Rebecca Richardson’s custom 4.7kg Specialized Aethos

This is the custom Specialized Aethos Rebecca Richardson (Team Brother UK) rode to third place in this year’s UK National Hill Climb championships.

Hill climb specialists are renowned for making the machines they ride as light as possible and there were plenty of feathery creations on display at this year’s event.

However, Richardson’s Specialized Aethos was among the most impressive on the day. It featured a smattering of saucy tech to take her bike down to just 4.7kg, making it one of the lightest Specialized Aethos builds out there.

The beautiful but brutal Winnats Pass in the Peak District hosted the championships for the 11th time this year. The climb is only 1.5km long yet rises at an average gradient of 12.1 per cent, with ramps of more than 17 per cent, over rough tarmac.

The terrain combined with the savage weather conditions at this year’s event made it a particularly stern test for every competitor and meant equipment choice was crucial in each rider’s bid for glory.

Something special

Being super lightweight as it is (Specialized claims that a size 56cm frame weighs 585g), the Aethos frameset Richardson used required little modification, however the collection of components that adorned it was a little more idiosyncratic.

Starting at the front of the bike, Richardson used Shimano Dura-Ace Di2 levers (with grip tape used in place of the rubber hood covers) mounted to a Darimo Ellipse bar.

Darimo is a boutique Spanish components manufacturer specialising in ultra-lightweight finishing kit.

Richardson also used the brand’s IX2 stem, saddle and T1 Loop seatpost, which is notable for the loop of Dyneema cable it uses to fix the saddle onto the post instead of a regular clamping system.

For that four-piece set of finishing kit, we’d estimate a total weight of around 370g, which is mind-bogglingly svelte.

Richardson’s Aethos rolls on Vittoria’s papery-thin and supple Corsa Speed tubular tyres and tubular wheels from German components brand AX-Lightness.

AX-Lightness says its Ultra Disc 25T wheels – in their stock guise – weigh just 845g, yet Richardson has looked to shed further weight by building them up with Berd’s polymer String spokes.

Berd says its spokes have twelve times the strength-to-weight ratio of steel spokes, meaning Richardson should have been able to achieve superlight wheels that didn’t give away as much as they could have in terms of speed-sapping lateral flex.

So as not to undermine that feathery rolling stock by bolting on chunky plates of metal, Richardson turned to Ashima for its Airotor rotors, which come in at a claimed 85g each, approximately 20g lighter per rotor than the equivalent Dura-Ace option.

Driving force

Richardson’s drivetrain is very loosely based around Shimano’s Dura-Ace R9170 groupset, but it has had so many mods that it is almost unrecognisable.

The chain is probably the only thing to remain untouched. The 2× crankset has been ditched completely in favour of a 1× 32t chainring mounted to a SRAM XX1 Eagle crankset.

The cassette has been whittled down to just five sprockets, to save a chunk of weight and preserve an efficient chainline, and in another nod to efficiency, CeramicSpeed’s OSPW system has also been fitted.

Speedplay’s titanium-spindled Nano pedals top off an impressive build that helped Richardson take third place on the day.