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Mountain Bike Hydration Backpack ST 900 12L 2L Water - Black

Regular price: $99.99 Regular price:

The 12 litre capacity is well-distributed for bringing what you need. Enjoy the mesh at the back and various adjustments.

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Sale price: $99.99 Regular price:

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San Francisco, 735 Market St. Options

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About this item:

  • Capacity: 6 L bag with a 2 L bladder for hydration
  • Multiple compartments: Many compartments for tool and item storage
  • Stability: Adjustable straps
  • Carrying comfort: Mesh straps and foam padding for excellent comfort
  • Use: For hiking, camping, and other outdoor activities
Model: 8300158

Product Features

Mountain Bike Hydration Backpack ST 900 12L 2L Water - Black | This hydration backpack is designed to keep you easily hydrated when mountain bike touring for less than 4 hours.

The 12 litre capacity is well-distributed for bringing what you need. Enjoy the mesh at the back and various adjustments.

A photo of the Mountain Bike Hydration Backpack ST 900 12L 2L Water - Black in use
A photo of the Mountain Bike Hydration Backpack ST 900 12L 2L Water - Black in use


A usable volume of 12L and a 2L water bladder: drinking for up to 4 hours.

Multiple compartments

1 large compartment, 1 tool pocket, 2 side pockets, 1 helmet gusset, etc.


Adjusts with the shoulder straps, the waist strap, and the chest strap.

Carrying comfort

There are 3D mesh pads at the back and hips for ventilation.


The bag comes with a built-in protective rain and mud cover.


VIOO CLIP light attachment point on the back

Questions & Answers

Product Customer Reviews

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Easy to use

Easy to use

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I have used it daily for over three years for my commute. The capacity (12L) is perfect: enough to carry my lunch and my work clothes, while being forgotten and maintaining good visibility behind the shoulders. The bag does not move over time. I have never used it for leisure outings: I prefer a 5 or 7L saddle bag and a bottle in order to gain a little comfort and maintain good back ventilation.

no complaints

no complaints

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Easy to use

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Like most decathlon items, it has a fairly good balance in quality/price, highlighting its comfort. All that remains is to test the resistance to battle and durability over the years of use.

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Practical product with…

Practical product with volume without being too big, no discomfort when carrying. 👌

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Perfect capacity, well designed for…

Perfect capacity, well designed for the back and the yellow protection with its storage (which was missing from its predecessor). Only positives

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at the top neither big nor small several storage spaces

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The back is breathable enough and the zipper is smooth

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Great buy

The ideal cycling backpack for trips.

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Fits well, holds nicely on the back, the waistband is where it should be and not under the breasts. You just can't attach a helmet, which even the seller doesn't claim, and the helmet belongs on the head, not on the backpack, so no major problem. The only thing that bothers me is that when the waist pack is turned on, the excess part of the strap slides to the fastening buckle and makes an eye on each side, it would be enough to tighten it tighter. Otherwise, great satisfaction, it fits a windbreaker, tools, snacks for the whole day, I can only recommend it.

The weight of the backpack is a bit heavy, but the stability is okay.

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A little too expensive

A little too expensive

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Hello, very satisfied with…

Hello, very satisfied with this bag, suits me because of its morphology, its ease of installation, enough pockets; nevertheless I would appreciate the shower "Zip" closure on all access pockets. Also, a little more pocket depth where the headset sits would be a perfect addition. Cheers, Alan.

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Additional Product Information


Bag: 50.0% Polyester, 50.0% Polyamide ; Water pouch: 100.0% Thermoplastic Polyurethane

Maintenance tips:

For hygiene reasons, we recommend cleaning your water bladder after each use. To help you clean out the tube, you can order a special brush using product ref. 5935596. This kit comes with a hanger to make it easier to dry out the inside of the bladder.Tip: If you don't want your drink to taste like plastic, wash the bladder, dry it well, and place it in your freezer. Take it out a few hours before your ride. This will stop any flavour transfer.

Bring with you...

This hydration pack comes with a 2 L water bladder. But also remember to bring:- your food (granola bars, energy gels, etc.)- your multi-function adjustment tool (ref: 8386669)- a puncture repair kit (inner tube, tyre lever, hand pump, puncture repair spray, CO² cartridge, etc.)- your chain rivet extractor and a quick link - a piece of identification, blood type card- a means of payment and a telephone- a 1st aid kit- etc...

A large water bladder

With its 2-litre capacity, your water bladder will last you around 3 hours of riding. Its wide opening makes it quick to fill up. When closing it, make sure the slider clips into place to ensure it won't leak.

Great water flow

Before you set off, remember to remove the air to improve water flow. Just turn the hydration bladder upside down once filled, direct the air bubbles towards the tube opening and suck them out. The bite valve is lockable (rotates 180°) to prevent leaks when not in use. It won't drip, even when in the open position. To get a good flow when drinking, pinch the valve with your mouth and suck.

Care tips

To make your bag last longer, we recommend waterproofing it before you first use it. Even though the fabric is already water-repellent, extra waterproofing will stop mud getting caked onto it. Before each ride, remember to wash and dry your water bladder with the help of the cleaning kit (product ref. 5935596).If you don't want to get a plasticky taste, put your dry water bladder in your freezer. This will stop any flavour transfer.

Extending the product's lifespan

Remember to take a look at our water bladders support page to help your product last longer.

Product testing

At Decathlon, all of our products are tested by a panel of users in the conditions for which the products were designed. These tests are led and monitored by our design team. All of these tests allow our product managers, engineers and the whole mountain biking team to develop, create and design technical products that guarantee customer satisfaction.

Storage instructions

Once clean and dry, keep your backpack and water bladder in a dry place and away from direct sources of heat. Clean by hand in soapy water.




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