I managed to get in a short ride on Friday, a longer one on Saturday
and a medium one today. Right up until I was half way home today,
there had been no sign of the creaking noise that came before my last
crank loosening, so I was really hopeful that the more careful
installation had done the trick. Then, suddenly, it returned.
Dismayed, I rode gently home, coasting whenever possible, and wiggling
the crank to feel for looseness at every red light. It felt
absolutely fine the entire way home. I paid careful attention to the
creaking, which was intermittent. While it definitely seemed to be
louder and more frequently when pedalling hard, it didn't seem to
happen exactly once every revolution. It also sometimes happened even
when pedalling gently. I was starting to suspect that perhaps the
creaking sound is not the left crank at all.
I removed the kick stand, which is always slowly moving around, as I
am afraid of tightening the bolt too hard and crashing the chainsay
tubes, but that wasn't it.
My next suspicion was that the chainring bolts, or some part of the
interface between the chainring, crank spider and chain guard, was
squeaking. The whole thing doesn't sit together *quite* right since I
removed the larger chainring, so this seemed pretty likely, but taking
all of this apart, cleaning it, lubricating it and reassembling it did
nothing.
During the test riding after fiddling with the chainring, I noticed
that I was unable to create the sound by coasting with the pedals
horizontal, standing out of my saddle and bouncing on the pedals, then
slowly rotating the pedals 180 degrees backward and bouncing on them
again. This puts a lot of stress on the crank-BB interface in two
opposite directions one after the other, and because you are coasting
during it the chain, chainwheel and other possible sources of sound
are still. I also noticed that I could sometimes cause the creak even
when pedalling backward, which puts very little stress on that
interface. All of these things reinforced my growing suspicion that
the crank was not to blame. Even after this rough treatment, the left
crank still feels totally solid, even when I hold the right crank
tight in one hand and wiggle the left with the other.
Suddenly, during a mount or dismount, I forget which, I heard the
creak - while the bike was stationary, front brake applied! Some
quick bouncing confimed it - the creaking is coming from the saddle!
Well, the saddle, or the saddle clamp, or the seatpost, or the
seattube. But I can pretty consistently create the sound by rocking
back and forth on the saddle, and this also explains why I never heard
it during my crank torture test above - because I was out of the
saddle. It also explains why the creaking seemed to happen at the
same rate/intensity as pedalling. When pedalling hard, each thrust
tends to push you backward into the saddle a litle bit.
I feel a bit silly at this revelation, but perhaps I shouldn't. It's
quite hard to localise the sound of a squeak while riding, and the
saddle/seatpost area and the bottom bracket area are both "right below
me". This is mostly good news - a squeaking saddle or seatpost
problem is probably going to be a relatively easy fix, and it means
that maybe the crank really is going to be okay this time. On the
other hand, if this is the same creak I heard shortly before the last
crank loosening, it means it was only a coincidence that the sound
turned up shortly before the crank came loose, and the crank in fact
came loose *silently* and without warning, which makes me nervous. Or
maybe that was a "causal creak" and two creaks sound much a like to
the untrained ear. I dunno. Anyway, I'm going to focus my trouble
shooting efforts now on the saddle and immediate vicinity.
Due to all this obsessive listening to my bottom bracket area, I've
noticed that even when the creak isn't happening, things aren't
totally silent down there when I'm pedalling hard. During all the
crank wiggling, I've come to notice that there is quite a bit of play
in my pedal bearings, which I didn't even think to adjust before
installing them, and I think that is probably one of the main sources
of sound during heavy pedalling. So, this coming Thursday I might
take my pedals (which I realised today aren't unbranded, as I thought,
but are actually by SR! The branding is just very out of the way)
apart, clean and regrease the bearings and try to adjust them to have
as little play as possible. I'll also grease the threads. The
quieter everything is down there, the more comfortable I'll be taking
longer journeys.
