UK hill climb season is approaching its frantic crescendo this weekend in the small town of Matlock, Derbyshire. Over 400 competitors will tackle the truly formidable Bank Road, an 834 metre blast at an average gradient of 11%, but that includes a flatter final section that goes some way to disguising the maximum slopes of 22% that exist at the tail end of the main drag. It’s a brute.

UK hill climbs are not governed by the UCI, but rather by CTT (Cycling Time Trials) and as such the rules governing everything from sock height to tube depths go totally out of the window, as does the usually ever-present 6.8kg weight limit. As long as you’ve got a helmet and lights you’re basically good to go and can ride whatever you like, which means we get to see some truly mad weight weenie builds that, if I’m being honest, scare me a little.

Perhaps none are more sketchy than the new race rig of defending champion Harry MacFarlane. Last year he stormed to victory aboard a 16 year old bike – a 2008 Cervélo RS covered in paint pens – overturning the incumbent Andrew Feather in the process.

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This year he’s aboard something newer, and dare I say much more sketchy. A rim brake Trek Emonda, stripped of paint and decked out in some mad frankenparts, but perhaps the most terrifying thing is the logos on the downtube, which have been physically cut out from the downtube and inlaid with a single layer of carbon weave to create an ultralight ‘MAC’. I shouldn’t have to say this, but don’t try this at home. Why did he do this, I had to ask, given as it will only save a handful of grams at most?

“Why not”, was the simple answer.

I’ll be bringing you a full tech gallery from the event shortly, but this build is worth poring over in detail as a wonderful amuse-bouche.

Harry Mac's hill climb bike

Unless you know your silhouettes, you’d be hard pressed to know what this was at a glance, but it is a Trek Emonda that I believe suffered a crack from where the bars span and hit the top tube. A perfect candidate to have all the paint removed and some mega mods undertaken. (Image credit: Will Jones)

Harry Mac's hill climb bike

This ‘MAC’ logo was physically cut out from the downtube, before a single layer of carbon weave was inlaid behind it and lined in pen, perhaps in homage to last year’s winning machine. If you think you’ve ever voided a warranty… (Image credit: Will Jones)

Harry Mac's hill climb bike

The stem is a total unknown, but that has been sanded back and physically bonded to a set of Prime handlebars. I’m told together the setup somehow weighs less than a Darimo cockpit. (Image credit: Will Jones)

Harry Mac's hill climb bike

It’s incredibly neat considering it’s a DIY job. (Image credit: Will Jones)

Harry Mac's hill climb bike

The tape on the top tube is there to stop the unwrapped bars cracking the frame again. I have to say I really do miss raw carbon; it needs to make a comeback. (Image credit: Will Jones)

Harry Mac's hill climb bike

‘Slayer 700 OCLV Carbon’ lurks beneath the surface. (Image credit: Will Jones)

Harry Mac's hill climb bike

As the bike uses SRAM Red eTap there’s no need for internal cable routing, so the ports have been blanked out. (Image credit: Will Jones)

Harry Mac's hill climb bike

A square of grip tape on each shifter paddle makes finding them a little easier when you’re turning yourself inside out. (Image credit: Will Jones)

Harry Mac's hill climb bike

These brakes may look like the fabled Cane Creek ee models, but they are in fact AliExpress knockoffs. (Image credit: Will Jones)

Harry Mac's hill climb bike

Still, they’re extremely pretty nonetheless. (Image credit: Will Jones)

Harry Mac's hill climb bike

A 38t single, hexagonal (yes, hexagonal) ‘Spreng Reng’ chainring provides the drive up front. This is paired to an 11sp cassette at the back with a 30t largest sprocket. (Image credit: Will Jones)

Harry Mac's hill climb bike

A single sided Favero Asioma power meter takes care of pacing, if such a thing can exist in events like these. (Image credit: Will Jones)

Harry Mac's hill climb bike

The saddle is formed from the constituent parts of two broken Berk saddles bonded together and mounted to a USE aluminium seatpost that turned out to be lighter than MacFarlane’s carbon options. Can you spot the light? (Image credit: Will Jones)

Harry Mac's hill climb bike

Yep, that black blob on the back is the rear light. At 0.8g it’s designed to be a headlight in a remote control car, but now it’s there to get by the commissaires. (Image credit: Will Jones)

Harry Mac's hill climb bike

I’m not sure it’s the most effective way to be seen, but as the course takes place on closed roads I’m not going to worry about any of the riders’ illumination strategies. (Image credit: Will Jones)

Harry Mac's hill climb bike

There’s a similarly tiny white light at the front. I was told there were lighter options available, designed to go inside balloons and remain airborne, but that felt like it might stray the wrong side of the rules I think. (Image credit: Will Jones)

Harry Mac's hill climb bike

On the day Macfarlane will swap out the wheels here for a mad set of 770 Brisk tubulars with Vittoria Corsa Speed tubs fitted to get the weight down to a mind-bending 4.8kg. (Image credit: Will Jones)