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Gallery: AC Invitational bike show, part two

Above Category's exclusive show featured two Olympic bikes, plus master-level craftsmanship from Baum, Sarto, Enve and English.

Rob English
by Rob English 04.09.2024 Photography by
Rob English
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Last week, after Portland’s MADE show (where I unfortunately caught COVID-19), I had the opportunity to attend a new, limited bike show, the AC Invitational, staged by boutique shop Above Category of Sausalito, California: 11 brands, just two bikes each. You can find our first gallery from the show – with bikes from Mosaic, No. 22, Bastion, Prova and Scarab – here.

After the AC show I felt a bit better and was able to take a fun urban ride with two friends, dodging tourists on the Golden Gate Bridge before exploring the back streets and parks of San Francisco. I had never been up to Twin Peaks before; the views were spectacular! We randomly made a passing enthusiast’s day when he was surprised to discover three English bikes outside a sandwich shop … And then even more randomly, ran into fellow builder Adam Sklar out running errands on one of his bikes. I love these sort of chance encounters! 

For part two of the AC Invitational coverage we have the treat of two genuine Olympic gold-medal winning designs, custom carbon from the US and Italy, plus custom road bikes in titanium and steel.

Factor

I was stoked to see the incredibly rare Factor Hanzo Track bike on display – having only previously seen it in a feature on Escape before watching the Australian team pursuit squad ride these bikes to victory in Paris. In person it is narrower than seems plausible! It also most likely wins the award for shortest thru-axle (I think the front one is only 40 mm).

The three-man design team at Factor has veterans of the Cervelo and Argon 18 Olympic pursuit bike projects, and it took all that experience, especially with working within the UCI constraints, to create the fastest bike they possibly could. The integration of the aerobar riser into the fork means it is definitely a measure-twice-cut-once scenario. But anyone riding this level of track bike surely knows their position very precisely. It is almost surprising to see a regular threaded bottom bracket and crankset on this bike where almost everything else is completely custom. But this perhaps makes sense for availability of parts for picking crank length and chainring sizes to suit different riders and tracks.

Factor's Hanzo track bike, in a white frame with low-key gold branding and shimmering Black Inc carbon disc wheels.
The aero bar riser juts directly out of the steerer tube area on the fork, ahead of a cover that accesses the headset.
As seen from the back, the Hanzo nearly disappears, seen as just a thin blade of carbon fiber with only a base bar and aero extensions and the wide-set fork legs not in line with the frame.

Sarto

Sarto made the trip over from Italy with examples of their custom carbon craftmanship. Here we have their gravel bike, which boasts an impressive 44 mm tire AND a 2x crank with a SRAM front derailleur. I assume there’s some careful positioning of the front derailleur mount; fitting tires this size around the SRAM battery on the derailleur is a challenge!

The tinted carbon weave on the main tubes flows into the marble-like carbon at the joints which shimmers under the clearcoat. Fittingly, Sarto calls the effect seen on the joints Black Marble, and the very short version of how it’s done is by crinkling the outermost layer of carbon in the mold. Sarto produces its carbon tubes in-house, before using a tube-to-tube construction which allows for full custom geometry. The joints are overwrapped for strength. The matching fork has a flare on the rear of the crown to flow smoothly into the down tube; this smoothness contrasts with an angular design near the dropout, which accommodates the disc rotor and caliper.

A black Sarto gravel bike with a gleaming black frame and blackout logos.
A slim, spartan SRAM Red disc caliper sits flush to the back of a direct-mount platform on the carbon fork leg.
Looking down the seat tube at the bottom bracket, which has ample clearance on 44 mm-wide tires even with a 2x crankset. The carbon weave is again visible.

Baum Cycles

Darren Baum’s personal Celaris road bike has a bit of a weight-weenie feel to the build (nothing wrong with that!), featuring lightweight components from Darimo, Carbon-Ti, CeramicSpeed and Partington. The bike looks very slick with the hoses hidden internally despite a regular 1-1/8” upper headset bearing – Darren’s modification of the Enve In-Route fork makes this possible.

