The Rose X-Lite CWX-4100 is a quick, fast-handling aero road bike with disc brakes, and although £4,700 is clearly a lot to spend, it represents good value. You really are getting a lot for your money here.
The CWX-4100 – the name sounds to me like it should belong to some sort of droid – is at its best when you're hammering. The aggressive riding position and the frame's aero features announce loud and clear that this bike is intended to be ridden fast.
Weighing in at just 7.46kg (16.4lb) – light for something with deep, aero-optimised tubes and disc brakes – and with loads of stiffness through the central section of the T40/T60 carbon-fibre frame, it feels every inch a race bike whether you're tearing along flat roads or scampering up the climbs.
The handling is sharp too, the tapered head tube (1 1/8in upper, 1 1/2in lower) and Rose's full carbon fork giving you the confidence to dart about in a group, and there's no wandering when you throw the bike over hard into corners.
You might well have your own thoughts on the rights and wrongs of disc brakes on a road bike, particularly on an aero road bike, but the Shimano RS-805 brakes fitted here certainly perform far more consistently than rim brakes across a range of different weather conditions. That's not to say they're entirely unaffected by the wet, but the difference isn't huge; you never find yourself waiting for them to bite like you can with rim brakes acting on carbon, and that gave me the assurance to keep pushing hard on damp roads, particularly when descending.
The performance-driven ride characteristics won't be for everyone, of course. The CWX-4100 doesn't offer a relaxing ride – the geometry is too aggressive for that – and the near-vertical seatpost doesn't flex a whole lot, giving quite a firm feel at the saddle, even though I found the Fizik Aliante fitted to be a great shape. You can fit tyres up to 28mm for more comfort but even so, if you're after a bike for chilled out weekend pootles, this ain't it. This is most definitely a bike that suits a rider who likes to go full gas.
I've already touched on the geometry a couple of times so let's deal with that next. We have the 57cm model here with a 530mm seat tube, a 561mm top tube and a 160mm head tube. The stack (the vertical distance between the centre of the bottom bracket and the top of the head tube) is 563mm and the reach (the horizontal distance between those two points) is 400mm.
That's a low and stretched go-faster setup. You do require a certain amount of flexibility to maintain your riding position on a bike like this, of course, but there are aero gains to be had if you can.
The seat angle is steep for a road bike at 74°, and you can effectively make it even steeper – to over 76° – by flipping Rose's carbon seatpost around so that the layback faces forward. This moves the saddle so that you're closer to sitting over the bottom bracket, making it easier to achieve a flat-backed riding position if you want to use clip-on aerobars for triathlon or duathlon. It's okay, Profile says you're allowed to fit them to the carbon-fibre Canta Ergo handlebar specced here.
Speaking of the bar, it's compact (125mm drop/70mm reach) and I found it to be really comfortable, especially that wide top section that spreads the pressure on your palms. The drops have a decent amount of rearward sweep too, so those with large hands won't feel cramped.
The CWX-4100 frame has been designed to slip through the air cleanly, with truncated aero-profile tubes, a deep-section seat tube that's cutaway around the leading edge of the rear wheel, internal cable and hose routing, and an aero seatpost.
Rose claims that the X-Lite CWX saves 9 watts at 40km/h (25mph) over its predecessor, although that doesn't mean a lot unless you know the efficiency of that previous bike. Rose says the shape of the frame provides an excellent Cd (drag coefficient) value but we can't put bikes in the wind tunnel to verify that, we can just report the claims.
The concept of an aero road bike with disc brakes is bound to raise eyebrows because discs add drag. Rose isn't alone in doing this, though. Specialized has introduced disc brakes to its Venge, for example, and there are disc versions of Ridley's Noah SL. Plenty more are on the way.
The argument goes that a disc brake bike might not be as aerodynamically efficient as a rim brake version of the same model, but it's more efficient than a non-aero disc bike. Fair enough! If you want disc brakes on an aero frame, you can have them, and if you want rim brakes you can go for a different model.
Interestingly, the Rose CWX (flat mount disc brake) and CW (direct mount rim brake) bikes are actually built around the same frame, so you could buy a CW and swap to disc brakes further down the line. That keeps costs down for Rose (it only has to make half the number of moulds) and adds versatility. The mounts for the rim brake are positioned on the underside of the chainstays so they're not noticeable. I didn't even know they were there until I went looking.
The fork is disc-specific, though: bolt-thru axle, the same as the frame. It's not got a quick release so you need a hex key for changing an inner tube. Grrr!
You get three bottle cage bosses on the down tube, allowing you to choose between a more accessible upper position and a more aero lower position, and the DT Swiss RC 38 C wheels have been developed to offer a degree of aero performance. The rims have an 18mm inner width and are tubeless-ready, and the hubs use Shimano's Center Lock for mounting the disc rotors.
Rose builds each bike to order, so you get a certain amount of component choice. You can decide on the type of chainset you want, the cassette range, and you can choose from a range of handlebars, stems, saddles, and so on. You can also add pedals, aerobars, bottle cages and a bike computer, and the price will be adjusted accordingly. Basically, you can change things until you hit a satisfactory price and build. You do have to factor in a delivery charge because Rose is a direct-to-consumer brand. That's currently listed as £27.20. (And ignore the ‘sold out’ message on Rose’s website – if it's still there! – it has frames in stock.)
