We review the Jamis Xenith T1 Ironman triathlon bike

Jamis Xenith T1

Jamis Xenith T1

Jamis loads its smooth-riding Xenith aero frame with a Cobb saddle and carbon-rich kit to create an interesting and lightweight Ironman option. It’s definitely a steady cruiser rather than a combative speed demon racer, though – think more Rolls-Royce than Ferrari when looking at this particular option.


Things get interesting straight away on the Jamis thanks to the distinctive Windshield aero forks. The significantly raked and deep-bladed legs fatten and deepen as they near the crown to completely shroud the rear-mounted TRP U-brake from the airflow. The side-entry brake cable isn’t quite as aero but gives a very positive braking feel.

The short head tube allows you to adopt a very low forward position once you’ve swapped out the spacers, and the internal gear cable routing enters through the skinny top tube behind the stem. The ovalised top tube ends in a two-bolt seat clamp for the teardrop seatpost.

The seat tube flares out into a wheel-hugging curve, and both the seat and down tubes swell to the full width of the press-fit BB30 bottom bracket. The rear U-brake is mounted under the skinny S-curve chainstays, and the similarly curved seatstays are also super-slim. The alloy horizontal slotted dropouts use small stop screws to prevent the wheel slipping forward and rubbing on the frame. The smallest 47cm size uses 650c wheels to keep the looks and handling proportionate for petite pilots.


Jamis has also gone to the trouble of altering the crank length, bar width and stem length depending on frame size, which is a great boost to comfort and fit accuracy. The 700c American Classic wheels have a deep, convex 34mm rim, bladed spokes and super-skinny hubs for lightweight aerodynamics. The white painted marker spokes make it easy to find the valve for fast mid-race flat fixing, too.

The fat-armed, oversized axle chainset gets offset pedal drilling and a solid aero outer chainring, but it’s heavy. Happily the full carbon Profile cockpit isn’t and, together with the light wheels, this helps make the Xenith the lightest bike on test despite the deep-fill Cobb saddle. The split-centre perch divided opinion among our test team – some loved the squishy, rear-biased support and notched nose but others just couldn’t get comfortable on it however they set it up.


Most shops aren’t going to let a saddle swap get in the way of a sale, so it’s the overall ride of the Xenith that really matters. Initial impressions are very good. The Profile armrests are comfortably shaped and widely adjustable via the multiple mounting options and spacer kits. Most testers really liked the ‘kink down, kick up’ shape of the extensions, and the relatively short top tube naturally puts you into a classic right-angled elbow tuck position.

Jamis also supplies the Xenith with a massive stack of steerer spacers, so you can go pretty low without having to chop the steerer; the flexibility this offered our testers was a feature we really liked. As you might expect, the fat-legged fork gives a firm feel through the fat-bodied base bars. The mid-modulus carbon fibre frame, soft saddle, and skinny stays and top tube mean not much road grumble reaches your gusset though.

While the wheelbase is shorter than most, the Xenith holds a predictably straight line even on relatively gusty days, and the powerful brakes mean scrubbing off speed isn’t an issue. This all makes for a natural, comfy and easygoing steed that lets you settle into a steady spin if you want to hit your run as fresh as possible.

Unfortunately the Jamis doesn’t deliver as well in one important area: speed. While the big cranks and bottom bracket, teamed with light wheels and low overall weight, should mean that the Xenith leaps forwards as soon as you press the pedals, actual acceleration is disappointing. Our test team got the sense that a lot of their power was getting lost in the carbon lay-up (and the wheels, to a lesser extent).

Trying to pick up pace to match the other bikes on test created a flood of lactic but no matching surge of speed, and pursuits always became long and painful. The soft frame sensation was even more noticeable on out-of-the-saddle climbs, where the short head tube and skinny top tube allow the front end to flop around in relation to the rear, even if you’re only working with tired post-swim arms.

As a result we rarely left the saddle or ventured into the smaller cogs unless we absolutely had to. This meant we were mainly relying on high-rev seated efficiency to spin us up to speed without loading the frame too much. As you might expect, the flexy frame and wheels undermined decisive or dynamic moves, making roundabouts and twisting descents a nervous exercise in careful coercion, not aggressive carving.


  • Frame and forks

Size tested: 54cm
Sizes available: 47, 51, 54, 56, 58cm
Weight as tested: 8.43kg
Frame weight: 1,634g
Fork weight: 510g
Frame: Dyad Plus T700, mid-modulus carbon fibre
Fork: Jamis Windshield, aero, full carbon

  • Transmission

Chainset: Vision Trimax 175mm 52/38T
Bottom bracket: FSA Press-Fit 30
Cassette: SRAM OG-1070, 10-spd, 11-25T
Chain: SRAM PC-1051, 10-spd
Derailleurs: SRAM Rival braze-on front / SRAM Force rear
Shifters: SRAM 500 TT bar-end

  • Wheels

Front: American Classic 420 Aero 3
Rear: American Classic 420 Aero 3
Tyres: Vittoria Rubino Pro Slick, 700x23c
Wheel weight: 1,020g front / 1,450g back

  • Other components

Stem: Profile Design Aris, 90mm
Bars: Profile Design T3+, drop-bend extensions
Headset: Ritchey Logic Pro Drop-In
Saddle: Cobb Cycling V-Flow Plus
Seatpost: Jamis Aero, carbon
Brakes: Tektro R725

+ Smoothly comfortable, with size-specific geometry
+ Plenty of carbon parts keep weight to a minimum

– Soft frame means loss of acceleration and climbing potential
– Flexy wheels don’t help hustling or handling