Gallery: AC Invitational bike show, part one

by Rob English 03.09.2024 Photography by
Rob English More from Rob +

Above Category, a boutique bike shop in Sausalito, California, specializes in full-custom builds, working with a selection of builders around the globe to deliver complete bicycles to their clients. Realising that several of their vendors were already making a long trip to the West Coast to attend Portland’s MADE bike show, owners Chad Nordwall and Kalara Schuster decided to put on their own mini-show the following weekend, inviting those builders to stay on in the US a little longer. I planned a trip down around visiting some friends and was looking forward to it until I got sick after MADE, which unfortunately turned out to be COVID-19. Far from the plan, but I was able to adjust the trip a little, and although I wasn’t well enough for the group gravel ride on Friday afternoon, I was able to mask up and spend the day at the show and take some photos.

AC had the street outside their shop closed down, with 11 brands displaying two bikes each. There was free valet bike parking – the shop is on the main route for riders leaving San Francisco and heading out to Marin, so they could pause and check out some fancy bikes along the way. As with many of our tech galleries, this one’s best viewed on a large-format screen so you can get all the details. Here’s Part One, with Bastion, No. 22, Mosaic, Scarab, and Prova. Part Two will post Wednesday.

People walk on a closed street in Sausalito, California during the AC Invitational bike show. Umbrellas partly shade bicycles on stands as showgoers walk between the pavilions. — The outdoor venue in front of AC’s Sausalito shop proved a lovely way to see and show the bikes.

I was glad to get the chance for a closer look at some of the bikes I missed at MADE, and to see some brands that didn’t attend that show. I wish I had felt better to be able to speak with the builders more, but hopefully the photos mostly speak for themselves!

For part one we have three very different approaches to utilizing additive manufacturing, along with two more classical welded metal bikes featuring some incredibly intricate paint designs.

Bastion

Bastion launched the limited edition Arch Angel project at the beginning of 2023. Restricted to 88 bikes, this one says no. 81, so they are close to the end of making them! The use of 3D printing here is to create the lugs (and their themed adornment) of the frame and fork, and the stem of the integrated cockpit, plus the matching crankset. Bastion also produce the custom carbon tubing which is bonded in to complete the frameset. In the current age of ‘aero-everything’ it is kind of pleasing to see a bike at this level with little to no aerodynamic design, aside from hidden hoses.

A closeup of the gold wing motif on the head tube. Black, industrial-looking lugs frame carbon tubes with a geometric weave pattern.

The gold wing motif on the seat cluster, with wide-spaced seat stays wrapping around the seat tube.

The drive side of a 3D-printed Baston crankset, with a blocky black and silver arm fitted to an SRM 9 Power meter and Carbon-Ti chainrings.

The non-drive side shows the polished silver part of the crankarm.

A SRAM Red rear derailleur with an oversize CeramicSpeed pulley cage sits atached to the UDH dropout. ON the driveside dropout, another wing motif sits near a marking 81|88, showing this is number 81 of 88 total frames made.

Prova

From Prova we have a gravel bike frame built solely from titanium, but with printed parts used throughout – the top of the head tube, seat lug, driveside yoke and dropouts. These are welded together with titanium tubing in fairly large diameters to presumably produce a stiff frame.

New from Mark on this bike is the matching printed titanium fork. This is printed in three sections that are welded together, with a carbon steerer tube bonded into the crown. The shape perfectly matches up to the head tube, before tapering quite dramatically. I understand the design intent is to match the strength and weight of a carbon fork whilst offering better ride quality. I would be very curious to ride one! The hidden internal-wedge seatpost clamp that is built into the seatlug gives a very clean appearance that suggests an integrated mast at first glance.

An all-titanium Prova gravel bike, in a copper brown paint on the front half and brushed ti ont he rear. It features a titanium fork, carbon wheels, and ti EE Wings crankset.

The ti fork legs sweep sharply forward at the crown before tapering dramatically. A fork mount screw is shown at bottom right.

A closer look at the triple accessory mountson the titanium fork, finished in a dusky copper color.

The hidden seat faster is completely invisible in this right side shot of the brushed ti seat cluster. Weld joints are barely visible, and the seatpost enters the seat tube to create the optical illustion of a seatmast system.

The driveside dropout features an industrial-looking sharpness to its shape as it hides the SRAM UDH hanger system.

The non-drive side dropout features a similar sharply sculpted look to hide the flush-mount through-axle bolt.

