As a full-time professional mechanic, I notice many of the same questions and issues arise season after season. One that we revisit is: how can I tell if my seat post is slipping?
This is a problem that I ran into several times in the past few weeks. Make sure the saddle is at the correct height. You be the judge of what?s correct, don?t ask me. Always use a metric tape measure. Bikes are cool. They like the metric system.
Figure out a way to measure your seat height in a way that you can duplicate. The most accurate way is to measure 13 cm back on the saddle, hold the end of the tape measure there, sight along the end of the tape measure and see that it?s horizontal with the top of the saddle. Pull the other end down to the center of the crank bolt and take a reading. This will give you a consistent measurement from the same place on the saddle to the center of the bottom bracket. After a few times, you?ll be able to get an accurate number no matter what saddle or bike you use. Keep this number written down somewhere handy.
Now make sure your seat height is where you want it to be. Grab a clean shop rag, Oranj Peelz, and electrician?s tape. Clean off the seat post above the collar. Get rid of any grease or road grime. Cut a 10 cm piece of tape. Wrap it around the seat post, nice and even. Leave about a millimeter between the tape and the highest point on the seat collar.
After going over some pav?, you can now look down and see if there is still a tiny space between the tape and the seat collar. If there isn?t, that means it?s slipped down. If that happens, pull out the post, clean it, and smear some grease on it. Pull out the seat post binder bolt, clean and grease it. Reinsert the post to the proper height, reinstall the bolt, and tighten to the appropriate torque. Clean off the grease. Keep a spare binder bolt handy. They break.
Many cyclists spend more time on their bikes than the average American does in a car. The correct position matters. It?s useless to drop plumb bobs, shoot lasers, measure femurs, or multiply things by .887 if a seat post is slipping. This changes everything, and can possibly cause knee discomfort or damage. Whenever I am washing or working on a bike, I always check the tape. It?s a small preventive trick that works great.