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A reliable and high-performance cross country MTB.

All Bikes Cycling - Rockrider 8.1 Mountain Bike - Grey B'TWIN - Bikes
Reference : 8168918
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B'TWIN Rockrider 8.1 Mountain Bike - Grey

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The b'Twin Rockrider 8.1 mountain bike is a lightweight hardtail bike designed for regular riders who enjoy riding on trails and off road. A fantastic value for money Mountain Bike. Quality SRAM, SHIMANO and ROCKSHOX components. Reliable, high-performance XC aluminium MTB.

To view our full range visit our mountain bikes category.


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find out more about our returns policy.

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Product benefits

    • Lifetime warranty
    • Double-thickness 6061 T6 aluminium; racing geometry; 12.85kg in size M.
    • Low weight / lightweight
    • Double-thickness 6061 T6 aluminium; racing geometry; 1.850 kg in size M.
    • Accuracy / precision
    • SRAM X7/X5 27-speed drive train, Shimano Deore chainset.
    • Cushioning
    • Rock Shox Recon 100 mm hydraulic fork, handlebar lockout and bounce adjustment.
    • Brake control
    • TEKTRO AURIGA COMP 160 mm hydraulic disc brakes
    • Anatomic design
    • Sizes: S (155-165 cm) M (165-175 cm) L (175-185 cm) XL (185-200 cm)
  1. Guarantee : Lifetime warranty for the frame, stem, handlebar and seat post on this bike. Details on

Product information

S (1,55m-1,65m) M (1,66m-1,75m) L (1,76m ; 1.85m) XL (1.86-2m)
Wheel size
26 inches
Front suspension fork
12.8 kg in size M

your reviews

4.9 / 5

20 reviews

20 people recommend this product

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Can't fault it

Value, looks , ability.



  (United Kingdom)

30-39 years old    Man

4 5

used for More than 1 year Regular road cyclist , bought this bike to compete in a off road triathlon. Used it for a couple of events, including one yesterday, really testing course , the bikes was ace,
I would only upgrade to something lighter, but pretty sure this will do me in tears to come.

Awesome Hardtail MTB

Spec, weight, ride and feel

Tyers could of been better


  (United Kingdom)

30-39 years old    Man

5 5

used for 3 to 6 months I have wanted to get into riding trails for a while and when i was looking for a bike in the 500-600 pound bracket this was the only one that stood out. I loved the Grey paint job and the look of the bike, and after doing a bit of research the spec of the bike sold it.
The staff at the Bolton store have been great and helped me out when the chain broke, and its about to go in for its 3 month service. Its been ridding hard and it just takes it and soaks up the trails with little problem. I have replaced the tyers with some thing a bit more grippy, thrown on some shimano XT brakes and a shorter stem. These parts have transformed it from really good to amazing. Its so planted and confidant around the corners and i am starting to catch air now which is what i am wanting.
I know this is going to be my gateway bike into the bigger more expensive rides and i know i will keep coming back to it as my hardtail, with a few more upgrades it will stay fresh for years and compete with way more expensive bikes.

Love the bike, not so sure about the factory setup

Great bike for the price

Setup incorrectly, missing tools


  (United Kingdom)

20-29 years old    Man

4 5

used for 2 to 8 weeks I ordered my RockRider 8.1 online after being recommended it on a bike forum I read regularly. I received it a little over a week ago and have put around 100 miles on it so far, and I must admit I'm really enjoying it. It's comfortable, it handles well and feels plenty durable on the trails thanks to the Michelin Country Trail tyres fitted.
However, I was a bit disappointed upon receiving the bike. The handle bars were fitted upside down, and the rear tyre had been put on in reverse. To add to this, I did not receive a user manual as the quick setup guide hinted at, or a spanner for the pedals. Thankfully I had the tools required and so could remedy these issues easily.
All in all, the bike is great, and would recommend it to anyone new to mountain biking. I'm hoping the service I experienced was a one off, as the bike wasn't really usable in the state it arrived.

Rock Rider 8.1

Fanatstic bike it takes what you throw at it

Nothing worth mentioning


  (United Kingdom)

50-59 years old    

5 5

used for More than 2 years I have owned this model since 2010 its still as as good the as the day I bought it . I have covered many miles on and off road and when the time comes I would buy another

Response of the brand

Dear Sir,
Thank you very much for taking the time to post a review of the b'Twin Rockrider 8.1 Mountain bike.  It is a great quality bike with an excellent hard-tail frame.  One of our best sellers.
So pleased to read that you've been enjoying it since 2010.  Long may it continue.
Peter Lazarus UK Market Manager DECATHLON

Peter found this review helpful

excellent alrounder

the whole package for the price



  (United Kingdom)

30-39 years old    Man

5 5

used for More than 1 year I spent a long time researching the rockrider 8.1 and other bikes in this £500 price bracket and every time I came back to the same conclusion the 8.1 beat the rest of the bikes on the market for overall quality level of parts on it copared to all the brand named bikes out their so for me the decision was made take a risk on a store named bike and i was not dissapointed in the slightest it as took every thing ive thrown at it and more i ride to work every day rain snow or shine and i go on trails when i get time and i really enjoy the rides on it.I've had it for 18 months now and it's had a few problems with it but every time I've returned it to store and they've done a good job and replaced any faulty parts promptly under warranty thanks to decathlon it should keep me going for more years to come and I will certainly be looking to purchase another decathlon bike in the future when they bring out a better range of full suspension 29ers out.

Technical Information

  • 1

    Frame Double-thickness 8 series competition 6061 T6 aluminium frame; racing geometry; 1.85 kg in size M. Lightweight and resistant. Its geometry offers an ideal combination for climbs and descents.
    Available in 5 sizes: S; M; L; XL

  • 2

    Fork New Rock Shox RECON Silver TK 100 mm fork Remote Lock-Out on handlebars. Effective rebound adjustment, can be locked in place with a half turn of the lever.

  • 3

    Suspension /

  • 4

    Drive train SRAM X7 front derailleur
    SRAM X7 rear derailleur; 9 speeds;
    Push pull SRAM X5 levers.
    Shimano Deore M590 22x32x44 crankset with
    SRAM PG950 11x32 9-speed cassette. Very reliable and efficient drive train, even in extreme conditions.

  • 5

    Brakes TEKTRO AURIGA COMP hydraulic disc brakes with 160 mm rotors. Powerful, progressive in any circumstance

  • 6

    Handlebar Comp 600/ 640mm raised handlebar, oversize diameter for greater durability. The position is higher to provide more control and comfort without affecting performance.

  • 7

    Stem Rockrider Comp stem, oversize diameter, for more durability.

  • 8

    Steering Aheadset headset by VP.

  • 9

    Saddle New Rockrider COMP saddle by Velo

  • 10

    Seatpost Rockrider COMP seat post

  • 11

    Wheels Rockrider Comp 32 hole rims by Rigida Hub JT D041/D142, 2 mm stainless steel spokes Sealed bearings.

  • 12

    Tyres Nouveau Pneu Michelin Country Trail

Information / Concept / Technology

Restricted use :

Not designed for: BMX, Dirt, descent, or free ride.

Stock advice

The b'Twin mountain bike should not be stored outdoors for long periods of time. It should be stored in a cool, dry place, away from corrosive products and salty air.

Care instructions:

Graissez régulièrement votre chaine, vérifiez régulièrement la pression de vos pneus (conseillé à chaque sortie) et vérifiez (tous les 3 mois) l'état de vos gaines ainsi que l'ensemble des serrages des vis et écrous.

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