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Disk brakes might be useful



 
 
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  #61  
Old February 13th 19, 05:42 PM posted to rec.bicycles.tech
David Scheidt
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Posts: 1,346
Default Disk brakes might be useful

Sir Ridesalot wrote:
:On Tuesday, February 5, 2019 at 10:34:24 PM UTC-5, Frank Krygowski wrote:
: On 2/5/2019 8:48 PM, AMuzi wrote:
:
:
: [raised eyebrow] 1000 miles? every year? yikes!
:
: I also consider rims a consumable, but due to heart-shape format or too
: many eyelets pulled through. I've never worn out a rim's brake surface.
:
: I'm glad you said that. I was feeling inadequate because I don't think
: I've ever worn out a rim's brake surface.
:
: I've replaced rims mostly when potholes have damaged them so badly that
: I can't jack the dents back out (and I've jacked out several bad dents).
: Also when switching from 27" to 700c.
:
: Is there a rule of thumb for how thin I can let a braking surface get?
: I'm talking about ancient rims that have no indicator groove.
:
: --
: - Frank Krygowski

:I saw one rim at a bicycle co-op that had failed. The guy who owned it
:said that he felt the brake pad rubbing for quite a bit before the rim
:brake track folded outward. My guess is that you'd know a failure was
:imminent IF you pay attention to odd things on your bicycle. His wheels

The one I have ahd fail on me failed without warning. It was an old
wheel, on an old bike, that'd I'd bouht used. No idea how many miles
it had (not many of mine, though.) Fortunately, it happened at zero
miles an hour.


:had those wear indicator grooves in them. I wonder if those grooves are
:stress risers when a rim starts to get worn a bit?

:Cheers

--
But all of a sudden Igor Stravinsky shows up with bag of psilocybin
mushrooms and a chainsaw.... -- Jens
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  #62  
Old February 13th 19, 09:58 PM posted to rec.bicycles.tech
[email protected]
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Posts: 1,261
Default Disk brakes might be useful

On Wednesday, February 13, 2019 at 8:36:36 AM UTC-8, Joerg wrote:
On 2019-02-11 18:15, David Scheidt wrote:
AMuzi wrote:
:On 2/6/2019 11:25 AM, Ned Mantei wrote:
: On 06-02-19 16:38, Joerg wrote:
: I have used up some rims over my riding years. Back as a
: student when I did 6000 miles per year I "solved" the
: problem of having to spoke in by buying another used
: beater bike every year. After I bought my first custom
: road bike I had it done at the LBS because I am not that
: good in trueing a wheel.
:
: Waiting too long can be risky and not all rims have good
: indicators when they are about to go. My sister had a
: violent rim blow-out on a mountain bike. Luckily it was
: the rear wheel. Of course, according to Sir, our family
: must be a bunch of carnivores and rim eaters.
:
: Not long ago I replaced the front rim on my everyday bike.
: This was a DT-Swiss rim, which had as a wear indicator some
: tiny holes a mm or so deep in the side. The rim should be
: O.K. as long as you can see the holes. They were still
: visible, but there was a slight grab at one spot while
: braking, and there the rim joint had become visible. I
: decided to replace the rim to be completely safe, and had
: certainly got my money's worth since it was about 9 years
: old. Out of curiosity I showed the rim to the LBS expert. He
: broke the rim into pieces, with a for me surprising result:
: Part of the rim wall was only about 0.75 or 0.8 mm thick, so
: well into the danger zone. Glad that I was cautious, even
: though transferring the spokes to a new rim and getting
: everything adjusted took more than 4 hours.
:
: Ned

: "transferring the spokes to a new rim and getting
: everything adjusted took more than 4 hours."

:including occasional meditation sessions and painting the room.


While I have no doubt that you, or anyone who builds wheels more often
than I do, could do it much faster, 4 hours is about what I'd expect
it to take me.


I prefer the five minutes it takes to swap out a brake rotor, then use
the remaining 3:55h to ride 8-)

--
Regards, Joerg

http://www.analogconsultants.com/


I still have a problem with all of the braking forces being applied at the end of the fork rather than at the head of the fork. I can't see that it matters on a suspension fork but on a road bike it's another matter. But I can see the value of using cheaply replaceable disks and pads on very expensive wheelsets.
  #63  
Old February 13th 19, 10:12 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 6,016
Default Disk brakes might be useful

