The Speed of Sound

Now that bicycle frames are available in every conceivable configuration and material from boron to bamboo (you can get both from the same company by the way), the bicycle industry is finally admitting that it's mostly just tire volume and pressure that's informing your bicycle's ride quality and performance, which is why the roadies are allowed to use wider tires now:

See, they couldn't have told you that before, because if people knew then what they know now then nobody in their right mind would buy a carbon fiber bicycle.  They'd have simply kept what they had and bought some Paselas:

(28mm Pasela: the only road bike tire you need.)

Of course now they're telling you that you also need new wheels for your new wider tires, and of course disc brakes to stop them with, but that's a whole other story.

But there is another crucial factor that determines how your bike rides.  No, it's not your frame's elastic modulus or resonant frequency or cognitive dissonance or anything like that.  It's a far more profound quality called "acoustics:"

So how do your bicycle's acoustics affect its ride quality?  Well, they don't.  But you think they do, and that's what matters.  Consider, for example, that chain ejaculator we looked at yesterday:

This device keeps your chain in a constant state of moderate moistness, just like a Matthew McConaughey movie.  In so doing, it claims to increase your power transmission by 12 watts--which is a load of utter crap, as drivetrain efficiency is mostly a function of sprocket size and chain tension:

The researchers found two factors that seemed to affect the bicycle chain drive's efficiency. Surprisingly, lubrication was not one of them.

"The first factor was sprocket size," Spicer says. "The larger the sprocket, the higher the efficiency we recorded." The sprocket is the circular plate whose teeth catch the chain links and move them along. Between the front and rear sprockets, the chain links line up straight. But when the links reach the sprocket, they bend slightly as they curl around the gear. "When the sprocket is larger, the links bend at a smaller angle," Spicer explains. "There's less frictional work, and as a result, less energy is lost."

The second factor that affected efficiency was tension in the chain. The higher the chain tension, Spicer says, the higher the efficiency score. "This is actually not in the direction you'd expect, based simply on friction," he says. "It's not clear to us at this time why this occurs."

But try telling your ears that.  When your chain is thirsty for lube it makes pedaling your bike sound like you're raising a medieval drawbridge, which in turn makes your bike feel slower, even if it's really not.  So it makes perfect sense that a clueless Fred with a £250 chain-slathering device is going to mistake his bicycle's sudden silence for 12 more watts of pure, unadulterated speed.  (Until the thing malfunctions, dumps a bunch of chain lube onto the rear tire's contact patch, and causes him to crash--and I'm saying "him" because only a man would be dumb enough to buy one of these gadgets.)

The same thing goes for bottom bracket stiffness.  For years the bicycle industry has been telling us that your spindly, diminutive bottom brackets are robbing you of precious watts.  Consequently bottom bracket shells have gotten bigger and bigger, to the point where they're now just gaping holes that you have to stuff full of various adapters:

Do you really thing a giant sandwich of crush washers and spacers and seals and shims and washers and plastic sleeves and whatever else they stuff in there is somehow more efficient than the square taper cartridge bottom brackets of yesteryear?

Of course not.

The way your bottom bracket sounds, though, is hugely important.  For example, recently the generic stock bottom bracket on my Marin Pine Mountain 1 started making noise on the climbs, so I replaced it with one of those boringly solid Shimano Hollowtech II ones that last roughly forever:

Can you possibly discern bottom bracket stiffness or frame flex through two big fat 27.5+ tires at extremely low #whatpressureyourunning?  No.  Did swapping one pair of thread-in bearings for another make any appreciable difference apart from silencing the bike?  No.  But I can assure you that with a quiet bottom bracket I suddenly felt like I was rocketing up the same climbs upon which I had once struggled, and that I was riding a totally different bicycle, one that was somehow newer and better and maybe even lighter.  (A quiet bottom bracket is a powerful thing.)

Of course, the irony is that those new giant bottom bracket shells are more likely to creak, but it's a worthwhile trade-off because they also allow bike manufacturers to use gigantic crabon tubes, and that's where the real acoustic benefits come into play:

(A big-ass downtube and bottom bracket shell.)

See, nothing sounds faster on a bicycle than a big hollow plastic tube.  It amplifies everything: the click of the shifter, the thrum of the road surface, the gun-cocking sound of your chain dropping into a smaller cog...  A plastic bike with giant tubes rolling on those whooshy plastic wheels sounds as tight and lively as a snare drum--and if you add the weaponized whirr of a loud freehub and the servo sound of an electronic shifting group then Fred's spank-bank doth overflow:



BikeHugger really oughta be careful because he's gonna go blind:



And of course gravel opens up a whole new exciting world of acoustical possibility:



Ah, so soothing...  It's like listening to a gentle spring rain fall on your windowsill while you're frying bacon in a skillet.  Sure, you can ride pretty much any bike on gravel, but you can expect tomorrow's dedicated gravel bikes to be 100% acoustically optimized to amplify that wonderful sound and keep you in a state of bacon-y bliss.

So to recap, I'd estimate that (assuming correct fit and geometry of course) bicycle performance breaks down thusly:

Tire Pressure/Volume/Etc.--50%
Aesthetics:--20%*
Acoustics:--20%
Miscellaneous (wheels, frame materials, ergonomics, blah blah blah):--10%

*[For purposes of this analysis "aesthetics" also includes weight, since the only time it means anything is when some Fred lifts your bike at the coffee shop.]

In other equipment news, I guarantee you that Freds are going to be wearing self-lacing cycling shoes within the next two years:

Yep, you can add "lace tension" to the array of electronic systems riders will have monitor while on the bike, right alongside wattage output and shifter battery life and dropper post position and suspension setting and chain lube flow rate.  Come on, a drop-bar mounted "sprint" remote that increases lace tension by 2.5Nm increments?  The gimmicks practically invent themselves!

Though if self-lacing comes to Brooks then we'll really be in trouble:

(Pic from Lovely Bicycle)

I hear remote saddle lace tension adjustment will be an option on the new electronic shifting group from Rivendell:

(Rivendell's new bar end-mounted electronic shifter.)

Can't wait!