Even the most basic repairs can go badly—sometimes comically—wrong. Here are five common rookie-wrench mistakes and our expert's instructions for avoiding them.
At the DIY-wrenching classes I teach, I encourage my students to mess up as much as possible while they're learning—because when you make a mistake, the memory of what went wrong stays with you. I've heard tales of simple blunders, grand catastrophes and everything in between. But most of the time, my students tell me different versions of the same five stories over and over again. With luck, you'll remember them—and these simple fixes—to avoid making the same errors yourself.
Don't Hang Yourself
THE MISTAKE: When one student's shifting suddenly went wonky, he thought adjusting the derailleur's cable and limit screws would do the trick. But during a ride, his chain fell off his big cog and flew into the spokes, breaking six of them. Then the derailleur broke off, spun around and exploded against the frame.
THE FIX: Aside from cable stretch, which occurs naturally (especially when a cable is new), a bent derailleur hanger is the cause of most shifting problems. To diagnose, shift to a middle cog in the rear, then hop off your bike and squat behind it, holding it upright by the rear wheel. Look at the cage of the rear derailleur (the part that holds the two pulleys) and compare it with the cogs. They should all line up vertically. If it looks bent inward or even slightly twisted toward the wheel, the derailleur hanger needs to be straightened or replaced. To prevent the aforementioned catastrophe, stay out of the largest cog (your easiest gear) on the cassette until you can get to a shop.
Love Your Chain
THE MISTAKE: Many students come to their first class with dried-out chains chirping like birds. Then there was the guy whose rear rim, frame and even brake pads were splattered with lube. He cleaned and reapplied lubrication perfectly on schedule, but never wiped his chain down afterward, causing the lube to coat most of his bike.
THE FIX: A poorly lubed chain has a shorter life span and diminishes the bike's performance, so oil it about every 100 miles or whenever your bike gets wet. For every minute you spend greasing it, spend two holding a rag lightly against both sideplates of the links as you spin the chain backward. Excess oil attracts dirt, and over time that dirt will work its way to the moving parts inside, leaving you with a gritty mess that creates almost as much damage as no lube at all. With proper care, your chain should last 1,500 to 2,000 miles.
Know the Lingo
THE MISTAKE: The intricacies of cables and housing confuse my students. Inside the housing there's a thin plastic sheath that helps the cable move smoothly—but the sheath eventually collects dirt particles, which cause friction and interfere with the cable movement. Got that? Here's the thing: You can't replace your housing without replacing your cables, because it's basically impossible to thread a used cable through new housing. So rather than trying to explain all that, bike shops usually just tell you that you need new cables. Which is true, sort of, because you need new housing. (Sigh.)
THE FIX: Replace your cables and housing once a year, at the same time, especially if you ride off-road. And any time a cable is frayed, switch it out as soon as possible.
Take It All Off
THE MISTAKE: One student thought he'd mastered the tire change—he could even do it with one bead left on the rim. Then he flatted five times on one ride. Finally, before putting on a sixth tube, he removed the tire from the wheel, thoroughly inspected the rim and rubber, and found a tiny metal wire poking through.
THE FIX: Remove the tire completely and run your hand along the inside of the tread, both clockwise and counterclockwise. Otherwise, it could turn out like the time your dad said, "Hey, I know a great shortcut!" on a family road trip.
A Clean Bike Is a Fast Bike
THE MISTAKE: A student who'd used a pressure hose to clean his bike learned a tough lesson as we disassembled each set of bearings. They had all rusted almost to the point of seizing. "Oh," he said as we took apart the headset. "That's why it's been so hard to turn."
THE FIX: Applying water under high pressure blasts dirt into your bike's sensitive hidden parts, or blows out the grease and lube that prevents contamination and rust. Use a hose running not much harder than your granny's watering can. Or use a bucket with soapy water, a sponge and an assortment of brushes—even old dishwashing scrubbers and toothbrushes.