Like the Holy Grail and the lost city of Atlantis, the quest to produce the lightest bike in the world is as elusive and alluring as ever. Yes, bicycle physics has proved that aerodynamics and stiffness are more fruitful engineering targets, but there’s a certain je ne sais quoi about being able to pick up a bike with your little finger that makes even the most hardened pragmatist weak at the knees.
At a Cyclist-verified 5.11kg for a size 56cm, the Fuji SL 1.1 is such a machine. It’s not quite the world’s lightest production bike, though – that’s either the Merida Scultura 9000 LTD at 4.56kg or the AX-Lightness Vial Evo Ultra at 4.44kg (although the latter has yet to materialise in significant numbers) – however that is of no odds to Fuji. Lightness for lightness’s sake was never the SL 1.1’s primary goal.
Investing in bonds
‘The SL frameset is 237g lighter than the Altamira SL [Fuji’s previous lightweight racer], yet we also managed to increase stiffness by 11% at the bottom bracket and 9% at the head tube,’ says Fuji’s global product manager, Steven Fairchild. That means a claimed 740g frame with a 293g fork, representing savings over the Altamira SL of 110g and 127g respectively. That bike was already exceptionally light, so where has Fuji found these additional savings?
‘The rear stays and dropouts are formed in one section, and are hollow from the chainstay up through the seatstay. This also eliminates a lot of the bonded joints, removing excess material,’ explains Fairchild. ‘We are one of only three brands that can make frames in this way. We also use a very high strength carbon for the flat sections of the top, seat and down tube and fork blades, which is lighter and stiffer but which must lay flat. Put it through even a 2° or 3° bend and it begins to fracture.’
The bonding is not immediately obvious from the outside, but the SL is made in two halves (other bikes tend to be made in multiple pieces): a main triangle and rear triangle that join partially up the seatstays and along the chainstays. The flat sections Fairchild is referring to are the edges of the main triangle tubes and fork, which have the profile of a squared-off circle.
Over 100g saved on a frame is decent, but saving 127g on a fork – nearly a third of the weight of the Altamira’s fork – yet increasing its stiffness is very good going indeed. To do this, Fuji has moulded a ‘Reinforced I-Beam’, an internal rib that runs down the middle of each fork blade to bolster stiffness. Clever stuff, but Fairchild says it’s only possible because of the specific factory Fuji works with in the Far East: ‘That rib helps increase stiffness by 18% but adds just 12g. We couldn’t do that without our factory’s manufacturing expertise. We’ve utilised a lot of their suggestions, and in so doing we’ve created their – and our – lightest frame to date.’
Component conundrum
A lightweight frameset is one thing, but it needs to be adorned with the right parts to be a lightweight bike, so it’s no surprise to see Sram Red, the go-to groupset for the lightweight category, on the SL.
Unlike brands such as Merida or AX-Lightness, Fuji has stuck with the groupset’s stock chainset, but it has deviated in the brake department, plumping for Eecycleworks’ EeBrakes, which weigh just under 200g a set, including pads.
Elsewhere, Fuji has specced Reynolds’ top racing hoops, the tubular RZR 46s, which weigh a claimed 968g for the pair, and a seatpost/saddle combo from Ritchey that weighs 251g. Finishing off the package are carbon bars and alloy stem from in-house brand Oval.
As bike spec lists go it’s a tasty one, but one can’t help thinking that the SL could have been even lighter with some even more exotic components. Take the Ritchey Superlogic Vector Evo Streem saddle. It has a cover and foam, two potentially superfluous elements that you won’t see on the Ax-Lightness Vial. Or the cables for the groupset, which are stock as opposed to the ultra-light Jagwires found on the Merida Scultura. Or even the bars and stem; solid performers but there are undoubtedly lighter options out there. So has Fuji missed an opportunity to be crowned the true King of the Weight Weenies? The answer is a resounding no.
‘Sure, we could have gone lighter, but that would have meant speccing more fragile or uncomfortable components,’ says Fairchild. ‘We wanted a bike that was mainstream and could be ridden for hours at a time, that was serviceable and, most importantly, accessible.’
At £8,499 for the SL 1.1, accessible is a relative term, but with lower spec bikes starting at £1,599, there might just be an SL for everyone. Look out for a full test soon.
evanscycles.com