Obviously, £4,700 is a lot of money to spend on a bike, but the Rose X-Lite CWX-4100 offers much in return. You get a stiff and lightweight frame, Shimano's superb Dura-Ace Di2 groupset, hydraulic brakes and well-proven carbon wheels. The complete package is a lightweight, fast-handling aero road bike that'll suit riders with a need for speed. Rose might not be the biggest brand out there but this bike is the real deal.
A fast and sharp-handling aero road bike with top-level components and the all-weather assurance of disc brakes
road.cc test report
Make and model: Rose X-Lite CWX-4100 Di2 Disc
Size tested: 57cm
About the bike
State the frame and fork material and method of construction. List the components used to build up the bike.
Frame: High Modulus Aerospace Carbon Fibre T40/60, H.O.C.-Technology
Fork: X-LITE CW High Performance, 1 1/8in - 1.5in, full carbon
Chainset: Shimano Dura-Ace 52/36T
Cassette: Shimano Dura-Ace 11-28
Front Derailleur: Shimano Dura-Ace Di2
Rear Derailleur: Shimano Dura-Ace Di2
Saddle: Fizik Aliante
Handlebar: Profile Canta Ergo
Stem: Ritchey WCS
Seatpost: Rose Carbon Flip Flop
Levers: Shimano R785 Di2/hydraulic disc brake
Brakes: Shimano RS-805
Wheels: DT Swiss RC38 DB
Tyres: Continental Grand Prix 4000S 25mm
Tell us what the bike is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about the bike?
Rose says, "All those who love technical details will love the X-LITE CWX-4100 Di2. This bike is full of highlights that make your mouth water. The sophisticated, aerodynamic carbon frame is accompanied by a Shimano Dura-Ace Di2 groupset. It provides the gold standard of rear derailleur art. It is extremely precise and quickly changes the gears – a dream in your hands. And since Shimano's engineers did a great job, it not even weighs 100 grams more than the comparable mechanical Dura-Ace groupset.
"A pair of really good wheels is also part of the bike's outstanding equipment. As the name suggests, the DT Swiss RC 38 Spline Disc wheels are compatible with disc brakes which is why they come with thru axles on front and rear. Apart from high modulus full carbon rims, the system wheelset offers straight pull spokes, which significantly increases the stability of the wheels."
Frame and fork
Tell us about the build quality and finish of the frame and fork?
The build quality is very good throughout.
Tell us about the materials used in the frame and fork?
The frame is made from T40/T60 (Toray) carbon fibre.
Tell us about the geometry of the frame and fork?
It's an aggressive geometry. We have the 57cm model with a 530mm seat tube, 561mm top tube and 160mm head tube. The stack (the vertical distance between the centre of the bottom bracket and the top of the head tube) is 563mm and the reach (the horizontal distance between those two points) is 400mm.
The seat angle is steep (74°) and you can make it even steeper (over 76°) by flipping the seatpost around if you want to fit aero bars and treat it as a time trial bike, for example.
How was the bike in terms of height and reach? How did it compare to other bikes of the same stated size?
A 530mm seat tube and 561mm top tube are both short for a bike with a 57cm stated size.
Riding the bike
Was the bike comfortable to ride? Tell us how you felt about the ride quality.
There's very little give in the almost vertical seatpost, so it's a firm ride, but that doesn't mean it's uncomfortable. You can fit tyres up to 28mm if you like. We had 25s on and I didn't feel the need for anything larger.
Did the bike feel stiff in the right places? Did any part of the bike feel too stiff or too flexible?
The stiffness to weight is high. The frame feels stiff, especially through the centre.
How did the bike transfer power? Did it feel efficient?
It feels efficient, yes.
Was there any toe-clip overlap with the front wheel? If so, was it a problem?
Just a touch and not a worry.
How would you describe the steering? Was it lively, neutral or unresponsive? Closer to lively than anything else. This is a bike that's easy to manoeuvre.
Tell us some more about the handling. How did the bike feel overall? Did it do particular things well or badly?
I found it to be a really chuckable bike. You can move it about really easily to navigate through a group of other riders.
Which components had the most effect (good or bad) on the bike's comfort? would you recommend any changes?
I liked the Fizik Aliante saddle and I also got on well with the Profile Cante Ergo handlebar.
Wheels and tyres
Did you enjoy riding the bike? Yes
Would you consider buying the bike? If I wanted disc brakes and an aero frame it would be one to consider.
Would you recommend the bike to a friend? Yes
Use this box to explain your score
This is an expensive bike, clearly, but you get a lot for your money both in terms of the equipment and the performance. It's a very good buy.
About the tester
I usually ride: My best bike is:
I've been riding for: Over 20 years I ride: Most days I would class myself as: Expert
I regularly do the following types of riding: commuting, club rides, sportives, general fitness riding
Mat has worked for loads of bike magazines over the past 20 years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for seven years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a past winner of the Cycling Media Award for Specialist Online Writer.