Essential Knowledge Guide

Setting Up Your MTB
Seat Rail Adjustment (Cockpit Length Part One)

Now that we have determined your Maximum Effective Power Stroke with the seat height adjustment, let's go on and find the proper alignment for all that power.  All seats (I imagine, anyway) are built on a pair of rails that allow the seat to be moved forward (towards the front of the bike) or backwards (towards the rear of the bike).  This is so you can align the downward force of your legs over the pedals properly.

Now you need a piece of string with a nut or some weight tied to the end.  The string needs to be longer than the bone between your knee and ankle. 

Ride your bike for a little while to get your normal riding position.   Park on your wall or tree.  Back pedal until your crank arms are horizontal to the ground.  Hold the free end of the string on the inside of your forward knee. Just below and inside of your knee cap there should be a bone sticking out a little.

The weighted end will hang freely near your shoe.  When the weight hangs still, it should direct a line fromt the inside of your knee, through the ball of your foot and the pedal axle.

Notice the yellow line in the picture to the left.  This is what you are looking for.

If the weight hangs too far forward, move your seat back, and vice versa for hanging too far back.  Once you get this close, go for comfort.  Seated in riding position, most of your weight should be on your sit bones.

Most seat posts have a single clamp and bolt that holds the seat on.  It's usually located directly behind the head of the post.  Loosen this bolt while taking care to keep the clamp from changing it's tilt.  Slide the seat forward or back as necessary, and tighten the bolt once again.  If you go back up and look at the picture of my post and seat, it'll probably look different than yours.  The Syncros head has two bolts instead of one, which makes the seat harder to adjust.  However, it is a great deal more accurate for tilt adjustments. 

You may notice from the picture above and to the right that I have a plastic paddle stuck in the leg of my riding shorts.  Hey, I didn't have any string!  So I used a paddle-ball game instead.

Now you have maximum power on your down stroke.  But there are still a few more steps to setting up your bike.  Now we are concerned with your "attack position" and comfort.  Specifically, we will look at the height and tilt of your handlebars, and then explore one more seat adjustment.