Dahon frame

[[email protected]]

Hi,

I've got a Dahon Mu P8 which I bought in spring 2007. The frame broke
5 months later just above the soldering for the tube mount (where the
seatpost slots in). This kind of crack would probably happen if the
seatpost was above its max setting but I am nowhere near the max!

I got my bike back 12 weeks later (!). Now, it's been about 3 months
of cycling on the new frame and I am concerned the frame is going to
break again. I've got the exact same creaking noise happening arount
the same spot on the frame when riding it. It is not showing any
visible signs yet but the noise gets more frequent and at this rate it
won't last another month!

I've seen at least one other person with that problem on a different
(older) model (http://groups.google.co.uk/group/uk.rec.cycling/
browse_thread/thread/fa7a665c84cbfae0/58498b9a466bf33f?
hl=en&lnk=st&q=dahon+broken+frame#58498b9a466bf33f)

Has anybody experienced anything similar on a Mu P8 or other Dahon
models?

Regards,
J.

 

[TerryJ]

On
> hl=en&lnk=st&q=dahon+broken+frame#58498b9a466bf33f)
>
> Has anybody experienced anything similar on a Mu P8 or other Dahon
> models?
>

This is no help to you, but I have a jetstream xp 30 months old and
given it a hammering on long rough rides on roads and trails . I weigh
15 stones. I have been expecting something to break among the delicate
lightweight parts but so far nothing has.I put long bar ends on the
carbon bar and although something creaks when Honk up hills it seems
to be surviving.I destroyed one of the lightweight QR levers very
quickly but am more careful with the others. Even the wheels are still
quite true.
TerryJ

 

[Rob Morley]

On Mon, 12 May 2008 07:13:37 -0700, jacky.evanno wrote:

> I've got a Dahon Mu P8 which I bought in spring 2007. The frame broke 5
> months later just above the soldering for the tube mount (where the
> seatpost slots in). This kind of crack would probably happen if the
> seatpost was above its max setting but I am nowhere near the max!
>
> I got my bike back 12 weeks later (!). Now, it's been about 3 months of
> cycling on the new frame and I am concerned the frame is going to break
> again. I've got the exact same creaking noise happening arount the same
> spot on the frame when riding it. It is not showing any visible signs
> yet but the noise gets more frequent and at this rate it won't last
> another month!
>
Sounds like they might have had a bad batch of frames - the tube right
next to the weld is weakened by welding heat, but that should be
corrected by heat-treatment after the frame is built. It's also possible
that the seatpost is undersize (or the seat tube was reamed oversize)
which would place higher loads on that area - if there's significant
wobble when the clamp is undone you could try shimming the seatpost (Coke
can is the classic shim material .

 

[[email protected]]

On 13 May, 10:26, Rob Morley <[email protected]> wrote:
> On Mon, 12 May 2008 07:13:37 -0700, jacky.evanno wrote:
> > I've got a Dahon Mu P8 which I bought in spring 2007. The frame broke 5
> > months later just above the soldering for the tube mount (where the
> > seatpost slots in). This kind of crack would probably happen if the
> > seatpost was above its max setting but I am nowhere near the max!
>
> > I got my bike back 12 weeks later (!). Now, it's been about 3 months of
> > cycling on the new frame and I am concerned the frame is going to break
> > again. I've got the exact same creaking noise happening arount the same
> > spot on the frame when riding it. It is not showing any visible signs
> > yet but the noise gets more frequent and at this rate it won't last
> > another month!
>
> Sounds like they might have had a bad batch of frames - the tube right
> next to the weld is weakened by welding heat, but that should be
> corrected by heat-treatment after the frame is built.  It's also possible
> that the seatpost is undersize (or the seat tube was reamed oversize)
> which would place higher loads on that area - if there's significant
> wobble when the clamp is undone you could try shimming the seatpost (Coke
> can is the classic shim material  .

That sounds interesting about the sizes. I suppose you are talking
about the different diameters in that area. Well, I think this bike
has a peculiar design because it has a very large tube (the seatpost
tube contains a pump). Additionally around that area there is another
internal cylinder (probably 10cm long, 1mm wide) which acts like your
shimming I suppose. It seems most of the support is on this internal
cylinder but not too sure. The clamp is secured quite tight so that
may have an impact!? I'll look into this additional shimming....
Thanks for your help.

J.