Boo Bicycles is continually fine tuning their bamboo and carbon fiber frame construction to make the bikes lighter, stiffer, stronger or whatever other metric would improve the ride for the given application. One of their more techy solutions is S2 Glass, an impact dispersion fiberglass that’s placed into the bamboo tubes and expanded. Them lets them use thinner wall bamboo tubes, down to 2.5mm thick compared to 3.5 to 4.0 without it. It saves about 50g for something like a downtube, yet makes it way more impact resistant.
The new Boolossal SL gets that tubing and a trick new full carbon thru axle dropout. There’s no metal on the bare frame other than the water bottle bosses…
The rear axle threads into the Santa Cruz derailleur hanger part.
The carbon is built up around custom mandrels and hand shaped. The bamboo comes all the way down to the axle, but there’s a lot of carbon over wrap to make sure it’s very stiff and strong.
The S2 lined bamboo tube is shown on the left. On the right shows how they butt the bamboo so that the carbon wrap is flush with the wood’s surface (on some bikes).
The SL bikes are their premium offering, yet they’re selling more and more of those. They get hand selected bamboo for each tube and special manipulation of each tube to make it as light as possible for the intended rider and usage. They’re also full custom, as opposed to stock sizes for non SL bikes.
Other upgrades for SL include internal routing. The Boolossal has 197mm rear thru axle spacing and a PF121 full carbon bottom bracket shell.