The welds may be mostly covered by paint, but show an impressive uniformity and neatness. This alone is not enough to demonstrate a good weld (that would be checking for full penetration through the joint), but this level of presentation from an established builder shows the quality and attention to detail is there. Darren and I discussed some of the static deflection tests I have been doing – he is keen to replicate that work in his shop, so we can compare notes and hopefully agree on an easy, basic test standard that others can perform to and enable building a larger dataset. 

A bright, matte-orange Baum Celaris with low-profile carbon fiber wheels.
More exceptionally clean welds at the BB area, with the matte orange paint giving way to a satin natural titanium finish on the chainstays.
A clean exit port for the electronic front deraiiler cable. The derailleur sits above black Carbon-Ti chainrings on a Shimano Dura-Ace crankset.
Shaped seatstays and an arced bridge between them. "D. Baum" is visible on the top tube, noting that it's Darren Baum's personal bike.

English

[Escape expressly asked Rob to include one of his builds from the show. -Ed.] Amongst all the large tubes and bright paint there was a tiny little bike with skinny tubes painted a stealthy flat black. This English was built in collaboration with AC for a 5’0” rider who weighs a mere 80 lbs. The design goals were to achieve the fit required with good handling and no toe-overlap. And to be as light as possible!

We choose to build around direct-mount EE brakes that allow for 32 mm tires. Creating room for the rear brake on such a small frame meant the seatstays needed to sit as high as possible, which led me to doing a mini-fastback style instead of my usual wishbone. A custom steel fork enabled the brake choice plus gave me flexibility with the offset to meet the design requirements, and the steel stem was built to match. The final weight came in at 14.8 lbs, and Rahi is very happy with her “Obsidian Dart.” There is an Above Category write up on this build here.

An all-black steel English road bike. It is very small, made for a tiny rider, and has a lightweight, almost gossamer look to it.
Delicate seatstays end in a fastback style at the seat cluster. An ee Brake caliper is attached direct-mount to the stays.
The head tube area, featuring a short, custom stem, a very short head tube with perfect fillet-braze joints to the top and down tubes.
A carbon handlebar is shown close up clamped in the custom stem, which features a lightened clamp section.

Enve

Enve brought an example of their Utah-built Custom Road bike, which is a bespoke-sized frame with an integrated seatmast and aerodynamic detailing. Enve went to the trouble of creating tooling for multiple offset options for the proprietary fork, which allows them to maintain handling characteristics across sizes. The finish shows just what their paint shop is capable of when given free reign and the galaxy as inspiration! This includes the one-piece bar/stem and even the headset top cover and preload cap.

An Enve road bike in a gorgeous blue to black fade with matching-painted stem and all black components. The paint starts blue at the stem with purple highlight sections faded to a star-spotted black at the rear dropout.
Subtle metal-flake paint at the rear dropout evokes stars against the black of deep space.
Enve's "Made in Ogden" logo on the down tube, with the Utah state border outlined in a glowing purple white and a star where Ogden is.

Pinarello

For the final bike we have our second Paris Olympic success story, with the Pinarello Dogma XC full-suspension design that carried Tom Pidcock to one of the most exciting finishes at the Games (Pauline Ferrand-Prévot rode the Dogma XC hardtail to gold). The hole above the BB is an interesting feature, but could provide a convenient handle for portaging for those of us without World Cup handling skills and power. Aerodynamics typically isn’t so much a consideration for XCO; nevertheless I like the teardrop shaping at the back of the integrated bar/stem.

The shock mount incorporates internal routing for the lockout, and there is an included proprietary chain keeper for extra chain security. And when there are TWO riders who were simultaneously World and Olympic champions riding this bike in races (even if PFP often opts for the hardtail version), the rainbow bands plus gold paint scheme seems quite correct! 

A Pinarello Dogma XC full-suspension bike, done in a striking paint job that starts in gold along the top tube and rear triangle, is masked to white, and ends in a rainbow block motif around the bottom bracket.
The one-piece bar-stem above tthe gold-painted top tube and head tube.
The block-style rainbow paint scheme at the bottom bracket.

What a run of handbuilt bike shows we have been privileged to this summer! I think we are finally at the end for now – time to reflect on all the incredible design, fabrication, craft and finishing that was displayed, and to take that inspiration out on rides and back to the workshop.

A huge thanks to the crew at Above Category for hosting the event!

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