Seat post slides down
 

https://cimg3.ibsrv.net/gimg/bikefor...04143edffa.jpg
I have a seatpost that keeps sliding down and I got someone to have a look at it last week. A free bike mechanic. They put degreaser on it and the solution seem to work for a bit but then started sliding again. No matter how tight I try and clampit it makes really no difference. It's just seems to have gotten worse in the last 6 months. I have it held up at the moment with some items that were in my bike related box if you will and it seems to be working for now. I don't know if it's good solution but someone reading this might have a better solution than this

Have you check if you have the correct diameter seatpost for your frame?

Check to see that the seat tube itself and the clamp is not damaged or cracked. If nothing seems wrong, you can make a secondary clamp from a quick release clamp. I had to do this for my Brompton. This one is made from a seatpost quick release post. I had to file away the lip on the clamp to make it work.

https://cimg6.ibsrv.net/gimg/bikefor...f341211989.jpg

thanks its the same seatpost thats been on for years so kind of no need. fits fine . issue is new

Hi there is only one clamp on mine and no way to put another as far as i can tell. mine doesnt look like that. not a brompton. no cracks etc. not sure what you mean by the lip

It will work. Your seatpost is round, right? Look at this one, as a example. See the lip. Look carefully at it.

yes thats whats on the bike already. What lip? sorry i dont understand

Yes there is seatpost clamp on yours already. You would add one like the one I linked too but you would have to modify a bit. If you look carefully at it there is a lip on the inner edge. That lip needs to be filed down.

sorry i dont get it. So i would have 2 exactly the same? i dont see where or how. i honestly have no idea what a lip is on this

No, the original one clamps around the seat tube and forces the seat tube to pinch the seatpost. The additional one goes around the seatpost only, and prevents it from slipping down. There is a video of this made by a forum member and posted on the forum somewhere.

not with mine. i only have one clamp or quick release

You have to buy the second one. Sorry, I can not explain it better. You buy the second one like the one I linked too for your diameter seatpost. Then you modify it by filing off the lip. Then you install it. Then your seatpost won't slip anymore.

oh ok i cant see where to place it. the first one is the right size. hmmmm i dont know what to do. i guess it will have to be a mystery. sorry i just dont get it. maybe my photo is misleading because of all the things i have on the seatpost. maybe thats the reason

Bingo! It's hard to figure out what's what in that photo. Could you strip off the stuff that is irrelevant and take additional pictures?

Oh, I took another look. It appears that you added all of that junk to serve as spacers between the top of the seat tube and the bottom of that trailer hitch you have clamped onto the post. My bet is that you have a crack in your post clamp. It's small enough so it is not apparent when released, yet opens up slightly when clamped so that it's less than functional. A new clamp will probably do the trick. Also, we routinely grease seatposts before installation so that they don't corrode and stick in the tube. This grease does not affect positive clamping if the clamp is good.

I had a seatpost (painted black) that was slightly undersize, kept sliding down. Got tired of that, so I cleaned off the grease and masked off the part of the post above where the post went into the frame. Then sprayed a few thick layers of black spray paint onto the post. Let the paint dry and harden sitting outside for about a week where it was in the sun during the day. Then put it in the bike. The extra thickness of about three layers of spray paint was enough to make it slightly bigger and quite slipping.

By way of explanation, here is the , I was referring to.

All anyone is saying is add another quick release to the seatpost stem, so the seatpost can't slide further down onto the frame. You'll have 2 quick release clamps (1 on the bike, and ANOTHER on the seatpost stem itself), and it should solve the problem.

this is it without all the stuff
 

yes it does open up slightly when clamped. will have to take a closer look with my glasses on. ok good to know about the grease. ok will measure so i can get a new clamp

oh thanks that explained it well. ok will measure and order

oh thanks i cycle everyday so wont be able to plus cant leave anything out due to high theft area. the other person gave a good solution i understand now

So seems if i get the 31.8mm one it will do the job? https://www.aliexpress.com/item/4001...apt=4itemAdapt

Measure it. Only you or a bike shop can do that. I would not source from Aliexpress as it will take a month to get it. Amazon or your bike shop would be faster.

oh sorry forgot to mention the measurement. 27.4mm. so seems right. yeah i have had things take anything up to 6 months from them but mostly under 3 months . lately tho(i think they now have a warehouse in australia or some of the sellers are here) i have been getting things within 2 weeks. local bike stores are so over priced and often dont have anything to sell except a very limited amount of seats, bells....well just super limited. i have never been able to source anything from them that i have asked for in over 10 years

27.2 mm is a standard one. So it's probably that.