take a Hummingbird, a Brompton T-Line, or a Birdy and make them into ebikes without external battery packs?

[@GrinTechnologies]

In general you want an external battery pack, it is much more versatile than one integrated with the bike.
This has nothing to do with the subject of this video though (v7 regen torque arms)

[@MakeTechPtyLtd]

Beautiful product. Well done.

[@mensch4434]

very nice 👍
but a question: do i need two of them for each side of the wheel or is one enough?

[@GrinTechnologies]

One should be enough for most applications. If you're going to be running a system with very high power and powerful regen then 2 isn't out of the question.

[@CamiloSantana]

happy with mine but I did have to TIG weld the torque arm to the clamping block. I think it's because the road bike fork itself flexes more than expected for the part... still plenty happy with it 😊

[@zoobiewa]

Why only 12 or 14mm axles? So many motors have the 16mm.

[@mishala7079]

Could you clarify when we would need to replace an older Grin torque arm?

[@GrinTechnologies]

Only if you have a system with regen braking and find that your axle nuts keep getting loose

[@nettoyageadriance]

These cowboys stand alone. Amazing!

[@wamdabikeandtricycle9540]

In my suntrip 2018 .I have used the same solution for the ezee motor

[@justchecking586]

Hi Grin, where can i buy your product? - Im based in London United Kingdom

[@velotill]

I keep wondering if in an ideal world there would be two torque arms (I know, hard to get it over the cable connector on the other side, but still...)

[@GrinTechnologies]

In an ideal world there would be no torque arms like this, they would always be integrated with each hub motor.
That said you can put on two arms for sure, many people do. It's not generally necessary, but it does provide some extra redundancy

[@anthonywalsh2164]

Is it better to have the regen motor on the front or the rear wheel?

[@the_lost_navigator7266]

The front, because the weight shifts to the front wheel(s) under braking so you can harvest more energy. Front wheel drive EVs make more sense for this reason, although many are rear wheel drive.

[@GrinTechnologies]

It really makes no difference at all, unless you are at a point of loosing traction control and have to back off the regen because of that. In practice you basically never run into that in biking conditions riding on pavement. Emergency panic stopping, like the kind that favors a front wheel over the rear, is the domain of your mechanical brakes.

[@lantice013]

ok... I needed to upgrade 2 of my old grin TA on my front 8tMAC

[@lufknuht5960]

I am surprised that you would depend upon hose clamps at the top instead of making the torque arm with a piece that goes behind the fork.

[@GrinTechnologies]

We don't follow the logic. This can go either in front of or behind the fork. The torque is totally bidirectional in a regen system, so it makes no difference whether it is in front or behind as far as if the force is pulling on the hose clamps vs pushing into the fork blade.

[@umi.1498]

What torque arm would you recommend for a 2000w motor?

[@GrinTechnologies]

This V7 arm if it's a motor that does regenerative braking and has at least an M14 axle. If you aren't doing regen, then the V5 or V6 arms are both quite good depending on the install location.

[@Sick666Minded]

got me two of them great video

[@neptronix]

Very nice!

[@AndreasConrad-p2e]

Brilliant

[@belgianbH]

Brilliant 👏

[@Deqster]

Alrighty cowpolk, that'll do'er. 🤣

[@jpsuperstar]

That was the best

[@Pushyhog]

thanks again.

[@charliebrown-np1tv]

i got to get this lol