They're handbuilt using Sapim CX Ray spokes, American Classic hubs and deep dish tubular carbon rims: 50mm for the front, mm for the rear. The front weighs g and the rear g - not a super light combination, but one that's certainly aerodynamic and affordable. Planet X also makes the Pro Carbon 82 which features an 82mm carbon rim, a full disk wheel, and offers Xentis four spoke and standard spoked Reynolds Alta Comp wheels as part of its bike builds.
The Pro 50 front handles like most deep dished front wheels including Lightweights that I've ridden. In a crosswind, it requires a bit more effort than a normal spoked wheel to keep straight, but nothing that you won't get used to after a few rides.
The only wheels I've come across that are immune to this effect are Zipps, with their flared aerofoil rims and golfball-like dimples. The Pro carbon rear is absolutely fine in a crosswind, because you've got most of your weight over the back wheel. It's almost-but-not-quite a disk, so it's great for hillier, technical courses where lighter weight and better handling come into play.
But if money is no object, a disk is still going to be your best option. Both wheels were fitted with Continental Competition 22 tubulars. These are tried and trusted by the pros.
They give a great ride and have a good deal of puncture resistance, but don't cost the earth. Summary Planet X's Stealth Pro Carbon is an excellent choice of machine if you're after a medium-budget time trial bike. With so many speccing options available, you should be able to find one that works for you, bearing in mind that it can always be upgraded.
But the heart of the bike is the frame, which is not too heavy, handles well and is aero enough to satisfy a podium finisher in the Tour de France. It's an amazingly good performer for the price, and right up there with the very best time trial machines.
Where time trial bikes excel is going fast in straight lines, as this is where you will benefit most from improved aerodynamics. Our machine came specced with Shimano Ultegra, with a few upgrades. The bike came with an Ergomo Pro power measuring device. Planet X offers a range of wheels with their bikes depending on your budget. Planet X Stealth Pro Carbon review. Latest deals. Our review A high quality, affordable machine with plenty of build options to suit your budget.
Skip to view product specifications. The overall ride of the Stealth is smooth enough to allow relatively long stints in the saddle. In terms of straight-line speed though, the advantage the Planet X wheels and Crono tubs provide is just astonishing. The horizontal dropouts with wheel adjuster screws mean you can tuck the wheel right into the wheelhugger cutout.
This pricing is possible because Planet X direct-sell from their warehouse. The Planet X semi-carbon cockpit is no lighter than an alloy equivalent and the base bar grip shape and sharp elbow pad edges caused several problems for our testers. The direct-sell situation means you can effectively custom spec your bike from an extensive range of alternatives, though.
The long and short of it is if you want to double your speed, aerodynamic drag is quadrupled and you will need to supply eight times the power to overcome that. You can do the calculations yourself on any good power vs speed calculator or with tools such as Best Bike Split.
Playing around with the numbers makes it very obvious that the small weight reductions possible with bikes pale into insignificance compared to aerodynamics and rolling resistance on anything but the steepest gradients. The obvious ones are around the leading edge. Time trial handlebars have taken a massive leap forward in recent years and a set of integrated handlebars such as those by Wattshop or Aerocoach , perhaps with electronic shifting, could really clean up the front end.
Likewise, an aero stem Profile Design has a couple of good options — the Aeria and the Aeria Ultimate and a set of more aerodynamically efficient brakes, such as the TriRig Omega X , would also be a smart upgrade. The wireless system makes for wonderfully clean builds, especially in a 1x system. SRAM also has lots of shifter button options , meaning you can really go to town on customising it for your own needs.
Better wheels could be a reasonably significant upgrade too. Since the bike has rim brakes, a set of HED Jet wheels, such as a Jet 6 front and a Jet Disc rear , would be perfect because they have aluminium brake tracks. Again, though, that would involve significant cash investment.
Simon von Bromley is a senior technical writer for BikeRadar. Simon joined BikeRadar in , but has been riding bikes all his life, and racing road and time trial bikes for over a decade. As a person of little physical talent, he has a keen interest in any tech which can help him ride faster and is obsessed with the tiniest details.
When you buy through links on our site we may earn an affiliate commission, but this never influences our opinion. My Grandad doing a time trial in Yorkshire in the early s, before tri-bars existed. The frame is built using T carbon fibre. The rear brake attachment point is annoyingly small and fiddly.
It looks like it was designed to be fast on a CFD programme without the brake in place. Tyre clearance in the fork is tight, even with 23mm tyres.
I had a hard time sourcing a replacement front derailleur hanger when the original one bent out of shape. The rear disc wheel has a flat non-driveside profile. A small strip of gaffer tape can be used to cover the valve hole. A Shimano RS81 C50 front wheel was one of the cheapest aero wheels available in The Shimano RS81 front hub has good quality cup and cone bearings.
A 23mm on the front is a little more aerodynamically efficient, especially because the RS81 C50 rim has a reasonably narrow external width.
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