Quad Lock Motorcycle Knuckle Adaptor: When and How to Use It
By Quad Lock USA® - Official Store | Published: 2026-10-13
Category: How-to Guides
Learn when a Quad Lock Motorcycle Knuckle Adaptor fixes handlebar clearance and angle issues, plus a step-by-step install for a secure, adjustable phone mount.
Quick answer
Use the Quad Lock Motorcycle Knuckle Adaptor when your handlebar, fork stem, or mirror mount leaves the phone too low, too close, or at an awkward angle. It fits between the mount and the index head to add height and a second adjustment point, so you can set a clear, stable viewing angle without changing your entire setup.
What the Knuckle Adaptor actually changes
The Knuckle Adaptor is a small intermediate piece that goes between a Quad Lock Handlebar, Fork Stem, or Mirror Mount and the index head. It adds height and one more pivot point, which means you can tilt and position the phone independently of the mount base. That extra range matters when your bars are crowded, your screen sits too flat, or your phone blocks the instrument cluster. Because it is part of the Quad Lock 360 system, it also works with other 360 components such as the MAG Head if you want faster attach and detach.
When to add a knuckle adaptor (and when to skip it)
Add the adaptor if you have tried adjusting the mount itself and still cannot get a comfortable, glare-free view. It is also useful if you switch between a phone and a larger device, or if you want to raise the phone above a tank bag or bar clamp. Skip it if your current mount already gives you the angle and height you need, or if you are using a mount that already includes enough articulation. More parts mean more potential movement points, so keep the setup simple unless the extra adjustment solves a real problem.
Check compatibility before you buy
The Knuckle Adaptor is designed for Quad Lock Handlebar, Fork Stem, and Mirror Mounts and is compatible with all Quad Lock 360 products. If you are building a custom setup, confirm that your mount uses the 360 interface. If you are unsure, the safest approach is to start with the mount you already own and add the adaptor only when you can identify the specific clearance or angle issue it will fix.
Step-by-step: installing the Knuckle Adaptor
- 1. Confirm your mount and bar size: Identify whether you have a Quad Lock Handlebar, Fork Stem, or Mirror Mount. If you are using a Handlebar Mount PRO, check that the correct spacer is fitted for your bar diameter (22.2mm, 25.4mm, 28.6mm, or 31.8mm). Common mistake: guessing the bar size and leaving the mount loose. A snug base is the foundation for any added adaptor.
- 2. Remove the index head from the mount: Loosen the existing fastener and separate the index head from the mount base. Keep the hardware in a safe place; you will reuse it to attach the knuckle adaptor. Checkpoint: if the fastener is damaged or stripped, replace it before continuing so the final assembly can be tightened securely.
- 3. Fit the knuckle adaptor between mount and index head: Place the knuckle adaptor onto the mount base, then attach the index head to the adaptor. Hand-tighten the fastener just enough to hold the parts together while you test the range of motion. Common mistake: fully tightening before you have set the angle. Leave it snug but adjustable for now.
- 4. Set your viewing angle and height: With the phone attached or a phone-sized object in place, adjust the knuckle and the index head until the screen is readable and does not block your view of the road or instruments. The adaptor gives you one extra pivot point, so use it to fine-tune rather than forcing the mount base into an extreme position. Checkpoint: sit on the bike in your normal riding position. If you have to lean or crane your neck, keep adjusting.
- 5. Tighten all fasteners and check for movement: Once you are happy with the position, tighten the knuckle adaptor and index head fasteners firmly. Grip the mount and try to twist it; there should be no play. If it moves, tighten a little more without over-torquing. Common mistake: leaving one pivot slightly loose, which can cause the phone to droop over bumps. Re-check after the first ride.
Key product facts
- Motorcycle/Scooter - Knuckle Adaptor: Suitable for Quad Lock Handlebar, Fork Stem and Mirror Mounts, the Quad Lock Motorcycle Knuckle Adaptor can be integrated between the mount and the index head to provide extra height and another level of adjustability when setting your smartphone viewing angle. Compatible with all Quad Lock 360 products. This tells you exactly where the adaptor fits and what it adds, so you can decide if it solves your height or angle problem without replacing your existing mount.
- Quad Lock 360 Head - MAG Head: Integrate the Quad Lock MAG Head with Quad Lock 360 and experience super fast mounting. Strong hold magnets and additional shear resistance provided by the Quad Lock interface keep your phone secure. The magnet array and Quad Lock interface ensure you always mount your phone straight. If you want quicker attachment and a clean, straight mount every time, pairing the knuckle adaptor with a MAG Head can give you both adjustability and speed.
- Replacement - Handlebar Mount PRO Spacer Set: Replacement spacers for the Quad Lock Motorcycle Handlebar Mount PRO. To fit handlebars 22.2mm, 25.4mm and 28.6mm, and 31.8mm in diameter. If you are installing the knuckle adaptor on a Handlebar Mount PRO, these spacers let you adapt the base to common bar diameters before you set your final angle.
