On Sat, 10 Jun 2006 03:33:38 +1000, big Pete
<
[email protected]> wrote:
>
>I have just bent my rear derailleur hanger. Can I cold set it back or is
>the frame trashed?
If the dropout is steel, you can probably bend it back into place. If
it's aluminum, and the hanger isn't a replaceable piece, then the
frame is probably trashed, but you might as well try bending it back
anyway.
>If I do cold set it back will it bend again?
If the cause of the derjam isn't prevented from recurring, then yes,
the der will jam again, and the hanger will get bent again.
>I have a
>chicken and egg dilemma, did the hanger bend because the derailleur got
>caught in the back wheel or did the hanger bend (during shifting maybe)
>then the derailleur get caught?
IME, it has always been the case that the der jammed into the wheel
and was pulled around, but it's also possible for a stickjam in the
der to allow the der to be pulled around as the rider pedals,
particularly if the rider is out of the saddle climbing when the
jamming object strikes.
>I did a fast shift at the bottom of the
>hill then after about 50m I noticed all the problems.
That sounds distressingly familiar. Was this a bike that perhaps
hasn't seen any lube on the mounting bolt area in a long time? If
that pivot is gummed up and not free-moving, it can cause some strange
motions in the der, possibly resulting in a derjam. My oldest
(current) roadie had that happen shortly after I got it; that's part
of the reason that I take lots of ordinarily ignored stuff apart and
relube it when I get a new-to-me used bike.
>This is an 80’s
>steal frame so I have no nice removable hangers.
Yes, but the hanger is probably nice and malleable; it will most
likely be possible to put it back almost exactly where it was.
>Also I think I have
>killed the threads of the hanger (derailleur was pulled out of its
>mounting hole), how is that fixed?
There's a nifty threaded bushing that can often be used to overcome a
stripped der hanger tab, and in many cases you can install one of the
retrofit hanger tabs that are intended for use with frames that don't
have a hanger on the dropout. For the latter option to be useful, the
der needs to have enough reach to still be able to shift on to the
largest sprocket after having been moved about 4mm to the right by the
insertion of the tab.
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