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Air shocks, hydraulic brakes.

All Bikes Cycling - Rockrider 520 S Mountain bike  B'TWIN - Bikes
Reference : 8208678
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B'TWIN Rockrider 520 S Mountain bike

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athletic MTB riders touring off-road in the country or mountains. Optimised brakes & weight: Take on the steep slopes.

To view our full range visit our mountain bikes category.


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until £479.99 - %

From £479.99**

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Price in store £0.00 £479.99 **

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Home Delivery
free on orders over £70* - More information

Freedom of Return
find out more about our returns policy.

Safe payment
PayPal, Verified by VISA & MasterCard SecureCode.

Important: When you purchase a bike online, pedals are not fitted and the stem/bars are not adjusted. Please visit this video to see how to correctly set up your bike.

Life Time Warranty: B'TWIN makes the life time warranty for the frames, brackets, stems and rigid forks. Guaranteeing your Bike for life!

Product benefits

  1. 1
    Lifetime warrantyB’TWIN guarantees the frame, stem, and handlebar for life.
  2. 2
    Cushioning120mm fork with lockout & 120mm hydraulic air shock, for precision adjustment!
  3. 3
    Low weight / lightweightAir shocks: lighter and more precise. Lighter drive train. 14.9 kg in M.
  4. 4
    Accuracy / precisionPrecision suspension adjustable according to your weight. 27-speed SRAM X5.
  5. 5
    Brake controlTektro hydraulic disc brakes: powerful, progressive, robust.

Guarantee : Frame, handlebar and stem have a lifetime guarantee.2 year guarantee for parts (excl. wearing parts)


Product information

M(1.65-1.75), L(1.75-1.85), XL(1.85-1.95)
Black / White / Red
Wheel size
26 inches
fork and shocks
14.7 kg in M without pedals

your reviews

4.7 / 5

6 reviews

5 people recommend this product

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Fantastic value/performance combo

90% of the performance but 40% of the cost!

no rear lock-out


  (United Kingdom)

50-59 years old    

5 5

used for 2 to 8 weeks I bough two of these to replace the family's current aging hardtails.
Fantastic value and spec for the money - we were resigned to spending £1k on a full suspender at this spec so got two bikes for the price of one!
Done around 100km so far on a mixture of bridle paths, single track and forest trails - really smooth.
Well made and finished - paintwork and welds immaculate. Nice touches like the rubber protectors on the cables. Off to the Alps on Friday for a week's MTB'ing and have no worries about how this bike will perform.

excellent bike

geat value for money



  (United Kingdom)

50-59 years old    Man

5 5

used for 7 to 12 months love this bike, the value for money is second to none.
needed to play with rear shock/damper to get it right for me,but easy to do.
Have been preaching the merits of it to all my friends.

excellent bike for the money

great handling, well built bike

nothing yet


  (United Kingdom)

30-39 years old    Man

5 5

used for 1 week or less Excellent bike for the money the rear suspension is very active and soaks up the bumps well, I had to play with the pressure as would be expected but eventually settled on 120psi for my 65kg weight plus riding gear.
The front shock has a top end clunk which is normal for bottom end forks but I found leaving the lockout at 1 o'clock and about four clicks on the preload worked well.
Overall I am very pleased with the bike and you would struggle to get better at this price range.

Great feel bike but sloppy sram x5 gears

Nice weight and balance fun to ride

sram x5 gears are too slow in changing to Mtb with


  (United Kingdom)


3 5

sram x5 gears are too slow in changing to go Mountain Biking on hills with as I got stuck many times. The Decathlon mechanics could not improve the gears. The bike is nice feel to ride on, but because of sloppy slow gears in changing it is more suited for riding flatter xc.

Response of the brand

Dear Sir,

I'm sorry to read that the SRAM x5 gears have not performed as well as expected. This groupset is sometimes found on bikes exceeding £800 in other international brands and is generally considered to be a good workhorse.

There may be another underlying issue regarding the gears as they should function perfectly well under normal conditions. Would you like one of our technicians to give you a call? If so, please get back to me and I can arrange this.


