Planet X SL Pro Carbon review

Very light and the price is right

Our rating 
4.0 out of 5 star rating 4.0
GBP £999.99 RRP | USD $1,628.58

Our review

Great kit and ultra-light
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The Planet X screams value for money from the rooftops with a megaphone. And if you ride for fun and fitness then the carbon frame’s qualities come into their own. Not all of the testers were convinced by the bike’s handling when it was really cranked up, but for a budget all-carbon bike the Planet X is going to take a lot of beating.

  • Frame: Strikingly compact carbon fibre with a full-carbon fibre fork is a rare sight at this comparatively modest price (8/10)
  • Handling: Perfect for sportives and fitness riding, though stronger riders might find the front end a little bit lively (7/10)
  • Equipment: Achieves maximum marks for getting Shimano’s high-end, high-performance Ultegra 6700 groupset on a bike that costs less than a grand (10/10)
  • Wheels: Light, and quick to get up to speed (8/10)

Looking at it on paper, the SL Pro Carbon appears to be a bit of a bargain. Planet X have somehow managed to stick a groupset that is priced at nearly £800 on a complete bike that costs just under £1,000.

We’re assuming there isn’t an army of alien automatons making bikes for the online retailer… But however it is achieved, the result is a bike that tips the scales at just over 17lb; an incredible achievement for the price. So that SL – for Superlight – is entirely accurate.

At a relatively modest pace the ride feels smooth and controlled, small road bumps being evened out by the carbon, and the lightness of both the frame and the wheels is much appreciated on the hills. The weight difference compared to other bikes at this price is striking. For fitness riding, training and even sportives, we’d have no hesitation in recommending it.

But when it came to cranking up the gears, getting out of the saddle and sprinting, some of the riders were really able to feel the front end flexing. The fork is remarkably light for the price, but also the steerer tube came fitted with a couple of spacers and it’s possible that cutting down the steerer and whipping out those spacers might have tightened the front end and reduced some of the flex.

Interestingly, while most manufacturers have moved away from radically compact frames, Planet X have stuck with it – and with good reason. The advantage of a small triangle is that it will be inherently stiffer and lighter than a larger equivalent, and while there were doubts over the front end, there was nothing but confidence in the rear.

It reminded us of Giant’s original TCR, the pioneering modern compact bike. It was plenty stiff enough through the bottom bracket and the long, oversized seatpost gave enough comfort over most road surfaces, with the carbon frame coming into its own and cancelling out the worst of the road buzz.

It’s hard to find fault with Planet X’s kit, with the newest incarnation of Ultegra a fantastic find on a bike at this price. Not only does it resemble Dura-Ace, but mechanically it’s pretty much identical and only weighs a few hundred grams more.

The hollow chainset is stiff, and the shape of the new levers appealed to everyone, the only criticisms concerning the amount the lever has to move in order to change gear, with some riders preferring the shorter arc of SRAM’s levers.

As well as a light frame and groupset, the Planet X also has light wheels. They’re built with own-brand rims and hubs, spoke tension felt pretty even, and they felt stiff enough too. Although they might be ripe for an upgrade a few years down the line – for something to better complement the Ultegra kit – we can’t see you having any immediate problems with these. Tyres are Schwalbe’s 23mm Luganos, which major on durability rather than being lightweight with minimal rolling resistance.


When it comes to value for money, we thought the Boardman Team Carbon had set the bar very high for what you can buy for £1,000, but if anything, the Planet X has raised it a notch or two. If you’re looking for a very light bike on a limited budget then the Planet X has to be in your sights.

Product Specifications


Name SL Pro Carbon (10)
Brand Planet-X

Available Sizes L M M L XL M L XL S S M S M L S M L S M L XL L XL S M S M L S M L XL S M L XL
Rear Wheel Weight 1595
Top Tube (cm) 54
Standover Height (cm) 74
Seat Tube (cm) 42
Chainstays (cm) 47
Bottom Bracket Height (cm) 27
Weight (lb) 17.1
Weight (kg) 7.75
Stem FSA OS 120 forged alloy, 4-bolt 31.8mm bar clamp, twin-bolt 1 1/8in steerer clamp
Shifters Shimano Ultegra 10-speed STI
Seatpost FSA SL-250 alloy, 31.6mm x 350mm, forged twin lateral bolt seat clamp
Seat Angle 73
Saddle Planet X padded leather, Ti rails
Rims Planet X deep section machined aero
Rear Hub forged low flange sealed cartridge
Bottom Bracket Shimano Ultegra external sealed cartridge alloy cups
Rear Derailleur Shimano Ultegra, short cage
Headset Type FSA standard ball and cone integrated ahead, 1 1/8in, contact seals
Head Angle 72.5
Handlebar FSA Wing alloy anatomic deep drop, 42cm c-c
Front Wheel Weight 1115
Front Hub forged low flange sealed cartridge
Front Derailleur Shimano Ultegra
Frame Weight 1057
Frame Material Carbon monocoque, steel headset inserts, alloy BB sleeve and dropouts, replaceable gear hanger.
Fork Weight 362
Fork All carbon, 1 1/8in steerer; alloy dropouts
Cranks Shimano Ultegra 2-piece alloy with hollow steel spindle, 170mm arms, 110mm bcd, alloy rings
Cassette Shimano Ultegra 10-speed, steel cogs on alloy carrier
Brakes Shimano Ultegra forged alloy dual pivot
Wheelbase (cm) 99