Boo RS-M 29er Review: Part 1

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Since they hit the market, Boo Bicycles has been on my list of “bikes I want to ride”, because of their bamboo frames.  Unless you have been living under a rock for the past couple of years, bamboo has been picking up steam as a quality frame material for bikes.  If you take a look at Boo’s “About” page, bamboo is the magical unicorn of frame materials that is “stiff like carbon, supple like custom Ti, and lively like handmade steel.”  If bamboo us the wunder-material that Boo presents it as, this bike was going to go down like nobody’s business, and climbing speed would only be governed by the power of your legs.

The posse at Boo was kind enough to put their RS-M 29er hardtail in my hands to put it through the ringer.  Aside from the bamboo frame the bike is spec’ed out with a Lefty fork, XX1 drivetrain, and some sweet Enve wheels.  I’ve had a little over a two months of riding on the RS-M now, and despite the fact that it was the snowiest February in Denver’s history, I was able to get some miles logged on the bike.  Because I think the frame material is as interesting as how the bike rides, I decided to turn this into a two part write up.  Before I get into my thoughts on the ride quality of the bike I had a few questions about both bamboo as a frame material, and Boo’s approach to making frames.  Jacob at Boo was kind enough to provide some in depth answers to my questions.  Because the answers went into great detail, I’ll do a second post that is a review of the bike.

 1.)    Broken carbon frames can be repaired for a reasonable price.  If something happens to a bamboo frame what are the repair options?  How much would one expect to pay?

First and foremost, we choose bamboo not because it’s a green material, or because it’s novel, or because it looks like functional art–we choose bamboo because we believe it makes the best riding bike for most purposes. Period.

That said, we actually don’t know what a bamboo failure looks like yet, as it hasn’t happened. Also, I’d like to point out that while carbon repair may be more affordable monetarily, it is anything but when looking at the opportunity costs. Probabilistically speaking, these damages and repairs happen in-season, while training for some important event, leading to large periods of downtime on the race steed. Also, what mental confidence is the rider left with on that technical MTB decent, or the 55 MPH road decent, after a frame failure (even one that has been repaired).

Years ago, we discovered that roughly 5% of frames would encounter small splits in the bamboo. However, because of the way this natural composite forms, with all fibers running the length of the tube, these small splits are not structural, and simply cosmetic. This is similar to the way logs in a log cabin can have huge, several inch wide splits in its logs, with no structural impact whatsoever. In our case, the split just needs to be sealed from the elements and color matched to the frame. We know all this now after tons of testing. In fact, we enlarged a split on one of our demo MTBs until it ran the entire length of the down tube, and it was wide enough to stick a nickel through. James Stemper then rode this same bike to 30th at Leadville 100 (even after getting slightly lost, and stopping to shit in the woods).

Anyway, this all isn’t to say that frames won’t break, I’m a realist and shit happens. So, in short, if a Boo breaks and it’s our fault–it’ll be repaired for free. If a Boo breaks and it’s your fault–we’ll get you on another frame for 40% off retail, and wholesale on components that happened to be involved in the accident. It’s pretty simple, we stand behind our product.

2.)    What sort of life expectancy does the frame have?

To the point of question 1), we actually don’t know the life expectancy of a frame, as many of the originals (now 7 years old) are still going strong. Many of the older models that aren’t still on the road/trail were simply upgraded to newer technology, rather than reaching the end of their usable life. This would lead one to conclude that life expectancy is much greater than the rate at which technology changes in the industry. Also to the point of question 1), in the effort to build a durable investment good, we do our best to stay ahead of technology, and build anticipated changes into our frame technology.

3.)    The hardtail is pretty heavy (especially for the price tag); does the benefit of bamboo outweigh the weight penalty?

