Folding Bikes - Dahon seatpost woe

I picked up my Dahon Mu P8 from my LBS over the weekend, rode it home, folded it and left it in my home office ready to use on my daily commute to work. Whilst unfolding the bike, I tried to raise the seatpost bit it was rather stiff so I twisted it to remove it from the frame. The photos show what's happened to the post which is quite badly scratched:

Photo 1 (http://www.johnoconnell.plus.com/images/SeatPost01.jpg)
Photo 1 (http://www.johnoconnell.plus.com/images/SeatPost02.jpg)
Photo 1 (http://www.johnoconnell.plus.com/images/SeatPost03.jpg)

Have any other Dahon owners had similar problems with the seat post?

Rgds

Johno

No, I've used my MUP8 for about five months and haven't had any problems.

I picked up my Dahon Mu P8 from my LBS over the weekend, rode it home, folded it and left it in my home office ready to use on my daily commute to work. Whilst unfolding the bike, I tried to raise the seatpost bit it was rather stiff so I twisted it to remove it from the frame. The photos show what's happened to the post which is quite badly scratched:

Photo 1 (http://www.johnoconnell.plus.com/images/SeatPost01.jpg)
Photo 1 (http://www.johnoconnell.plus.com/images/SeatPost02.jpg)
Photo 1 (http://www.johnoconnell.plus.com/images/SeatPost03.jpg)

Have any other Dahon owners had similar problems with the seat post?

Rgds

Johno


I had something similar happen to my Piccolo years ago. I didn't clean the post and it tends to get scratched over time. There's nothing wrong with it and it's safe.

Those scratches look rather severe to me. That is not normal. Looks like there is a sizeable particle embedded in the seat tube which is doing the scratching. Real bummer, to have a new post scratched like that. I would loosen the release all the way, pull the post out and carefully examine the inside of the seat tube. Some (perhaps all?) Dahons have a removable seat tube shim from plastic, a grain of sand can embed itself in there.

Those scratches look rather severe to me. That is not normal. Looks like there is a sizeable particle embedded in the seat tube which is doing the scratching. Real bummer, to have a new post scratched like that. I would loosen the release all the way, pull the post out and carefully examine the inside of the seat tube. Some (perhaps all?) Dahons have a removable seat tube shim from plastic, a grain of sand can embed itself in there.
I removed seat post and examined the inside of the tube - I could see a few holes at positions where there are welds outside the tube, therefore the inside of the tube isn't completely smooth and the end of the seatpost has probably caught one of the holes and taken a sliver of metal with it.

The seatpost is so badly scratched now that I can't get it back into the frame without some force.

I'm wondering if the frame is defective due to the holes inside the seat-tube? I'll see what my LBS makes of it this weekend....

I would think they would warranty it. I have not had this problem.

I removed seat post and examined the inside of the tube - I could see a few holes at positions where there are welds outside the tube, therefore the inside of the tube isn't completely smooth and the end of the seatpost has probably caught one of the holes and taken a sliver of metal with it.

A request for feedback to other Dahon 20" folder owners out there: can you check the inside of your bike's seat-post tube to see if there are any holes/imperfections inside the tube at positions where there are welds outside the tube?

I'm just curious to know if the issue I've encountered is common to other 20" Dahons out there.

Thanks very much in advance

Johno

QUOTE :A request for feedback to other Dahon 20" folder owners out there: can you check the inside of your bike's seat-post tube to see if there are any holes/imperfections inside the tube at positions where there are welds outside the tube?

I'm just curious to know if the issue I've encountered is common to other 20" Dahons out there.
Quote end ........


Hello
in order to look for holes / imperfections one would have to know what is a hole/imperfection and what is usuall and what is an imperfektion ....

Holes are not necesary imperfections as holes need to be in the inside of the frame to gas off any welding gases , and also to let moisture vent out .... every frame has holes ...

Dahon uses the thick shim which doesnt even let the seatpost touch the frame.... Now, when you push the seartpost all the way in it will touch , most likely at the very end of the frame.... that would be a good spot to look for any burrs or bents , than take a round file and get rid of them ..( bike upside down )
Otherwise check if there is some dirt in the shim, take the whole shim out and see if there is something lodged in...



thor

I've had a similar, but not as severe a problem with two of our three Boardwalks.

My problem seems to be the after market aluminum shims I installed 1 1/2 yrs ago. My wife's bio-logic seat post started to score like that - I sanded it and the shim with fine emery paper (and checked for burrs, too). I re-assembled it, but scoring got worse. Finally, figured I needed to wipe/wash off the resulting metal dust, as it was causing it to get worse.

I still have the original plastic shim on my S1 and have had no problem with its Thud Buster seat post, but I also remove the Thud Buster seat post when I fold the bike to be sure. I also use that seat post on the D7s and have no problem with scoring on the portion of the post that goes into the bike frame (the minimum amount given my 6'3" height).

Dahon uses the thick shim which doesnt even let the seatpost touch the frame
Took another look and you're right there.

The shim is quite badly scratched and feels quite rough when I wipe it's surface with my finger. Also the securing collar is a bit dented on top so perhaps a piece of material from that got into the tube. As far as I can see, the part of the tube below the shim looks fine (to my untrained and inexpert eye) and I'd be surprised if the end of the seat post made contact with it on he way down, particularly as the seatpost end is slightly tapered and contains a Zorin Postpump.

I'm taking the bike back to my LBS soon so I'll see what they make of it (the guy in the shop mentioned filing down any burrs in the tube), but I think the shim and seat post should be replaced under warranty by Dahon , particularly as the latter is now unusable and I've ridden the bike just once.

Yup, my black anodized seatpost on my Speed P8 took a similar hit the first time I folded is all the way.

I cleaned out the inside of the seat tube and the outside of the seat post with a rag and something like 409. I then put a little grease on the seat tube.

No more scratching, but now my seat was sinking a few inches a ride, no matter how tight I cranked the quick release. More 409 to remove the grease from the post and tube.

Then all was good.

Thanks to everyone for your feedback and info

Johno