B’Twin Ultra 900 AF review

Since renamed as the Van Rysel RR 900 AF, the Ultra offers Shimano 105 and Mavic Aksiums at an incredible bargain price

Our rating 
4.0 out of 5 star rating 4.0
GBP £799.00 RRP

Our review

One of the best value road bikes out there — easily the equal of most £1,000 bikes
Buy if, You want the very best fast road bike possible and your budget tops out at £800
Pros: Quality triple-butted aluminium frame delivering a fast, dynamic ride and the best kit you’ll find at the price
Cons: Oversize seatpost and awkwardly placed rear direct-mount brakes
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Editor’s note, August 2019: Decathlon rebranded its road range for 2019, replacing the Ultra 900 AF with the identically kitted out Van Rysel RR 900 AF. Along the way, Decathlon’s designers ditched the under-chainstay rear brake, one of the only features of the bike we didn’t particularly like. Make sure you also check out our review of the next model up, now known as the Van Rysel RR 920 AF.

“To B’Twin or not B’Twin?” is a question that Shakespeare sadly didn’t pose in the opening of Hamlet. Which is a bit of a shame, as it would probably have been a pretty straightforward poser for the Danish prince to answer, as B’Twin’s Ultra 900AF road bike is “a hit. A very palpable hit.” Ah well, back to the more sensible bike-related stuff now…

  • The B’Twin Ultra 900 AF was one of our Bike of the Year bikes for 2018. To read reviews of the other contenders and the categories tested across road, mountain and women’s bikes, visit our Bike of the Year hub.

B’Twin is the moniker that French sports supermarket Decathlon uses for its sports clobber, but the name has also adorned team bikes ridden by Ag2r and FDJ’s professional riders over the years, so it should have a bit of nous when it comes to putting together bikes for the more modest power outputs produced by the rest of us.

The B’Twin Ultra 900 AF is by the far the least expensive of our nominally £1,000 bikes category in Bike of the Year testing this year. It has a compact 6061 aluminium frame — complete with the UCI’s seal of approval — with internal cabling, non-smoothed welds and a complete raft of Shimano 105 parts in its direct-mount brake incarnation. The wheels are Mavic Aksiums with Mavic Aksion tyres too, something you might expect on a bike costing £200 more.

A wallet-friendly price, yes, but far from cut-price kit
A wallet-friendly price, yes, but far from cut-price kit

I did have a couple of minor reservations when I first saw the Ultra 900 AF because it has a couple of features that have gradually been falling out of fashion over the last few years. I’m talking direct-mount brakes mounted behind the bottom bracket and large diameter seatposts; the only other top 10 bike with a 31.6mm is the Boardman Team Carbon.

These mean a few potential issues. Out-of-the-saddle climbing can result in brake rub, though I’m glad to say that I didn’t experience this during testing, and it may only affect those with more Chris Hoy-like power outputs.

The second factor is that it’s a fiddly location for fettling the brakes and that they’re likely to pick up even more dirt, oil and grit than standard seatstay brake bridge-mounted brakes.

Mavic Aksium wheels and 25mm Mavic Yksion tyres
Mavic Aksium wheels and 25mm Mavic Yksion tyres

This is something that B’Twin is obviously aware of because the brakes are going to be moved on future versions of the Ultra AF. The positive, though, is that the brakes do work very well, with loads of controllable power.

The other concern — that seatpost — was also largely overcome by B’Twin. The triple-butted aluminium frame is stiff and very much performance orientated, and I felt that the seatpost might make it too harsh through the saddle, but it manages to stay on the right side of firm.

The seatstays are slimmer than some and the lack of a brake bridge will reduce stiffness too, and there’s enough of the seatpost exposed to provide at least some give. The carbon fork legs do the same at the front.

With some of the money you’ve saved you could always get yourself a carbon post or an adaptor for a narrower seatpost for more comfort. And I reckon Specialized’s 26mm tyres and some 28mm rubber would fit, adding a little more plushness too.

B’Twin Ultra 900 AF overall impression

B’Twin’s designers have created a bike that scores highly for a quick, dynamic and enjoyable ride. The geometry falls between full-on race bike and endurance, and you could use this for pretty much anything.

It’s sharp enough for racing, comfortable enough for fast sportives, and you could squeeze in a pair of aftermarket mudguards to create a slick winter trainer. Fast and furious or slow and steady? The choice is yours and you can even flit between the two.

Shimano 105 throughout
Shimano 105 throughout

The gearing matches the reasonably aggressive geometry, with a ‘pro-compact’ 52/36 chainset paired with an 11-28 cassette. This means you can power up sprints until your thighs are bursting, though the 36×28 bottom gear did make my steeper test climbs more of a challenge, and if hills aren’t your thing, take note.

B’Twin’s Ultra AF 900 may not be quite as light as some of the other aluminium or carbon fibre bikes in this price bracket, but it’s not significantly weightier, and it does dip under the 9kg mark. That’s not staggeringly light, but is extremely impressive for the price and is also a low enough weight for your non-cycling pals to pick it up and be very surprised.

It was a surprise, too, just how good this bike was overall. There are a couple of surprising kit choices, but this is one of the biggest bargains out there. A triple-butted frame with a lifetime guarantee, which is good enough for competing on (even in UCI events if you’re feeling ambitious), balanced with sufficient comfort for longer, more leisurely days.


Product Specifications


Name Ultra 900 AF
Brand Btwin

Available Sizes XS S M L XL
Rear Tyre 25mm Mavic Yksion
Frame size tested M
Wheelset Mavic Aksium
Weight (kg) 8.91
Stem BTwin 6061
Shifters Shimano 105
Seatpost BTwin Competition
Saddle BTwin Comp Ergo
Rear Derailleur Shimano 105
Brakes Shimano 105 direct mount
Handlebar BTwin 6061
Front Tyre 25mm Mavic Yksion
Front Derailleur Shimano 105
Frame Material Aluminium
Fork Carbon, aluminium steerer
Cranks Shimano 105 52/36
Cassette 11-28
All measurements for frame size tested M