How to install a bike seat post

If you need a new bike seat post, you might not necessarily need to replace your whole bike. Here are some tips from our team on how to easily fix a new seat post so you can get back out on the trails. 

Tools to install a seat post

The first thing you need to install a seat post is a suitable hex/allen key. One usually comes with the seat post when you buy it, but you can also buy sets of hex keys in various sizes. The allen key can be used to loosen the clamp bolts of both the old and new seat posts. In most cases an allen key size 4, 5 or 6 will do.

Before sliding the seat post into the bike frame, make sure to take some precautionary measures to prevent the tube from rusting later down the line - this will stop the seat post getting stuck, and will also help with maintaining or adjusting your seat post again later. For an aluminium frame and a carbon seat post, choose a suitable silicone spray. For a carbon frame use carbon paste to prevent rust, and apply it evenly on the inside of the frame and seat post tube.

Loosening and installing the seat post

Classic seat posts are attached to the bike frame with one or two bolts. Loosen the clamp or bolts at the bottom of the seat post with the hex key to pull the seat post out of the seat tube. Place the seat post on a table with the saddle facing down. 

You’ll notice a range of adjustment points indicated on the rails. You need to clamp the rails to the seat post in between the two endpoints of the markings. Do not mount the saddle beyond the markings, as this can increase the risk of a saddle-frame break. Different saddles will have different saddle adjustment ranges, so make sure to test your sitting position when buying a new bike saddle.

Next, loosen the seat post bolts which clamp the saddle to the seat post. Turn the top plate of the clamp to remove the saddle.  If the old seat post is too worn out, replace it with a new one. Now you can clean, grease and afterwards reinstall the old seat post again. Use assembly grease or special carbon assembly paste to prevent dirt or moisture from penetrating the seat tube and causing corrosion or wear. You can avoid stuck seat posts by adding grease to your regular bike maintenance routine.

Before removing and loosening all bike parts, it is important to measure the distance between your saddle and handlebars, the height of your saddle, the fore-aft position and the tilt so you can make sure your new seat post sits in the same position. 

When you’re ready to install the new seat post, fit the saddle to the frame again by sandwiching the saddle rails in the saddle rail channels of the two clamp plates. Turn the clamp bolts with your fingers until tight - but not too tight, so you can still adjust the position of your bike saddle.

Now you need to adjust the saddle forward or backwards using the range of adjustment markings on the rails. Once you’ve got it in the perfect position, tighten the clamp bolt(s) to fix the saddle. Sometimes your seat post will have an additional bolt which can be used to determine the angle (or tilt) of your saddle. 

When all these adjustments have been made and you’re happy with the positions, tighten all bolts as much as you can. Then, slide the seat post back into the frame and set it to the right height. Finally, tighten the seat post clamp bolt or the quick-release lever to connect the seat post to the frame again. Now you’re ready to get back out on the trails!

How to make sure the seat post is in the right position

Make sure to check the front and rear of the seat post, so that the front of the seat post always points to the tip of the saddle and vice versa. If you use a torque wrench to tighten the bolts, the bicycle frame or the seat post won’t be damaged. The torque specifications can normally be found in the manual of your bike. For safety and a comfortable ride, it’s important to properly tighten your seat post and bike saddle with the right torque. 

A seat post is correctly set when all moving parts of the seat post can no longer slip and the height, fore-aft position and tilt of the saddle fit your sitting position, your type of bike, and the terrain you’ll be riding on.

Head to our Cycling Inspiration hub for more bike maintenance tips. Ready to replace your bike with a new set of wheels? Browse the new range of Raleigh electric bikes now.