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Decathlon B’Twin Ultra 900 CF 105



A beautiful frameset that excels in comfort and performance wrapped in decent components at a very competitive price

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The Ultra CF 900 is further evidence, if any was needed, that B'Twin knows how to build awesome-riding race bikes which offer excellent stiffness, handling and speed while also managing to be unbelievably comfortable. Bung in a sub-£1.5k price tag for a full-carbon frame and fork, Shimano 105 groupset and Mavic wheels, and it really is an exciting package.

  • Pros: Excellent comfort levels, stiff bottom bracket area, fun ride
  • Cons: Lighter wheels are needed to really release the full potential of the frameset

With its 'UCI approved for racing' logo on the top tube and its geometry, I was really expecting the Ultra CF 900 to be a no-nonsense speed machine, sacrificing comfort for performance, especially when you take into account those huge tube profiles. In use, though, it is completely the opposite.

> Find your nearest Decathlon store here

The ride is sublime, absorbing pretty much everything the road surface can chuck at it, so you just waft along at a very impressive pace, smashing mile after mile without effort.


B'Twin says that the frame was specially designed for the most demanding climbers and sprinters, and its stiffness is centred primarily around that massive bottom bracket, chainstay and down tube junction. No matter what I could throw at the Ultra CF when out of the saddle, I couldn't get even the slightest hint of flex anywhere in the bottom half of this frame.


To get this level of stiffness in the frame while still allowing enough 'give' in other places shows some clever frame design and use of the various carbon grades used in its construction.


The handling is sweet too. The head angle is 73 degrees, which isn't massively steep for this kind of bike, but it's enough to keep the front end quick and precise without instilling any form of twitchiness. The Ultra CF is a fun, quick-handling machine to ride, no matter what your level of ability; it flatters.

The fork stiffness matches that of the frame, so banking the bike over from side to side and under heavy braking never finds any level of understeer or vibration through the legs.


You aren't always going to be smashing it down hills, though, so it's great that the handling works a treat when you're just cruising along at a steady rhythm too. A lot of bikes that are great in the bends, the harder they are pushed, can become a little bit of a handful when things calm down, but the B'Twin remains balanced at all but the lowest of speeds.

It's not going to cut through the rush hour traffic as smoothly as a commuter bike, but flat cornering and meandering through the lanes is a relaxing experience and makes the Ultra CF 900 just as much a joy for group rides with buddies as it is on the rivet. It really is a very complete package.

Frame and fork

The Ultra CF 900 is based around the Ultra Evo Dynamic frameset, which in this medium size has a claimed weight for the frame of 850g and just 320g for the fork, which is impressive. You can buy the frameset package for £999.

I've mentioned the tube profiles already but it's safe to say that they follow the common theme of chunkier at the front and bottom, with the upper tubes introducing a little bit of extra flex for comfort.


The head tube is a boxy affair with various edges and profile changes so that it can blend into the Evo Dynamic fork.


Its size also allows for the huge, square-profiled down tube, which shifts shape down towards the bottom bracket to cope with the change of forces between the steering and pedalling at the business end.


The top tube is wide and flat at the front before it narrows towards the seat tube, and the curve from front to rear should tame the stiffness a little.


The bottom bracket shell is press-fit 86, which won't be everyone's cup of tea, but on race frames the benefit is obvious. Pressing the bearing cups into the frame means the shell can be wider, the same as a standard shell including outboard bearing cups, so you still keep the same Q-factor, the distance between the crank faces. This allows for a wider down tube, seat tube and huge chainstays for power delivery.


The downside of press-fit bottom brackets can be creaking if the tolerances between frame and bearing cups are a little sloppy. With next to no rain here for weeks, it's been tough to test.

The frame uses its own specific carbon seatpost in a five-sided design, so if you like to upgrade your components you are going to be out of luck here. It's held in place by an internal wedge system for a clean look and it certainly works as I had no slippage issues at all.


Other neat little details include the mounting point on the bottom bracket shell for the included chain catcher to avoid the risk of chainsuck wrecking the frame.

