Vision Metron Crankset

The Vision Metron carbon crankset will certainly turn heads at your local time trial or triathlon, if you're willing to pay significantly more than most high-end cranksets for the claimed superior aerodynamics that the carbon fairing over the chainrings offers you. I'm not convinced that the watt savings are hugely significant, and bang for your buck there are certainly better places to upgrade your bike for speed savings; but as a money-no-object purchase for those that need plus-size chainrings for their time trial bike, it's an impressive bit of kit.

Pros: Looks amazing, smooth pedalling experience, bottom bracket standard is highly adaptable

Cons: No wind tunnel data available to justify spend, very expensive

FSA's Metron crankset has been around since 2013; this is the latest version. Aero cranksets have never really caught on even though there have been numerous attempts in the last decade or so, and currently there's nothing of the sort available from the big component brands such as Shimano, SRAM or Campagnolo; although the latter have recently changed the shape of their new Record and Super Record cranksets to make them more aerodynamic. Zipp have long since discontinued their Vumo Chrono aero crankset which was probably the closest comparison to the Metron though there are still some around if you have an eye-watering £799 spare.

The Metron is Shimano/SRAM compatible and needs a BB386 EVO bottom bracket, which for me meant getting a converter for the pressfit 30 bottom bracket on my Ridley Chronus time trial bike, and getting the ever-reliable Tom at Green Park Bike Station to fit it. FSA make a wide range of bottom brackets to convert the various standards out there to BB386, so you should be able to find one to fit your bike.

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I tested the Metron with 54/42 chainrings, giving myself a slightly harder gear than my usual 53/39 for the rapid time trialling that I imagine in my head that I'm capable of. FSA lists chainring combinations of 53/39, 54/42, 55/42 and 56/42; although we can only find the smaller two sizes for sale online.

After a bit of front mech adjustment I was good to go, able to get away with using my 11 speed Shimano chain already on my bike, and over the test period I was very pleased with how the chainset rode. There wasn't a hint of creaking out of the bottom bracket, and it felt very stiff under (what felt like) high pedalling forces when I was properly going for it.

While I can vouch for the smooth pedalling action and stiffness of the oversized spindle/bottom bracket combination, what I couldn't really quantify was the aero benefit of the fairing over the chainrings. I asked FSA how much faster I could expect to be, and unfortunately I didn't come away with anything too convincing. Here's what they told me: "The wind tunnel technology is a regular part of our research and development, and CFD (computational fluid dynamics) is used to interpret data and refine product design for ultimate aerodynamic performance. The data and comparative test are confidential, and only for our use."

So while FSA say they've done their homework, we're to take their word for it and there's nothing concrete in terms of watts or seconds they can quote to convince me I'll go any faster. They do say this latest version produces 7.5% less drag than its predecessor, but for me what would be really interesting would be a comparative test with a Shimano Dura-Ace crankset, for example.

I noticed when covering the Tour de France depart back in July that no FSA-sponsored pro teams were using the Metron on their time trial bikes. FSA told me: "We've discussed with The FSA/Vision pro athletes, but they prefer to use the PowerBox power meter (included on FSA's Powerbox crankset) instead of the Metron TT crankset. Why? Because they need to monitor their watts during the effort, to the detriment of the aerodynamics."

Read more: Which chainset is right for you?

That's all well and good, but there are other places you can measure power, so you'd think pro riders would convert if the speed savings were significant.

In terms of what else is out there, as mentioned previously cranksets offering aero benefit are few and far between. Rotor's Flow Aero crankset without chainrings is £405.99 so can probably be built up for less than the price of the Metron after adding chainrings. If you just want to size up then [ur=http://www.chainreactioncycles.com/shimano-dura-ace-r9100-double-chainse...'s top-of-the-range Dura-Ace crankset[/url] is available in sizes up to 55/42 for much less than the £499.99 RRP. You can also get aero chainrings from the likes of Rotor and Osymetric if you want to customise your current crankset.

The Metron crankset is fitted standard on a couple of time trial bikes you can buy off the peg, such as Ribble's new Ultra TT, and this is the only way I could ever justify buying it.

Overall I very much enjoyed having the Metron on my time trial rig for a while, adding some extra bling and providing a smooth, creak-free experience in use. But for the price I don't think it's the most cost-effective way to upgrade your bike, and would be a niche, money-no-object purchase even for dedicated time triallists.

Verdict

Super smooth and stiff crankset that will probably save you some watts, with a very big price tag