March 18, 2015

Boo SL Series: Building the Ultimate Bamboo Race Bike

by Nick Frey

Winner winner, chicken dinner!  Amanda Miller takes home gold at the inaugural 2015 Fat Bike National Championship on her Alubooyah

Winner winner, chicken dinner! Amanda Miller takes home gold at the inaugural 2015 Fat Bike National Championship on her Alubooyah

Here at Boo, we’re constantly innovating and refining every step of our frame construction process.  And the proof of this R&D is in the pudding: an Elite National Championship title, multiple appearances in the World Championships, and professional podiums on road, gravel, and dirt.  No other bamboo bike on the planet can claim a comparable pedigree.

Young Brannan "Brano" Fix on his way to 15th overall at the Cyclocross World Championship in Tabor, CZ on his Boo RS-X

Young Brannan “Brano” Fix on his way to 15th overall at the Cyclocross World Championship in Tabor, CZ on his Boo RS-X

Six years after first launching this company and racing successfully at the highest levels, we’re no longer confronted with disbelief—is bamboo strong enough?  The answer is obviously yes.

But there is indeed curiosity about bamboo’s performance, and especially how it compares to carbon fiber, titanium, and steel.  Short answer: it compares quite favorably in many conditions, and that’s why we use it!  You can read all about bamboo and how it compares here.

Every so often, we at Boo have some really big innovations that cause us to release an entirely new flagship model.  The last time was three years ago, when I debuted my RS-R: an all-out racing machine which further integrated carbon fiber into a hybrid design with our famous Iron Bamboo, and a bike I raced on the domestic US professional road circuit in 2012.

The RS Series is our top Boo model, and comes in the form of road (RS-R), cyclocross (RS-X), and mountain bike (RS-M).  In 2013 and 2014, I focused on mountain bike racing with a couple elite race wins and a proud moment at the Leadville 100 about seven months ago taking 21st overall, with a time of 7:19:18.  Both of these RS Series bikes, my RS-R and RS-M 29er, knocked my socks off as a racer, especially on demanding terrain.

Their incredible comfort and sublime handling let me ride faster, longer.  While a bike might feel fast and responsive in a parking lot test, I’d put these bikes through the ringer in some of the hardest races in the country.  They became an extension of me as a rider—unlike anything I had ever raced before in my life.

Now three years old, the RS Series has proven itself on the world stage.  It has turned many hundreds of customers into true believers and garnered rave reviews.

But we’ve never been satisfied with incremental improvements at Boo.  While we’re constantly manipulating the treatment of our bamboo and layups of carbon, some Big Ideas have been brewing and the time is nigh to release the product of much cogitation, engineering, and development.  This is our new flagship product, the Boo SL Series.

Boo SL-G custom frame with ISM, full CX1 Hydro (46t chainring, 11-32 cassette), Enve SES 3.4 Disc wheelset wrapped in Challenge Gravel Grinders (38c)

Boo SL-G custom frame with ISM, full CX1 Hydro (46t chainring, 11-32 cassette), Enve SES 3.4 Disc wheelset wrapped in Challenge Gravel Grinders (38c)

Boo’s SL Series has a singular goal: to form a more perfect union between bike and rider

We would not be satisfied making the frame 8% stiffer and 14% lighter.  That’s what everyone else does, and it doesn’t necessary mean the new bike is any better.  That’s because a better bike, quite simply, is one that more nearly acts as an extension of the rider, rather than a machine separate from its pilot.  A truly brilliant bike is one that actually makes the rider better.

Our belief at Boo is that bamboo, coupled with other materials in a hybrid form, creates a better bike because it possesses traits that allow the rider to be better.  A better rider is one who is more confident in sketchy conditions.  A better rider is one who is less fatigued after pounding rough surfaces for hours.  A better rider is one who spends less energy and concentration fighting his or her machine and has more time to focus picking a better line, improving position, dosing out an effort, or simply enjoying the ride.

The SL Series has, from the start, been thought of as a giant evolutionary step in our path towards further connecting bike and rider, increasing the performance of both.  The SL should be lighter without sacrificing durability.  It should be more responsive without increased harshness.  If should be purpose-built for the rider, customized from scratch, made to order.

