Comparing the Leatt X-Frame, Asterisk Ultra Cell, and Mobius X8? This guide breaks down protection, comfort, fit, and innovation across all three premium knee braces so you can choose the right one for your riding style.
Knee braces are one of the most important pieces of protective gear in off-road and motocross riding. The forces placed on your knees during crashes, hard landings, and quick direction changes can lead to serious injuries if you’re not properly protected. A high-quality brace can make the difference between riding next weekend or spending months recovering.
In this blog, we’re comparing three of the most trusted knee braces available today: the Leatt X-Frame, the Asterisk Ultra Cell, and the Mobius X8. Each of these models is designed with a different take on fit, function, and technology, and each has earned its place in the premium category.
Our goal is to break down how these braces perform in the real world. We’ll look at comfort, protection, adjustability, durability, and overall value so you can choose the one that fits your riding style and your body.
Leatt X-Frame Overview
The Leatt X-Frame is a premium knee brace built for riders who want serious protection without unnecessary bulk. Designed with both safety and performance in mind, it blends lightweight construction with advanced certification and rider-focused features.
Protection and Certification
The X-Frame is CE EN1621-1 certified for impact protection and meets medical device standards in both the United States and the European Union. It is engineered to help reduce injuries to the ACL, MCL, and meniscus—three of the most common and damaging knee issues in off-road riding.
Materials and Construction
The brace features an injected carbon composite frame that offers strength without adding weight. Its slim profile improves the connection between rider and bike, making it easier to grip and control. The asymmetrical hinge design mirrors natural knee movement, reducing restriction while improving stability.
Fit and Comfort
Weighing less than many competitors, the X-Frame is built to be worn all day. It comes with two different thickness pad sets, allowing for a more personalized fit. That said, getting the right setup is key. Improper adjustment can lead to pressure points, particularly on the shin.
Durability and Real-World Use
The X-Frame has been tested in rugged conditions and through multiple crashes. Riders consistently report that it maintains both structural integrity and protective performance over time, even with regular use.
Key Downsides
While the brace offers excellent protection and comfort once properly fitted, the initial setup process can take time. Riders with sensitive shins or unusual leg shapes may need to experiment with padding or placement to get it just right.
Asterisk Ultra Cell Overview
The Asterisk Ultra Cell is a high-performance knee brace built for serious off-road riders who demand full-range protection, long-term comfort, and innovative features. With more than a decade of refinement behind its design, this brace is a favorite among riders who need gear that stays in place and works under pressure.
Protection and Certification
The Ultra Cell offers complete knee protection throughout the full range of motion. It is engineered to shield the joint during flexion, extension, and lateral movements, helping to reduce the risk of ACL, MCL, and meniscus injuries. The design has been developed and tested over many years, making it one of the most proven braces on the market.
Materials and Construction
Asterisk uses a carbon fiber epoxy matrix for the frame, which creates a strong yet lightweight structure. The Asymmetry Glide hinge is designed to follow the natural path of the knee, allowing smooth movement without sacrificing stability. Patented components are integrated throughout, making this one of the most technically advanced braces available.
Fit and Comfort
The Ultra Cell is known for its comfort. Its cuff system offers customizable tension and comes in multiple size options, allowing for a more precise and stable fit. Riders often report that the brace stays in place without pinching or sliding, even during extended use. This makes it a top choice for long races or all-day trail rides.
Innovation and Extras
One standout feature is the boot anchor system, which helps keep the brace from rotating or moving during a crash. It connects directly to your boots, creating a secure lock between gear and rider. Adjustment points throughout the brace allow you to fine-tune the fit quickly and easily.
Key Downsides
The boot anchor system, while effective, can be inconvenient for riders who rotate between multiple pairs of boots. Each pair must be fitted with its own anchor point, which may limit flexibility and make quick gear changes more difficult. However, for riders with a consistent setup, this system adds another layer of security.
Mobius X8 Overview
The Mobius X8 is a standout in the knee brace market thanks to its unique design and innovative approach to stabilization. Built for riders who want modern technology, tailored fit, and all-day comfort, the X8 combines smart engineering with high-performance materials.
Protection and Certification
At the core of the Mobius X8 is a patented tendon back plate system. This design disperses impact force over a wider area of the knee and provides strong lateral and rotational stability. It is particularly effective at reducing stress on the ACL and surrounding ligaments during crashes or sudden movements.
Materials and Construction
The X8 uses a composite frame with a reinforced tendon plate to deliver structure without adding bulk. It is lined with soft EVA foam padding that cushions the leg and helps prevent chafing. The brace is built to hug the leg closely, allowing riders to maintain control and feel while squeezing the bike through corners or obstacles.
Fit and Comfort
Fit customization is a strong point for the X8. The brace includes multiple strap positions and adjustable patella pad sets, allowing riders to fine-tune the feel based on leg shape and size. The dial-adjusted back plate ensures even pressure across the knee, reducing hotspots and helping the brace stay put during hard rides. In most conditions, it remains secure and comfortable with minimal need for adjustment.
Innovation and Design Highlights
What sets the Mobius apart is its dial system, which replaces the traditional Velcro-only approach. This adds a layer of precision and durability to the fit. The design offers modern features in a lightweight, low-profile format that appeals to riders who value both tech and simplicity.
