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Brake pads eating rims?



 
 
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  #21  
Old June 29th 05, 04:41 AM
Patrick Lamb
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Posts: n/a
Default Brake pads eating rims?

On Tue, 28 Jun 2005 20:42:21 -0400, "Phil, Squid-in-Training"
wrote:

I've used the same pads they sell at Walmart... They picked up grit and lost
all braking power. I then switched my brakes to dual-pivots with
10-year-old Shimano 105 pads and they work very well.


Maybe that's the key to using Shimano pads -- they need to be aged 10
years or so. Forget aging those tubulars, age the brakes!

Pat

Email address works as is.
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  #22  
Old June 29th 05, 05:12 AM
jim beam
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Default Brake pads eating rims?

wrote:
Hi all,

Bought a new road bike this year:
Shimano WH-R550 wheelset
Tektro RX40 brakes

Rode maybe 50 miles, and found that my braking power was weak. Also, I
heard what I can only describe as a horrible scraping sound.

So I remove my wheels and inspect my brake pads. What do I find?
Several chunks of bright, shiny metal (I assume from my rims).
My LBS tells me that "Yeah, they're crappy brakes" (actually referring
to the brake pads). He gave me some DA pads for replacement.

I cleaned up the rims, put the new pads on the bike and voila!
Instantly better stopping power......

Rode yesterday morning...everything was okay until a 50mph twisty
descent. Near the bottom I did some *moderate* braking (slightly more
pressure than my typical controlled traffic light stop, just to get me
back down to 35-40 mph). Suddenly, I hear that horrible "eating your
rims" sound.

Since I'm in the middle of a long ride and have no extra pads, I stop
and dig out the shards of metal in my rear brake pads. Then, I proceed
to test 'em out, only to discover that the front brakes have become
relatively weak/noisey. Stop again, and find that the front pads are
wearing in an irregular pattern (more wear on bottom than on top...but
no metal this time). Both sets of pads appear to be properly aligned
with the rim when engaged.

WTF? Does this happen to anyone else? Why are my rims being eaten? I
don't care about replacing worn brake pads once in a while, but
replacing my new rims on my new bicycle......grrrrr.

FWIW, I have heard about using KoolStop Salmons, but my LBS didn't have
any. I'm not convinced that they'd be much better than the DA
pads....to me it seems like a rim problem. Should my LBS deal with
this, or am I stuck with crappy rims?

TIA,
Dave

the previous generation of shimano have significant toe in set at the
factory. toe in, while allegedly good for squeal and definitely good
for modulation, is absolutely a nightmare for its ability to trap grit.
you could not contrive a better way to be more destructive.

my solution is to either run campy brake calipers with their factory
orbital pad holders & set them flat with the rim, or if using shimano,
buy after market orbital pad holders and mount those flat with the rim.
you may be interested to know that the current [new] generation of
shimanos have orbital pad holders from factory. [shimano learn as they
go.] this cuts down grit embedding almost to zero, regardless of the
pad you use.

  #23  
Old June 29th 05, 08:13 PM
external usenet poster
 
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Default Brake pads eating rims?

i bought long dirt bike salmon pads for the rainy season. puttem on the
rear centerpulls with a conti set of salmons on the front. still not
setup right and the rim is greasy, no brake prep.
ahhh now it stops!! no more sliding into the canal past the bread truck
to fight it out with the gators.

  #24  
Old June 30th 05, 04:12 AM
Collin
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Posts: n/a
Default Brake pads eating rims?

wrote:
Neil Collin writes:


When you replace your pads, also carefully sand the rims down with
very gritty sandpaper in the direction of rotation. The objective
is to smooth out those pits. I found that the pits have burrs on
them which embed in the new pads, which in turn exacerbate the
problem. So, if your rims are sanded down and cleaned to remove all
those microscopic pieces of aluminum (incidentally aluminum oxide
has a hardness index close to quartz) and you put clean pads on,
that should do the trick.



Don't do that. There is no need to remove any more material from the
rim, it is already damaged enough. If you use Kool-Stop salmon
colored pads, there is no need for any of that. In fact the rougher
the rim (longitudinal grooved) the easier it will be to brake hard
right away with new pads an the smaller the tendency to squeal.
That's why rims are machined these days, because it suppresses squeal
for new bicycle demo's.

I guess I wasn't clear enough. I sanded my rims longitudinally to give
them the same effect as machined rims, hence the recommendation for
course sandpaper. Worked great. But you've never noticed the little
burrs on the edges of those grooves? I checked them out with a loupe
and they were obvious.

Also your earlier post about running cement powder over your rims while
braking seems to be a similar idea. Maybe that would be a recommended
alternative?
I don't know what benefit you imagine by sanding the rim. There are
no "pits" in the rim. There are only grooves from aluminum oxide
cutting tools embedded in poor brake pads.


  #25  
Old June 30th 05, 06:02 PM
Phil, Squid-in-Training
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Posts: n/a
Default Brake pads eating rims?

jim beam wrote:
wrote:
Hi all,

Bought a new road bike this year:
Shimano WH-R550 wheelset
Tektro RX40 brakes

Rode maybe 50 miles, and found that my braking power was weak. Also, I
heard what I can only describe as a horrible scraping sound.

So I remove my wheels and inspect my brake pads. What do I find?
Several chunks of bright, shiny metal (I assume from my rims).
My LBS tells me that "Yeah, they're crappy brakes" (actually
referring to the brake pads). He gave me some DA pads for
replacement. I cleaned up the rims, put the new pads on the bike and
voila!
Instantly better stopping power......

