text: Small Shop: A Zero Waste Online Shop — How to Shop for a Second-Hand Bicycle
  So, you've decided that you want to start commuting by bicycle more often. That's awesome! And you've decided that you'd rather buy a second-hand bike than a brand new one. Good for you! By buying second-hand, you avoid creating more demand for new bicycles, and you potentially get a great deal on a bicycle that is in really good condition.
  Where to Buy Second-Hand Bikes
  Depending where you live, there may be several ways to find a good used bike.
  Many big cities host bike jumbles, where buyers and sellers meet in a common space and exchange all varieties of bicycles, components, and gear. Manchester happens to be home to the biggest bike jumble in the world - Bike Creche takes place in the National Cycling Center and is happening in a few months on Sunday, February 11 2018.
  Many bike shops deal in second-hand bikes, and many give the bikes a certain level of maintenance or refurbishment before re-selling them. Bicycle Garage in Manchester has a range of used bikes in addition to their new models.
  Gumtree (UK) and Craigslist (US) are good options, since you can often preview the bikes in person before you buy. Ebay is another option, but has the drawback of not being able to see the bike before you buy.
  Many cities also have Facebook groups for buying and selling bikes and bike parts.
  The only downside to buying second-hand is that you aren't necessarily guaranteed of the condition of the various components (parts) of the bicycle. However, by asking a few questions and giving the bike a good once-over, you can ensure that you're buying a quality machine. Here are a few things to look for:
  The frame is the body of the bike, usually made of tubes of metal, to which everything else (wheels, handle bars, pedals) is attached. The fork is the bit to which the front wheel is attached. Have a look at the frame and fork from all angles (front, back, both sides, top, and underside) and make sure there is no structural damage to them. Look for cracks and major dents.
  Small dings or chipped paint in a metal frame are usually cosmetic and not harmful, however anything that looks like it will compromise the strength of the bike should be a reason not to buy it. Ask the owner if the bike has ever been in an accident, and how it has been stored. Hopefully no one will try to sell you a bike that's going to fall apart, but you never know, and sometimes its previous owner might not be aware that it's dangerous.
  Steering Alignment & Headset
  Make sure that the stem, frame, and fork are in alignment. When you're looking down at the bike from the top, when the wheel is in line with the top tube of the bike, the handlebars should be perpendicular to the wheel.
  Pull the front brake lever tight (in the UK your front brake lever is usually on the right, in the US it's on the left - I have no idea why they are different) and rock the bike back and forth, front to back. If you feel any movement between the head tube and the fork, the headset (the parts inside the frame that make you able to steer the bike) is loose. You can put your finger over the crack between the head tube and the fork to help you determine this. A mechanic can tighten this for you, but a loose headset may be unsafe to ride.
  Conversely, a headset that's too tight can make the bike difficult to steer. Pick up the bike by the front end, and turn the wheel left and right. It should turn easily and smoothly - if it doesn't it's probably too tight.
  Pick up the front end of the bike by the stem and spin the front wheel. It should spin in a straight line without wobbling back and forth, left to right. Do the same for the rear wheel. If it wobbles, the wheel is "out of true" and will need to be adjust by a mechanic.
  Take a look at the tires (the rubber part that goes around the wheel). First, make sure they have air in them (they should feel firm, and not depress when you push on them). If they don't, ask the owner to pump them up and make sure they are puncture-free and will hold air. If not, you'll need to replace the inner tubes inside the tires before you can even ride the bike.
  Second, all tires will have some sort of tread pattern on them - on some it will be very minimal, and on others it will be obvious. Look at the very middle of the tread, and compare it to the part of the tread that wraps around the side of the tire. If the tread is completely worn smooth in the middle of the tire, it is more prone to punctures, and will need to be replaced soon.
  It's no big deal to buy new tubes and tires, but it is an expense, and if it looks like the bike you're buying will need new ones soon, you may be able to negotiate the price of the bike accordingly.
