Alpinestars ST-1 Waterproof Motorcycle Pants
Built for commuting and adventure touring through changing weather, the Alpinestars ST-1 combines a waterproof liner, removable insulation and flexible knee protection in a streamlined textile riding pant. Its pre-curved fit helps you move comfortably on the bike, while waist and ankle adjustments let you fine-tune the fit for the ride.
Waterproofing and Seasonal Comfort
- A fixed waterproof liner provides wet-weather coverage.
- The included 80g thermal liner adds warmth for cold starts and evening rides. Its zipper attachment keeps it anchored, and it can be removed when conditions warm up.
- A fixed mesh liner adds comfort inside the pants.
Materials and Construction
The shell uses a 600D polyester fabric blend, with ripstop reinforcements on the inner legs for added abrasion resistance and contact with the bike. Alpinestars' ACTIVE touring fit combines pre-curved legs, shaped knees and an ergonomic crotch construction to support movement in the riding position.
Armor and Safety Certification
- CE-certified Class A motorcycle garment to EN 17092-4:2020.
- Included CE Level 1 Nucleon Flex Plus knee protectors offer a flexible, breathable, low-profile design.
- A three-position, color-coded pocket system lets you adjust the knee armor to suit your leg length and riding posture.
- Reflective thigh details help improve conspicuity in low light.
- Compatible Bioflex hip protectors are available separately.
Fit, Storage and Jacket Connection
- Waist volume adjusters and lower-leg hook-and-loop ankle adjustments help tailor the fit.
- Two zippered front pockets keep small essentials close at hand.
- A connection zipper attaches to a compatible Alpinestars motorcycle jacket to help keep the outfit together and reduce wind entry at the waist.
Included with the Pants
The ST-1 includes its detachable thermal liner and Nucleon Flex Plus knee armor. Jackets, boots, helmets, gloves and other riding gear shown in styled photographs are sold separately.
Color Options
Black offers a subdued, versatile finish. Khaki / Sand is Alpinestars' Dark Khaki Sand Black Red Fluo colorway, with contrasting black panels and bright red accents.
Men's Textile Pants Size Chart
Alpinestars' body-measurement guide is shown below in inches. These are body measurements, not the dimensions of the finished garment. Khaki / Sand is listed in Small through 3X-Large; Black is listed in Small through 4X-Large.
| Size | Waist (in) | Hips (in) | Inner Leg (in) |
|---|---|---|---|
| Small | 29 1/2 - 31 7/8 | 35 3/8 - 37 5/8 | 30 1/4 - 31 1/8 |
| Medium | 31 7/8 - 34 1/4 | 37 5/8 - 39 3/4 | 31 1/2 - 32 1/4 |
| Large | 34 1/4 - 36 1/4 | 39 3/4 - 41 7/8 | 32 5/8 - 33 1/2 |
| X-Large | 36 1/4 - 38 1/4 | 41 7/8 - 44 1/8 | 33 7/8 - 34 5/8 |
| 2X-Large | 38 1/4 - 40 1/8 | 44 1/8 - 46 1/4 | 35 - 35 7/8 |
| 3X-Large | 40 1/8 - 42 1/8 | 46 1/4 - 48 3/8 | 35 - 35 7/8 |
| 4X-Large | 42 1/8 - 44 1/8 | 48 3/8 - 50 5/8 | 35 7/8 - 36 1/4 |
How to Measure and Check Fit
Measure around your natural waist at the navel and around the fullest part of your hips, keeping the tape level. For inner-leg length, stand upright and have someone measure from the crotch to the bottom of your leg.
Try the pants with the layers and boots you intend to ride in, including regular clothing if you plan to wear them as overpants. Check freedom of movement while seated with your knees bent, then position the knee protectors over your knees using the adjustable pockets. Recheck the waist and ankle closures with the thermal liner installed and removed.