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Alpinestars MTB Bionic Men's Shorts
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Item # APN0025

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Item # APN0025


More protection for your bottom line.

Alpinestars MTB Bionic Shorts prevent injury by absorbing shock and impact. Ventilated foam covers your hip bone, tailbone, and thighs while hard polyurethane panels cover your thighs and tailbone for extra protection. Mesh and Lycra fabrics are lightweight and breathable, so you can work up a sweat without feeling sticky.

  • Lycra shorts with mesh panels
  • Hard PU hip and thigh padding
  • Foam tailbone padding

Tech Specs

[padding] foam, [shorts] Lycra, [panels] mesh
Protection Area:
thigh, tailbone, hips
Recommended Use:
mountain biking

Size Chart


Men's Apparel

35 - 36in

(88.9 - 91.4cm)

37 - 39in

(94 - 99.1cm)

40 - 41in

(101.6 - 104.1cm)

42 - 44in

(106.7 - 111.8cm)

45 - 47in

(114.3 - 119.4cm)


30 - 31in

(76.2 - 78.7cm)

32 - 33in

(81.3 - 83.8cm)

34 - 35in

(86.4 - 88.9cm)

36 - 38in

(91.4 - 96.5cm)

39 - 41in

(99.1 - 104.1cm)


40 - 41in

(101.6 - 104.1cm)

42 - 43in

(106.7 - 109.2cm)

44 - 45in

(111.8 - 114.3cm)

46 - 48in

(116.8 - 121.9cm)

49 - 51in

(124.5 - 129.5cm)


19 - 20in

(48.3 - 50.8cm)

21 - 22in

(53.3 - 55.9cm)

23 - 24in

(58.4 - 61.0cm)

24 - 25in

(61 - 63.5cm)

26 - 27in

(66 - 68.6cm)











How to Measure:
For best results, take measurements over your underwear.
Measure under your arms, around the fullest part of your chest.
Measure around your natural waistline, keeping the tape a bit loose.
Measure around the fullest part of your body at the top of your legs.
Using pants that fit well, measure the crotch seam to the bottom of the leg.

Reviews & Community


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Save me from plenty

  • Familiarity: I've used it several times

These bike shorts are a really good fit. I mostly downhill mountain bike with them. They have taken a few hits -when I go one way and my bike goes another with me landing on my sides most times I can honestly say I feel secure. They wash and hang dry fast ready for the next day. Glad I bought them.


  • Familiarity: I've used it several times
  • Fit: True to size
  • Size Bought: Large

I got the L, I usually take a M bib and shorts. They fit well over a chamois, wore them all day and hardly noticed them. Climbed over 2,000 ft one day, no problems. My wife also has a pair, took a spill one day, few bruises but none on her hips or tail bone so yes I reckon this is a good product, probably go a size up.

Really, really good protection!

  • Familiarity: I've put it through the wringer

No chamois, no big deal. These shorts breath very well and fit nicely between my Endura snap lock Liner and Shorts. The protection is outstanding. Unlike other reviewers I do wear these shorts in XC trail situations, while pedaling, even uphill! (In the hot and humid jungle trails of Oahu). A recent thigh bruise kept me off the bike for nearly a month, so I bought these. The key is hard plate padding. My soft pad shorts did not do much for hard falls on the thigh/hip areas. These are much better. I occasionally bounce off trees on very tight jungle singletrack. Knuckle, elbow, and especially hip protection are a must here. The tailbone plate is not noticeable after a few hours in the saddle, and those who have broken their tailbone will REALLY appreciate the protection here. (I'll be skiing in these as well). If these pads were just 1/8" thinner they would rate 5 stars. If you're getting older and do not heal as well as you once did, the same applies. For me anyway, less concern about the inevitable crash equals more confidence/ better performance on the bike/boards.

Heavy duty protection

  • Familiarity: I've put it through the wringer

I wear these when dirt biking and would only recommend them for dirt biking and downhill/lift served. These are not anything you are going to want to do a lot of pedaling in. As mentioned below, there is no chamois, but that is a non-issue IMO for dirt bikes and downhill.

The padding is the toughest I have seen on a pair of padded shorts, they mean business. I have worn and seen many a foam padded short, and they have nothing on these.

