Fuji’s SL 1.5: fewer frame sections make a featherweight ride

Hands on with the 6.4kg Dura-Ace equipped carbon racer

Debuted during the 2015 Vuelta a Espana under Caja Rural-Suguros RGA, Fuji’s SL took over from the Altamira as the brand’s top non-aero race bike, with the flagship SL 1.1 frame claimed at a feathery 695g. However, despite that weight loss, Fuji claims the SL is significantly stiffer than the Altamira.


Although there are one or two other production bikes that can claim to be lighter, the SRAM Red-equipped SL 1.1 complete bike weighs in at a face-meltingly light 4.96kg/10.91lbs. Such a figure does however come with a $9,999 / £8,499 price tag.

Related reading: the new Fuji SL – almost 2kg too light for the pros

We’ve just received the SL 1.5, a slightly lower model in Fuji’s new range. At under half the price, it’s surprising to see it shares the 1.1’s frame (albeit with different paint). By comparison, the SL 1.5’s Shimano Dura-Ace mechanical build is heavier, but the complete weight is still an impressive 6.4kg/14.1lbs. Add some pedals, bottle cages and a computer, and you’ll likely still be under the UCI’s 6.8kg weight limit.

Though we’re not usually fans of gold on bikes, the sl 1.5 has just the right amount of bling:

The secret to the SL’s weight is in the tubing

Following on where the much-loved Altamira left off, the secret behind the SL’s performance on the scale is Fuji’s ‘High Compaction Molding’. This combines internal and external moulds to evenly distribute resin and create a frame that’s just as clean on the inside as it on the outside. Not only does this shed unnecessary weight; it also lessens the possibility of weak points (AKA stress risers) in the frame.

Fewer joints, less weight

Though many are claimed to be, most frames are not a true carbon monocoque. Usually, they’re instead made in a few pieces and then bonded together. While this process is easier than producing a one-piece carbon frame, the bonded joints add weight. Improved manufacturing techniques have allowed Fuji engineers to keep bonded joints to a minimum – just the two at the chainstays, and two at the seatstays – thus saving weight.

Lots of tube shapes happening here:

There is no mistaking the SL 1.5 is a racer

Fit-wise, our size 54 sample SL is quite racy, with a 73-degree head angle, 545mm top tube and 974mm wheelbase. Combined with its low weight, this should provide for a snappy ride in every respect.

At the front we see a carbon tapered steerer tube, 135mm head tube and Fuji’s unique  ‘Reinforced I-Beam’ carbon fork. Here, a carbon support runs up the length of the fork legs, which is said to vastly increase the rigidity of the structure.

Elsewhere we find a variety of tube shapes, a beefy PF30 bottom bracket shell with a creak-free Praxis conversion bottom bracket, squared-off chainstays and dainty ovalised seatstays.

The finishing kit comes from Fuji’s sister componentry brand Oval, with a carbon 27.2mm seatpost, carbon bars, padded seat with a cutout and a unique-looking alloy stem.

As a part of ovals optimal stiffness construction, the top stem bolts are to be tightened to the recommended torque before the lower bolts:

The Oval stem feautres a new Mesh Fit bolt pattern – we’re beginning to see a bit of this new technology among component brands

The Oval 707 3D forged alloy stem employs what Oval calls Optimal Stiffness Construction, reputed to better distribute stress from the bars to the stem without adding weight or reducing strength. While Oval’s claims that its Winglet Faceplate and ‘Variant Thickness’ CNC machining distribute stress better throughout the structure may be nothing more than marketing jargon (this is the bike industry after all), the Mesh Fit bolt pattern has merit. Oval says to tighten the top two stem bolts to 5nm first (closing the gap), and then torque the lower bolts. This new clamping method is something we’ve also seen recently from PRO components and Canyon.

According to Oval’s documentation: “By creating a six-degree tightening angle on the stem; an increase in friction force was attained compared to that of conventional clamping locks. The Mesh Fit design requires minimum tightening torque to create maximum engagement force. This ensures not only even distribution of stress, but also prevents overly tight situations that would cause potential damage to the handle bar.”

Vittoria 25c rubino pro tyres aren’t the lightest or most supple rubber, but they’re still a reliable work horse:

The Oval 773 wheels and Rubino Pro rubber appear to be a winning combination

Also of note are the Oval 733 aero aluminium clinchers. For an OEM-spec wheel, they are respectably light at 1445g and feature a 22.5mm rim width that spreads the 25c Vittoria Rubino Pro rubber nicely. They’re also tubeless ready (you’ll need rim strips, valves and sealant), and are 33mm deep with a slight aero profile. The wheels turn on sealed bearing hubs with a six-pawl alloy freehub featuring “anti-bite guard to fend off cassettes from digging in”. You also get Oval-branded internal cam skewers, which have plenty of clamping force.

Fuji has wisely combined a 52-36t crankset with a 11-25t cassette for a gear range ready to tackle just about anything, though we wouldn’t mind a 28t cog at the back while we burn off all the Christmas ham and eggnog.

The SL also features internal cable routing, and should you decide you want Di2 later down the line, the frame is ready for electronic drivetrains as well. There’s also a factory-installed chain catcher for added security and protection to the lightweight frame.

fuji kept bonded joints to a minimum to save weight, with the sl only having four bonded joints:

Is the Fuji SL ‘worth the weight?’ Only time will tell

We’ll be testing the SL 1.5 over the coming months, but in the meantime, check out the photo gallery above for more detail.


The Fuji SL 1.5 retails for £3,399 / $4,740 / AU$6,999.