Hand-laid unidirectional carbon fiber

Hand-laid unidirectional carbon fiber


There are numerous innovations that are unique to the new SL bamboo race bike:

  1. a zero-metal 142×12 thru-axle rear dropout with carbon post-mount disc brake
  2. an interior S2 Glass reinforcement of the bamboo top and down tubes that increases stiffness, reduces weight, and does not degrade ride quality
  3. larger diameter, thinner tube walls in the front triangle for more precise handling in demanding conditions
  4. a carbon layup optimized for ultimate lateral stiffness at the head tube and BB junction
  5. massive tire clearance by deleting the seat stay bridge and configuring a new chain stay shape
  6. increased compliance at the seat tube by using much thinner, curved bamboo seat stays
  7. full-carbon integrated seat mast with internal hydraulic disc brake cable and Di2 routing—lighter, cleaner, lower center of gravity, and impervious.




Nick Frey 20mi into the infamous Landrun 100 (2015) which should go in the history books as one of the gnarliest events on the calendar

Boo founder Nick Frey 20 miles into the 2015 Landrun 100–one of the gnarliest events on the calendar

The first SL Series model is the SL-G.  Just like the RS-R three years ago, this is my personal race bike.  I’ll be targeting events like the Dirty Kanza 200 and Crusher in the Tushar.  In fact, just yesterday I raced the Landrun 100 and was reminded just how insane these events really are.

Gravel presents a new and unique set of priorities when thinking about a bike and an event.  Because the SL-G is custom-tailored to the rider, I decided I would make an all-out race bike that would be faster than absolutely anything else in the most treacherous gravel imaginable.  I have a decent amount of experience racing gravel—a Boo CX won the first Crusher and my last Tour of the Battenkill was unfortunately epic—and generally know what I want.

In my opinion, many “gravel bikes” are simply heavy, slow-steering, and a bit uninspired.  Sure they’re versatile, durable, have disc brakes and large tire clearance…but I believe a majority of these “do anything” drop-bar bikes are simply posing.  They don’t dramatically alter the actual engineering and structure of the bike, simply the form.  The SL-G has an inherently different structure than anything else on the market, and its use of supple bamboo and stiff carbon fiber makes it the absolute best gravel weapon available.

I created my SL-G’s geometry around a custom fit from Retül.  Their fitting and measurement accuracy is astounding, and the ability to perform a dynamic fitting is quite revolutionary.  I have never been more comfortable, and when the going gets rough, that is even more paramount.


Custom geometry design for Nick's SL-G gravel race bike

Custom geometry design for Nick’s SL-G gravel race bike


The trick with gravel racing is to have a “flexible” position on the bike—one that isn’t too stretched (LONG days in the saddle will not be pleasant) but also not too slack and upright.  A position that’s too upright results in a more vertical torso, and therefore less “suspension” in the upper body.  To illustrate with an extreme example, when one’s torso is vertical and the rider hits a bump, the entire upward movement of the saddle transmits directly into the torso and the rider’s entire upper body is thrust upwards.  When that same rider’s torso is more diagonal, only the hips are thrust upwards and the rest of the torso rotates about the shoulders, lessening the shock to the body.

A longer position also better distributes weight and allows the rider to move around on the bike.  When I descend a steep hill on sketchy, loose, rutted gravel, I slide back on the bike and let the front wheel float a bit, adjusting to the various lines others have taken and not fighting the handlebar.  When climbing, I move forward on the bike and get a bit more upright to use different muscle groups—very important when you’re in the saddle for over four hours at race pace.

This means you want a slight raise of the bars relative to the road bike, but no difference in the length of the cockpit.  The increase in height helps reduce neck fatigue, gives you a bit more room to stretch out when standing out of the saddle, and provides that increased positional flexibility.

When thinking about geometry, most “gravel adventure bikes” simply want to go straight.  That means they’re easy to ride all day, but they don’t handle well when racing all day.  For me this is a very important distinction.  I plan to do some big adventure rides on this bike, but the main goal is to make a bike that will help me ride as fast as possible in Crusher and DK200.  That means it’s not an adventure, all-day bike that goes straight—it’s a race bike that can be ridden fast all day and isn’t too twitchy, but definitely doesn’t steer slowly.


Drop bars, carbon wheels, 2.1" tires with plenty of mud clearance and carrying capacity.  What else could you want?

Drop bars, carbon wheels, 2.1″ tires with plenty of mud clearance and carrying capacity. What else could you want?

The beauty of the SL-G is that my personal goals are my own and are reflected in my bike’s design, down to the smallest details.  Another person’s goals may be different: riding conditions, speed, surfaces, terrain, anticipated weather, etc.  We build the SL-G specifically for the person…this is one-size-fits-ONE.

If you’re interested in the best possible bicycle investment, make sure to keep the SL Series in mind.  We’ll be debuting an SL-R, SL-M, and SL-X in the future…every one will be custom and unlike anything else you’ve ever ridden.