You get full internal cable routing from front to rear and it's well placed to avoid any frame rub. The rear brake exits on the top of the top tube rather than the side, which means it stays close to the seatpost avoiding irritation on your thigh.


When it comes to mounting points, you get two sets of water bottle cage points and that's it; it's a race bike after all, so don't expect mudguard or rack mounts.


The dropouts on the frame and fork look to be carbon fibre, which loses a little bit of weight, but you do get a replaceable mech hanger at the rear should you drop or crash the bike.


The rest of the fork is carbon fibre too, from leg to steerer, and it is a cool looking design with its chunky legs at the crown along with the recesses for the direct-mount front brake calliper.


Geometry and sizing

Geometry-wise, the Ultra AF 900 is very racy, even though it doesn't feel that extreme in use.

This medium model has a seat tube length of 490mm, top tube of 560mm and a shortish head tube of 150mm.


With stack and reach figures of 548mm and 398mm respectively, the ratio here is just 1.37 which is very race orientated. Race bikes are generally around 1.4, with endurance bikes sitting at a more relaxed 1.55.


The Ultra CF is available in sizes XS to XL, with top tube lengths of 530mm to 585mm.


The Ultra CF 900 comes with a full Shimano 105 groupset throughout, which is nice to see. At this price point it's still not unheard of to see a scrimping on the brakes or chainset.


The gearing is aimed at the performance rider, as you'd expect, so B'Twin has gone for a 52/36 semi-compact chainset option up front, with an 11-28, 11-speed cassette at the rear.


It's a decent spread of gears for the type of riding the Ultra is aimed at, but one thing I do like about the way that B'Twin specs its road bikes is to always fit a medium cage rear mech.


The short cage 5800 105 option, according to Shimano, only has the range to go up to a 28-tooth sprocket so if you want lower gears you'd need to swap the mech. With this medium cage as standard you can swap to an 11-32, for instance, without any setup issues.


The new R7000 105 groupset is now available, but this 5800 version is still a good 'un so if you can pick up a bargain it's well worth the punt, as you can tell by my review here. The shifting is precise and relatively light to the touch and the braking through the dual-pivot callipers is spot on.


Both the mechs can handle shifts under a reasonably heavy load without too much grumbling, but best of all is its reliability and durability.


The groupset I reviewed in the link above is coming up on four years old and has covered the best part of 25,000 miles, with pretty much all of that being in the winter as it's on my Kinesis T2 do-everything bike. I've changed the chain and cassette a few times, but everything else is still running smoothly with very little wear.

Wheels and tyres

The 900 gets a set of Mavic Aksium wheels, which is pretty good for the money. They are solid performers and a good entry-level set of wheels especially if you want something durable and smart looking without worrying too much about weight.


They aren't the lightest, nudging 2kg once the rim tapes and skewers are added, which does take the shine off the Ultra's frame and fork a touch. I ran the same bike with a sub-1,500g set of deep-section carbon wheels and it really unleashed the quality of the frame.

As I say, though, it's good to see a wheelset of this quality at this price point. If taking to the pothole-strewn back lanes is your thing rather than a day in the mountains, you aren't going to be complaining.


Mavic supplies its own tyres with its wheels as part of a package these days, and I'm glad to say they've improved over earlier versions. Original models of the Yksion weren't very good when it came to puncture resistance, and grip was mediocre in the dry to downright sketchy in the wet. These are pretty impressive. The grip is much improved, as is their ability to resist the puncture fairy. They roll pretty well too, so I'd be in no real hurry to swap them out.

Finishing kit

Up front you get a basic but decent aluminium alloy handlebar and stem combination. They are both stiff in use but the frame manages to damp things down a bit so it doesn't bring any discomfort to the ride.


On the medium model the handlebar is 42cm wide and the stem is 110mm in length, but this changes depending on the size of the bike. The bar has quite a shallow set of drops, which means they are usable by pretty much anyone.


Atop that frame-specific seatpost is a B'Twin branded saddle and I must admit on first impressions I didn't think I was going to get on with it as it's quite flat in profile. In use, though, it was fine because it has plenty of padding without being squidgy, plus it also has plenty of length to let you move forwards and back depending on how you ride.



