Seat sliding down

[pumpkinpony]

Mine was doing that - I took it to the LBS and he 'roughed' up the seat tube and put a friction compound on it. Worked well!

[PamNY]

I really wanted the hose clamp to work, but I have a classic NYC antitheft chain on my saddle. Can't take the saddle off and I couldn't get the hose clamp back together after I opened it up.

So I had no choice but to go the the LBS. This will forever be the mystery problem with a mystery solution. The very busy LBS fixed it while I waited (on a sunny Sunday afternoon). The mechanic speaks little English, and I speak little Spanish so we couldn't really communicate. They didn't charge me, so I didn't press the point, and hightailed it for Central Park.

Bike is fine now, and thanks for the suggestions. At least I know what they might have done.

[W15]

I had that isssue with a carbon seatpost and hairspray solved the problem! I borrowed hairspray from a woman in my office, sprayed it on, let it mostly dry then set the post to the appropriate height and let it dry completely and have not had an issue since.