I noticed there are lots of newbie questions asked here. So why not compile a good old FAQ? You are welcome to add your bits of wisdom.

1. What kind of bike should I buy?

Surprisingly, if you have to ask this question the answer won't matter that much, because you need to gather some experience first. Follow your preferences and common knowledge. If you want...

...just to get from A to B --> buy a commuter bike / hybrid bike / touring bike

...travel or cover long distances --> buy a touring bike

...to zip along asphalt strips and never leave the road --> buy a road bike

...to venture offroad --> buy a hardtail mountain bike

...to do some serious all terrain riding -> buy a trail bike / all mountain bike / enduro bike

...to race down mountains at top speed -> buy a downhill bike

...to ride on the beach --> buy a fat bike

...to hop over rocks and stairs --> buy a trials bike

...to jump and nothing but jump --> buy a dirt jump bike

...to impress teenage girls with bike tricks --> buy a BMX bike

2. How much money should I spend?

Simple answer to that: as much as you can afford. Quality and longevity correlates with price. Unless you have good knowledge of bicycles and manufacturers, buy a big brand like Giant, Trek, Merida, Cannondale, Specialized, Bianchi, etc. Do not buy an el-cheapo Chinese bike from Tesco unless all you want to do is ride to the next 7-eleven shop. These bikes wear out fast and when they do, they can become a safety hazard. If you are on a small budget, consider buying a used brand name bike instead.

3. Where should I buy?

Fortunately, there is a website that offers a comprehensive list of bicycle stores (some with reviews) in Thailand: http://bicyclethailand.com/bike-stores/ - For the 2nd hand market, check out thaimtb.com (if you can read Thai).

4. Is it worthwhile importing a bicycle into Thailand?

Most of the time, it isn't. You will have to pay for shipping and customs, and the latter can be complicated and expensive. For most big-brand retail bikes, there isn't much of a price advantage. However, if you fly abroad you can carry back a bike in your baggage and probably save customs and shipping. Or you could buy a frame abroad and build it up here, so there are some exceptions.

5. What are the idiosyncrasies of the Thai bicycle market?

There are a few. First, it is difficult to find large frames from size "L" up. Second, most bicycles shops are mom-and-pop stores with limited stock and selection. Third, most of them don't speak English (surprise, surprise, you are in Thailand). Fourth, shops in Thailand seldom carry the latest models; expect the current year's models to arrive around June. Fifth, there is a dynamic 2nd-hand market and used bikes / old models fetch relatively high prices compared to Europe or America.

6. What frame size should I buy?

Bike fitting is not black magic, but a matter of experience. If you haven't done it yet, first determine the best frame size for you by using a chart or an interactive calculator. There are different charts for different types of bicycles (e.g. mountain bike, road bike, etc.) and there is always a bit of variation, which means that two arbitrary "M"-sized frames won't feel the same, as frame geometry varies. Frame geometry determines ride characteristics and ergonomics. Keep in mind that you can adjust seat post, saddle, stem and handle bars which determine the contact points. These adjustments are just as important as getting the frame size right. Experiment with them to optimise posture, balance, and ride characteristics.

good idea, Chiangmaiexpat!

7. Should I go for disc brakes or rim brakes are good enough?

There are other types of brakes of course, but I'd say they are not so widespread.

In many cases rim brakes are enough to stop your bike: commuting, lazy touring, city rides, fitness (cardio) training etc. But they have a very serious disadvantage comparing to disc brakes. They lose most of their braking power in wet conditions. This may be important when you go through a hard traffic in the city, or descend a steep hill. Rim brakes also "eat" your rims, as it comes from their name. Especially in wet conditions the abrasive wear of your rims will be much higher.

In these terms disc brakes are more reliable. They are also easier to maintain (change pads) and usually need less maintenance. Disc brakes can be hydraulic or mechanical. Mech brakes are cheaper and easier to service, but still efficient. Hydraulic brakes may need to be taken to a skilled technician when you need to bleed them.

8. I've ridden my friend's bike (of the same type) recently and noticed that I can go faster than I do on mine. I am not happy with my bike anymore, what should I do?

Unless you ride a heavy metal machine built with water pipes, do not hurry to throw your bike out. Take a look at your wheels first.

Most of the bikes including the road racing ones come with very cheap entry level wheels. Wheels, I'd say, form about a half of your bike's agility. The stiffer they are - the better your effort is transferred to the ground, the faster you go.

Cheap entry level wheels are also less reliable and have to be serviced often: spokes lose tension, rims become wobbly, so you lose a lot of your power to surpass your wheels' deformations. Take your wheels to a wheel builder to check them, and should you still be unhappy, try to put your friend's wheels on your bike and ride.

Tires (tyres?) are also very important as their rolling resistance may vary significantly from model to model. The pressure is also significant - always check your tire pressure and keep it within a recommended range (usually printed on the tire) having in mind your weight and riding conditions. A difference of 0,3 - 0,5 bar may change a lot.

9. I've followed the item 6, but my butt still hates my saddle. Should I buy a wider/softer one?

Not always a wider or softer saddle means more comfort. Moreover, a sport saddle may feel much more comfortable if it suits your constitution, unless your usual rides are a few hundred meters to the 7-11. There are many saddle makers and most of them have comprehensive guides (on websites) on how to chose your saddle. Many shops offer test saddles that you can try to ride and understand what you really need.

Remember: do not rely on your feelings if you try a saddle on a stationary trainer. Everything may change when you are out on the road.

Pls feel free to delete anything you find irrelevant. And accept my apologies for my bad English.