Meet the Birdcage Boxer, featuring a titanium lattice frame and a mystery BMW motor
Two wheels, a seat, a big ol' motor and the absolute bare minimum of other stuff supporting them. The Birdcage uses 134 nine-millimeter titanium rods to create a surreal see-through lattice frame on one of the most spectacular custom BMWs we've seen to date – and the motor presents a bit of a mystery.
Inspired by the Maserati Tipo 61 Birdcage, a 1960s-era race car with an incredibly intricate space frame tube chassis, Alan Stulberg and the team at Revival Cycles has built a total eye-popper for this year's Handbuilt show in Austin, Texas.
Looking like some kind of skeletal ghost bike, it's built around a big boxer engine, hidden behind podracer-style aluminum covers that the team knocked up with a little assistance from expert metalworker Craig Rodsmith on a three-day visit to Revival. That hulking boxer is much, much bigger that anything you'll find in a BMW showroom – indeed this entire custom may best be viewed as a teaser for a new large-capacity BMW boxer engine and streetbike series.
All that's obvious at this stage is that it has staggered cylinders, the left leading the front by a couple of inches, with cooling fins, a new type of differential drive, and that those cylinders are enormous and quite long, indicating a torquey, cruisy style of power delivery. Could we be looking at a 2,000cc heritage cruiser motor here? Time will tell.
To call the Birdcage clean and minimal is to undersell it. There's no headlight, dash, front brakes, radiator, mirrors or visible fuel tank. Gearshifting appears to happen via a suicide hand shift on the right hand side of the bike, with a single reversed lever on the droopy left handlebar controlling the clutch and ... we can't see, but possibly a brake pedal on the left foot, which is where you'd stick it if you wanted to keep it as close as possible to the caliper and reduce ugly hydraulic lines. Any electronics are entirely hidden, and the thin throttle and clutch cables are really the only "plumbing" we can see in these photos.
The front suspension is a pair of custom aerodynamically covered forks with a telelever-esque brace going back to the engine mounts and a single monoshock. The rear looks like a hardtail setup, but rear suspension is listed as a custom "pinion" design. Perhaps the axle is free to move up and down on a gear inside that rigidly mounted rear hub, with the drive shaft pivoting to meet it – the brake caliper is mounted in such a way as to potentially allow a little vertical disc travel. Either way, we've pored over a ton of build pictures at the Revival website and found nothing to suggest how the rear wheel might move up and down.
The seat? Probably not that great for an Ironbutt attempt; it's a small, rigidly mounted metal platform. But that's OK, Revival designed this thing to be more of a land speed style machine anyway ... and actually plans to run it on the salt. Yikes. It might not end up being much of a rider, but it's a heck of a looker - and we just love the structural elegance of that titanium frame. Very cool.