Peter Lazarus
UK Market Manager - Decathlon

Martin found this review helpful

Rockrider 6.5 star buy

Very smooth big improvement over the 6.3

At this price none really


  (United Kingdom)


5 5

I had a XL 6.3 which I was more than happy with was great off road and on .. My mistakes was taking a frame which was to big for me .. Sold it but went up a grade to the 6.5 .. And my word it's a big step up the bike rides even better smoother on the gears better styling all round the proformance if you thinking of buying a 6.3 ... Save that little more and get the 6.5, it really feels like a Big step up. I'm keeping it for another 3-6 months then looking at trying a 9.1 or 9.2
Hope this helps

Technical Information

  • 1

    Frame New 6061 aluminium oversize S.I.X frame with 120 mm rear wheel travel, based on a monopivot suspension system offering high sensitivity to small shocks but also gives the bike sturdy resistance to strong impacts. Weight= 2.7kg in size M, without shocks.

  • 2

    Fork Hydraulic Rockrider fork with 120mm of travel, with magnesium blade for lighter weight, with lockout at the top of the right damper for rolling terrain, and with easy adjustment of the pre-load (fork hardness) at the top of the left damper. A fork which has already proved itself.

  • 3

    Suspension X-Fusion E1 air shocks, lightweight, specifically adapted to the S.I.X. frame, easily adjustable to the rider's weight thanks to the schrader valve: a great balance between sensitivity and performance

  • 4

    Drive train Shimano Tourney front derailleur, Sram X5 rear shifter and derailleur: very good combination in terms of comfort of use, speed of gear changes, and reliability. Thanks to its 27 speeds and its quick gear changes, it is easy to find the right gear for each new type of terrain.
    Bottom bracket Suntour XCT triple chain wheels, 22/32/42 teeth. 9 speed Sram ESP 5.0 cassette, 11 x 34. Sram chain with quick-release.

  • 5

    Brakes Tektro Auriga Comp hydraulic disc brakes, offering high braking power while remaining progressive and easy to dose. 160 mm front and rear discs. Front and rear "postmount" callipers, directly screwed into the frame and the fork: gain in weight and ease of adjustment! Discover the power of hydraulic disc braking, you will not be disappointed!

  • 6

    Handlebar Oversize 640mm diameter Rockrider Sport aluminium handlebar, for better rigidity and stability on descents.

  • 7

    Stem Rockrider forged aluminium oversize diameter stem for more rigidity, with a 6º "backsweep" angle. The components are marked to help you find the best setting.

  • 8

    Steering Semi-integrated headset for improved watertightness, precision while riding, and a built-in look. 120 mm Rockrider mono-density grips.

  • 9

    Saddle Rockrider by Velo bi-material saddle with a sporty look. Comfortable, narrow saddle to avoid thigh chafing.

  • 10

    Seatpost Rockrider 29.8 mm diameter seat post, length: 350mm. Quick, tool-free saddle tightening.

  • 11

    Wheels Rockrider Sport wheels, with 32 hole double-walled aluminium rims: guaranteed shock and warp resistance, and lightweight! Aluminium hub compatible with disc brakes only.

  • 12

    Tyres Front and rear KENDA Nevegal 26x2.10 rigid bead tyre, known for its versatility: it behaves well on all types of surface, whatever the weather (dry or wet), thanks to its deep and well distributed tread, and its "Stick-E" rubber which provides good grip. Tyres with inner tube.

Information / Concept / Technology

S.I.X. suspension system: Monopivot frame for greater simplicity and sensitivity, based on 120 mm travel.

Restricted use :

not designed for: BMX, Dirt, Freeride and Descent.

Stock advice

Store in a cool, dry place, away from corrosive products and salty air.

Care instructions:

We recommended reading and following the maintenance instructions provided with your Rockrider bike. The maintenance instructions and component settings are available on The safety visit (3 months after purchase) at your local store's workshop is FREE and RECOMMENDED.

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