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That'd make sense. I'll investigate....
ETA:
Today's activities:1) Remove the Brompification handlebar clamp and try to measure the width of the jaw - difficult as it has asymmetric legs and they have a radius with no definitive edge to measure from.
2) Place same clamp in 3" vice (the 5" one is somewhere under the stairs and I can't be arsed) and using a 450mm tommy bar, crush the clamp in the vice to try and reduce the width of the jaw. Using my digi-verniers, I may have reduced the width by 0.3mm. Or by nothing.
3) Replace clamp on bike and go for a ride which reveals reduced, but still-present chitter.
4) Dig out original Brompton clamp from storage, fit to bike, go for a ride which ascertains there is no audible reduction in chitter.
5) Remove Brompton clamp from bike, measure the width of the jaw and put it in the crusher.
6) Re-fit crushed Brompton clamp to bike, go for a ride which ascertains there is no further audible reduction to chitter. It is reduced, but it is still there.
7) Decide to re-fit Brompification clamp, and supplement it with MkI inner tube (see above) as this seems to be the only way I can achieve a chitter-free ride.
I can't help but think that there is a correlation between chitter manifesting itself, and the wearing-away of the powdercoat from the mating surfaces of the hinge - giving it a
metal-on-metal scenario - which on a three year old bike, which has hardly seen any use other than the occasional weekend - is probably about right.Unless, of course, anyone has any better ideas.
JurekB-
I can't help but think that there is a correlation between chitter manifesting itself, and the wearing-away of the powdercoat from the mating surfaces of the hinge
I'd agree, and therefore conclude it's probably ok, but it seems to manifests itself beyond an acceptable level considering your involvement and experimenting in trying to sort it out. Frame is guaranteed five 5 years, why not claim a new one?
If the crushing of the Brompton clamp had sorted it I would have also said the same, you shouldn't have to rectify the clamp opening along with the age of the frame, that's not what the design is intended for: the tapered contact surfaces between the hinge and the clamp should take care of any surface wear, like the (normal) loss of prefer coating in some area of the hinge.The fact that the inner tube trick works is weird. And because introducing a spacer in the closed hinge seems to work, could it be that the hinge's spindle needs replacing as it maybe the thing that (if out of alignment maybe?) prevents a good contact in the closed hinge?
veLLo
@JurekB do you still get this noise with the original hinge clamp plates? the brompfication clamp shape is ever so slightly different and can bottom out before fully clamping up. I have seen one case like this.