| This seems like as good a time as any to discuss purchasing and sizing a bicycle. If you already have a bike and aren't interested in getting another one, you can skip down to the Sizing section. Having more than one bike is way cool, though, especially if your bike is your only form of transportation.
I'll start by saying that low-end bike-store bikes have gotten a lot better over the last 10 years; you can't really go wrong. As a general rule, it's worth spending extra money up to about $700 or $800;after that you're paying for stuff you don't really need. If the guy at the bike store is telling you about some cool feature the bike has (like under-bar push-button shifters) you are probably paying for stuff you don't need. The features you need on your bike are pedals that go around, brakes that work and shifters that work; everything else is vestigal. That's not to say that you should buy the cheapest functional bike; you should just be aware that extras aren't really necessary.
Note that I said low-end *bike-store* bikes. Do not buy bikes from Target, Toys R Us, or any other non-bike store. Those bikes are cheap in dangerous ways; the brakes are particularly bad. They're heavy, they're constructed by morons, and they are practically impossible to adjust properly. Do yourself a favor, buy a reasonable bike. Expect to spend $250; in this case, you get more than what you pay for.
I should get some terms defined here. Your frame has 4 tubes:
TOP TUBE: The, uh, top tube. The rear brake cable usually runs along it.
SEAT TUBE: The tube that holds the SEAT POST.
DOWN TUBE: The other main tube, the diagonal one on the bottom. It has shifters on some road bikes, usually has waterbottle brazes, and the shifter cables usually run along it.
HEAD TUBE: *Not* a cheesy porn flick. This is the short tube that connects the down tube to the top tube. Inside it are the STEERER TUBE and the STEM.
STEERER TUBE: The tube connected to the FORK (which holds the front wheel) and the STEM through the HEAD TUBE.
STEM: Controls the STEERER TUBE and holds the handlebars. It is adjusted via an allen bolt (usually) on the top.
SEAT POST: Holds the seat. It is adjusted by a bolt at the top of the
SEAT TUBE. It holds the seat in a clamp; the seat is adjusted via a bolt on this clamp.
I look for the following minimal features in a bike:
ALUMINUM WHEELS: Not only are they lighter than steel, they're easier to keep in adjustment, and they are *much* better at braking when wet. They say that upgrading your wheels is the easiest way to upgrade the performance of your bike; start off with good ones.
NO IDIOT LEVERS: If your bike is a road bike with the curved "drop" handlebars, the brakes are mounted on the "hooks." On cheap bikes, in addition to the main brake lever, there is another lever that extends inwards, parallel to the bars. Do not buy a bike with these; they are extremely dangerous (they don't brake well enough to use in an emergency) and they're a sign that the bike is not designed well. If your bike has these levers, I suggest removing them. NO STEM SHIFTERS: Again, this is for road bikes; on some bikes, the shifters are mounted on the stem (the thing that holds the handlebars). The idea is that they're closer to your hands and therefore easier to use; the reality is that you have to raise your center of gravity while twisting your body to use them. They also are very susceptible to being hit by your knees while climbing (a very bad scene), and in an accident they can wind up goring your throat. Insist on down-tube or bar-end shifters for road bikes.
As you probably know, there are three main types of bikes:
ROAD BIKES: Dropped handlebars, thin tires, down-tube shifters. Road bikes are lightweight and fast and have significant advantages over the other types for road riding. They can also ride on packed dirt roads without much trouble; they can't ride in loose dirt or sand. One drawback road bikes have in Berkeley is that, because of their narrow tires, they don't handle bumps and potholes as well as the other types. One advantage they have is that thieves don't seem to be interested in them.
Touring bikes, such as the Bridgestone RB-T, are road bikes with wider tires and a more relaxed geometry to handle bumps better. I find them to be excellent for commuting; my main commuting bike is a Schwinn Voyageur (sadly, Schwinn no longer makes it). They are slower than other road bikes but faster than the other types.
One problem you'll have buying a road bike is that most bike stores don't carry inexpensive ones, so you'll find it difficult to get a test ride on anything cheaper than $500. Since I highly recommend a test ride, this is a significant drawback.