Key Downsides
A few riders report minor strap snagging when putting the brace on or taking it off. There can also be slight movement during very long or hot rides, especially when not paired with knee brace socks. These issues are minor and often resolved with proper setup, but they are worth noting for riders who log extended hours on the bike.
Side-by-Side Comparison Table
Here’s a direct breakdown of how the Leatt X-Frame, Asterisk Ultra Cell, and Mobius X8 stack up against each other in key categories. Use this chart to quickly compare performance, comfort, and design features.
|
Feature |
Leatt X-Frame |
Asterisk Ultra Cell |
Mobius X8 |
|---|---|---|---|
|
Frame Material |
Injected carbon composite |
Carbon fiber epoxy matrix |
Composite frame with reinforced tendon plate |
|
Hinge System |
Asymmetrical hinge for natural movement |
Asymmetry Glide hinge with full knee tracking |
Dial-controlled tendon back plate system |
|
Fit and Adjustment |
Two pad thickness options, needs fine tuning |
Multiple sizes, customizable cuffs |
Multi-strap layout with patella pad options |
|
Comfort |
Lightweight and slim, all-day capable |
Widely praised for plush fit and pressure relief |
EVA foam padding, low bulk feel |
|
Stay-in-Place Reliability |
Secure with proper setup |
Boot anchor prevents brace rotation |
Secure with dial tension, minor slipping possible |
|
Durability |
Proven to last through repeated crashes |
100+ hours reported with no wear issues |
Highly durable with minimal degradation |
|
Certification and Coverage |
CE EN1621-1, medical device grade |
Full-coverage knee protection |
Strong lateral and rotational support |
|
Price Range |
Premium |
Higher-end premium (around $1000 per pair) |
Premium |
|
Known Weaknesses |
Shin discomfort if setup is off |
Boot anchor can be inconvenient |
Strap snagging, occasional movement in heat |
Each brace offers premium protection and performance, but the best choice will depend on your preferences for fit, setup complexity, and ride conditions.
Which Knee Brace Is the Best?
Each of these braces brings something different to the table, and the best choice depends on your priorities as a rider.
Leatt X-Frame is a great option for riders who want a slim, lightweight design that still meets strict safety certifications. It allows for natural movement on the bike and stays out of the way while riding aggressively. If you are willing to spend a little time getting the fit dialed in, this brace offers excellent protection without unnecessary bulk.
Asterisk Ultra Cell stands out for its all-day comfort and long-term durability. The customizable cuff system and full-range knee coverage make it a favorite for riders who demand a stable, no-fuss brace that stays put through every type of terrain. It is especially well suited for long rides and race days. If you can work around the boot anchor system, it is one of the most secure fits available.
Mobius X8 is best for riders who want adjustability, innovation, and comfort all in one package. The dial-controlled back plate offers even pressure across the knee and reduces shifting during the ride. Its slim design makes it feel more like a natural extension of the leg, and the strap system allows for a tailored fit across many leg shapes.
Final Takeaway
All three models are high-end and offer excellent protection. The right choice comes down to how much adjustability you want, how the brace feels once it is on, and what type of riding you do most. There is no wrong pick here—just the one that fits your body and riding style best.
Real-World Feedback and Community Insights
Across forums, YouTube channels, and product review sites, all three braces have earned solid reputations—but for different reasons.
On Reddit, riders often mention the Leatt X-Frame as a reliable, minimalist option that feels natural once properly adjusted. Some point out the learning curve with shin fit, but most agree it holds up well in harsh riding conditions and multiple crashes.
Asterisk Ultra Cell gets consistent praise for its comfort and stability. Riders who wear it during long races or enduro events say it stays in place and never causes pressure points. YouTube reviewers highlight how easy it is to set up and forget. The only recurring complaint is the boot anchor system, which adds time to gear changes if you rotate between boots.
The Mobius X8 stands out in reviews for its unique design and dialed-in feel. Reviewers on Dirt Bike Test and Motocross Action Magazine call the tendon back plate a real innovation, especially for distributing impact evenly. Some users mention occasional shifting during sweaty rides, but many say that brace socks solve the issue completely.
From influencers to grassroots riders, the overall feedback confirms these are three of the best braces on the market. The choice usually comes down to personal fit and preferred features.
Further Resources and Reviews
Leatt X-Frame
Asterisk Ultra Cell
Mobius X8
These sources include spec details, rider impressions, and how each brace holds up over time. Perfect for checking fit guides, sizing tips, or seeing real feedback from trail and track riders.
TL;DR Summary
Leatt X-Frame
-
Lightweight with strong certifications
-
Slim and low-profile for better bike control
-
Best for riders who want performance and don’t mind adjusting the fit
Asterisk Ultra Cell
-
All-day comfort with full-coverage protection
-
Boot anchor keeps it locked in place
-
Ideal for racers and long-distance trail riders
Mobius X8
-
Highly adjustable with unique tendon plate design
-
Dial system offers even pressure and secure fit
-
Great for tech-minded riders who want modern innovation
Top Pick by Category
-
Comfort: Asterisk Ultra Cell
-
Innovation: Mobius X8
-
Durability: Leatt X-Frame
Final Recommendation
Choose the Leatt X-Frame for lightweight feel and certification-backed safety.
Choose the Asterisk Ultra Cell for race-ready comfort and a brace that never moves.
Choose the Mobius X8 if adjustability, stability, and modern tech are your top priorities.
All three are excellent. Your body shape, riding style, and gear preferences will point you to the right one.
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