unfixed seat is bettern than fixed seat when cycling?

Question

slightly up and down can avoid shock.
free left and right helps speed?

Answer 1

Speed is directly related to "power to the pedals". Anything that absorbs this power and doesn't let it transfer to the pedal (and through the gears to the rear wheel), is sucking down your speed and energy.

This includes such items as: vertical suspension on front OR rear OR seat, excessive horizontal motion (like that caused by the 'wiggly' seat you describe in your question), soft soles on your shoes (allowing your feet to absorb some of the effort and therefore detract from what goes to the pedal), poorly aligned chain and rings, large wheel contact patch (think wide soft tires), and so on.

Simply put, a fixed seat will be better in the long run for making your cycling simpler and easier.

That being said - not all seats are created equal. Find one that suits your anatomy the best, and stick with it. Comfort rules over the mechanics every time ... if you don't enjoy getting on the bike, eventually you're going to find reasons to leave it in the garage and do something else entirely. And yes - this MAY indeed mean one of those springy, swivelling monstrosities that seem to be the norm for today's cruiser style bicycles!

Answer 2

Fixed seat is better, since if it is not clamped down it will be dangerouse. However, you can get a shock post, which will give you some of the benefits of a full susser. However, if you want speed, fixed seat, since some of the power that you would put into the peddle is absorbed by the extra suspension.

Luck

Answer 3

If the seat is too high or too low it will affect the mechanics of your pedaling motion. Too low and you will hurt your knees, too high and your hips will rock back and forth.