MOUNTAIN BIKES: Straight handlebars, big knobby tires, handlebar shifters. Mountain bikes own the lion's share of the new bike market; they're fun to ride and cool to look at (people who want to look at their bikes rather than ride them tend to buy mountain bikes). They are great at handling bumps and can also ride in loose dirt or on singletrack trails. They are significantly slower than road bikes on roads; just yesterday I was riding my mountain bike and felt like I had no energy at all. They also are targets for thieves in Berkeley; if you own a mountain bike, be prepared to take extra precautions to protect it.
Mountain bikes are viewed as being more comfortable because your riding position is more upright; this is incorrect. This position is more comfortable only while you're looking at the bike, or perhaps sitting on it in the bike store. It puts more strain on your lower back, and the lack of extra hand positions also causes problems on long rides. Mostly because of the theft issue, I can't in good faith recommend a mountain bike for commuting in Berkeley. If you're looking for a bike you can take anywhere, or if you specifically want to ride off-road, mountain bikes are great, but I think taking them to campus every day is a bad idea unless you have a private office where you can keep them.
HYBRIDS: After the mountain bike boom of the early 80's, people started realizing that they weren't riding their mountain bikes off-road. Since mountain bikes have significant disadvantages on-road, hybrids were created to combine the features of mountain bikes and road bikes. They usually have an upright riding position but less so than mountain bikes. Their tires are wider than road bikes' but usually not too knobby. They often have handlebars with more hand positions than mountain bikes do.
As you might expect, they are faster than mountain bikes but slower than road bikes. They are theft targets more than road bikes but less than mountain bikes. They are better in loose dirt than road bikes but aren't really appropriate for serious off-road riding. I find that hybrids make decent commuting bikes, but the upright riding position makes them undesirable for long rides. For around-town riding they're good though. There tend to be a lot of hybrid selections under $500 since they're aimed at casual users.
There are also recumbents (bikes on which you sit on what looks like a deck chair) and tandems. Recumbents are comfortable and attract a lot of attention; they are bad at climbing hills but good at flats and downhills. There's a growing recumbent market. Tandems (two-man bicycles) are the most fun you can have on two wheels, but good ones are expensive.
HOW TO CHOOSE A BIKE
First, obviously, you need to decide how much money you are prepared to spend. I advise being generous, as I said earlier; spending extra money will get you a better bike. Expect to spend at least $250; you won't get many choices at that level so realistically you should expect to spend $300. If you can't afford to spend that much, you can get good deals on good used bikes. If you look around lots of people never ride their bikes and eventually wind up just dumping them. A used quality bike will serve you much better than a new Target junker. Once you have a price range, head to a bike store. Do not allow yourself to be rushed; test-ride a number of bikes and don't skimp on the rides (details on test riding below). Consider theft resistance; does the bike have a quick-release seat that you'll need to buy a cable for, or take with you? Look at the frame joints; are the welds (or brazes) clean or sloppy? Are the wheels true? The brake lever end should have a maximum travel of about 2 inches (a little less for mountain bikes) and you should not be able to bottom it out. Are the brakes sidepull or cantilever? (Cantilever brakes are mounted on pivots on the fork and seatstays, with the main cable pulling a transverse cable, which straddles the wheel. Sidepulls are mounted directly above the wheel with the cable pulling them together on one side.) Cantilever brakes are good if you plan to put fenders on the bike (which immensely improves cycling in the rain). Sidepull brakes tend to work more smoothly and stay in adjustment better.
HOW TO TEST RIDE A BIKE
The main things you're interested in on a test ride are to find out how the bike handles bumps, to find out how the brakes and shifters work, and to see if it was well-built. Before you go to the bike shop you should have a plan for where you intend to take the bikes you test. Take the bike on Hearst or somewhere similar; how much does it jar you when you're going downhill? When it hits bumps, do you hear unexplained rattles? You should expect your rear derailleur to snap when you hit bumps, but if other things on the bike are rattling it's a sign that something is cheap or poorly fitting.
