dam seat post
 

i have a 2004 trek 6700. the seat post has a tendency to slip down a tiny bit every 3 or 4 rides. today my legs didn't feel so good on the way home. when i got home i measured the seat hight, and sure enouph it dropped about 3/4 of an inch. i have the lithium grease on the seat post, because without it the post somehow makes a ticking noise. keep in mind i weigh 265 pounds. I am tightning the quick release about as tight as i can get it... have to really push to close it. would a non quick release bolt fix my troubles? any other suggestions?

i knew it... there is no answer to my problems!!

Well you might try getting rid of the Quick release on the seat post clamp and going to one with an Allen screw. It should be more secure. I certainly would try this.

Doc

You might want to take your post to a shop and get it miked against some other posts of the "same" size. Get one that is largish. A light knurling, some shops have a gadget for doing it, might be do it as well.

I've usually found that binder bolts aren't as tight as quick releases. However, I'm a big believer in the uses of old tubes. See if you can fit a section of old road tubing in there, in between the post and the frame, and be super careful not to drop it into your frame :) If you can fit this, it should work. If you do decide to go with a binder bolt, one nice thing is that you can use a section from an old mtb tube as a gunk guard. You slide the post through it when you install it, and this covers the gap between the frame and the post, so that no ooze and water get in there. Like a suspension fork boot. One of the many uses of old tubes...

A beer can shim can also work,as can roughing up the post with coarse sandpaper.

I've had the same problem. I ride daily over 8 miles of gravel road which is very washboarded and potholed lately (hasn't been graded for 2+ months). Every few days I notice my legs are uncomfortable, so I stop and raise the seat an inch or more. I've got the quick release as tight as I dare, so I'm going to replace it with a bolt.

Make sure to grease the cam part of the quick release lever. I had a similar problem and thought I was really tightenning the quick release, when it was actually the friction between the two bearing parts I was feeling. Once greased, the lever turned smoothly and with less effort so I could properly tighten it.

Dave

I had this same problem on my commuter bike. :mad:

I went the route of an allan head binder bolt and have had no more problem with the seat post slipping down! :p Worked for me. ;)

Get rid of the grease. Is the seat post alloy or carbon? If the latter, no grease. If the former, have you tried either a shim in the seat tube or the old standby -- teflon tape - a couple of turns around the seat post prior to insertion. Have you tried getting rid of the quick release and using a bolt ... might be able to get a bit more traction. Is the seat post OEM stuff or aftermarket. Is it the right size.

Hi
A common problem. As you are 265lb, get rid of the Quick Release clamp and install a normal 5 or 4mm allen key bolt clamp. There are a number of soloutions to the slippage if this does not work. Make sure the post is not a slack fit or you will end up cracking the frame! These soloutions will also stop the ticking noise.
1.Clean off the grease on both the seatpost and inside of the tube. Smear seatpost with Loctite 222 low strength (purple) threadlock, available from friendly engineering stockists in 6mm tubes. This will set gently and prevent the seatpost slipping, but allow you to easily get the post out in the future. It will also prevent corrosion of the post or frame as it excludes air. It sets when you tighten up the clamp and air is excluded. This is the best cure. Don't use other threadlocks if you want to remove your seatpost later!!!!!
2. Find a workshop with a 'Stein' Knurler which will put a criss cross pattern on the seatpost and prevent the slipping.
3. Rub the seatpost with candle wax or beeswax and install. This will grip better and still prevent corrosion.
There are a number of other 'dirty' ways to do things to seatposts /frames to stop them slipping but I will not upset the engineers who view this forum!!!
Hope this helps

i took off the grease, and used a piece of beer can as a shim. I went to get a bolt (instead of quick release) but they had to order it. no grease and the beer can appear to have fixed the problem.. Cheapest fix so far!!! (i was forced to buy and drink a 6 pack of beer, to have enough cans to practice, and cut the piece just right.)

Probably the most elegant solution would be to have the seat post knurled. That would be so cool. If your lbs can't do this, a general machine shop can.

Doc

well the beer can shim worked for a while... but it was a MAJOR hassle trying to adjust the seat. so i finally broke down and got a non quick release seat clamp. problem is now 100% fixed. did this about a month ago, just forgot to update the board. i now have it greased the way it is supposed to be, and not hearing any noise, and absolutely no slippage.