On the question of the fairly sudden appearance of major creaking and
clacking when standing or sitting and pedalling:
Thanks for the several replies cautioning to beware of a cracked frame or
other causes requiring perhaps simple relubing or something similar.
Turned out what had happened is that with installation of new deraileur
cables, new chain and new rear cassette, the first couple rides had
stretched out the cables.
It was explained to me that this caused the chain to be moving through the
sprockets out-of-line, and causing the creaking and clacking.
The LBS did a quick look and immediately said the cables were stretched,
and with a 2 minute re-adjustment of the cables everything was silenced
down.
I'm not sure why it makes those specific noises, but if the mis-alignment
of the rear deraileur can cause an off-center tensioning and feeding of the
chain, maybe it's the noise of the chain clicking over onto the, now,
slightly off-center cogs.
After adjustment, subsequent ride was almost completely silent and shifting
is now working superbly.
The Wrench said that it's not uncommon for a new installation to need a
short break-in period for the chain and cogs and a re-adjustment.
Sure is a joy to ride now that everythings re-aligned. Amazing how
distracting a few noises can be. I can ignore them if I know it's just
something minor, but, hah, I usually imagine the worst, expecting anything
from a hidden crack in the frame to a broken crank.
Thanks,
Hoff