I have 1 minor gripe about them: I wish they came up a little higher. With my long-ish butt, they barely cover my crack. Not a huge deal since I have dirt bike pants on and a tucked in jersey, but something to be aware of.

Excellent , but no chamois.

  • Familiarity: I've used it once or twice and have initial impressions

I've given a lot of thought to this review. I had to decide between 4 or 5 stars and the issue is fairness. In fairness I must point out that the product description is not misleading , they never claim it has a chamois so to be fair I should not dock it a star for that... However it should have a chamois in my opinion and this review is my opinion. So what to do 5 or 4 stars? I have decided to give it 5 stars because the padding is the best I have seen so far and although I wish it had a chamois it is still the best product in it's class and that deserves 5 stars. I am wearing the Troy Lee liner that came with my Troy Lee Ace shorts under the padded shorts then pulling the Ace shorts over that. I have a 35" waist and bought the Ace shorts in 36" for this purpose and am very pleased with the combo. I bought XL in these shorts and they fit perfect. Alpinestars has earned a little more respect from me, I have high expectations and these shorts are impressive. I recommend these shorts and I highly recommend pairing them with the Troy Lee Ace short, this is the best combo I have used.

Unanswered Question
Avg. ride time: 15m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Could these be used for snowboarding too?...

Could these be used for snowboarding too? I don't fall very often anymore, but having hip bursitis, I would like to minimize damage from further impacts. How good is the hip protection vs 661 or POC (w/o chamois). Figured I could use these for double duty those few times I go downhill moutain biking Thanks.

Chuck Norris wants you to get these shorts

    Finally! Somebody made shorts with hard armor in all the right places. Too many other shorts have left my hips wide open to injury because the upper and lower pads were poorly padded and placed. I don't know what the gripe is with people being bothered by the tail bone section. It doesn't get in the way at all as long you aren't sagging these like an eager to get owned wangster street rat. Maybe if you're sitting perfectly perpendicular to the ground you'll get some discomfort, but if you're actually wearing these, chances are you'll be leaning forward in an aggressive stance. The mesh and thong like construction of materials is perfect and allows me to go freebird on hotter days. Be warned however, the material is so light and stretchy that after a while the crotch will slide back and forth with your legs as you pedal. If you've ever watched those cartoons with the little guy being chewed alive by the big monster and you can see the inside of the mouth as he's being chewed up.... well that what will happen to your junk if you pull these up too high. Get some chamois butter to help out. The elastic band on the bottom of the legs are really really tight, but they should stretch out over time. If they don't I'll be tempted to cut them open and sow in an extra inch of material, because after about five hours of wear your thighs will be begging for mercy. Also don't let anybody see you wearing these in the open, cuz that bright red star on the tailbone section is screaming, "I'm a piece of meat check out my ass!" Seriously Alpine Star, you're over doing it with the logos. No bad ass biker wants to be seen with a flashy bright red star on his ass, because that is definitely not cool. As I'm typing this, I've procured a sheet of sand paper to sand it out. If you want protection, nothing is better than hard armor. Bulky foam isn't going to save your ass from the corner of a rock or rail, only hard armor has what it takes to properly disperse the blow, and these shorts dish it out in spades.

    btw, I'm a 32 waist, and according to the size chart I need a Medium. I have the mediums but they are just ALMOST too tight to wear. I'm a skinny guy, so any other dude or gal with my waist size who has normal to muscular legs will probably benefit from getting the Large size instead.

    These have no chamois so what do you...

    These have no chamois so what do you recommend wearing under them? I just got them and haven't worn them yet. They fit really well but I can't wear them al fresco when there's no chamois!

    Just get a mtb short liner with chamios. Sugoi usually makes a nice one (which Hucknroll sells). Or Zoic maybe.

    Good Protection, Great Fit

      I have both these and the soft foam padded shorts from Alpinestars. The MTB Bionic give a significant amount of protection and feel like they will protect me well the next time I take a digger. The mesh is super breathable so getting swamp butt while riding is probably not a concern. The only grip I have about the shorts is the tail bone protection. Its a little to hard and sometimes is noticeable while in the saddle pedaling. Other then that one gripe, the shorts are great and are an example of the quality products Alpinestars produces.