B'Twin being the in-house brand of Decathlon sports stores means it can employ a direct-to-consumer model which ultimately keeps the costs down; and if you happen to live near a store, you can get to see the bike in the flesh and throw a leg over it for size.

> Decathlon road bikes – a buyer’s guide to the B’Twin range

This Ultra CF 900 package comes in at £1,399, which is really good value for money when you take into account the quality of the £999 frameset.

Canyon has to get a mention when it comes to direct to consumer sales and its Ultimate model is probably the best comparison. The Ultimate CF SL 7.0 model is a close match to the B'Twin, with a carbon frameset, Shimano 105 and Aksium wheels for £1,449 plus postage, which adds on another £30 or so.

It does get an upgraded set of Continental tyres and a Fizik saddle, though, and we've always found it to have a good ride, similar to that of the B'Twin, a beautiful combination of comfort and speed.

> Buyer's Guide: 12 of the best £1,000-£1,500 road bikes

Another very good carbon fibre-framed race bike at a very good price is Focus's Izalco Race range (I tested the Shimano Sora model here), with the 105 model priced at £1,399, the same as the B'Twin.

For the Ultra CF 900 to be uttered in the same circle as both of these bikes is praise indeed.

A carbon-framed bike with 105 can easily cost much more: take the Trek Emonda SL 5, for instance, which costs £1,800.

If you want the Ultra CF in a different setup you can go for the 920 with Ultegra, Deda finishing kit, Mavic Cosmic Carbon wheels and a Fizik saddle for £1,999. The 920 is also available in a Campagnolo Potenza build with the same finishing kit but Campag Zonda wheels for the same money.

For ultimate bling, though, there is the Dura-Ace model with Zipp 303 wheels, carbon handlebar and an upgraded Fizik colour-coded saddle for £3,499. A lot of money yes, but far from expensive for what you are getting.


The Ultra CF 900 is built around what can only be described as an excellent frameset. It's a real rider's bike with loads of feedback from the frame and fork no matter whether you are just cruising along or smashing it through the technical bits.

Comfort, as I've mentioned, is pretty special too.

It's a sensible entry into the performance road world and the frameset is ripe for upgrades as you improve.


A beautiful frameset that excels in comfort and performance wrapped in decent components at a very competitive price test report

Make and model: BTwin Ultra 900 CF 105

Size tested: 54cm

About the bike

State the frame and fork material and method of construction. List the components used to build up the bike.

From Decathlon:


B'Twin Ultra Evo Dynamic frame is the most advanced frame available to tackle mountains and win the most demanding classic races.

Weight: 850 g in size M (without accessories).

A blend of HM and IM carbon fibres for one of the best weight-to-speed ratios on the market.

The frame was specially designed for the most demanding climbers and sprinters. The bottom bracket is a standard PressFit 86 for greater stiffness of the chassis.


The B'Twin Ultra Evo Dynamic fork is exclusive to the B'Twin Ultra Evo Dynamic frame.

Weight: 320 g.

Full carbon fork.


B'Twin aluminium competition frame Oversize ERGO

Size / Width axis-axis

S: 400 mm

M / L: 420 mm

XL: 440mm

B'Twin oversize competition aluminium frame


XS: 90mm

S: 100mm

M: 110mm

L: 120mm

XL: 130mm


11-speed Shimano 105 groupset.

The 105 offers the same precise indexing as the Ultegra and Dura-Ace groupsets.

The derailleurs feature an all-new design. The front derailleur has a guide combined with a new spring mechanism that ensures smooth shifting between chainrings.

The rear derailleur now sports the same tried-and-tested mechanism found on the Dura-Ace groupset (cassette with 32 teeth max. for high-mountain cycling).


Shimano 105 11-speed ultra-versatile, 11x28 cassette.

11 ; 12 ; 13 ; 14 ; 15 ; 17 ; 19 ; 21 ; 23 ; 25 ; 28.

Crankset: Shimano 105 5800, 52x36.


