Hot on the heels of last year’s aero bike, the Transonic, Fuji have launched the Fuji SL, a super-light climber’s bike.

With a raw frame weight of 695g, the SL is 19 per cent lighter than any frame Fuji have made before and a frame capable of competing weight-wise with almost anything on the market. Claimed weight of the top-level 1.1 bike with a SRAM Red groupset and Reynolds RZR 46 tubular wheels is 4.96kg. It’ll cost you £8,499.99, though.

The SL is scheduled to make its official debut with the Caja Rural-Seguros RGA team at this weekend’s start of the Vuelta a Espana, and if you can’t wait that long Fuji have put together this teaser:

Fuji say that the fundamental basis of the SL’s strength-to-weight ratio is their use of ‘High Compaction Moulding’. The technique uses internal moulds to smooth out wrinkles and excess resin build-up in the carbon at more complex areas (like the head tube or bottom bracket). Fuji used this technique on their Altamira bike in 2013, but have used it in more locations on the SL’s frame like the seattube and fork crown.

Similarly, Fuji have reduced the number of bonded joints in the SL frame to four (down from eight on the Altamira) making the frame stronger and lighter. Reducing bonding joints improves strength because joints are inherently weaker than solid carbon tubes, and it lowers weight because they don’t have to be reinforced to guarantee that strength. All in all, the SL is 237g lighter than the Altamira.

As you can imagine, Fuji have put numbers on the improvement in the SL’s frame over the Altamira, claiming it to be nine per cent stiffer in the headtube, 11 per cent stiffer in the bottom bracket and 18 per cent stiffer in the fork. And speaking of that fork, it uses an interesting technique called ‘Reinforced I-Beam’ (RIB) technology to add extra strength. What that means is that a reinforcing spine (or rib…) of carbon runs down the inside of the fork blades, adding extra strength and stiffness over a hollow fork blade.

The SL frame also varies according to size. Fuji understand that different size frames (and different size riders) need particular requirements. So, for example, and SL in 61cm would have larger tube diameters than the same frame in size 46cm. There are also two different fork offsets for different sizes in the range that helps to keep handling and ride quality consistent throughout.

Speaking of sizing, the SL will be available in seven sizes (46, 49, 52, 54, 56, 58, 61cm) and the geometry is race oriented, as you’d expect. A 56cm model has, as you’d imagine, a 56cm toptube, 155mm headtube, 73 degree headtube and seattube angles, and a stack and reach of 559mm and 382mm. A chainstay length of 405mm and wheelbase of 983mm should keep the handling sharp and punchy.

The Fuji SL is due to land in the UK around October, and will be available through Evans Cycles. There will be five models available with pricing as follows, though it’s worth noting while the 1.1 and 1.5 use the top-level, 695g frame, the 2.1, 2.3, 2.5 use a more affordable (and so heavier, though exact weight is tbc) frame made from a slightly lower grade of carbon fibre.

SL 1.1 (SRAM Red 22)                      £8,499.99
SL 1.5 (Shimano Dura-Ace)            £3,399.99
SL 2.1 (Shimano Ultegra Di2)        £2,599.99
SL 2.3 (Shimano Ultegra)                £1,599.99
SL 2.5 (Shimano 105)                       £1,499.99

Website: Fuji Bikes