Top Hard Enduro Knee Protection

Hard enduro is slow. You crawl up rock steps, paddle through roots and stall on climbs. Most falls happen at walking pace. That changes what hurts you.

At speed, the risk is a hard hit. At walking pace, the risk is a foot planted on a rock while the bike and your body keep moving. The knee twists. That is how ligaments go. Then there are the hits: a kneecap into a boulder, a shin into a log, the bike landing on your leg in a rock garden.

The days are long, too. The Red Bull Erzberg Rodeo Hare Scramble is "1 mountain. 500 starters. 27 checkpoints. 4 hours time," per the organizer. You push, lift and walk the bike for part of that. Whatever you strap to your knees has to stay put, breathe, and let you walk.

Knee protection comes in two forms:

If you ride hard enduro often, we'd weigh ligament protection heavily, not only impact protection. This follows from the injury data in the next section: ACL, meniscus and MCL injuries are the most common knee injuries reported, and braced riders reported fewer of them.

The key study of knee braces in off-road motorcycling is often quoted without its limits. Here are both.

Sanders et al., 2011

Sanders and colleagues published "Knee injuries and the use of prophylactic knee bracing in off-road motorcycling" in the American Journal of Sports Medicine. The abstract reports:

• Design: a descriptive epidemiology study. 2,115 off-road riders answered an internet survey over one year. Riders were grouped by whether they wore knee braces.
• Exposure: 39,611 riding hours. 57 riders (2.7%) had at least one knee injury, 89 injuries in total.
• Most common injuries: the anterior cruciate ligament (ACL), the menisci and the medial collateral ligament (MCL).
• Overall rate: 3.675 injuries per 1,000 rider hours without braces, against 1.587 with braces (P < .001).
• ACL rupture: 1.518 against 0.701 per 1,000 rider hours (P = .0274).
• MCL injury: 0.799 against 0.111 per 1,000 rider hours (P = .002).

The authors conclude that bracing "appears to have a beneficial effect" against MCL and ACL injuries and overall knee injury.

Its limits

Our reading of the design, based on the methods in the abstract:

1. Riders chose whether to brace. It is not a randomized trial. The two groups may differ in skill, bike or riding style.
2. Injuries were self-reported through an online survey, not taken from medical records.
3. Small numbers. 57 injured riders carry the whole comparison.
4. Off-road in general. It covers off-road motorcycling, not hard enduro specifically.

Within those limits, its results point one way. The paper's own background notes that brace studies in other sports disagree, which is why the topic "remains controversial."

What braces can cause

A 2018 case report by Erwood and colleagues describes two motocross riders who broke the femur (thigh bone) at the top edge of their knee braces, 22 cm and 21.1 cm above the center of the knee. The authors suggest a rigid brace protects the ligaments but may focus force where the frame ends. This is why makers now build in weak points: Leatt says the C-Frame chassis has "built-in fracture points" designed to break before the shin or thigh bone does (Leatt). Two cases say nothing about rates, but they explain the design.

Older race data

A 12-year study of European motocross competition (15,870 riders, 1980 to 1991) counted 344 ligament injuries. 206 of them (59.9%) were in the lower limbs, "especially on the knee." The pattern matches Sanders.

EN 1621-1:2012 is the European standard for motorcycle limb joint impact protectors: shoulder, elbow, hip and knee. Its full title is "Motorcyclists' protective clothing against mechanical impact – Part 1: Motorcyclists' limb joint impact protectors – Requirements and test methods." The Estonian Centre for Standardisation catalogue lists it as valid from 4 January 2013, replacing the earlier edition. Its scope covers protectors built into riding clothing or "used as separate items," which includes strap-on guards and the knee cups of braces.

The impact test

REV'IT!, which certifies its own armor to the standard, describes the test: a 5 kg striker falls from about one meter, so the impact energy is at least 50 J. The lab measures how much force passes through the protector, in kilonewtons (kN). Lower is better.

REV'IT! lists two conditionings: 48 hours at 23 °C before the ambient test, and 72 hours at 70 °C above water before the wet test.

Level 1 and Level 2

The force limits come from Knox. The descriptions come from Alpinestars' EN 1621-1 user leaflet. SATRA, a test lab, adds that no single value should be over 50 kN.

The level is a pass mark, not a score. Alpinestars says its Bionic 10 Carbon and Bionic 7 braces "attained transmitted force values below 26kn" and were awarded Level 1 (manual). Two Level 1 products can sit far apart inside the band.

Type A and Type B

Alpinestars' leaflet: "There are two protector types – Type A and Type B, these refer to the size. Type B protectors are larger than Type A protectors." Type is about the area the protector covers, not how well it absorbs a hit. MET, which sells Type B knee pads, states Type B certification means "39% more coverage on knees" (MET).

