Weird mechanical problem

On Sat, 7 Nov 2020 21:21:54 -0500, Frank Krygowski
wrote:

On 11/7/2020 4:55 PM, Jeff Liebermann wrote:
On Sat, 7 Nov 2020 13:22:27 -0500, Frank Krygowski
wrote:

Yesterday we rode with a friend. At times during the ride, her bike was
making a very loud clicking noise, very sporadically, only while
pedaling. It wasn't synchronized with crank rotation, wheel rotation,
chain rotation or anything else I could spot...

Can I guess(tm)?

Asynchronous noises are usually caused by two or more damaged
components that only make a noise when they come into alignment. If
there was a depression in both the bearing cup and the spindle, that
might produce a clicking noise when the two damaged surfaces come into
alignment. However, that would not explain the rather long time
between clicks. The third part of the puzzle might be single ball
with a flat spot. The time of all three parts to come into alignment
seems about right for a "long" period.

Perhaps I should explain a bit more about the long periods of silence.
They were often much more than fifteen minutes. In fact, we rode for
over an hour before I heard (or at least noticed) the clicks. Granted,
she was usually quite a few feet behind me, but not always.

And the clicks were amazingly loud. Not just a mild "tick tick" - more
like "Wow! What's that noise your bike is making!" - impossible to ignore.

Assuming I'm correct, how could a pedal be damaged when aligned in
three places? Corrosion would be my guess(tm). If the bicycle was
sitting in one place, in a wet environment, with no grease on the
bearings, water could build up around the lowest part of the bearing.

I've seen rusted bearings, rusted cups, and rusted spindles, but I've
never done a post mortem to see if the rusted areas aligned in the
position the pedal was stored. I do exactly what you did, which is
disassemble, clean, replace the balls, grease, and adjust.

Yep. I expect she'll be willing to leave the pedal with me. I'll
disassemble again to re-inspect, just for curiosity. Maybe I can get
some decent photos. But I know good closeup photos of tiny mechanical
parts are not simple.

I have no idea why it would be so tricky to adjust, unless the cup is
out of round or something else is mangled.

Ask the owner if the bicycle was stored in a fixed position for a few
months in a potentially wet environment.

This is one of our best friends. Her bike is very well cared for -
actually pristine. It's stored in an attached (semi-heated) garage.

One possibility has since occurred to me: I counted the balls I removed
(13 & 10 IIRC) and replaced the same numbers (inner and outer), but I
have no guarantee that those numbers were correct. I wonder if (say) the
inner race was short one ball. If the resulting gap between balls
happened to line up with a slight eccentricity on either the pedal axle
or pedal body, it might allow contact where there should be a tiny
clearance.

I can envision such a problem being much worse when the adjustment was
as bad as this one was, and becoming much reduced but not cured with
proper adjustment. (But who knows how it ever came out of adjustment...)

I'll report further after another disassembly.

The so called "rule of thumb" for loose balls in a bearing is 1 less
then the maximum that will fit. Which has worked well in my
experience.
--
Cheers,

John B.