Rose X-Lite CWX-4100 Di2 Disc

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.

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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.

Geometry

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.

Frame

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.

> Read our guide to the fastest aero road bikes

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.)

Conclusion

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.

Verdict

A fast and sharp-handling aero road bike with top-level components and the all-weather assurance of disc brakes