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The Xenith SL moves Jamis upscale and offers a top-shelf race-ready package at an attractive price(Image credit: James Huang)

Jamis Bicycles’ top-end Xenith SL road racer might not please the UCI but that shouldn’t stop the rest of us from having some fun on this featherweight flyer.

We’ll plead guilty to sometimes over-emphasising the importance of minimal mass but there’s little argument to just how a 6kg bike feels under foot particularly when there is so little sacrifice in terms of performance as seems to be the case here. Some of the credit undoubtedly belongs to the speedy Zipp hoops and their appropriate balance of low mass and sleek aerodynamics (if you’ve never tried a set of deep-section carbon tubulars, put off the kid’s college education for a semester and treat yourself) but even swapping in some Mavic R-SYS reference wheels did little to alter the bike’s get-up-and-go attitude.

As a result, sprint performance is, as you’d expect, plenty fast and handling reflexes are appropriately sharp in combination with the frame’s relatively neutral 73/73 degree parallel angles and 271mm bottom bracket height. Naturally, a bike that is both stiff and light should also be a climber’s dream and the Xenith SL is no exception… that is, until you run out of gears which doesn’t take long given the stock setup’s 52/38T chainrings and 11-23T cassette – particularly if your test patch is the Rocky Mountains. Pure climbers likely won’t have any issues here but something a little more befitting the rest of us would be very welcome here.

Just about the only place where we were mildly disappointed (and we mean mildly) was in the Xenith SL’s ride quality. When fitted with the stock Zipp 404 tubulars, the Xenith SL delivers a buttery feel with excellent road feedback and a decent amount of liveliness. However, much of that smoothness went away when we fitted more conventional clinchers; small chatter was still absorbed well but anything bigger than typical road texture was felt loud and clear. The ride certainly wasn’t harsh by any means in most situations but it’s definitely on the firmer end of the spectrum, especially up front.

Critical frame design elements include the rounded triangular-profile top tube and down tubes, full-length twin seat stays (as opposed to more common wishbone configurations) and asymmetrical chain stays, all of which are said to offer the holy grail of stiffness and comfort. The top tube and down tube are also size-specific to maintain intended ride characteristics across the fairly generous 48-61cm size range. Rear dropouts are stiffer and more reliable forged one-piece aluminum units instead of the more commonly used two-piece bits.

Our top-end test bike’s stock build kit takes full advantage of its lightweight foundations. Only FSA’s superb K-Force Light crankset and an X10SL chain from KMC punctuate the nearly complete SRAM Red gruppo. Cockpit components include an Easton EA90 stem, EC90 Equipe SLX bar and EC90 post topped with a Selle San Marco Aspide saddle. As if there was any remaining doubt as to the Xenith SL’s intended use, Jamis also includes a set of premium Zipp 404 carbon wheels and Vittoria Corsa Evo CX tubulars.

The Easton EA90 stem was superb and lends ammunition to the argument that carbon fibre offers little advantage here. The accompanying carbon SLX Equipe bar, though, is still lighter, more comfortable and yet stiffer than any comparable aluminum bar but the unique bend might not be for everyone. The forward-leaning kink up top provides plenty of room for your wrists when you’re in the drops but also puts undue pressure right on your ulnar nerve if you happen to rest your hands up there.

Unfortunately, the EC90 post was a bit of a letdown. While it never slipped during use, the molded-in carbon serrations eventually began to round off after a few adjustments and the generous 25mm of offset might be excessive for some riders’ physiques. We had to slam the Selle San Marco Aspide saddle all the way forward on the rails for a proper knee-over-pedal spindle measurement but at least the perch was reasonably supportive and comfortable in spite of the relative lack of padding.