XXS / XS / S: 170 mm

M: 172.5mm

L/XL: 175mm

KMC X 11 chain.


Shimano 105 Direct Mount (front)

2 symmetrical mounting axes for more effective braking control and power. Adjustable spring tension on the front calliper.


Mavic Aksium 17 C wheels

Materials: S6000 aluminium.

Height: 21mm

Internal width: 17mm

Front without tyre: 865g

Rear without tyre: 1015g


Lacing: radial on the front and rear on the side opposite the freewheel, crossed in pairs at the rear on the freewheel side

Number: 20 at the front and rear


New Yksion 700x25 tyres for added comfort and performance.


B'Twin Sport Ergo Chromo


Pedals not included.

Tell us what the bike is for

Decathlon says, "Designed for road cycling races and frequent training sessions on flats or in the hills. This B'Twin carbon road bike is great at picking up the pace come race season, thanks to its sturdy yet lightweight frame and Shimano 105 11-speed drivetrain.

The frame is UCI-certified for road cycling races

One of the best weight-to-speed ratios on the market

Ergonomic saddle for comfort"

Frame and fork

Overall rating for frame and fork

Tell us about the build quality and finish of the frame and fork?

The finish is impressive, as is the build quality. A solid feeling frame and fork.

Tell us about the materials used in the frame and fork?

Both the frame and fork use a mixture of various grades of carbon fibre to achieve the ride qualities and stiffness found.

Tell us about the geometry of the frame and fork?

It's a racy setup but it never actually feels that extreme. Full details can be found on the Dura-Ace model page -

How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?

The stack height on this medium model is 548mm and the reach 398mm, giving a race orientated ratio between the two of just 1.37.

It's exactly where I expect to find a bike of this type.

Riding the bike

Was the bike comfortable to ride? Tell us how you felt about the ride quality.

Yes, the frame and fork absorb a lot of road buzz.

Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?

Yes, very stiff indeed thanks to the oversizing of the bottom of the frame.

How did the bike transfer power? Did it feel efficient?

Impressively efficient. A lighter set of wheels will make a huge difference, though.

Was there any toe-clip overlap with the front wheel? If so


How would you describe the steering? Was it lively Fast without being twitchy.

Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?

The Ultra is beautifully balanced regardless of your speed, so it is a very easy bike to live with and control.

Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?

The saddle was surprisingly comfortable.

Which components had the most effect (good or bad) on the bike's stiffness? would you recommend any changes?

The stem and handlebar are very stiff.

Which components had the most effect (good or bad) on the bike's efficiency? would you recommend any changes?

Like I said above, if you want the ultimate speed machine then lighter wheels will unleash the speed from the frameset.

Rate the bike for efficiency of power transfer:
Rate the bike for acceleration:
Rate the bike for sprinting:
Rate the bike for high speed stability:
Rate the bike for cruising speed stability:
Rate the bike for low speed stability:
Rate the bike for flat cornering:
Rate the bike for cornering on descents:
Rate the bike for climbing:

The drivetrain

Rate the drivetrain for performance:
Rate the drivetrain for durability:
Rate the drivetrain for weight:
Rate the drivetrain for value:

Tell us some more about the drivetrain. Anything you particularly did or didn't like? Any components which didn't work well together?

In this 5800 guise the 105 groupset performs near faultlessly. The longer rear mech cage is great for being able to accept bigger cassette sprockets.

Wheels and tyres

Rate the wheels for performance:
Rate the wheels for durability:
Rate the wheels for weight:
Rate the wheels for comfort:
Rate the wheels for value:

Tell us some more about the wheels.Did they work well in the conditions you encountered? Would you change the wheels? If so

The Mavic Aksium wheels are solid performers and are exactly what I'd expect to see on a bike of this price and performance. An upgrade to lighter options really brings the bike alive.

Rate the tyres for performance:
Rate the tyres for durability:
Rate the tyres for weight:
Rate the tyres for comfort:
Rate the tyres for value:

Tell us some more about the tyres. Did they work well in the conditions you encountered? Would you change the tyres? If so

The Mavic tyres are pretty good all-rounders. They warded off punctures and the grip is more than acceptable.


