# Dahon - seat post slipped



## mobi (19 Mar 2014)

My 2-month old Dahon Vybe's seat post slipped suddenly while I was riding! It caught me completely off guard and by sheer luck I was not seriously injured. 

I think there is a design flow. The bottom of tube post is open rather than sealed. As a result, the seat post slipped and hit the ground.

I escpated with aching legs but it could have been nasty. 

After that it slipped twice more!

This was already serviced in Halfords 2 weeks back. By now I lost all confidence on the bike and took it to Halfords for a refund. To give them credit, they refunded me without quibble. They said this is not uncommon and they couldn't gurantee that it would never happen!

I exchanged it for a normal mountain bike (it even fitted inside my car).


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## Kies (19 Mar 2014)

My dahon is second hand, but the seat post never slips


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## morrisman (19 Mar 2014)

Sounds as it the seat quick release clamp needed adjusting, a two minute job? The reason the seat post goes right through the frame is to make the folded size the minimum possible.


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## mobi (19 Mar 2014)

Yes it could have been adjusted. But the statement from Halfords "there is no guarantee that it won't happen again" had completely put me off the mechanism.

I didn't commute with the bike and only few times I actually folded it. Still it failed. 

Yes, I understand seat post goes thru frame to reduce folding size but somehow it didn't inspire my confidence on the bike. 

I could have given it another chance, but this incident forced me to think it I need folding bike and my conclusion was that "not really".


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## Davidc (19 Mar 2014)

If you can't set the bike up yourself get a good bike shop to do it.

The seat post on any bike will slip down if there's a badly adjusted QR or inadequately tightened bolt, and on a folder that will make it go right through.

I occasionally buy things at Halfords, but wouldn't ever let them near either of my bikes.


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## MarkF (19 Mar 2014)

I've had 3 Dahons with no issues, my elderly mother now rides one of them, again, with no issues. It's very unusual to have a slipping seatpost that can't be quickly and easily fixed, Are you height/weight proportionate?


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## mobi (19 Mar 2014)

As per Google, there are similar incidents and some people were seriously injured because of that.


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## the_mikey (19 Mar 2014)

It does sound like the seatpost clamp needs adjusting. I have a Tern link D8 which has a similar seatpost, but regardless of whether the seatpost tube is open or closed, the same thing would happen if the clamp isn't adjusted to the required torque. Most bicycle seatpost are like this.

Bicycles are machines that require attention, maintenance and some respect. If you can't set the bike up then take it to a bike shop. (not halfords).


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## Davidc (23 Mar 2014)

mobi said:


> As per Google, there are similar incidents and some people were seriously injured because of that.


There are people injured by badly adjusted/maintained/serviced machines of all sorts, every day. Bicycles are no exception to this.


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## shouldbeinbed (23 Mar 2014)

mobi said:


> My 2-month old Dahon Vybe's seat post slipped suddenly while I was riding! It caught me completely off guard and by sheer luck I was not seriously injured.
> 
> I think there is a design flow. The bottom of tube post is open rather than sealed. As a result, the seat post slipped and hit the ground.
> 
> ...


 If the air leaks out of the tyres on the mountain bike do make sure you highlight it as a design flaw and pass it off as somebody elses responsibility to check routinely for you.

simple physics, a folding bike sestpost is a longer lever than a regular seatpost and will flex & move relatively more when ridden, it is also designed to release and slide into the frame, This means that it should be checked more regularly than a short seatpost. Know your machine and no problems, enjoy the MTB.


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## mobi (24 Mar 2014)

I beg to differ here. Tyre is a consumable item. So this can't be compared against seat post which is an integral part of the bike.

The reasons I termed it as design fault (this is entirely my personal opinion BTW)

- the bottom of tube was open, so when slid, it went down too much. So the design was done in favour of more compactness rather than being a safe.

- if such seat posts are to be raised and lowered too often (because it is a folding bike) it often became difficult to judge the exact length of seat post each time. I often ended up being either too high or too low and then had to adjust more. How much more difficult would have been to put a marking on the seat post so that I could always set it up a desired position (say position 5 for example).

- if it happened to a cheap folder I wouldn't have complained. But I paid a premium for Dahon and simply expected it to be better. May be all folders behave in same way so that is an error of judgement on my part.


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## RecordAceFromNew (24 Mar 2014)




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## morrisman (24 Mar 2014)

mobi said:


> - the bottom of tube was open, so when slid, it went down too much. So the design was done in favour of more compactness rather than being a safe.



It's a folding bike, its whole raison d'etre is compactness when folded


> - if such seat posts are to be raised and lowered too often (because it is a folding bike) it often became difficult to judge the exact length of seat post each time. I often ended up being either too high or too low and then had to adjust more. How much more difficult would have been to put a marking on the seat post so that I could always set it up a desired position (say position 5 for example).



Good point but not difficult to implement yourself if it makes your life easier


> - if it happened to a cheap folder I wouldn't have complained. But I paid a premium for Dahon and simply expected it to be better. May be all folders behave in same way so that is an error of judgement on my part.



The whole problem just seems to have required a couple of turns on the quick release nut. I have a Tern D7 which requires the QR to be nipped up now and again but it needs the tyres pumped up and the hinges checked as well. All mechanical items require maintenance from time to time.


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