To test the shifters, start by riding on a flat road and shifting through all the gears. Does it easily shift into the lowest gear? If you over-shift into the lowest gear, does the derailleur sound like it wants to self-destruct into the spokes? (If it does, stop over-shifting, but that's a count against the bike.) Does it shift cleanly into the highest gear, without jumping over the end? Can you shift between the front chainrings easily, without the chain jumping off? On a triple crankset it can be expected that the chain will jump off sometimes when shifting to the smallest chainring, but on a double it should never hop off and it should never hop off when shifting to the large chainring. Try out each cog for a while; does the chain run smoothly and quietly on each cog, or does it chatter or jump off one or more?
Try to downshift while pedaling uphill; it's harder to shift with tension on the chain and cheaper shifting systems will fail to. If you're spending$500 or more, though, you should insist that the bike be able to make this shift cleanly.
When you're riding uphill, do you hear pinging sounds in the wheels? If you do, they were poorly built; the sounds will eventually go away but the wheel will need to be re-trued.
Head downhill and hit the brakes; do you stop smoothly? Do you feel like you have control over your deceleration? Cantilever brakes are somewhat rougher than side pulls and feel spongier, so expect that.
Walk the bike while turning the handlebars, do they turn smoothly through their range of motion, or does it feel like there are notches at various points (especially straight ahead)? Try some medium-speed turns on pavement; does the bike corner solidly (if a road bike; knobby-tire bikes corner horribly on pavement)?
If you are planning on riding off-road, find a dirt trail or two (there are some on campus) and see how the bike handles them; can you accelerate from low speed on the dirt? Can you turn without skidding? Can you shift on a bumpy section?
As I said, try out a number of different bikes in your price range; there's no way to measure how good a bike feels to you. And most importantly, once you buy it, RIDE BIKE!
SIZING A BIKE
There is no formula to determine perfect bike size and adjustment; there are plenty of rules of thumb, but really bike adjustments are a highly personal thing. You are the only one who can determine your perfect setup. That said, here are some rules of thumb: Your seat height should be adjusted so that your leg is almost fully extended at the bottom of your pedal stroke. Test this by sitting on the bike leaning against a wall. Put your heels on the pedals and pedal backwards; your leg should be fully extended at the bottom. Most people adjust their seats too low; I've seen "cycle safety" manuals that recommend keeping your seat low enough that you can put both feet on the ground while sitting on your seat (HINT: Do not do this). Low seat height is the major cause of cycling knee injuries. You can adjust the tilt of the seat by loosening the bolt on the clamp underneath it. Most people are comfortable when their seat is level, or tilted just slightly forward, but again, this is mostly a matter of personal preference. I've ridden comfortably with a seat tilted back. Stem height is another preference thing; most people are comfortable when the height of the stem is about the same as the height of the seat; higher will give a more upright riding position, lower will bend you over more. Mountain bikes usually have stems that place the handlebars a little higher than the seat to promote the upright riding position.
Stem extension is a measure of how far in front of the head tube the stem holds the handlebars. It cannot be adjusted without buying a new stem, but you might be able to get a good bike shop to swap stems on anew bike. If it feels like the handlebars are too far away, a stem with a shorter extension (ahem) might be good for you. If you have along torso, a longer extension could help. If you have dropped handlebars, the tilt of the bars can also be adjusted; usually the bolt is under the stem where it clamps the handlebars. As a general rule, the end of the bars should be aiming at a point somewhere between the top and the center of the rear wheel, but again, that's a preference thing. Some people do wacky things with the bars, pointing the ends straight up in the air or having them upside down. I recommend against that; it invites impalement. Also, ALWAYS keep something stuffed in the end of your bars, whether it's the plug that game with the handlebar tape, a fancy expander plug, or a champagne cork.
That's about it for the adjustments. Always remember that your gut feelings are more important than the rules of thumb; if you are more comfortable, especially on long rides, with some non-standard setup, by all means use it. And by all means, ride that bike!
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EXPLOSIVE FRAME
