Boo SL-G Custom Gravel Bike

Starting At

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The SL-G is our top of the line custom geometry gravel bike.  A road-geometry race bike, the SL-G excels in extremely rough terrain–flint, hard rock, and washboard dirt roads.


Our SL Series represents the pinnacle of bamboo and carbon technology, and is focused on delivering the ultimate performance from both materials.  This series is fully-custom and offered on a made-to-order-only basis.

$4495 gets you our fastest, most responsive, and comfortable gravel race frame, hand-tailored to your measurements and objectives.  It doesn’t get better than this.

Boo SL-G: Built to fit, rip, and last

Built from a custom BikeCAD designed to your exact measurements and specifications, the SL-G fits its rider like their favorite bibs.  Those long days in the saddle stay comfortable much longer than on a stock geometry frame.

Bringing this rig to a halt on loose surfaces requires fat gravel meats and stout stoppers—the SL-G has this covered with ample tire clearance (up to 42mm) and a 12x142mm QR thru axle rear end.  We hand-wrap the carbon around the bamboo and a custom-machined axle assembly, then remove all metal to create a custom-molded carbon and bamboo thru-axle dropout.  Its stiff, stout, and light.

We also give our Tam Vong bamboo tubing a special interior S-2 glass layer for extra reinforcement.  This strong and absorptive material distributes impacts over a greater surface area.  Think of a massive, sharp chunk of Dirty Kanza flint striking the down tube–the bamboo and S-2 glass absorb and disperse this impact, deflecting damage and maintaining the frame’s structural integrity.

Going for a clean, low-profile look? The SL-G frame is drilled to accommodate internal routing of Di2 wires and hydraulic brake hoses.  The SL-G is also our stoutest frame yet, and it’s backed by the Boo Warranty and our satisfaction guarantee.

Which bucket list race will you be tackling first with your SL-G?



COMPLETE BUILDS$7,000-10,000+


Contact us for a quote!  We love talking bikes.

  • Please tell us a little about the SL-G you are interested in building. A Boo representative will follow-up with you as soon as possible.

Customizing Options

2 reviews for Boo SL-G Custom Gravel Bike

  1. John B

    Rode a Boo SL-G on 2016 Ride the Rockies Day 4, which took us from Copper Mountain to Lake Granby via Colo 9, Ute Pass, US 40, and US 34. The ride included about 18 miles of dirt road. Total ride distance was about 85 miles.

    The bike I rode was the medium-frame SL-G gravel bike equipped with hydraulic disc brakes and Shimano Ultegra Di2 electric shifters. I used their saddle (WTB Silverado). Both front and rear hubs were thru-axle. The ENVE carbon wheels were shod with 700×28 tyres. Ran them at +/- 95psi.

    The morning started out at a brisk 28F. Wore a medium thickness full-finger glove, which made it difficult to operate the shifters. During the ride from Copper to Silverthorne the right shifter was not working very well, and finally quit totally about 8 miles from the first rest stop. The mechanics at the rest stop discovered that the connector at the shifter had worked loose. After re-connecting it, the shifter worked fine the rest of the day and was easy to operate, even with a light full-fingered glove.

    The bike probably weighed about 19-21 lbs. A bit heavier than my Bianchi Infinito CV road bike, although felt as light or lighter than my Foundry Auger CX bike. It was definitely lighter than last year’s BOO Bike of the same model. Confirmed that with the BOO reps at the end of the day. They have figured out a way to bore out the bamboo on the inside and line it with a layer of fiberglass to lighten it w/o loss of strength.

    The SL-G tracked smoothly on pavement and was quite responsive to pedal effort. Have ridden some carbon bikes that feel a bit squishy (1). Not so with this bike. Have heard that titanium bikes can have a squishy feel although have never ridden one. Steering was nice with no twitchiness at all.

    It climbed nicely for someone who unfortunately has not been able to do much climbing this year. However was able to keep up with a group of mid 30’s riders on the climb up Ute Pass. Actually dropped a couple of them on the last bit of climbing before the road levelled out.

    The bike descended on the pavement like any other good bike; nice and stable in the turns. One could easily start pedaling hard coming out of the turns and feel the bike accelerate.

    Decided not to slow down when I hit the dirt road. Was going about 40mph. The bike maintained the same level of stability that it had on pavement. There was road vibration in the handlebars, although not enough to be annoying or make one feel that the bike could not be controlled. The rear of the bike never squibbed around on the road surface like a carbon bike will. I was able to point it anywhere and push it as hard as I could pedal without any concern for the variable road conditions. The road surface was hard-packed dirt with a little loose gravel and no washboards. The usual level of imperfections and uneven surface one finds on a dirt road. This is the most stable bike that I’ve ever ridden on dirt. My Foundry is quite good, this bike is excellent. Would happily ride it all day on dirt roads. All that I would change would be the saddle. The WTB worked fine although I’ve found that the Sella SMP Glider works best for me.

    The rear tube blew out at the Hot Springs rest stop. No fault of the bike. Discovered an imperfection in the ENVE tyre liner that had worn the tube thin; the heat of the day caused the blowout. Some electric tape on the imperfection and a new tube put me on the way to a nice cruise on up to Grand Lake.

    For age reference: I am 60 years old.

    (1) Squishy: Defined here as a bike with more “give” in the frame than one expects; there’s a half to full heartbeat between the time you mash down on the pedals and something starts to happen. Also comes with a slight lack of road feel.

  2. Nick Frey

    As a founder of Boo Bicycles, I may be biased…but I’ve raced and ridden most of the top bikes in the world. And the SL-G is simply the most remarkable combination of stiffness, responsiveness, and supple, sublime ride quality I’ve ever experienced. The bike reacts instantly to my inputs, but I don’t need to DRIVE it when I’m eight hours into a 13 hour race like the Dirty Kanza 200. It just disappears underneath me, and feels more comfortable than an old baseball glove…yet when I get out of the saddle and attack up a climb, the bike moves forward with such ferocity it’s almost frightening. I can never go back to carbon monocoque ever again…the SL-G is my dream bike and is a joy to ride fast, slow, long, short, up, down, and in every condition.

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