Officially launched in Kona, the Diamondback Serios is a brand new offering from a company brand new to the tri scene. It's got some interesting features, and is a unique take on the current trend of combining aerodynamic integration with ease of use. Of course, no bike is perfect and I have some small qualms about the bike, most notably its direct-mount only brake mounts. Like the Cannondale Slice, also just launched, Diamondback has decided that the Serios would ONLY be made to accept direct-mount brakes of the Shimano standard (honestly, why not just make the fork with that third hole for standard brakes, like the Quintana Roo PRSix?) Eventually, FSA will release its centerpull direct-mount brake, and other parties might as well. But for now, potential buyers of the Serios must be content with a rather unsightly, unaero front brake and cable routing. Same for the rear, although at least that one is out of sight below the BB. With that major gripe out of the way, let's take a look at the rest of the bike, most of which is pretty good indeed.
Starting from the front end, the Serios uses a tapered fork that runs from 1-3/8" at the bottom to 1-1/8" up top. Although I'm generally not a fan of anything larger than 1-1/8" anywhere on a tri bike, the Serios still keeps things pretty narrow considering the larger bottom bearing. Their rationale was that the larger size helps with stiffness, but I've never found that to be lacking on bikes with standard bearings. Weirdly, the top of the head tube looks wider than the bottom, even though it has the smaller bearing. Anyway, the top of the steerer is standard, meaning you can mount any stem you like up there.
On the top Serios F and Serios AF models, the bike includes a semi-integrated stem designed around the bike's lines and meant specifically for the HED Corsair aerobar. Technically, the stem will accept any 31.8mm OS handlebar, but the integration features mean it might have a hard time mounting to some bars, depending on their shape. For example, I'm quite sure that a PRO Missile EVO bar won't fit this stem. Not sure about other bars.
One very nice feature of this front end setup is the inclusion of aero-matched spacers that come with the bike. These allow you to raise either the integrated stem OR a standard stem of your choice, while maintaining a good aero match with the rest of the bike. The top tube is raised, so it will act as a fairing for the first 30mm or so of spacers you might use. And this gets to a really interesting point, and something I love about the bike: there are two cable entry points. One is right on the top tube, making for clean routing if you use spacers to raise the stem up. The second is on the front of the raised top tube, allowing the cables to completely hide if the stem is slammed. If that sounds confusing, just check out the gallery below. But this just underscores my gripe about the front brake: if you're going to make all the OTHER cables so clean, why not also clean up the first cable the wind sees at the front brake?
Just behind the steerer tube, we see a pair of bosses for top tube accessory mounts. Nice. I'm always glad to see more bikes use this standard, and a bit disappointed when I don't see them. Moving back, we see a seat tube built at 77 degrees, with enough fore-aft adjustment to allow you to hit almost any position you like. I'd like to see it a little steeper, maybe with less setback and more forward offset. But it's certainly usable by any standard, especially given that it comes stock with a lovely split-nose Adamo saddle. Vertical dropouts make for easier wheel changes (I'm not a huge fan of horizontal dropouts).
Diamondback's numbers show the Serios to be a rather fast frame, testing favorably against bikes like the Cervelo P5 and Trek Speed Concept. It's not too difficult to believe those numbers, given the nice deep chord lengths of its head tube profile, which according to Diamondback get as long as 200mm at the fork crown. The shapes are all nice and smooth, no weird choices or awkward lines. Like Trek (and unlike Cervelo, Specialized, and Felt), Diamondback hasn't completely closed the gap between down tube and front wheel, but perhaps that was in part to achieve a deeper fillet behind the head tube.
I'm looking forward to building up one of these beauties in the near future, so stay tuned for another in-depth review. Until then, enjoy the gallery from gorgeous Kailua-Kona!