rockrider e-st900 electric mountain bike review

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With e-bike technology advancing all the time, it was inevitable that some of the more high-tech wizardry would start trickling down to the cheaper end of the scale. Having looked at the new Rockrider E-ST900 electric mountain bike from Decathlon, that trickle is more like a flood! In this review, I will see if this great new E-MTB is too good to be true.

the new decathlon rockrider e st 900 electric mountain bike is fun to ride

When I first checked out the spec on this bike, I was amazed at what it had to offer at such a low price. Firstly, the Brose ‘T’ mid-drive motor is one of the best on the market.

Specialized have been using the Brose ‘S’ motor on their high-end electric mountain bikes for a couple of years now, and although the ‘T’ version doesn’t produce quite as much torque as the ‘S’ model,  it is still nice to see such a good quality motor on a relatively cheap e-bike.


Decathlon has always designed and produced excellent bikes. Their B’TWIN range has always been popular, but recently they have dropped the B’TWIN moniker from a lot of their bikes.

When  I first looked at the specification of the Rockrider E-ST900 and then saw the price, I thought there had been some mistake! I will go into more detail regarding the specification below, but let’s just say it’s remarkable that they have built such a good electric mountain bike and they can sell it at such a great price.

rockrider e-st 900 electric mountain bike front view

I have ridden and reviewed more electric mountain bikes than I can remember, and nothing has come close to this on price and specification. Usually, you would need to be spending at least £500 more to get a similar specification Giant, Cube or Specialized.

The centrepiece of this bike is the Brose ‘T’ motor. For those of you who are unfamiliar with Brose, they are a German company and the fourth largest family-owned supplier of components for the automotive industry, specialising in electric systems for vehicle doors, seats and electronic systems for steering, brakes, transmissions and engine cooling.

the Brose ebike motor fitted to the rockrider e-st 900

Their Brose e-bike motor is widely regarded as one of the best in the industry and is often seen on high-end electric mountain bikes.

But it doesn’t end there

Not only has the Rockrider E-ST900 got a fantastic motor, but the 36v 14ah (504Wh) Samsung battery should also give a potential real-world range of 80 miles plus.

If the electric components weren’t good enough, there are Rockshox  JUDY front forks with 120mm of travel, and the excellent Shimano Deore M6000 1 x 10 groupset, with an 11-42 rear cassette. Tektro TKD 32 hydraulic disc brakes with 180mm discs. And to cap it all off – 27.5″ x 2.8″ tyres on Sunringle DUROC 40 tubeless-ready wheels with thru-axles.

Anyway, I’m going to stop rambling and get on with the specification overview.

👉All sizes in stock now – visit Decathlon here

Features and Tech Specs

Electric Motor

I think Decathlon have proven that they are serious about being a major player in the electric bike industry. Choosing the Brose motor is a wise move. Fitting it to an e-bike at this price point is a game changer!

As I have said previously, the Brose motor is one of the best in the e-bike industry. The ‘S’ version is commonly found on electric mountain bikes in the £4000 plus price range, and the Brose motor is used by over 30 manufacturers worldwide. The Brose ‘T’ motor produces a respectable 75nm of torque, which puts it firmly in Bosch CX and Shimano Steps E7000 territory.

Of course, these motors will produce peak power closer to 400w when in Boost mode, but the top-assisted speed is limited in compliance with European law to 15.5mph.

The motor can provide up to 320% extra assist, thanks to the ‘flex power mode’. The electronic torque sensing pedal assist is one of the most advanced systems currently in use, taking thousands of measurements per second.

When you ride a Brose-powered electric mountain bike, you do feel like you’ve gained superhuman strength!

Not only is the Brose motor powerful, but it is incredibly quiet and efficient. Meaning you can stay on the trails for long, and ride further.


Accompanying the motor is an excellent, compact display, that fits discreetly on the left-hand side of the handlebar. This tells you everything you need to know, including speed, range, battery indicator and power level – Economy, Economy +, standard and boost.

the rockrider e-st 900 display

I could rabbit on all day about how great this motor is, but I think by now you get the idea. Let’s move on to the battery.


The compact battery pack that fits neatly into the frame, uses the excellent Samsung SDI 18650 lithium cells. With a total energy capacity of 504Wh (watt hours), this battery is well above the norm for an e-MTB at this price point.

