Get To The "Which One Should I Buy" bit already!

Fine, fine. Or rather, I'll tell you which one not to buy (unless you really know what you're doing, in which case you shouldn't be reading this):

• Any really, really cheap bike. If it costs less than about 250 dollars/euros, even on special offer, it's almost certainly junk.
• Anything with rear suspension.
• Anything resembling the torture instruments the Dutch inflict on themselves.
• A road racer.
• Anything marketed as a "city bike."
• A BMX bike, unicycle, fixed-gear, downhill bike with gi-normous tires, Custom Cruiser, expensive touring bike or cyclocross bike, or any other specialty bike.

A so-called Dutch bicycle. This one's hiding, because it doesn't want to cause any pain to anyone by having them ride it. Avoid. They're heavy, wobbly, slow, hard to maneuver, hard to stop, and give you a very poor riding posture. I once rode one right into some rose bushes when coming back from a party one summer night; took me weeks to get all the thorns out. On the upside, they can be rather pretty, if well made, they last forever with minimal maintenance, and riding a Dutch bike is great cardiovascular exercise, even if most pedestrians will overtake you.

But I want a...!

Fine, go ahead. Just don't blame me when it all goes wrong. All the bikes on the above "avoid" list have their legitimate uses, and if you're sure that your needs fit one of those legitimate uses, knock yerself out. (I have two road racers myself.) But if you drop four grand on a super-duper fully-suspended lacquer-painted downhill marvel, don't be surprised when (a) you'll find that it's not that great at going up hills, and (b) it got stolen 24 hours after you bought it. However, be especially skeptical of "city bikes" and really cheap bikes -- there really aren't many things they can do that something else couldn't do better and (in the medium term) cheaper.

Screw custom cruisers and bling-bling Klein downhill bikes. Tandem's the way to go if you want to get some attention -- and offer them a ride too.

Really, tell me. What should I buy?

Since you insist, dear imaginary reader.

If we cross out cheap junk bikes, Dutch bikes, racers, downhill bikes, and specialty bikes, what does that leave us?

• Fitness bikes. If your main use is exercise, go for it. However, if you need to leave it unattended outdoors, go with something else: it'll get stolen, and even if you're insured, it gets annoying to replace a bike that you've just managed to break in. In my opinion, a fitness bike is the only "specialty" bike a novice might want to consider, since it's an excellent ride, easily adaptable to different missions, and much more approachable and versatile than e.g. a road racer (which, I can tell you, is not much fun in a city full of curbs, tram tracks, sewer lids, and similar fun).
• Trekking bikes or "hybrids." If your main use is urban utility cycling with some fitness and touring thrown in, a trekker or "hybrid" is probably your best bet. They're not as pricey as fitness bikes and therefore less attractive to thieves, they ride reasonably nicely, and they can be easily adapted for a variety of different uses. (A hybrid is basically a mountain bike with bigger wheels, and a trekker is basically a hybrid kitted up with baggage racks.)
• Mountain bikes. If price was not a consideration, I'd only recommend a mountain bike if you intend to bike off-road, and in that case I would urge you to save up and get a good one costing a grand or more. However, for some reason they're very popular, and therefore if you're looking for a bargain, you're much more likely to find it in a mountain bike than a trekker or fitness bike. While most mountain bikes are just about useless for anything in the state in which they're sold, they're easy to adapt for a number of missions, including utility, fitness, and even touring. So, if your main concern is utility cycling, especially in an old-world-y city with lots of curbs, cobblestones, tramway tracks, potholes, sewer lids, and such, a mountain bike may be just your thing. I would steer you away from disk brakes, though -- they're thief magnets, and they add cost and weight to a bike without really providing any benefits you'd notice unless you're actually blazing down a muddy path somewhere.

A decent bike can be had for about 350 euros/dollars, less if you find a special offer or buy off-season, more if you want to dress it up a bit. Decent mountain bikes are the cheapest, and decent fitness bikes are the priciest: expect to spend about 500 and up on a fitness bike. Trekkers are somewhere between the two.

Don't get one of these. Either it'll scare the living daylights out of you and make you stop cycling altogether, or a spin on open road on it will make every other type of bike feel like complete rubbish. And you can't really ride it in the city because you'll smash the rims on curbs and it'll get stolen them minute you look in another direction. And you'll look pretty silly into the bargain. Oh, and you can get a half-dozen perfectly serviceable bikes for the cost of just one of these.

What to watch out for?

Look out for pigs with lipstick. That is, junk bikes that have had one or two flashy and expensive parts hung on them -- typically the rear derailer and/or a disk brake. If you see an obviously expensive part on an obviously cheap bike, it's almost certainly a pig with lipstick, and you should avoid it. Pigs with lipstick cost about as much, or just a hair less, than the minimum price you'd expect to pay for a solid entry-level all-rounder. So if you see a Shimano Deore XT derailer on a bike costing 300 bucks, a warning bell should go off -- that part belongs on a bike with a four-figure price tag.

Poor Brandy. Nobody deserves a bike like this: this one's a pig with a lot of really cheap lipstick on.

On the other hand, shop towards the end of the season, when the stores are clearing out the bikes to make room for snowboards. Big chains are perfectly acceptable places to find bargains on last year's bikes -- my sister got her extremely solid road bike from InterSport for a song, since she bought it in mid-winter. Mid-price big-chain brands like Nakamura, Nishiki, Insera, Scott, or Decathlon are sort of like the Toyotas of bikes -- there's nothing particularly exciting about them, but they'll get the job done just fine at a reasonable price. There's absolutely nothing wrong with buying your bike from a supermarket or general sports store, as long as you avoid the pigs with lipstick who also like to lair there.

The "Shimano series" of mountain-bike components which you'll find on most MTB's and hybrids, from most to least expensive, is XTR, Deore XT, Deore LX, Deore, Alivio, Acera-X, Nexave, and then some number-coded stuff. XTR is pure bling, while Nexave borders on junk. Acera-X is still just a bit dodgy, but everything from Alivio to Deore XT is worth what it costs. The corresponding series for road parts is Dura-Ace, Ultegra, 105, Tiagra, and Sora. (The latter is funny because it's Finnish for "gravel" which is one place you don't want to take a Sora-equipped bike.) However, Shimano doesn't make any really shoddy road parts; Sora is roughly at the level of Alivio or Acera-X, so there's not anything wrong with, say, a fitness bike that mixes Sora and Deore. However, beware of bikes with wildly different levels of components mixed together -- an Alivio-based bike can be nicely jazzed up with LX or XT shifters and rear derailer, but Acera-X or anything below it does not belong with Deore XT or LX. It can be a bit hard to detect cheap-outs, though, since there are plenty of manufacturers of perfectly good hubs, bottom brackets, cranksets, and brakes, and if you don't really know what to look for it might not be easy to see whether a hub is cheap junk or well in line with the rest of the bike. The TANSTAAFL principle is a pretty good guide for bikes too -- if a deal looks too good to be true, it probably is.