Rate the controls for performance:
Rate the controls for durability:
Rate the controls for weight:
Rate the controls for comfort:
Rate the controls for value:

Tell us some more about the controls. Any particularly good or bad components? How would the controls work for larger or smaller riders?

Basic but decent performing stuff for the money. I wouldn't be in a massive rush to upgrade anything.

Your summary

Did you enjoy riding the bike? Yes

Would you consider buying the bike? Yes

Would you recommend the bike to a friend? Yes

Rate the bike overall for performance:
Rate the bike overall for value:

Use this box to explain your overall score

The Ultra CF 900 represents a well-priced package centred around an awesome frameset. It's a great bike as it is but also ripe for upgrades as you improve in performance and fitness.

Overall rating: 9/10

About the tester

Age: 39  Height: 180cm  Weight: 76kg

I usually ride: This month's test bike  My best bike is:

I've been riding for: 10-20 years  I ride: Every day  I would class myself as: Expert

I regularly do the following types of riding: time trialling, commuting, club rides, sportives, fixed/singlespeed

As part of the tech team here at F-At Digital, senior product reviewer Stu spends the majority of his time writing in-depth reviews for, and ebiketips using the knowledge gained from testing over 1,500 pieces of kit (plus 100's of bikes) since starting out as a freelancer back in 2009. After first throwing his leg over a race bike back in 2000, Stu's ridden more than 170,000 miles on road, time-trial, track, and gravel bikes, and while he's put his racing days behind him, he still likes to smash the pedals rather than take things easy. With a background in design and engineering, he has an obsession with how things are developed and manufactured, has a borderline fetish for handbuilt metal frames and finds a rim braked road bike very aesthetically pleasing!

Add new comment


Nick T | 5 years ago

The route of those cables from the bars to down tube looks very odd indeed

ChasP replied to Nick T | 5 years ago
Nick T wrote:

The route of those cables from the bars to down tube looks very odd indeed

They come sitting foreward in a more conventional position, see the photo in the comments above. Maybe the tester thought it was more aero tucking them to the side?

Vejnemojnen | 5 years ago

this bike was tested-featured by a local site few weeks ago. And they praised the frame being very good, in both comfort and efficiency as well. And the tester found the saddle to be the same shape as Fiziik Antares, with a little more gentle padding.


After all, you can always change components, but still, the most crucial factor is the frameset.


very curious, googled the article, and found an english version. How?

Parkrider | 5 years ago

Why the front brake is a direct mount while the rear brake caliper is a normal mount?

darrenleroy | 5 years ago

*Sits back and waits patiently in hope of a disc break frameset version.* 


kil0ran | 5 years ago
1 like

Interesting - that's the first time I've seen Decathlon offering a frameset option. 

aegisdesign replied to kil0ran | 5 years ago
1 like
kil0ran wrote:

Interesting - that's the first time I've seen Decathlon offering a frameset option. 

It's a bit of a hard sell though at £999 when you can have a complete bike with very decent components for £300 more. You'd probably be better off buying the bike, stripping it and selling the components.

Let's see if the frameset comes down in price in one of their sales.

Cateric | 5 years ago
1 like

Since purchasing this bike in mid-May 2018 in Canada and having ridden it daily for a total of 2500km.  Decathlon certainly have gained my loyalty with the quality product they put out. Irrelevant of it’s cost. And it’s just to show us that doing our own homework is worth it. Big name bike manufacturers should do the same. Because, Big name = Big price tag is not the only way to go. As in this case going with B’twin = better value.

Avatar | 5 years ago

Brill, but nobody will buy it as always. Btwin at over a grand is a hard sell to the roadies. I would have it,change the wheels and murder it out.

Joe Totale | 5 years ago

The Ultra 920 which is the same frame with Cosmic Carbons and full Ultegra 8000 for £2000 strikes me as being an utter bargain and nowhere comes close to offering that kind of value. 

You could easily race that thing and win those races, hell it's probably more bike then most of us will ever need! 

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