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-   -   Saddle keeps going down over bumps! (http://www.bikeforums.net/folding-bikes/503740-saddle-keeps-going-down-over-bumps.html)

trekdude 01-19-09 10:05 PM

Saddle keeps going down over bumps!
 
I just got a new Dahon Broadwalk folder. I got it for Christmas and just recently took it on a bike path. When I ride over bumps or bumpy roads, the saddle keeps going down and have to pull over to lift the saddle up and lock the latch. Does anyone experience the same problem with Dahon saddle/post? What should I do? Please help. Thanks!:cry:

ChiapasFixed 01-19-09 10:15 PM

clean and degrease the seat post and the tube with solvent. lubricate and tighten the quick release mech. should do it

havm66z 01-20-09 04:23 AM

When I bought my Dahon, I watched part of the pre-delivery inspection. Saw the mechanic lubricate the pedal threads, and then the seatpost.

The damage (greasing the seatpost), was over before I could protest. I just brought the bicycle home, cleaned and degreased it. And sent them an email a week later after road testing.

Foldable Two 01-20-09 11:34 AM

Make sure you have the QR adjusted properly - the handle should meet resistance 90 degrees before it's final, resting position.

Had similar problem on my Boardwalk D7 (a previous bike). I went to an Aluminum seat post sleeve. That stopped the slipping, but it could/did cause some galling of the seat post itself. Not sure how much you weigh, but I'm 200 lbs, and that's likely a factor as my much lighter wife didn't have the problem.

rhm 01-20-09 11:46 AM

I had this problem on my Mini; I had to take a file and slightly widen the slot in the seat tube, so the clamp could compress it a little more. I took off less than half a mm. After that, never had this problem again.

KitN 01-20-09 01:39 PM

I've had this problem with my folder (not a Dahon). Going over bumps and potholes in NYC forces me to stop every few minutes to adjust the seat. It's really annoying.

I was just sent a new seatpost so I hope that helps. (It's been showing here 3 days straight, I haven't had a chance to test it out...)

EvilV 01-20-09 02:44 PM

My Merc Bike used to do this until I cleaned the seat post and tube with alcohol. I tightened the lever too and it stopped (pretty much). It does sink over a quite long period, but it used to go down half an inch in five minutes when it was new. Now I get weeks before having to adjust the post again.

caotropheus 01-20-09 10:43 PM

As a bike mechanic in the past I had to release stuck seat posts because of lack of grease. I saw cracked frames when people tried to release with a bench vise aluminum seatposts seized on steel frames. I also had the same problem of seatpost sliding down with one of my first MTB. I solved my problem cutting a strip of aluminum from a pop can and inserting it between the seatpost and the seat tube.

brakemeister 01-21-09 08:42 AM

bicycle mechanic or not..... this lets somebody believe that it is ok to grease the seatposts ...and I will get angry calls after that

DO NOT GREASE THE SEATPOST on a Dahon ....

PERIOD !!!

Keep it clean and put some more pressure on the quick release lever instead

NO GREASE !!



thor

trider 01-22-09 04:19 PM

Seatpost
 
Right........DO NOT GREASE THE SEATPOST ON ANY BIKE. Keep it CLEAN. Every now and then put a couple of drops of sewing machine oil (or some other kind) on the quick realease lever. NO GREASE ON THE SEATPOST, THOR IS VERY CORRECT. I know all of this to be true because I started riding bikes the first week of Oct. 2008. A little knowledge is amazing to the ignorant.

kamtsa 01-22-09 10:21 PM

Got today a my new BF NWT and the seat post was clearly greased. I wonder if this is from the factory or the local LBS.

Kam

caotropheus 01-22-09 10:43 PM

Greasing the seatpost is like many of the discussions in cycling, either you love it or you hate it. The point of grease on the seatpost is to avoid it seizes inside the frame. There is a simple alternative for grease that is once in a while to move the seatpost a bit up, down and sideways to avoid it seizes. This operation needs to be more frequent is the bicycle is exposed for long periods to the weather. I suppose this is not a problem in a folding bicycle because every now and then we fold the bicycles and we have to collapse the seatpost inside the seat tube, right?

jur 01-22-09 10:58 PM

I think there is a case for grease to be made for aluminium seatposts in steel frames if, as caotropeus says, it's never moved - dissimilar metals. For alloy frames, due to similar metals, I think it's not necessary.

Peter Reich has recommended that you use Boeshield T-9 on the post, allow it to dry out overnight, and wipe off excess. I think what this is meant to do is fill in scratches to ret@rd oxidation of the alloy.

See this thread.

EvilV 01-23-09 04:38 AM

Quote:

Originally Posted by caotropheus (Post 8231584)
Greasing the seatpost is like many of the discussions in cycling, either you love it or you hate it. The point of grease on the seatpost is to avoid it seizes inside the frame. There is a simple alternative for grease that is once in a while to move the seatpost a bit up, down and sideways to avoid it seizes. This operation needs to be more frequent is the bicycle is exposed for long periods to the weather. I suppose this is not a problem in a folding bicycle because every now and then we fold the bicycles and we have to collapse the seatpost inside the seat tube, right?

The seat post on a folder is up and down like the proverbial wh*res drawers, so it isn't ever going to stick. Also - I take account of Jur's point about alloy posts not sticking in alloy frames. I used to have a Marin mountain bike that stood outside for a long time when one of my idle sons had the use of it. I recovered it when he went to college and decided to refurbish it - the seat post could not be moved - alloy post, steel frame - four years outside - no way. I tried everything to move that, except sawing it off and putting a hacksaw blade down the tube and sawing through it down its length. It was totally welded to the frame. In the end I gave it away to an old man who couldn't push the gear on his single speed anymore. He's still riding it in its granny gears at 86.


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