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Leatt 3DF AirFlex Knee Guard (discontinued)

Vital Rating: (Good)
Leatt 3DF AirFlex Knee Guard
 Leatt 3DF AirFlex Knee Guard  Leatt 3DF AirFlex Knee Guard
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Tested: Leatt 3D Airflex Knee Guard

Rating: Vital Review

Review by Lee Trumpore // Photos by Lee Trumpore and Emily Scott

Once upon a time armoring up for a mountain bike ride meant either dressing up as a ninja-turtle or just wearing long sleeves. If you're either too young or too new to the sport to remember those days, trust me, you aren't missing much. It's a good time to be a mountainbiker. In addition to several wheel sizes and a half dozen axle standards there are multiple options for just about everything, from the gear you keep in the garage to the gear you hang in your closet (and if you're anything like me, the gear you scatter around the house somewhere in between). To the point, 'body-armor' doesn't have to be armor-like anymore and with the unstoppable boom in aggressive all-mountain/trail riding and the advancement of enduro/racing bikes the less-is-more approach has been a welcome change. Leatt's new 3DF Airflex knee guards certainly look to be pushing this new theme to the limit, which for some riders might beg the question 'when is less simply too little?'


Leatt 3D Airflex Highlights

  • Super slim 6mm CE impact certified
  • Weight: 105-grams per pad
  • Armorgel ultra slim impact absorbing gel
  • MoistureCool wicking fabric
  • Silicone lamination to keep protector in place
  • CE certified for impact protection EN1621-1
  • 3D design, meant to increase comfort
  • MSRP: $100 USD

Initial Impressions

The ultra light weight of the Airflex pads was apparent the minute the empty feeling box landed on my doorstep. At 105-grams each these pads probably weigh less than the cardboard they came in.


In terms of craftsmanship and general appearance the Airflex knee guards are well constructed and and thoughtfully executed. The seams are soft and high-contact, high-movement areas are lined with a smooth nylon trim that should help to ward off chaffing and rubbing on longer rides. From the choice of materials it's apparent Leatt wasn't just going for light weight but maximum ventilation as well, with perforated fabric used liberally throughout.


The individual pads are clearly marked 'left-side' and 'right-side' though as far as I can tell they are both entirely symmetrical. With legs and knees being funny shapes my best guess is the labels ensure you end up wearing the same pad on the same leg each time for a more consistent fit over time. When it comes to much of my gear I'm a big fan of simple color schemes, and Leatt's choice of black and understated grey graphics is a winner in my books. Time then to get these pads dirty.

On The Trail

Even after using some of the lightest pads on the market for the past year, the Airflex knee pads left my knees feeling almost naked; almost akin to a pair of knee warmers I might wear on my roadie. Ventilation is top notch and with winter days here in Taiwan still topping out in the 80's this was certainly welcome on some of my longer days in the saddle.


However, what they gain in weight and venting the Airflex pads give up a bit in overall comfort. Due to their extreme minimalist design there is no internal relief or knee-cup which means the front of the pad is in constant contact with your kneecap and will give a slight sensation of tightening with each pedal stroke.


Obviously this isn't exactly unique to the Leatt design but is worth mentioning, if nothing else because the rest of the material felt like it was barely there. The 2 rubberized elastic cuffs also had a habit of working their way out of place and towards my kneecap, though it should be noted that the actual padded part always stayed put. Again, this wasn't a huge bother or necessarily a design flaw but likely the result of using thinner and thinner materials that don't have as much rigid support on their own. On the flip side, of course, this is a pair of ultra-light, incredibly breathable knee pads that most of the time barely feel like they are there at all.


As I eluded to at the beginning, there will come a point where less becomes too little. While for some riders this starts with anything that doesn't include a plastic shell there are plenty of others who are happy to give up a bit in terms of maximum impact protection in the name of comfort, weight, and portability. I'm most definitely in the latter group, but I have to admit I was initially skeptical of just how far Leatt had pushed the minimal concept with the Airflex pads. 6mm of padding is exceptionally thin. And while the Armorgel used over the knee does harden noticeably on impact, its lack of overall surface area means that more of the impact can be felt directly on the knee rather than being spread out across it. 


The few times I did crash on my knees I definitely 'felt' more of the impact though I can't report any increase in cuts or bruising as a result. I'd feel confident wearing the Airflex pads for most rides and the vast majority of crashes that I encounter, but for rowdier days or trails with lots of sharp pointy rocks I'd probably reach for something with just a little more coverage.

Things That Could Be Improved

While I found the fit and ventilation to be top-notch for the most part it was a bit annoying to readjust the upper cuff as it worked its way down a couple of times each ride. Perhaps designing a crease into the padding across the top of the kneecap would facilitate it bending a bit more, and having a bit of a 'hinge' might prevent the cuff from being pulled down while pedaling. It would be nice if the padding was designed to flex around the kneecap rather than across it.


I understand that knee protection is going to be different for everyone, but I consider the bones on the sides of my knees to be just as important as those at the center. The Leatt Airflex pads come up short in this department, providing no protection at all to the side of the joint. I'd love to see the padding wrap around the sides bit more even if it means adding a few grams to the weight.

What's The Bottom Line?

There will always be compromises, and we generally face a basic choice between heavy and bulky or light and well-ventilated at the expense of overall protection. The Leatt 3DF Airflex kneepads toe the latter line about as close as possible while still being able to provide legitimate protection from impacts. While for some riders these might be just the pads they have been waiting for, others (like me) might consider them a worthy addition to their gear bag for certain kinds of riding, and for a few they're probably not quite enough. But like I said at the start it's good to have options, and right now the options are good!

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About The Reviewer

Lee Trumpore has been riding bikes for more than 20 years on just about every material and technology the bike industry has come up with. In more than a decade of professional DH racing, Lee won a Collegiate National Championship and was a mainstay at major North American races as well as occasionally snagging a last page result in the World Cup series. Testing prototype components and suspension setups was common during his racing days. He has a smooth, light style on the bike even while holding it wide open. An East Coast native, his favorite trails are fast and flowing technical descents with as many corners as possible and just enough moisture to keep things interesting. Nowadays, rather than racing the clock, he'd rather enjoy a rad descent after a hard pedal to the top. A closet nerd with a Master's degree in education policy Lee currently lives in Taipei, Taiwan where he splits his time teaching mathematics to the next generation of computer geniuses and behind the lens as a photo mercenary for Vital MTB and other industry clients.


Product Leatt 3DF AirFlex Knee Guard
Riding Type Trail
Pad Type Soft Shell
Material Armourgel ultra slim impact absorbing gel and MoistureCool wicking fabric
Knee/Shin Coverage Knee Only
Size S/M, L/XL, or XXL
Color Black
Miscellaneous CE certified for impact protection EN1621-1
Super slim 6mm CE impact certified
Pre-curved 3D design for fit and function
Perforated padding for ventilation
Silicone printed, non-slip cuffs
Silicone printed, cupped knee grip
Weight: 250g / 0.5 lbs (pair)
2015-2018 model years
Price $99
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