T+ and T-

Two optional tests check the protector when hot and cold. SATRA gives the temperatures: +40 °C and −10 °C. A pass adds T+ or T- to the label. Alpinestars warns that heat and cold "may reduce the performance of the protector, even if T+ and/or T- are present."

What the standard does not cover

• Ligaments. The test measures force through the protector. Nothing in it measures twisting or hyperextension. An EN 1621-1 label on a brace describes the knee cup, not the hinges.
• Abrasion and tearing. It is an impact test.
• Retention. A protector that has slid down your shin protects nothing. Fit is on you.

Guards and braces are regulated in different ways, so the claims on the box mean different things.

Impact protectors are PPE

In the EU, impact protectors fall under the PPE Regulation (EU) 2016/425. Annex I sorts PPE into three risk categories. Category II "includes risks other than those listed in Categories I and III." Alpinestars states its EN 1621-1 protectors are Category II PPE (leaflet).

For Category II, Article 19 requires an EU type-examination by a notified body (module B), followed by production control (module C). An independent lab checks the design. Alpinestars names its lab for the Bionic braces: "Notified Body #0498, Ricotest" in Italy (manual).

Braces are often medical devices

Many braces are also registered as medical devices. In the EU that means the Medical Device Regulation (EU) 2017/745. Article 52(7) lets makers of Class I devices "declare the conformity of their products by issuing the EU declaration of conformity" after drawing up their own technical documentation. No notified body is involved for a non-sterile brace without a measuring function.

POD's EU declaration for the K8 3.0 shows this plainly: "Class 1 (non-sterile; no measuring function)," declared by POD under Annex IV of the MDR. The stated purpose is "external support, stabilization and protection of the knee."

In the US, a brace is a "limb orthosis," a Class I device exempt from premarket notification (21 CFR 890.3475). FDA registration "does not in any way denote approval of the establishment or its products" (21 CFR 807.39).

What each maker claims

Our view: a medical device registration tells you the maker has declared a medical purpose. It does not tell you an independent lab has checked anything. An EN 1621-1 certificate does involve a notified body, but only for impact. That reading comes from Article 52(7) of the MDR and Article 19 of the PPE Regulation. Read both claims for what they are.

EN 1621-1 protectors carry a pictogram. Alpinestars' user leaflet and brace manual decode it. A Bionic 10 Carbon knee cup reads "K TYPE A, 1, T+ T-" next to the motorcycle-use symbol.

For a knee and shin guard, look for K+L. That code means knee plus leg: the certified zone runs down the leg, not just over the kneecap.

What to check in the paperwork

Annex II, point 1.4 of the PPE Regulation says the instructions must give, among other things: the performance levels, "the significance of any markings," the notified body's name and number, the standard with its date, and the web address of the EU declaration of conformity. If a product claims CE impact protection and none of this is in the box or online, ask the maker.

For a brace sold as a medical device, look for the EU declaration of conformity under the MDR. It should name the device, its class and the maker. POD publishes its declaration on the product page.

A brace that twists on your leg cannot hold your knee. A guard that slides down cannot cover it.

Sizing a brace

Brace makers size by knee measurements, not by pant size.

Source: Alpinestars Bionic manual. Alpinestars supplies a measuring tool and still "strongly" recommends trying the brace on. POD sizes the K8 3.0 by knee width and knee circumference.

Fitting steps

Alpinestars' fitting procedure for the Bionic brace, in short:

1. Fit it with the undersock, boots and pants you ride in. Pants go on top of the brace.
2. Braces are left and right. Put each on the correct leg.
3. Straighten your leg fully and place the brace. It should grip the sides of the knee so it stays on, loosely, with no straps closed. If it does not, fit the extra side padding.
4. Close the straps in the order the manual gives.
5. Bend your leg. The knee cup should stay centered over the knee.

Stopping slip

• Socks and sleeves. Brace makers sell long socks for this. Alpinestars' knee brace socks have "an elasticated upper hem with internal silicon grip to keep the socks in place."
• Straps set once. Fox's Titan Pro D3O guards use three straps and a Posi-Lock buckle with "one-time strap adjustment" (Fox). Set them on the leg, then leave them.
• Walk and kneel before you ride. Ten minutes of walking, squatting and kneeling in full kit shows you more than any size chart. The reason is simple: in hard enduro, you will walk and kneel with it on.

Hyperextension stops

All three braces here limit how far the knee can straighten. The stop angle is how many degrees short of straight the brace stops you.

