Someday soon, your bike will emerge from its deep freeze inside a snowbank and you will get that irresistible urge to ride it. Before giving in, you should check a few things. Here is your checklist, with tips.
Round-ness and spinny-ness are two key attributes of bicycle wheels. So start your bike-check by determining if these still hold true. Steel wheels, like the one to the left, are made with galvanized steel spokes that get brittle from road salt and exposure to the elements. Some spokes may have loosened or even broken, which will bring your wheel out-of-round (or "true"), and make the rim more susceptible to bending when you ride over a pothole.
You can pluck individual spokes to assess their tension, your goal here being to identify outliers: too-loose spokes will emit a low thud; too-tight spokes will emit a high-pitched pling. A reasonably round bike wheel is a spiderweb of tensions that cancel each other out almost perfectly. When spun, an out-of-true wheel's rim will swing either side-to-side (if there are loose or broken spokes) or up-and-down (if it has been bent by a pothole). Wobbly wheels make for an unsteady ride and affect how tight you can make your brakes before the brake pads start rubbing the rim.
The other thing to check is whether a bike wheel's axle turns freely and without grinding. Briny snowmelt can enter a wheel's hub and mess with the grease that keeps the bearings turning. If you hear a crunching sound as you ride, or if the bike wheel quickly grinds to a halt when lifted off the ground, your hub may need an overhaul.
Hubs can also loosen, in which case the bearings will have "play" – meaning that you can move the rim side-to-side laterally, despite the wheel being tightly fastened to the bike. (Needless to say, riding like this is not safe: when I was just learning to hack bikes, I once ground to a halt when the bearings fell out of a loose hub I had improperly tightened. This forced me to drag my bike onto the subway.)
Poor braking can be due to one or more things you should check for: worn out brake pads; broken or rusted up brake cables; and rusted or seized-up brake calipers. Pebbles and small metal shards off the wheel's braking surface embed themselves in the soft brake pads, turning them into scouring pads that rapidly eat up the rims while reducing braking performance. Briny meltwater seeps into the plastic sheathing that carries the brake cables, causing them rust together and become welded. The springs inside the brake arms can also get corroded, causing brake calipers to seize up. Squeeze the brake arms together and note whether they spring back.
The squeak of a rusty bike chain is one of my pet peeves – and those who hose down that same rusty chain with WD-40 are another. You'll be surprised how easily you can resuscitate a stiff, rusty chain using only chain lube and a rag. Drip a drop of lubricant on each chain link until the whole chain glistens. Loosen up stiff chain links by grasping the chain and flexing it laterally while applying thumb pressure to each stuck chain link. As the chain starts to flex again, spin the cranks while passing it through the rag, thus distributing oil into each chain link while pushing out dirt and dissolving some of the stuck-on rust. Repeat the lube and rag treatment until the chain spins freely again. (As with other steel bike parts, you can use steel wool and some elbow grease to easily buff off surface rust.)
Gears make cycling easier, as the Sturmey-Archer advert of yore proclaimed. But it's a real bummer when you get on an outdoor bike only to find that you can only ride in one gear. The gear changers (or "dérailleurs," to the curmudgeons) could be the cause. Sometimes the control cables break or seize up; other times the changers get rusted up or bent. But even a one-speed bicycle is better than none at all.
Through the chainrings, the cranks transfer power from the pedals to the chain. Cranks are attached to the bottom bracket, which is basically a spindle sitting on bearings. Crank arms should still be straight, as should the pedals (these sometimes get clipped and bent by snow removal equipment in my part of the world). Cranks should spin freely, without crunching or wiggling side-to-side ("play").
The checklist above is long in helping you identify common bike problems, but short on suggestions on how to fix them. I did this for a reason: cost. The death of a lot of utility and commuting bikes is your inability to have them repaired in a cost-effective fashion. By the time you've done your upgrades and replaced broken parts, the costs in both time and money will exceed that of a similar bike bought locally. And that's a very logical decision to arrive at. Donating or cheaply selling a "broken"-seeming bike creates a market for those local scamps who fix bikes for dollars. (More on that later.)
But if you're willing to invest your time these all bike repairs you can learn to do on your own, with tools and guidance, at a bike co-op. And by scanning this checklist before visiting one, you can know roughly what to work on the moment walk through the door.
[Photo credits: BrokeinMileEnd]