Combined with the efficiency of the motor, a real-world range of 80 miles should easily be achievable, with a potential range of over 100 miles possible. Of course, if you spend all day hacking around in Boost mode, then you will deplete the battery a lot quicker.

the 36v 14ah samsung battery fitted to the rockrder e-st 900 electric mountain bike

The battery comes with a fast charger, and it can be easily removed using the supplied keys. Lithium batteries should always be charged at comfortable room temperature. In the winter you would want to take the battery indoors to be charged. In warmer weather, it can be charged on the bike.


Usually, electric mountain bikes at this price point have fairly entry-level Shimano groupsets fitted – we’re talking Altus, or maybe even Alivio. Decathlon has once again gone above and beyond by fitting Shimano’s excellent Deore M6000 1 x 10 groupset.  This includes an M6000 trigger shifter and an excellent Deore Shadow+ rear derailleur.

shimano m6000 10 speed groupset on the rockrider e-st 900

Up front, there is a perfectly matched 34t  Chainflow and anti-slip chainring. With gearing like this, the Rockrider E-ST 900 is aimed at serious off-road riders.

The groupset is finished off with an excellent KMC e10 turbo e-bike-specific chain. This shows good attention to detail on the part of Decathlon, as the Brose motor will put extra demands on the drive-train.


The Hydraulic brakes are courtesy of Tektro. The TKD32 brakes, combined with 180mm disc rotors front and rear provide good modulation and a nice amount of bite. They are middle-of-the-road when it comes to overall braking power, but they are more than adequate for a bike of this calibre.

Wheels and Tyres

The Sunringle DUOC 40 27.5″ wheels are tough and have aluminium hubs with sealed bearings. They are 36mm wide, and tubeless-ready, allowing for the extra wide 2.8″ Hutchinson Taipan Koloss tubeless-ready tyres.  These tyres will offer a good level of puncture protection, help with traction on steep climbs and inspire confidence when negotiating technical trails.

Thru axles add to the stiffness and robustness required for rigorous off-road riding.

Front Suspension

The RockShox Judy front forks are hydraulic and pneumatic, offering 120mm of travel, plus the usual lock-out and adjustment features.  They are fairly entry-level forks as far as Rockshox is concerned, but when you look at other e-MTBs in this price range, they usually use the very basic Suntour XCM forks, which aren’t a patch on these.

the rockshox judy 120mm forks fitted to the rockrider e-st 900 electric bike

As I have previously said, Decathlon wanted a budget mid-drive hardtail, that could be used for proper off-road riding, and not just light trail riding, like a lot of the other electric mountain bikes around this price.

Finishing Kit

All of the finishing kit is high-quality alloy Decathlon branded. And includes the B’TWIN ergofit EVO saddle, which is designed to be more comfortable for long days in the saddle.

rockrider e-st 900 handlebars

The stem can be adjusted for height, and the 720mm alloy handlebars ensure good control when riding off-road.


The frame has a more relaxed geometry and is made of good quality 6061 alloys with hydroformed tubes. The battery fits very neatly in the frame, and the welds are neat. This bike comes with Decathlon’s lifetime warranty, so you can be confident that it’s going to stand up to the rigours of off-road riding.

decathlon rockrider e-st 900 frame sizing

Who is the Rockrider E-ST900 aimed at?

This bike is so versatile that it can be used by anyone, from weekend warriors to daily commuters. A pannier rack and mudguards can be easily fitted if required – I think this would make an excellent and comfortable commuter bike. Due to the excellent battery range, it would also make an excellent electric bike for bikepacking helping you on your weekend adventures.

The Rockrider E-ST 900 electric mountain bike being ridden off road

As far as off-road riding is concerned, this bike is more than up to the job. When you look at the alternatives in this price range, it’s easy to see why the Rockrider E-ST 900 beats them hands down, not only on price but also on specification.

I would be confident in taking this e-bike on more challenging trails, and although I do believe it will have its limits, I do think you would have to go some to reach them.

👉All sizes in stock now – visit Decathlon here

Also available online from Decathlon Spain


Well, what can I say? I’ve ridden and tested a lot of e-bikes over the last three years, and nothing has come close to this in terms of value**, performance, battery range and components.

