Whenever purchasing a bike you have to be sure that you purchase the one that has a frame that matches your body needs. If you purchase one that does not have right sized frame then you just may not be able to adjust the level of seat to your needs. When straddling the bicycle it is important that the top tube of the bike and your crotch should maintain a distance of at least half inch between them. In case the space is just not sufficient then there are chances that you might hurt yourself. When paddling the bike your knees should be able to bend slight. In case your knees are straight then the seat is too high and if they are bent more then the seat is probably too low.
If the seat is of not perfect eight then there are chances that you might get them hurt when riding. In case you are unable to adjust the seat level to your desire then you might have to choose another bicycle. When purchasing bike it is important to note the seat angle because if the seat is tilted too much then the gravity might manage in pulling you down when riding. This will increase the amount of pressure you put on the handle bars, wrist, fingers, neck and arms. If you simply feel the seat is too much uncomfortable then you have to try and get it replaced or adjusted.
When purchasing bicycle for yourself you have to try and pay attention to the nose saddle as it needs to be exactly behind the bottom bracket. In case it is extended then there are chances that you might have to paddle behind or underneath you. When paddling in the normal riding position it is important that you should be able to paddle without exerting much pressure to avoid knee injuries and pain. Try selecting a bicycle that has perfect handle bar style. Most mountain bikes and cruiser style bikes are provided with handle bars that enable you to maintain an upright position when riding. It is important that you have to ride without actually hunching over the handle bar. Hunching can at times be very much uncomfortable as it tends to limit your visibility when riding. Even if you manage to stop fast there are chances that you might hurt yourself by flying over the handle bar. In case the bike has old fashioned handle bar then you can always manage to replace it with cruise styled handle bar without replacing the bike.
Always keep in mind that the handle bard should maintain the height with the seat level so you can maintain an upright position when riding. You can also try raising handle bar to the seat level, so if that is possible then you have to try and adjust it accordingly. In most cases you might also have to install a new brake along with shifter cables to make it a comfortable riding machine.