UPDATE-
Over the weekend I scrubbed the [censored] out of the rims (simple green/
bonami/ gray 3m abrasive pad, rubbing alcohol/paper towels) to be
absolutely sure the rims had no contamination. No help.
I picked up a set of Kool Stop MTB pads (dual compound). Mother of
screaming banshees!!! The squealing is unreal. I tried toe in with a
small paper clip setting, then using a jumbo paper clip as a shim to
set toe in. No improvement at all. The overall gross braking with the
KS MTB pads was better, but the shuddering at anything short of lock
up was maybe a bit worse than the original shoes. Add the squealing,
and fagettaboutit.
I did check the headset carefully and it has a small amount of wiggle
to it. I don't think that can cause the very slow speed grab/no grab,
but probably exacerbates the fork shudder. The LBS had the same
opinion. They will pull off the WTB Dual Duty wheel set and replace it
with a Mavic X139 set. I'm guessing the rim is similar quality and the
Deore hub is a small upgrade over my stock hubs. Hopefully have the
bike back on Wednesday.
It seems kind of odd that the rim machining could be the problem, but
on one side of the rim when I rubbed with crocus cloth I could feel
the rim grab and slip over multiple sections. On the opposite side of
the rim there was some of this, but it was fairly limited. I am
concluding the machining differences are the reason for the varying
friction (sliption?).
Next step-
My Trek 4300 went into the shop Monday for the brake shuddering
problems. The rims still seemed to be the primary culprit. The headset
had a touch of wiggle in it that may have exacerbated the fork shudder
at higher speeds.
I dropped by the LBS on Thursday morning to test and pick up the bike.
They originally said they would replace the WTB Dual Duty wheel set
with Mavic X138 wheel set. They actually used a Mavic X221 wheel set
(with Deore hubs). These are XC wheels and are narrower (and
presumably lighter) than the original wheels. They are probably a bit
too narrow for my existing tires (factory recommends up to 1.95"
tires, the stock tire is 2.1"😉. I'm not an aggressive off-road rider
(mostly street for me) so the trade to lighter weight is fine. I'll
probably get narrower tires anyway.
I tested the bike. The shuddering was eliminated with the new wheel
set. The headset had not been tightened at this point, so this rules
it out as the primary problem. I will monitor the wheels for a few
days as the original rims worked fine for a few days, then started to
have problems with the shuddering. The brake squealing however was
still horrid. The mechanic swapped out the wheels, but never did a
test drive with the bike to see if the shuddering was fixed. So, he
didn't know the brakes would squeal so badly (sounded like the
beginning of a car accident before the invention of anti-lock brakes).
He tried a bit of toe in to no success.
The next tactic was to swap out the brake arms with Shimano Deore V
brakes. After installing the new brakes the squeal was gone and the
brakes were smooth, consistent, and powerful. Unfortunately he changed
2 variables simultaneously (brakes and pads), so I don't know which
was the cause of the squealing. When I get the time I will put the
Kool Stop pads back on to see if the squealing comes back.
I still have two minor concerns. First is the new Shimano brake pads.
I have read many posts discussing how Shimano pads tear up rims. When
I brake the pads sound a bit like mild sandpaper (no point in tearing
up a new set of rims). As a comparison, the Kool Stop MTB pads on the
rear are practically silent when they are applied.
Second, when I ride, the spokes on the new wheels occasionally make a
pinging noise. I don't know if this is a real problem or just the
wheels and spokes settling in. I'll keep a close watch on the spoke
tension and trueness of the rims for a while to be sure nothing bad
happens.
Hopefully this lays the shuddering problem to rest. Thanks to all for
your input.
Tracy