With the Rockrider E-ST900, I think Decathlon has built an excellent electric mountain bike, and made it accessible to a lot more riders.

Previously, if you wanted an e-MTB with this kind of specification, you would be forking out £2000 plus. Here we have an e-bike with all the bells and whistles for nearly £500 less.

decathlon rockrider e-st 900 electric mountain bike review conclusion

For the price, I honestly can’t fault it. I like it so much, I’m tempted to buy one myself! When you compare this side by side with the competition, it becomes obvious that prestigious brands like Cube, Specialized, Trek and Giant can’t come close to this bike in terms of sheer value for money.

👉All sizes in stock now – visit Decathlon here

Also available online from Decathlon Spain

If you are fortunate enough to own one of these, please feel free to leave a comment and review below

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  1. Thank you for this detailed review. I have been looking at the Rockrider E-ST 900 at £1799.00 and the Haibike AllTrack 4 Hardtail Electric Mountain Bike 2023, BOSCH Perf. – Metallic Midnight Blue/Bronze for £1995.00. Cant decide which is best. Any advice on which you think would be best. Thanks

    1. Hi,
      It’s a close call! The Rockrider has a slightly better spec regarding components than the Haibike (Shimano Deore 10-speed vs 9-speed, Rockshox vs Suntour forks). The Brose and Bosch motor are very closely matched for performance, although the Bosch has a better reputation for long-term reliability. If it was my money I would spend a little bit extra and go for the Haibike. I prefer the frame geometry and integrated battery of the Haibike, and it would be easy enough to upgrade the components in future if needed.

      I hope this helps, let me know if you have any more questions.


  2. Thank you so much for detailed explanation of the bike.. I was checking the details and reviews before my purchase… and I got all the detailed information.. thank you ❤️

  3. Salve! possiedo una E bike rokrider ST900 e mi sembra che vada molto bene e dia un grande aiuto per superare le salite più ripide, ma sarei curioso di sapere se c’è molta differenza fra questa bici che monta un motore Brose T da 70 Nm e una che invece monta il Brose S mag da 90 Mn ( i 20 Mn in più fanno molta differenza?)

    1. Ciao,
      Ci sarebbe una differenza minima tra i due motori per la guida generale e un uso fuoristrada moderato. Noteresti la differenza solo se facessi salite fuoristrada molto ripide e tecniche.

  4. Salve, ho una est900+ e vorrei sostituire i copertoni con modello da strada. Ho visto gli Schwalbe super motoX: sapete indicarmi se posso montare la misura 27.5 x 2.40 oppure si deve per forza montare il 2.80? Grazie

  5. Hi – found your review to be really helpful.

    I been biking for yrs and my wife has a Scott road ebike which I occasionally borrowed

    took the plunge for some winter lockdown fun in the Mountains of Cambridge (joke). Cannot fault the bike.
    Re sizing I am 5ft 10 and went for the large which is about right for long bridleway tracks but if you are doing more challenging stuff then maybe go back to the Med.

    After picking it up I found there to be an annoying clank from the motor and I go a puncture on 3rd ride in. Took it in to my local Decathalon and they immediately said they would put new tyres on and they solved the clanking as the free initial service – so that was a good win! I now have a slow puncture on my front! so maybe I should go tubeless?

    I would agree with the gearing – I do find myself shifting for one gear and finding myself at the last one!

    also in the last few weeks have been going through a lot of mud and puddles and it copes really well.

    I looked online for some 2nd hand bikes and so In one respect at the moment this is not a big risk as if you really hate it (which I do not think you will) you could honestly probably sell it and lose a couple of hundred pounds only!)

    I just need to remember to stop grinning when I ride this to stop swallowing mud!

    1. Hi David,

      Thanks for sharing, glad you’re enjoying your bike. I would definitely recommend going tubeless on an e-MTB. One of the main problems with tubes is a tendency to get pinch flats when running at a lower pressure for off-road riding. The initial set-up can be a bit of a pain (and messy with the sealant) but once it’s done it makes all the difference. Another option would be to go for Schwalbe Marathon Plus MTB tyres – I use the road version on my touring bike and haven’t had a puncture in nearly 10,000 miles! They’re a bit on the heavy side but you won’t find a more durable tubed tyre.