  Side note: even if the tires on the bike you're buying have plenty of life left in them, you may want to consider budgeting for a new pair. If you're commuting often, you'll want something that is very puncture-resistant, and your local bike shop can recommend a sturdy, kevlar-lined, commuter tire. I've always run Continental Gatorskin tires on my commuter bikes, which run about £24 for a single tire, but have lasted me hundreds of miles with almost no punctures. Fewer punctures means fewer replacement inner tubes you have to buy, which can save you money in the long run.
  Take a look at the brake pads on the bike. If they are worn down to the grooves, they will need to be replaced soon in order to function properly. If the bike has been ridden with brake pads that are too worn down, they may have caused damage to the braking surface of the wheel. Take a look at the braking surface (the metal part of the wheel upon which the brake pad sits) and make sure that it's flat, and not concave in shape.
  Pull on the brake lever. If the lever depresses to the point where it's hitting the handlebar, the brake cable needs to be tightened. The brake cable should be tight enough that you don't have to pull the brake lever all the way to the handlebar in order to slow or stop. It's easy to replace brake pads, and to tighten brake cables, but knowing the above will help you to negotiate your price as well.
  Cables are what make your bike work and enable you to shift gears and to use your brakes. It's important that cables be intact in order to function properly. Have a look at the cables and cable housing (the tubing that goes around your cables) that run from your shifters to your drive train and from your brake levers to your brakes. If any of the cables are frayed or the housing is cracked, they will probably need to be replaced soon. You don't want a brake cable to snap mid-ride and leave you with little or no stopping power.
  The drive train of a bike consists of the chain, chain rings, cranks, cassette, and derailleur (image below). If the chain and cassette are rusted or caked with grime, chances are the bike hasn't been maintained much. A certain amount of surface rust can be cleaned, but if the whole drive train is rusted, it will need to be replaced.
  It's worth asking the owner how long she or he has had the bike, how much it's been ridden, and whether the chain and cassette have ever been replaced. A drive train is fairly easy to clean and lubricate (stay tuned for an upcoming post on how to do this), and your local bike shop will be able to measure your chain and tell you when it will need to be replaced in order to avoid mechanical problems. A chain that has stretched more than 1% over its original length will need to be replaced. A mechanic will be able to tell if it has.
  The bottom bracket is not a part of the bike that you can see. It's made up of the spindle that connects your cranks to your bicycle, and the bearings that allow your cranks to rotate freely. It needs to be replaced periodically. Ask the owner of the bike if she or he has ever replaced the bottom bracket. A good mechanic will be able to assess if and when you need a new one.
  Saddle & Grips or Bar Tape
  Less a safety precaution and more of a comfort one, have a look at the saddle and the handlebar grips or bar tape. If they are cracked, dirty, or worn down, or just plain uncomfortable, you may want to replace them at some point.
  Worth noting: even if a saddle is brand new and in good condition, it may not be the right saddle for you. Everyone's anatomies are unique and we all sit on saddles slightly differently. It can take some trial and error to find a saddle that will keep you comfortable on your commute, but your local bike shop may be able to let you demo some options.
  Just like with new bikes, it's a good idea to take a second-hand bike for a test ride. Ask the owner if it's alright if you take it out for a spin, ask them to help you adjust the saddle height so that you can comfortably reach the pedals, then ride around for a good 5-10 minutes, trying out the brakes and shifting through the gears. Make some right and left turns, and make sure you can turn the bike smoothly and easily.
  Once you've negotiated a price and made your purchase (yay!) I would recommend taking your new bike to your local bike shop for a basic tune-up. A good mechanic will get your gears shifting smoothly, your brakes nice and responsive, your drive train cleaned and lubed, and everything appropriately tightened and dialed. They'll also be able to help you get your seat height exactly right, which will make your commute comfortable and efficient.
  Buying a second-hand bike requires a little more savvy than buying a new bike, but by using the above guidelines you can make sure that you're buying a safe and quality ride! Happy cycling!
  Big thank you to Emily Samstag at Bicycle Habitat in Brooklyn, New York for cross-checking my facts. I'm not an expert, but she is!