I think so. Our bamboo has a progressive response curve. This means that under low-frequency inputs (think pedal cadence, and slow, technical rock gardens) the frame is very stiff, power transfer is excellent, and the bike has the precision of a scalpel. Under high-frequency inputs (think railing through an unexpectedly rough patch of single track, and cobbles or gravel wash boards in the road/gravel scene) the frame is much more compliant, yielding more traction and less punishment when slightly off the perfect line. Furthermore, while our bamboo’s bending stiffness is near that of a carbon tube, its torsional (twisting) stiffness is slightly less. This also means that you have excellent power transfer, and still have scalpel like precision, regardless of what part of the response curve you’re in.

On top of the ride quality argument, I personally like to take a physics approach to mass on the bike (after all, physics is my background). The only reason mass is a cyclist’s enemy is that it resists acceleration. Acceleration is technically defined as a change in the velocity vector (a change in speed, or a change in the direction of travel). That being said, the frame spends the majority of its time at pretty much constant velocity (maintaining average speed, and riding in relatively straight lines). This means that the frame spends the majority of it’s time with an acceleration at or near zero m/s/s. This is opposite to everything on the bike that turns in circles, as this means direction is constantly changing (a mass must necessarily have a change in direction in order to travel in a circle). For this reason, the rider would be well advised to spend money on reducing mass with the moving parts, while simultaneously enjoying the ride qualities described above. This is why we’ve curated the build you’re currently on–it’s light where it needs to be, yet durable and responsive where it needs to be too.

One could argue that the change in gravitational potential energy (pedaling up climbs) requires more work (Joules of energy). This is true. But I’d still argue that the sort of weight differences we’re talking about wouldn’t bring a competitive advantage to probably 80% of riders out there, while the durability and ride qualities mentioned above absolutely would.

Anyway, this is all to say that bamboo lends itself to a very unique and race-worthy ride quality, without sacrificing durability, that you simply can’t find with other materials–only you can decide if this trade-off is worth the slightly higher weight penalty. For me personally, assuming I’ve had my oats and coffee, this weight difference is usually small enough to take care of with my pre-race Porta-John visit anyway ;)

I’ll also let you know that there is a ton of room in our frame tech to play with weight reduction. Some of this will be revealed at NAHBS, where we will be debuting a new model that will take advantage of some rad stuff in the effort of reducing weight while not sacrificing anything I’ve mentioned so far. Nick and I have personally done a TON of engineering in both our carbon layup, and methods to hollow out our bamboo tubing even further, while maintaining all the benefits of bamboo. Stay tuned…

4.)    Can you do a FS bike with bamboo?  Is there a need to?

Anything’s possible with the right funding and resources. That said, we see no need, and have no desire to do this. As described in question 3), due to our unique ride quality, our frames are not punishing to the rider. This means less mental fatigue from not constantly having to be on the perfect line. Less micro adjusting, not having to get out of the saddle for small bumps. More confidence at speed and in the climbs. This all adds up over the miles and we’ve simply never found a need for full-suspension in XC racing. Also, none of us are really in to downhill specific stuff. While we have tons of respect for the sport, we simply haven’t invested the time to be good–and we’d never make a product we don’t personally shred.

5.)    Justify the $3500 frame cost.

Our bamboo is like a fine whiskey in that there is so much unseen craftsmanship and aging, before the “bottling” stage even happens. The bamboo is a very specific type, which really only reliably grows in Vietnam (this is why James moved there). It’s all grown and harvested in-house, often with years of curing between harvest and frame. We prefer a certain maturity in new growth too, which also often takes years. Harvesting happens in a very narrow window each year to ensure sugar content in the bamboo is low. This variety is a clumping variety (like crab grass in your yard) and some of the clumps are upwards of 100 years old. All of our bamboo procurement is really more art than science, and it can only come from the experience built up over 18 years, in Vietnam, with this particular strain of bamboo.

So there you have an in depth Q&A about bamboo bikes straight from someone who knows their shit (and a quick physics lesson to boot).  For many I assume the biggest hurdle associated with a Boo bike is the cost of the frame.  Enjoy the video below about “Building a Boo” (link if embed doesnt work for you).  Stay tuned for a further review of the complete bike, and whether or not I think the bike is worth the price tag.

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