seatpost sizes

nomotornozen

I needed to replace the seatpost for a Specialized Hardrock with a longer post, and took the old post to my LBS where the ordered a longer post after measuring the one that came with the bicycle when I bought it used this fall. The new post is long enough, but fits tighter than the first post. Both posts measure out to be within a few thousandths of each other, and that should be close enough for interchangability. I'm wondering how many different sizes there are for seatposts, and if the first post may have been the wrong size when I bought it but fit due to the fact that it was too short for me and wasn't inserted nearly as far as the new post. Or would there be another reason why the new post is so tight?

sir.crashalot

There is a boatload of diff sizes. I wish companies can agree on one or two diameters!!
Your Hardrock takes a 30.9, make sure this is correct before trying anything else. Check your seatube to make sure it is round, not oval or deformed. As well, make sure the inside is good and clean - free of debris and burs.
The seatpost collar bolt/qr should be good and loose before attempting to insert the post into the frame - don't forget to put some grease on it
Good Luck