Quick Answer: The Grin Technologies V5 Universal Torque Arm (about $25-30) is the best overall electric bike torque arm for 2026 — it fits front or rear, works on 12mm, 14mm, and 16mm axles, and mounts through a threaded eyelet. If your frame or fork has no fender or rack eyelet to bolt to, get the Grin V7 Regen Torque Arm (about $40-50) instead, which clamps directly onto the frame. Budget builders should get the Voilamart Universal 2-Pack (about $13-18) to cover both wheels at once. According to Grin Technologies (ebikes.ca), a 12mm hub axle producing about 40 N-m of torque puts nearly 1,000 lb of spreading force on the dropout — enough to crack an aluminum fork if the axle isn’t reinforced.
A torque arm is a small, cheap metal bracket, and it’s the one part hub-motor e-bike owners skip most often — right up until an axle spins loose or a dropout cracks. Here’s what it does and which five to buy.
What a torque arm actually does
- It stops the axle from spinning in the dropout. A hub motor’s axle is only held in place by friction from the axle nuts — under real torque, that’s not enough on its own, and the axle rotates inside the slot it sits in.
- The forces involved are bigger than they look. Grin Technologies (ebikes.ca) — the company that originated the ebike torque arm design roughly two decades ago — calculates that a 12mm axle producing 40 N-m of torque generates almost 1,000 lb of outward spreading force on the dropout material.
- Aluminum dropouts and forks fail differently than steel ones. Steel spreads gradually as a warning sign; aluminum tends to crack suddenly, which is why front forks — usually the weaker material — are the highest-risk mount point.
- A torque arm meaningfully raises the failure threshold. Endless Sphere forum data puts unreinforced spinout around 60-90 N-m; a correctly installed torque arm pushes that resistance past 150 N-m, which covers essentially every hub-motor kit sold for bicycles.
Best electric bike torque arms at a glance
| Torque arm | Best for | Mount type | Axle fit | Price |
|---|---|---|---|---|
| Grin Technologies V5 Universal | Best overall | Threaded eyelet | 12mm / 14mm / 16mm | ~$25-30 |
| Grin Technologies V7 Regen | Best for no-eyelet frames | Frame-clamp | 12mm | ~$40-50 |
| Voilamart Universal 2-Pack | Best budget | Hose-clamp + eyelet | Universal | ~$13-18 |
| NBpower M14 5-Pack | Best for bulk kit builds | Hose-clamp + C-washer | M14 | ~$18-25 |
| Grin Technologies V3 Front | Best dedicated front-fork pick | Fender eyelet | 12mm | ~$15-20 |
1. Grin Technologies V5 Universal — Best Overall
Grin Technologies V5 Universal Torque Arm
- Works on either the front fork or rear dropout, covering both mount points with one part number.
- Fits 12mm, 14mm, and 16mm axle diameters — the three sizes covering nearly every hub motor sold.
- 3mm stainless-steel plate that mounts through a threaded eyelet near the axle for a rigid fit.
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The V5’s biggest advantage is that it fits nearly every axle diameter and either wheel position, so it’s the one to buy first if you’re not sure which torque arm your specific hub motor needs. Grin Technologies built the original ebike torque arm design, and the V5 is the version most conversion-kit sellers still point buyers toward by default.
2. Grin Technologies V7 Regen — Best for No-Eyelet Frames
Grin Technologies V7 Regen Torque Arm
- Clamps directly onto the frame or fork tube instead of needing a fender or rack eyelet.
- Rated up to roughly 2,000 lb of clamping force — the highest holding power in this lineup.
- Fits 12mm axles, front or rear.
Not every frame has a threaded eyelet in the right spot — fat-tire and cargo bikes especially tend to skip them. The V7’s frame-clamp mount sidesteps that entirely, and its higher rated clamping force makes it the pick for higher-power kits where an eyelet-mounted arm would be marginal anyway.
3. Voilamart Universal 2-Pack — Best Budget
Voilamart Universal Torque Arm 2-Pack
- Two arms in one box — enough to fit both wheels on a dual-motor build or keep a spare on hand.
- Includes hose clamps, stainless nuts, and slotted C-washers for frames without a matching eyelet.
- Steel construction that covers the same core job as pricier single arms at a lower per-unit cost.
For a part this cheap relative to the axle and dropout damage it prevents, the Voilamart 2-pack is the easiest upgrade to justify — it’s less refined than the Grin arms, but it does the same essential job of keeping the axle from rotating in the dropout.
4. NBpower M14 5-Pack — Best for Bulk Kit Builds
NBpower Torque Arm, M14 (5-Pack)
- Five arms per pack, sized for M14 axles common on 1,000-1,500W Bafang-style conversion kits.
- Works front or rear, with hose clamps and C-washers included for frames without eyelets.
- Priced for builders doing multiple bikes or keeping spares for a fleet.
If you’re building more than one conversion — or running a higher-power M14-axle hub motor and want a couple of spares on the shelf — the 5-pack format brings the per-arm cost down without giving up the fit that matters most for these kits.
5. Grin Technologies V3 Front — Best Dedicated Front-Fork Pick
Grin Technologies V3 Front Torque Arm
- Purpose-built for the front fork, where a weaker fork material makes a torque arm most critical.
- Mounts through the fork's existing fender eyelet — no drilling or extra hardware needed.
- 1/4"-thick stainless plate sized specifically for 12mm front hub axles.
Front hub motors are the highest-risk case in this whole guide, since a fork is almost always weaker than a rear triangle. The V3 is built for exactly that mount point, and if your fork already has a fender eyelet, installation is as simple as one bolt.
How to choose an e-bike torque arm
- Measure your axle first. 12mm is the most common size on hub motors, but 14mm and 16mm show up on higher-power kits — a universal-fit arm like the V5 removes the guesswork if you’re unsure.
- Check for a fender or rack eyelet near the axle. If one exists, an eyelet-mount arm like the V3 or V5 is simpler to install; if not, a frame-clamp design like the V7 avoids needing one.
- Prioritize the front fork if you can only buy one. Fork material is typically weaker than a rear triangle, so a front hub motor is the higher-risk mount point even at moderate wattage.
- Torque isn’t the only factor — check your kit’s install guide. Bafang and other kit makers recommend a torque arm as standard practice; follow their documentation for the exact mount position on your specific motor.
The bottom line
Most hub-motor e-bike owners should get the Grin Technologies V5 Universal — a front-or-rear, multi-axle-size torque arm that fits the widest range of bikes. Riders whose frame has no fender or rack eyelet should get the Grin V7 Regen instead, budget builders get real protection from the Voilamart 2-Pack, anyone converting multiple bikes should look at the NBpower M14 5-Pack, and riders who only need to cover the higher-risk front fork can go straight to the Grin V3 Front. Building a conversion from scratch? See our best e-bike conversion kit guide, and if the kit’s controller ever needs replacing, our best e-bike controllers picks cover that too. For the rest of the upgrades most e-bikes skip, see our best electric bike accessories guide.