The head tube area is finished in a dull brushed copper with matching-painted stem. The tapered head tube has a silver badge, and weld joins on the head tube and top tube are barely visible under the finish.

The 3D printed driveside chainstay is flattened to offer extra clearance on the 1x drivetrain.

The non-drive view of the bottom bracket, featuring a T47 unit and polished silver EE Wings cranks.

No. 22

I was responsible for driving this prototype from No. 22 down from Portland. With it being the only one in existence I was very happy to get it handed over! This is the first fully-printed-in-one-piece titanium frame, which meant finding a very large printer – a little scary to consider how much the titanium powder would cost to fill that size print bed.

The fork and stem went through the same process. Not to make life too easy on themselves, the team at No. 22 designed the frame to use a custom carbon aero seatmast which was created for them by July Bicycles. Aerodynamics is such a black art – the ability to iterate in CFD allows for more controlled creativity, and it is fascinating to me that the design process here produced some relatively large and angular shapes. The ‘aero eye’ is often wrong when dealing with such a messy aero-optimization problem as a bicycle and rider. For this frame, using additive manufacturing allowed for tube profiles that would be impossible to produce by other methods. It is great to see these small companies pushing the limits of current technology – I look forward to seeing what aspects of this experimental prototype make it into No. 22’s range in the future.

A wild, brutalist-looking printed titanium frame from No. 22 looks sharp like a scalpel and sleek in matt black finish.

The head tube area is blunt Kammtail aero profiles in gold and black, with an integrated cockpit in sharp angles.

A top view of the integrated cockpit with a rectangulat black stem mounted flush to the steering axis.

A clever seat juncture features a backward Z-like bend to the printed seat stays as they meet the seat tube, rise up the tube and then blend with the top tube.

Printed in one piece, there are no welds on the No. 22, including at the dropouts, which sit above a SRAM Red derailleur and aero CeramicSpeed oversize pulley cage.

Another view of the dropout, non-driveside this team, showing its clean brushed finish and no visible welds, even on the disc brake post mounts.

A back view of the No. 22, showing the custom carbon seatpost housed in the 3D-printed titanium frame with seatstays squeezing the sides.

A broad shelf joins the down tube and seat tube above the bottom bracket, makign for a large BB area above the shell and sharp angles for the chainstays coming off it.

Scarab Cycles

For a complete shift, here we have a hand-built bike welded together from steel tubes, with external hoses and the ability to run mechanical shifting if desired. Scarab Cycles frames are built in Colombia and have embraced multiple paint methods to offer a wide variety of stunning finishes, many of them crafted by Indigenous artists. I could have spent some time just trying to spot all the animals hiding in the jungle on this gravel bike!

This bike might have the first thru-axle dropout I have seen with a built-in derailleur hanger, which is cleaner and stronger than having a replaceable one. In the unlikely event of managing to bend it, steel is happy to be bent back. The gently curving chainstays offer plenty of clearance for the 38 mm knobbies fitted, as well as for the crankarm. The flat-mount bosses are brazed in so smoothly that it could almost be a printed part.

A dark green Scarab steel bike with all-black components and a jungle-inspired pain scheme with small details and riots of color.

The Scarab's head tube, featuring external cable stops and a closer look at the jungle-themed paint.

An integrated derailleur hanger on the Scarab features a through axle shrouded by a dropout.

The non-drive dropout is similarly hiding the axle.

A closeup of the fork paint, showing jungle scenes with plants, colorful birds, and an orange and black-spotted cat.

Simple leaf designs on dark green on the non-drive side chain stay.

Sculpted seat stays are joined by an arched bridge, seen from the back. On the seat tube, the words "Hecho en Colombia" appear.

Mosaic

Speaking of intricate paintwork – I don’t know how the magicians at Mosaic create this finish, but the closer you look the tinier the details! Somehow I haven’t managed to actually meet Aaron Barcheck (Mosaic’s founder) yet, and failed to find a moment when he was free despite standing close to him all day. Next time …

This gravel frame has plenty of room for the fat 40 mm slicks thanks to careful tube shaping. Interestingly there is a BSA BB shell (with reinforced ends) instead of a T47, despite the build having fully internal hose routing – with no additional space inside the shell, the rear brake hose finishes its run externally under the chainstay. The unpainted lower part of the frame allows a clear view of the incredibly evenly laid-down weld bead, which is perfect even around the challenging BB area.