Super lightweight bike tech: is this 3.6kg bike the lightest in the world?

On a recent trip to Arizona, in the United States, Ollie Bridgewood got his hands on this bike from Fair Wheel Bikes. What's so special about it? Well the complete bike tips the scales at a feathery 3.6 kilos which makes it a whole 3.2 kilos under the UCI’s minimum competition weight limit.

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We have covered some super lightweight tech on GCN before but we have never come across a bike as light as this. So let's take a look at just how the guys at Fair Wheel Bikes have managed to build the bike up in such a lightweight package.

What frame has been used?

The heart of the bike is an alpha frame from the German lightweight brand AX Lightness which is a very light chassis. What does come as a surprise is the fact the frame is 58cm in size. This buck's the weight weenie trend of using the smallest frame possible to shed a few extra grams. Although the frame is undeniably very light at 705 grams, it isn’t actually the lightest frame on the market.

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The AX Lightness frame used for this build is a feathery 705 grams however this isn't even the lightest frame available

The fork that has been paired to the frame is from another German brand THM that is equally well known for its art-like carbon fibre components. At 250 grams the THM Scapula is a standard profile with a slight rake to it. This brings the total frame and fork package to 955 grams.

Hybrid groupset to save every gram possible

The shifters and groupset used on this bike are somewhat of an amalgamation of lightweight parts from multiple brands. The shifters themselves come from SRAM’s 10-speed mechanical version of the Red groupset as this remains the lightest groupset to have been made. That is not all though, to take things further the original rubber hoods have been removed and replaced with heat shrink plastic.

The levers themselves weren’t safe from the gram hunting with the original carbon lever blades replaced with a lighter version that has then been made even lighter with the use of a router to remove all the unnecessary material. In somewhat of a retro throwback, the front derailleur shifter has been removed from the brake lever and instead has been placed on the down tube.

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The levers have received a lot of heavy modification including using heat shrink for the hoods and removing all unnecessary lever material

The brakes are also from AX Lightness and as you would expect are a simple carbon fibre rim brake affair. To take the lightweight theme even further the brakes are fitted with super light cork pads and the retaining grub screws have been omitted from the build.

Even the cables have received the lightweight treatment with a narrower gauge cable inside the Alligator I-link mini outer housing. This size reduction is just part of the bid to save every non-essential gram.

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The cassette is a one-piece 10-speed 11-25 cassette from Recon, which we've seen on GCN before when we visited the Taipei Bike Show. They are more commonly known for the anodised cassettes that they offer however this cassette weighs just 90 grams, less than half of a Dura-ace or Red offering.

Although the rear derailleur may have started out its life as a SRAM Red 10-speed model it has now been heavily ‘tuned’ by Fair Wheel Bikes to remove every bit of non-essential material from it. All the bolts have been replaced with either titanium or nylon fasteners and the pulley wheels and cage are all made from carbon fibre.

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The drive train is a concoction of lightweight and modified parts

Interestingly the front derailleur is not from SRAM, it is instead from Campagnolo. The Record derailleur has not escaped the dieting programme. The reason this was selected was because it allowed for the greatest ‘tuning’ potential to remove more weight than other derailleurs.

Rounding off the drivetrain is the iconic THM Clavicular crankset that is ubiquitous with ultra-lightweight bike builds. The complete crankset comes in at a slight 280 grams which is nearly half a kilo lighter than other top-of-the-line cranksets. With a set of Fibre-Lyte carbon chainrings completing the chainset they themselves only add 50 grams to the build.

Schmolke/Mcfk one-piece cockpit

The bar and stem come from yet more German lightweight carbon specialists in Schmolke and Mcfk. Although on the bike it appears to be a one-piece bar and stem, it is in fact two individual components that Fair Wheel Bikes themselves have modified. By bonding the two components together that removes the need for a clamp and the bolts.

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The bars and stem started out as seperate components from different manufacturers but to save weight they have been bonded together

The bars are then shrouded in a cotton bar tape that totals just 14 grams. This is a cheap and effective way to save weight over more traditional bar tapes that can easily exceed 100 grams. The total weight of the cockpit including the bar tape is just 242 grams.

Super lightweight wheels

The bike rolls on a set of tubular wheels from AX Lightness that weighs a remarkable 688 grams for the pair. For context, a premium carbon front wheel on its own typically exceeds this and an entry-level wheelset can weigh upwards of two kilos.

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The wheels feature hubs from Tune including a prototype Mag 90 rear hub

Glued to the rims of the wheelset is a set of Tufo tubular tyres that measure in at a very slender 19mm. Each tyre weighs just 120 grams, half that of a standard road tyre however, there is no avoiding the fact that 19mm tyres are not going to be the most comfortable out on the road.

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Finishing off the rear wheel is a prototype Tune Mag 90 hub that never made it into production. Instead of using the typical springs and pawls or a ratcheting ring that almost all freehubs use, the Mag 90 uses a series of magnets to engage and disengage the drive to the freehub.

Forget a one-piece bar and stem, this has a one-piece seat post and saddle

Finishing off this build is a seat post and saddle unit made by Berk Composites. Instead of the traditional clamp that is fixed to the rails of the saddle, Berk has forgone the need for this by simply bonding the saddle in place on top of the seat post. Although this does save some grams it does however remove any ability to get the bike to fit you any better.

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Berk Composites have provided a one piece saddle and seat post that once again saves a handful of grams

Finishing off the bike

To complete the bike build a set of AeroLite pedals have been fitted that come in at just 58 grams for the pair. Although these pedals are remarkably light they are also considerably more fiddly to get used to and require a change in technique to get in and out of them. Instead of the familiar twisting motion we have all become used to, these pedals require you to slide your shoe across the pedals to slot over them. Once again an example of weight saving over practicality.

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There is no denying the lightweight credentials of the AeroLite pedals however they do seem to miss the mark in regards to functionality

The bike also uses ceramic bearings in both the bottom bracket and the headset. This isn't for the increased performance in regards to rolling resistance but simply because ceramic bearings are lighter than steel.

How does a bike like this feel to ride?

The guys at Fair Wheel Bikes say that a bike this light actually isn’t all that pleasant to ride. Sure it feels amazing on steep climbs, however on more typical terrain it is simply too light to feel planted and controlled. Interestingly they seem to think that the sweet spot between climbing performance and composure is around the 4.6 kilo mark, some 2.2 kilos under the UCI’s minimum weight limit.

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The craziest thing about this bike from Fair Wheel Bikes is that they have confirmed this is not even the lightest bike that they have made. That accolade goes to a custom-built bike that weighed a seemingly impossible 2.9 kilos for the entire bike.

What do you think of this super lightweight bike, do you think it is hot or not? Make sure to let your thoughts be heard in the comments below.