Babyheads - roundish rocks which tend to be found in a loose jumble on hairpin corners or other dificult-to-negotiate sections of trail.

Bacon - scabs on a rider's knees, elbows, or other body parts.

Back pain - Ow. As you get older and fatter - and you will - your back will hurt more and more. Then you will start to say things like: "I need those upright bars for...better control!" "I need that expensive freeride bike for...more speed!" And: "Golf really is an action sport!"

Bagger - one who always agrees to ride, party, gather, etc. but rarely shows.

Bail - to jump off in order to avoid an imminent crash.

Baja California - Minutes from a major airport in San Diego. Strange Donkeys in Tijuana. Tamales de Elote near Rosarito Beach. And 1,000 miles of wide open dirt. If Alaska's the last frontier, Baja's got to be the first. There's still no good off-road guidebook for the place, though - probably because everything's off-road there.

Balance Blackout - that short time during almost every ride when you start to fall, lose your balance without reason, or seem to be unable to clean even the simplest obstacle.

Banana Scraper - low hanging branches, the kind that smear the guts of that banana you put in the pouch on the back of your camelback when you don't duck low enough.

Beartrap - 1)to slip off a pedal, causing it to slam one in the shin, when one gets kracked with a pedal.
2)the toothlike scars resulting from being beartrapped.

Bar ends - mini handlebar add-ons that fit on the ends of mountain bike bars to add another riding position. Once the hottest accessory you could buy. Then, bike makers added them, standard. Now, people are deciding they don't need them at all, preferring riser bars. But Onza upon a time...

Barely Legal - A popular magazine. Best consumed with Girl Scout cookies. Send your offended cards and letters to the framers of the constitution, please.

Beer - Also delicious with Girl Scout cookies, but even better with pals after a bike ride. And the Moab brewery still sucks - it isn't just that the suds are weak, it's the awful, skunky taste. As a mitigating factor, though, this is basically true with all the pretentious, foolish microbreweries - the yuppie croissant shops of the 1990s.

Bell - The Bell biker was the first serious hardshell helmet. And Bell - which buys cadavers and then crushes their skulls in an effort to keep you safer - still makes terrific helmets. Plus, that cool Bell oval logo. Wear it On Any Sunday.

Biff - to crash.Synonyms: wipeout.  "I biffed and then wiped away the blood."

Binder bolt - the bolt used to fasten a stem inside a steerer tube or a seatpost inside a seat tube or a handlebar inside a stem.

Biopace - a now-discredited Shimano Techno-fad where the chainrings were made intentionally not circular -- instead, they were elliptical, in order to (allegedly) smooth the power delivery, by giving the rider an effectively lower gear for part of the spin cycle. Now used to describe any uneven pedaling motion. Also used as a synonym for pogo-ing.

Blocking - legally impeding the progress of riders in the pack to allow teammates a better chance of success.

Blow up - to suddenly be unable to continue at the required pace due to overexertion.

BMX - Bicycle Moto Cross: a type of racing done on a closed dirt track over obstacles usually on 20-inch wheel bikes with one gear.

Bob Jackson - In the great old days of touring bikes, Jackson built classic English fancies, with sculpted lugs, intricate paint jobs, and more drilled out parts than my dentist handles in a month. I still want one of these, so bad it hurts. You can see Jackson's influence today in bikes from Waterford, Rivendell, and most of all Bruce Gordon - and Bob himself is still kicking, too, building his classic tourists in his factory in Leeds, England.

Boing-Boing - a bike with full (front and rear) suspension. Might possibly be considered offensive by certain owners of said bikes.

Bolt-on - a woman with breast implants. Derived from the term for after-market bicycle parts that are literally bolted on.

Bomb - to ride with wild disreagard to personal safety.

Bombers - the earliest mountain bikes, converted from cruiser roadbikes to race down mountains.

Bon - what happens when you don’t eat and drink enough; a terrible pins-and-needles lightheaded feeling that can lead to a crash.

Boot - to expel pre-ride stomach fillers due to extreme physical exertion. "That climb was hairy, I think Brian had to boot back there."

Bottom bracket - the cylindrical part of a bicycle frame that holds the crank axle, two sets of ball bearings, a fixed cup, and an adjustable cup.

Bra - the rubber strip placed inside the rim to protect the tube from the nipples.

Brain - a biking computer, usually featuring an odometer, speedometer, clock, and other "important" display modes.

Brain bucket - helmet.

Brain Sieve - a helmet featuring more vents than protective surface.

Brake pad - (brake block) - a block of rubberlike material fastened to the end of a brake caliper; it presses against the wheel rim when the brakes are applied.

Brake shoe - the metal part that holds a brake pad and is bolted to the end of a brake caliper.

Brand Whore - a rider that will only buy high-end parts/gear with name recognition. Wouldn't be caught dead using LX level parts or wearing a pair of Nashbar shorts.

Bring Home a Christmas Tree - to ride (or crash) through dense bushes, so leaves and branches are hanging from your bike and helmet. 

BSG - acronym for "Bike Store Guy".

Braze-ons - parts for mounting shift levers, derailleurs, water bottle cages, and racks, which are fastened to a steel bicycle frame through a type of soldering process known as brazing.

Break, breakaway - a rider or group of riders who have escaped the pack.
Bridge, bridge a gap - to catch a rider or group that has opened a lead.

Brinelled - a type of wear in bearing components that is a series of dents in the races or cups.

Budweiser - World's yummiest swill. Drink it for hours, you'll have power.
And the Moab brewery can kiss - I mean, kick - Augie Busch's St. Looey tushie.

Bunch - the main cluster of riders in a race. Also called the group, pack, field or peloton.

Bunnyhop - An essential maneuver you can do. Forget all that phony-baloney advice about "pushing down on your front handlebars" in order to spring up. What a crock. Bunny hop this way: lock your clipless pedals in tight. Ride as fast as you can toward a (little) log. When you get right up to it, jump as high as you can and keep going forward. Keep doing it until you don't crash. Then try it on a bigger log.

Burrito - a rim braking surface that's bent inward towards the tube, forming a section that looks rolled like a burrito.

Bushing - a sleeve that fits between two parts to act as a bearing; often found in suspension systems

Butted tubing - tubing whose outside diameter remains constant but whose thickness is reduced in midsection where less strength is needed.

Buzz - euphoric feeling. Commonly used after a particularly hard passage is successfully completed. "I got such a buzz after that uphill grunt."