Jamis Xenith Pro

The Jamis Xenith Pro Di2 is one of the new crop of bikes using Shimano's Ultegra Di2 group to bring electronic shifting to the masses (or at least, down to a more affordable price point). At £2400, the Jamis is among the cheapest carbon-framed Ui2 bikes out there, but it's more than just a groupset, it's also a pretty decent bike in its own right.

Frame

The frame comes out of the same mould as the top level Xenith SL, employed by the UCI continental Jamis/Sutter Home squad in the US, only with lower grade fibers so you'd expect it to be racy. Up front, a tapered fork keeps everything pointing in the same direction while the downtube and stays combine to form a solid power transferring platform.

The bottom bracket is a suitably large Pressfit 30 number though an adaptor is used for the Shimano Ultegra cranks so you don't get the full stiffness benefit there. For a more in depth look at the frame and componentry, go check out what we had to say when the Jamis Xenith Pro hd just landed at HQ.

Geometry wise, the Xenith features fairly standard parallel 73 degree head and seat tubes, giving a trail figure of 58mm. I found this to be a good compromise between a razor sharp crit racer and a more laid back all-day cruiser. Through switchbacks, the Xenith feels quite neutral, neither diving into the corner nor feeling like an oil tanker. To get the best out of it, I found I had to be a bit more active with my weight shifts and really commit to line choices.

All those oversized tubes and the tapered headtube have combined to create a really solid platform for laying down the power. Despite my best efforts, I couldn't coax any chain rub out of the front derailleur. The fork is reassuringly oversized too and handles off-camber corners well; an area where less stiff forks can often be prone to drifting off line.

Despite the overall bike's more laid back handling traits (compared to more aggressive race bike geometry), I found that once you'd committed to a line, the Xenith never wavered from it.

Having praised the Xenith for its stiffness and solidity (the Jamis engineers have obviously made this a priority despite the lower grade fibres compared to the SL), the Jamis never felt like a bike that was eager to be accelerated and chucked around – it merely did its job of transferring pedal and steering input.

This can often be the case when using lower grade carbon and it's this ride feel that distinguishes the real top end, lightweight carbon frames from the rest. They urge the rider on with every pedal stroke and seem to explode forwards at the merest hint of power. The Xenith just doesn't have that spark or pizazz and lacks character in this aspect. This isn't a knock against it per se, and for the price it's a damn fine frame, but it's worth noting that it does lose something to the new generation of super-frames (think Canondale Super Evo and the like). But it also leaves quite a lot of money in your pocket compared to those bikes.

Ultegra Di2

Having spoken at length about the frame, I suspect that the real reason that people are considering this bike is the Ultegra electronic shifting. Functionally, Ultegra Di2 is so close to Dura Ace Di2 as to be virtually indistinguishable with the exception of the front shifts. Here, the off-the-shelf servo motors, as opposed to the Dura Ace version's Shimano designed jobs, are noticeably less quick and powerful leading to slightly slower shifts. When paired with the excellent Ultegra chainrings, front shifts under power are still possible although not 100% guaranteed. When paired with other chainrings, the front shifting is merely slightly better than the cable version.

Does the performance stand up to the hype? I'd have to say yes and would choose the Ultegra Di2 over cable Dura Ace (they both sit around the same price point) for most scenarios due to its reduced lever throw, better ergonomics and fit-and-forget nature. There aren't any cables to get clogged with grime and no housing compression to deal with – all you have to do is remember to charge the thing every 800 miles or so.

What really impressed me most with Di2 was the way it made changing wheels and cassettes, which can often lead to much tinkering with cable actuated shifting, super easy. A 20 second procedure to 'teach' the derailleur the appropriate cog spacing, and you'd have perfect shifting straight away. The stuff really was a joy to work on.

What's good too is the way that Jamis have gone the full hog and completely integrated the electronic cabling into the frame. The shift cables enter just behind the headtube and pop out just before their respective derailleurs. The brain is cleanly zip tied to a brake cable allowing easy access, while the battery sits on a custom mount under the downtube. It all fits together perfectly and cleans up the bike's appearance.

Components

Apart from the main attraction of the Di2, the Xenith Pro features an assortment of basic, but functional components with a few obvious cost-cutting items thrown in. Hey, what did you expect?

The wheels in particular, a set of Shimano's RS10s, are a notch below the rest of the bike. As training wheels, the RS10s perform well as they are stiff, strong and easily user serviceable. Their portly weight on the other hand really detracts from the Xenith's liveliness. Dropping around 500g of rotating weight with some lighter carbon/alloy clinchers led to a significant increase in the bike's responsiveness and playfulness. As always, wheels have a significant effect on the overall bike's character and in this case I'd recommend an upgrade.

Whilst Vittoria may have made their reputation as making some of the best tyres for the pro peloton, I was left extremely underwhelmed with the Rubino Pro Slicks on the Xenith. Whilst they did ok in the dry, in the wet, they were a liability and I managed to consistently loose the back end on turn in. Puncture protection was poor too and the casing seemed particularly prone to slicing. Despite only 2 months use, the tyres are now virtual write-offs such is the number of cuts.

Instead of going with the full Ultegra groupset to complement the shifting, the Xenith comes kitted with some non-series brakes. Apart from not fitting in with the rest of the group visually, I honestly couldn't tell them apart from the respective Ultegra units as they delivered the consistent, well modulated power that I've come to expect from Shimano's latest series brakes. No complaints there then.

Finishing kit from Ritchey is as good as always. I like the way Jamis have gone with the carbon seatpost which, aside from helping in the comfort stakes (maybe), looks just great with the carbon weave shining through the clearcoat. The seatpost clamp is simple but effective and I had no trouble setting up my favoured saddle.

Despite the current trend towards compact shaped bars, Jamis have opted to go with a Ritchey ergo-bend bar. Now, I don't really get on with ergo bars in general, but I found these to be quite comfortable. Reach and drop is larger than a compact, but still not so large as to challenge the less flexible. Bar width is proportional to frame size so smaller and larger riders should find themselves well accommodated.

The Selle San Marco Concor saddle is a nice addition to the overall package and makes a change from the usual Selle Italia which dominates the OEM market. Saddle choice is a highly personal thing and I suspect most buyers will want to swap in their favourite perch, but I found it to be surprisingly comfortable given its narrow width. There's plenty of padding on the nose for on-the-rivet riding and the slightly upturned tail helps to lock you in place whilst climbing.

Overall, wheels excepted, the Xenith Pro's spec stands up reasonably well to the immediate competition and certainly doesn't detract from the frame in any way.

Verdict

The Xenith Pro Di2 is one of the more accessible electronic shifting bikes currently available. A good, if slightly uninspiring frame and decent finishing kit complement the shifty bits well with only the wheels really letting it down.