In article . com,
says...
Seat post keeps slipping even though the quick release is very tight.
Dealer wants me to replace the QR with a bolt. I can actually rock the
post back to front a bit. This has never been the case with any of my
other bikes, and I don't want to crush the tube if the post is the
wrong size. Post looks like 30.9, tube looks like 31. Should I look
for a 31 post or just crank down the bolt. Thanks for the help. Pedro


Get a micrometer or vernier calipers, or have the LBS guy, measure both
parts. Do not crank it down first.