• Alpinestars Bionic-10 Carbon: interchangeable stops of 0, 5, 10, 15, 20, 25 and 30 degrees. It ships with the zero-degree stop fitted. Use the same stop in both hinges (manual).
• Leatt C-Frame Pro Carbon: "Hyper extension limitations 10º, 15º, 20º and 25º" (Leatt).
• POD K8 3.0: two extension controls, about 10–20° and 20–30° (POD).

Start with the smallest stop your knee needs, then ride a trail with steps before you race. We say this because of how hard enduro is ridden: you stand, dab and straighten your legs over and over on climbs, and a stop set too tight works against you all day.

Hinge types

Heat and walking

On a hot day of pushing and walking, a vented guard is easier to live with than a brace, and a brace is easier to live with than a torn ACL. That judgement weighs what a brace is, a rigid frame strapped over thigh and calf, against the Sanders injury rates above.

Kneeling on rock

You will kneel on rock to lift the bike, fix a flat or get it up a step. A knee cup rated to EN 1621-1 covers the kneecap. A K+L guard also covers the shin. In rocky races, we'd choose protection certified over the shin as well as the knee. The K+L code shows that: it means knee plus leg.

Boots and pants

Knee protection has to fit between your boots and your pants. Leatt says the C-Frame's shin plate "fits inside all boots" and the Dual Axis has a "slim shin plate for great boot fit." Try your brace with your own boots: the calf strap and the boot top must not fight each other.

Water and mud

Braces get soaked in water crossings and packed with mud. Alpinestars' manual says to check the hinges for foreign objects and clear them with water or compressed air, but never to use a pressure washer on the brace (manual).

Braces aim to limit harmful motion. Pads (guards) focus on impact. Fit and retention matter more than brand, because a slipping protector protects nothing. Here is how to choose:

1. Decide what you are protecting against. Twisting and hyperextension call for a brace. Blows from rocks and logs call for a guard. A brace with an EN 1621-1 knee cup gives some of each.
2. Read the certification. For impact, look for EN 1621-1:2012, the level, and K or K+L. For a brace, look for the medical device claim and the declaration behind it.
3. Measure. Knee width and circumference for a brace. The maker's chart for a guard.
4. Try it with your boots and pants. Walk, squat and kneel.
5. Check spare parts. Alpinestars lists strap, extension stop, calf frame and padding sets for the Bionic brace (manual).
6. Budget for a pair. Braces are often priced per knee. Leatt lists the C-Frame Pro Carbon at $384 for one and $709 for a pair (Leatt).

Our view: if you can afford a pair of braces, wear braces in hard enduro. If you cannot, a certified K+L guard beats nothing. Two things decide it: the Sanders rates for braced and unbraced riders, and the price gap: $114 for the Dual Axis guards against $709 or more for a pair of braces at the makers' list prices.

Cleaning

• Guards: Fox says to machine wash the Titan Pro D3O cold on a gentle cycle and line dry it (Fox).
• Protector inserts: Alpinestars says use a damp cloth and soapy water, and do not submerge them (leaflet).
• Braces: liners and straps can go in a cold machine wash. Clean the frame with a damp cloth and mild soap, rinse, and dry it before storage. No pressure washer, no tumble dryer (Bionic manual).

Store protection dry, out of direct sun, with nothing heavy on top.

Inspection and replacement

After every crash, bend the brace through its full range and look for cracks, chips, torn straps and grit in the hinges. Alpinestars' rules:

• A brace that is not intact, or has cracks, chips or torn straps, "must be replaced."
• Hinges that do not work correctly mean the brace "must be replaced or repaired." In doubt, ask an authorized dealer.
• Replace a protector after a severe impact, "particularly if the plastic has lightened in colour at the impact point."
• Alpinestars "strongly recommends replacing your protector every 5 years under normal use conditions."
• Do not use a product that "no longer fits correctly," and never modify, paint or sticker it.

Leatt's C-Frame is designed to break at set points before your bones do. Once it has, replace it.

1. Reading "Level 1" on a brace as ligament protection. The EN 1621-1 test measures force through the knee cup, not the hinges.
2. Reading "FDA registered" as "FDA approved." Registration "does not in any way denote approval" (21 CFR 807.39).
3. Buying a brace by pant size. Braces are sized by knee width and circumference.
4. Wearing pants under the brace. Alpinestars' fitting instructions put pants on top.
5. Mixing stop angles. Alpinestars says always use the same extension stop in both hinges.
6. Ignoring the shin. A K-only guard certifies the knee. In rock, look for K+L.
7. Trusting T+ in a heatwave. Alpinestars warns that heat and cold can reduce performance even when T+ or T- is on the label.

For the rest of your kit, see our hard enduro gear guide and first aid basics. For how we build these pages, see our gear methodology.