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Men's Mountain Bike Undershorts 900
The B'Twin 900 men's bib shorts are very comfortable thanks to an ergonomic pad with gel inserts. Mesh fabric lets moisture escape. To be worn underneath a pair of MTB shorts (size buttons).
Free shipping over $35
Final Sale: No returns or exchanges
Free pickup
San Francisco, 735 Market St. Options
Select an available color and size to see options.
Product Features
Sitting comfort
Ergonomic pad with gel inserts and 3 levels of density for added comfort.
Moisture wicking
The body stays dry as the fabric absorbs & diffuses moisture, drying quickly.
Stability
Elasticated fabric keeps the undershorts in place.
Compact design
Attaches to shorts with buttons at the waist.
Product Lifestyle Image Gallery
Image Gallery
Product Customer Reviews
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Size and construction good
Comfortable and perfect match to ST900 shorts. Thinner material than normal lycra shorts and a bit see through, so can't wear by themselves, but just fine with shorts.
Very comfortable, would recommend.
Not much to say about a pair of under shorts other than they fit and are comfortable over a couple of hours
I am very pleased with the service Decathlon provides and the quality of their products.
As others have said, the latest (2021) version of these are sized/cut for a child with a beer belly! OR a stick insect. Dont buy without trying on in store. Likely uou will need to size 2 times up and take the waist in. Decathlon, PLEASE fix the weird 'large waist/ultra skinny legs' fit - its mad! I have a 32" Waist, and like the pair of these I got years ago bought Large, which used to be for 82-89cm and fitted well32-34". The latest version Large MT900 now state on the label they are for 99-106cm (38-41")!! However, despite the claimed size I could barely get these on, they are so tight around the thighs and bottom, my legs started throbbing the legs were soooo tight. And I have a slim athletic shape legs/bum - not a 'Chris Hoy' figure. riends keep telling my I need to eat more and put on weight, so its not my shape, but these new cut of the shorts. The waist might just at a push stretch to 41" - but there is no way anyone with that waist would get them above their knees. The shorts themselves (my last pair) are excellent otherwise - the pad is fabulous, comfy, not bulky, light, doesnt get smelly. Such a shame they have totally ruined the cut. I am going to have to try an XL (for a slim build & 32" waist!) in store and hope I can then take the waistband in - as they are otherwise great undershorts. Maybe these were a mis-manufactured batch - however I also have the excellent and great value MT500 undershorts - and also an old pair - and its exactly the same issue, infact, even worse on 2 pairs of those I bought. You would need absolutely pipe cleaner legs, no bottom and a huge waist for the cut to have the correct snug but comfy fit.
Comfy for long rides
Very good fit, nice flexible material, pad comfortable with no rough seams. Only slight negative (though not enough to make it 4 stars) is that the padding is fine but may not be enough for a day in the saddle in rougher terrain. But hey, I'm being picky.
Good all round product
I have had good experiences with Decathlon products before so decided to try the under-shorts. Unfortunately none in store, I had to order online. I told Decathlon I was 36" inch waist (I am in fact 34") and they said I was size large. Product arrived and they are VERY snug, I am athletic and not a large build but these would only fit those with a stick insect type figure. So size up ! I also found there is a gripper on the legs, which I specifically asked about as I do not like them, again I was given bad information by Decathlon customer service. Advice; only buy Decathlon products in store where you can see and try on before buying and if out of stock, go elsewhere.
Good fit and style. Plenty of padding. To wear under mtb style shorts.
I've tried padded shorts and padded undershorts from other shops but these are the only ones that I find comfortable. My biggest problem with other makes is chafing at the groin/very top of the leg - these are sufficiently wide and padded to avoid that.
Bought for partner but returned. They looked great, fitted well/snug but he found them uncomfortable with the gel pad seating. I guess it’s something you get used to.
Never actually worn them as I used the size guide to order them and when they arrived it turns out the size guide was wrong and couldn't even get them on. However they do look really comfy.
Comfortable good fit, well made.
Size Guide
Additional Product Information
Composition
Main fabric
- 86% Polyester cationic
- 14% Spandex
Padding - Inner fabric
- 100% Polyamide
Padding - Outer fabric
- 77% Polyester cationic
- 23% Spandex
Care tips
Machine wash at 86°F. Synthetics cycle. Turn the article inside out. Use a minimal amount of laundry detergent. Do not use fabric softener. Line dry in a warm, ventilated area. Do not tumble dry.Do not dry clean. Do not bleach. Do not place on a heater to dry.
Product tests
Our team of product designers based at the B'Twin Village in Lille, France is continuously working to make cycling more comfortable for our users. Our mission is to create products that meet the specific cycling needs of our users and to eliminate obstacles to a good cycling experience. We then test our products in the field, as we are convinced that only by subjecting them to real world conditions can we continuously improve our products.
Origin
Imported
Superior quality. Unbeatable prices.
For 40 years, Decathlon has delivered the best value in the retail sports industry by offering high-quality, sustainable and cost-effective products.
Decathlon makes the difference
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Research and development
delivers high-quality cost-effective products
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State-of-the-art production processes
minimize manufacturing costs
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Optimized supply chain
reduces retail prices
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Minimal retail footprint
lowers overhead and indirect costs
Men's Mountain Bike Undershorts 900
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Heavy products return policy
If you return a product you will receive a refund for the purchase price plus any applicable sales taxes, less any non-refundable charges.
Decathlon will cover all shipping costs associated with your return except for items excluded from our return policy such as bikes, basketball hoops, snowboards, surfboards, tents, and other larger / heavier items.
Return costs for heavy products:
| Weight Thresholds | Shipping within California | Shipping outside of California |
|---|---|---|
| > 9 lbs | $20.00 | $25.00 |
| > 30 lbs | $50.00 | $65.00 |
| > 100 lbs | $100.00 | $125.00 |
| > 200 lbs | $200.00 | $230.00 |
If you return a product at any of our store locations, we will gladly help you find the best alternative product or refund you on the spot.