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Alpinestars Bionic MX Knee Protectors

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Alpinestars Bionic MX Knee Protectors

The Alpinestars Bionic MX Knee Protectors have an articulated thermoplastic shell specifically designed for each knee for superior protection, support and comfort. 


  • Articulated protector follows the movements of the knee joint
  • Impact resistant and ventilated thermoplast shell with aluminum reinforced knee cup for superior energy absorption
  • Ergonomically designed to fit the knees and the side of the bike with an asymmetrical form
  • Removable and impact resistant biofoam padding with a comfortable Lycra liner
  • Adjustable VELCRO® brand closures straps strategically placed to prevent skin abrasions
  • Durable billet aluminum hinges
  • Snap assembly for easy cleaning
  • One size

Alpinestars Knee Brace Sizing

Size Knee (cm)
SM 8-9
MD 9-10
LG 10-11
XL 11-12.5

Sizing information is provided by the manufacturer and does not guarantee a perfect fit.

How To Measure

K Knee Using a caliper, measure the width of the knee joint across the kneecap. The leg should be completely straight and in a weight-bearing position.
Product Style RevZilla Item # Manufacturer Product # Availability
Alpinestars Bionic MX Knee Protectors 305291 650-633-13 4XL/27040001 Available: Requires 1-5 business days lead time prior to shipment


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If your order arrives and it is not right, we will we'll fix it, NO NONSENSE, we promise.

Doesn't fit or just not happy with it? You can return any new, unused and unaltered item within 30 business days of delivery receipt of your item. We will issue a full refund to your original payment method.

See our full Return Policy for all of the pertinent details.

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Alpinestars Bionic MX Knee Protectors 3.5 5 6 6
Scratched my fairings, Bulky and worsens your leg grip It fits great. It stays on. It feels sturdy. However, it just isn't usable because it ruins your grip on the tank. You either need some sort of rubber surface on your tank or the side of the pads. It is bulky and plastic slides. I feel way more stable without these on. Worst part of this product is the fact that it smears all over the fairings. They are not coming off after repeating cleaning with regular cleaners/goo be gone. I'm going to have to sand these off and redo the paint. This purchase has been a very costly mistake. STAY AWAY IF YOU CARE ABOUT YOUR FAIRINGS July 25, 2014
Fair protection, but low bang for the buck I bought these knee guards 5 months ago, they only come in one size, so it doesn't really fit well if you have short legs as me (5ft 6in tall). The velcro straps aren't as durable as you would expect and promptly lose grip. The knee joint keeps clicking everytime you walk, and the pins holding the pads inside the chasis are weak enough as to break on the first cleaning process. Deeply disapointed of this particular item, despite I really do love Alpinestars. June 5, 2014
Great Knee Guards! 1) A little tight around the legs (thigh mainly, shin - not so much). 2) Great strap mechanism and good adjustment options. 3) Looks great, feels good and instills a good sense of protection. 4) Moves freely with knee movements, not restricting. A great knee guard with good value to money, I use it daily for commuting and it's awesome. September 9, 2013
The only thing I have sent back to Revzilla. Two things made me send these back, I really wanted them to work out. 1. One of the supporting straps (very small) wasn't sewn in. It is like the person or machine just missed their mark. 2. You have to have tiny legs for these to fit! I have thick legs but not what I would call overly large. The straps plain didn't reach above or below the knee. Here are my measurements, if you are near mine stay away from buying these. 20'' Above the knee 18'' Below the knee They look cool, I don't know if the pads inside are CE approved. And the plastic felt mid grade leaning to cheap. Like they would be good for one real crash, but that is just me guessing. Felt kind of like a Honda Civic, nice but not going to WOW you, but would do the job. April 21, 2012
Great Product! These knee pads are very comfortable and they mimic natural knee movement. The varying side straps are adjustable and can be adjusted to whatever fit you would like. High satisfied with these knee pads! September 6, 2011
Perfect Awesome product for what they are. Don't let your knees to be exposed on long rides. I use these for anything more than just around the town riding (have a pair if Dainese V knee guards for city crusing which are slimmer) The protection and padding in these are second to none. They are very comfortable and protective (for what they're supposed to do), they're lightweight to the point u forget you have them on, very breathable even though they don't flow air enough to be 5* in that category, but they won't let your knees be sticky and sweaty. I have a lot of protective gear ('coz i sacrifice all the bike tuning and customizing in favor of protection) and Alpinestars, Dainese and Forcefield are simply the best (in no particular order, they compliment each other extremely well with every brand bringing something else to the table, f.i. Forcefield-THE BEST back protector, shirt and shorts, A* THE BEST protective vest and street knee guards, Dainese THE BEST protective leathers...) Everyone who is like me- that cares about protection a little more than the average Joe-should honestly pick these up. $100 is a lot less than a patella tendon surgery (trust me, unfortunately i know) These won't protect you from ACL/MCL injuries, as they don't have the lateral support needed for this kinda protection, but the braces that do are about $500 more so you have to be reasonable. Overall, i haven't find a better, more comfortable patella, knee cup protection, that you can wear under a bit looser riding pants, yet April 9, 2011
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