Rode yesterday morning...everything was okay until a 50mph twisty
descent. Near the bottom I did some *moderate* braking (slightly
more pressure than my typical controlled traffic light stop, just to
get me back down to 35-40 mph). Suddenly, I hear that horrible
"eating your rims" sound.

Since I'm in the middle of a long ride and have no extra pads, I stop
and dig out the shards of metal in my rear brake pads. Then, I
proceed to test 'em out, only to discover that the front brakes have
become relatively weak/noisey. Stop again, and find that the front
pads are wearing in an irregular pattern (more wear on bottom than
on top...but no metal this time). Both sets of pads appear to be
properly aligned with the rim when engaged.

WTF? Does this happen to anyone else? Why are my rims being eaten?
I don't care about replacing worn brake pads once in a while, but
replacing my new rims on my new bicycle......grrrrr.

FWIW, I have heard about using KoolStop Salmons, but my LBS didn't
have any. I'm not convinced that they'd be much better than the DA
pads....to me it seems like a rim problem. Should my LBS deal with
this, or am I stuck with crappy rims?

TIA,
Dave

the previous generation of shimano have significant toe in set at the
factory. toe in, while allegedly good for squeal and definitely good
for modulation, is absolutely a nightmare for its ability to trap
grit. you could not contrive a better way to be more destructive.

my solution is to either run campy brake calipers with their factory
orbital pad holders & set them flat with the rim, or if using shimano,
buy after market orbital pad holders and mount those flat with the
rim. you may be interested to know that the current [new] generation
of shimanos have orbital pad holders from factory. [shimano learn as
they go.] this cuts down grit embedding almost to zero, regardless
of the pad you use.


Is that why we have horrendous brake adjustment procedures such as the Park
BT3 he

http://www.parktool.com/tools/BT_3.shtml

If Walmart V-brakes have orbital mounts, how come Shimano 105 doesn't? Like
you said, learn as they go.

--
Phil, Squid-in-Training


  #27  
Old July 1st 05, 02:47 AM
jim beam
external usenet poster
 
Posts: n/a
Default Brake pads eating rims?

Phil, Squid-in-Training wrote:
jim beam wrote:

wrote:

Hi all,

Bought a new road bike this year:
Shimano WH-R550 wheelset
Tektro RX40 brakes

Rode maybe 50 miles, and found that my braking power was weak. Also, I
heard what I can only describe as a horrible scraping sound.

So I remove my wheels and inspect my brake pads. What do I find?
Several chunks of bright, shiny metal (I assume from my rims).
My LBS tells me that "Yeah, they're crappy brakes" (actually
referring to the brake pads). He gave me some DA pads for
replacement. I cleaned up the rims, put the new pads on the bike and
voila!
Instantly better stopping power......

Rode yesterday morning...everything was okay until a 50mph twisty
descent. Near the bottom I did some *moderate* braking (slightly
more pressure than my typical controlled traffic light stop, just to
get me back down to 35-40 mph). Suddenly, I hear that horrible
"eating your rims" sound.

Since I'm in the middle of a long ride and have no extra pads, I stop
and dig out the shards of metal in my rear brake pads. Then, I
proceed to test 'em out, only to discover that the front brakes have
become relatively weak/noisey. Stop again, and find that the front
pads are wearing in an irregular pattern (more wear on bottom than
on top...but no metal this time). Both sets of pads appear to be
properly aligned with the rim when engaged.

WTF? Does this happen to anyone else? Why are my rims being eaten?
I don't care about replacing worn brake pads once in a while, but
replacing my new rims on my new bicycle......grrrrr.

FWIW, I have heard about using KoolStop Salmons, but my LBS didn't
have any. I'm not convinced that they'd be much better than the DA
pads....to me it seems like a rim problem. Should my LBS deal with
this, or am I stuck with crappy rims?

TIA,
Dave


the previous generation of shimano have significant toe in set at the
factory. toe in, while allegedly good for squeal and definitely good
for modulation, is absolutely a nightmare for its ability to trap
grit. you could not contrive a better way to be more destructive.

my solution is to either run campy brake calipers with their factory
orbital pad holders & set them flat with the rim, or if using shimano,
buy after market orbital pad holders and mount those flat with the
rim. you may be interested to know that the current [new] generation
of shimanos have orbital pad holders from factory. [shimano learn as
they go.] this cuts down grit embedding almost to zero, regardless
of the pad you use.



Is that why we have horrendous brake adjustment procedures such as the Park
BT3 he

http://www.parktool.com/tools/BT_3.shtml


/that/ thing is an abomination.


If Walmart V-brakes have orbital mounts, how come Shimano 105 doesn't? Like
you said, learn as they go.


  #28  
Old July 29th 05, 07:44 PM
notryt
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Posts: n/a
Default Brake pads eating rims?


Actually the tektro rx40 brakes are one of the better brake calipers o
the market. better than 105 by far and Ide say a tie with dura-ace. Iv
got both da and tektro on my bikes and cant tell any difference.. 105'
seemed mushy.. salmon pads are always a good upgrade and make any brak
noticably better.
If anyone has grinding noise problems, check your pads.. then you
rims.. Machined finished rims tend to do this more than any othe
cause. the smoother surfaced rims make for more even braking and les
noise. Anyone trying to save money would not be out of line to go fo
the rx40 calipers 10 grams more weight than da. but the brake i
definitely more aero than anything smimano, fsa, or campy makes. an
they are only $60.. no brainer! Notryt (cat:3

--
notryt

 




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