      All the best,

  6. Hi, great review. Decathlon are now selling this at £1799, do you think it still represents the best value in the sub £2000 bracket or should I be looking at other options?
    Battery range, reliability and light off reading are key requirements.


    1. Hi,
      I would still say the E-ST900 is great value at £1799 considering all the factors and the specification. I’m still waiting on details of some of the latest 2021 e-MTB models from Cube, Giant etc. But some of the latest bikes I’ve already had a brief look at don’t have the same spec until you get to the £2k mark.

      I hope this helps.

      All the best,

  7. Hi
    I am new to ebikes and can see the value in the E-ST900 is excellent. I am new to ebikes as I suffered a stroke 18 months ago that has left me with a weak left arm and leg. Hence an e bike comes to mind . Recently I rode a Panther rear hub drive bike which really suited me with easy handing geometry, however the price point of this bike is really close to the E-ST900 which technically is in a different class . Can you comment if the rockrider has easy handling . I will only be using on tracks and light terrain but cannot manage larger diameter narrow tryre trekking bike geometry?

    1. Hi Keith,

      Personally I found the handling on the E-ST900 to be very easy going and precise, although this is subjective. The tyres are plus-size 2.8″ wide with 27.5″ diameter and the frame design has a sloping top tube making it easy to mount / dismount. The handlebar is a typically wide 720mm MTB handlebar making the bike easier to control. The grips are comfortable as well. I would recommend going to a Decathlon store if you have one local to you. There is quite a bit of adjustment in the seat height, but if you prefer a more upright riding position it would be worth investing in an adjustable riser stem .

      If you are unable to view the bike in person, you’ll need to measure your total height and inside leg to make sure you get the right frame size. I’ve looked at the Panther Mountain Bike and it does look like it has a higher front-end, but I couldn’t find to frame geometry on their website to make a comparison with the Rockrider.

      I hope this information helps, if you need any more advice, please let me know.

      All the best,

      1. Hi Tony. I hope you’re keeping well? My situation is similar to yours. Have been a keen cyclist for decades and did many a long distance tour. Then at 65 I had faint which was diagnosed as a VT run ,meaning I had to have a ICD fitted. Long and short of it my long distance cycling with pals was curtailed. I tried an E Bike a couple of years ago and was impressed..but not with the weight or price. The review on the E ST900 seems to promise a lot, especially on distance. Whilst I’m still fit and active ,hill climbs, (I live in Edinbugh..plenty hills), are not really advised as the last thing I want is to trigger the ICD and lose my driving licence again, so the range and power of the bike ticks the boxes. A few months on does your review still stand? Regards Mike

        1. Hi Mike,

          Even though the price has been increased to £1799,the E-ST900 still represents excellent value for money. If you’re looking for an all-terrain e-bike, there’s nothing out there that can match the Decathlon bike for specification at the price. If you’re going to be riding mainly on tarmac, then I would recommend the Vitus Mach E Urban. I’ve just brought one of these myself and Wiggle are currently selling the 2020 model for £1649, which is great value. The Mach E weighs in at around 17.5kg, and uses the excellent Shimano Steps E6100 motor with 504Wh battery. I’ve ridden nearly 100 miles (with over 9000ft elevation) in the last week and still have about 20 miles left of assist left (using ‘eco’ mode only). The Vitus is more road orientated, although I’ve ridden a few miles of gravel track on Bodmin moor and it took it in its stride. The Rockrider is definitely better suited to tougher off-road riding, but could be fitted with mixed-terrain tyres to make it more tarmac-friendly.

          I hope this info helps, if you need any more advice, please let me know.


  8. I’m trying to figure out which one i should go for between this decathlon and the giant e+3.
    I know the giant one is more expensive, but which one has the best spec?

    thanks for this review.

    1. Hi,

      The Rockrider has a slightly better spec – 504Wh battery vs 400Wh battery, Shimano Deore 10sp (11-42) vs 9sp (11-36). Brakes are comparable. The main area I feel the Giant Fathom is a little better than the E-ST900 is the Giant / Yamaha Sync Drive Sport mid-drive motor – incredibly reliable and slightly higher torque output. The Giant doesn’t have a display though, just a keypad which you connect to a smartphone via an app. Having ridden both, if it was my money I would be inclined to go with the Rockrider as it’s just got a better overall spec for less money.

      I hope this helps.

      All the best,

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