On 2019-02-13 12:58, wrote:
On Wednesday, February 13, 2019 at 8:36:36 AM UTC-8, Joerg wrote:
On 2019-02-11 18:15, David Scheidt wrote:
AMuzi wrote: :On 2/6/2019 11:25 AM, Ned
Mantei wrote: : On 06-02-19 16:38, Joerg wrote: : I have used
up some rims over my riding years. Back as a : student when I
did 6000 miles per year I "solved" the : problem of having to
spoke in by buying another used : beater bike every year. After
I bought my first custom : road bike I had it done at the LBS
because I am not that : good in trueing a wheel. : :
Waiting too long can be risky and not all rims have good :
indicators when they are about to go. My sister had a : violent
rim blow-out on a mountain bike. Luckily it was : the rear
wheel. Of course, according to Sir, our family : must be a
bunch of carnivores and rim eaters. : : Not long ago I replaced
the front rim on my everyday bike. : This was a DT-Swiss rim,
which had as a wear indicator some : tiny holes a mm or so deep
in the side. The rim should be : O.K. as long as you can see the
holes. They were still : visible, but there was a slight grab at
one spot while : braking, and there the rim joint had become
visible. I : decided to replace the rim to be completely safe,
and had : certainly got my money's worth since it was about 9
years : old. Out of curiosity I showed the rim to the LBS
expert. He : broke the rim into pieces, with a for me surprising
result: : Part of the rim wall was only about 0.75 or 0.8 mm
thick, so : well into the danger zone. Glad that I was cautious,
even : though transferring the spokes to a new rim and getting
: everything adjusted took more than 4 hours. : : Ned

: "transferring the spokes to a new rim and getting :
everything adjusted took more than 4 hours."

:including occasional meditation sessions and painting the room.


While I have no doubt that you, or anyone who builds wheels more
often than I do, could do it much faster, 4 hours is about what
I'd expect it to take me.


I prefer the five minutes it takes to swap out a brake rotor, then
use the remaining 3:55h to ride 8-)

-- Regards, Joerg

http://www.analogconsultants.com/

I still have a problem with all of the braking forces being applied
at the end of the fork rather than at the head of the fork. I can't
see that it matters on a suspension fork but on a road bike it's
another matter.



When using 8" rotors it's not so bad and disc brake forks are supposed
to be designed to take that kind of load. I'd never use less than 8" up
front considering my weight and the fact that there is often cargo on
the bike.


... But I can see the value of using cheaply replaceable
disks and pads on very expensive wheelsets.


Also for less expemnsive ones. Whether retired or still working, one
must value one's time. 4h of wheel building and trueing isn't exactly my
favorite pastime.

--
Regards, Joerg

http://www.analogconsultants.com/
  #64  
Old February 14th 19, 05:10 AM posted to rec.bicycles.tech
Frank Miles
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Posts: 40
Default Disk brakes might be useful

On Wed, 13 Feb 2019 16:42:15 +0000, David Scheidt wrote:

Sir Ridesalot wrote:
:On Tuesday, February 5, 2019 at 10:34:24 PM UTC-5, Frank Krygowski
wrote: : On 2/5/2019 8:48 PM, AMuzi wrote:
:
:
: [raised eyebrow] 1000 miles? every year? yikes!
:
: I also consider rims a consumable, but due to heart-shape format or
too : many eyelets pulled through. I've never worn out a rim's brake
surface.
:
: I'm glad you said that. I was feeling inadequate because I don't
think : I've ever worn out a rim's brake surface.
:
: I've replaced rims mostly when potholes have damaged them so badly
that : I can't jack the dents back out (and I've jacked out several bad
dents). : Also when switching from 27" to 700c.
:
: Is there a rule of thumb for how thin I can let a braking surface
get? : I'm talking about ancient rims that have no indicator groove.
:
: --
: - Frank Krygowski

:I saw one rim at a bicycle co-op that had failed. The guy who owned it
:said that he felt the brake pad rubbing for quite a bit before the rim
:brake track folded outward. My guess is that you'd know a failure was
:imminent IF you pay attention to odd things on your bicycle. His wheels

The one I have ahd fail on me failed without warning. It was an old
wheel, on an old bike, that'd I'd bouht used. No idea how many miles it
had (not many of mine, though.) Fortunately, it happened at zero miles
an hour.


:had those wear indicator grooves in them. I wonder if those grooves are
:stress risers when a rim starts to get worn a bit?

:Cheers


I've worn through more than a half-dozen rims over the decades. What
really makes for the greatest wear is commuting in wet conditions, with
road grit acting as an effective abrasive, especially when trapped in the
brake pads. Living in Seattle means this happens a lot (and I lived in
Portland, Or for some years before moving to Seattle). This doesn't
happen on my bike that mostly stays inside in the rain.

One particularly memorable occasion was noticing that a rim was becoming
out of true. Noticing some serious grooves worn in the sides, I found
that I could put my thumb-nail through the sidewall! Ok, time to retire
that one!!

My wheels seem to stay true until the sidewalls get really thin (I build
my own). Once they start getting flakey I've cut them with a hacksaw and
examine the cross-section. It's been amazing to see how thin the
sidewalls have become before they are no longer serviceable.

HTH...
  #65  
Old February 14th 19, 10:57 AM posted to rec.bicycles.tech
Ned Mantei[_2_]
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Posts: 81
Default Disk brakes might be useful

On 14-02-19 05:10, Frank Miles wrote:
My wheels seem to stay true until the sidewalls get really thin (I build
my own). Once they start getting flakey I've cut them with a hacksaw and
examine the cross-section. It's been amazing to see how thin the
sidewalls have become before they are no longer serviceable.


Instead of using a hacksaw, at my LBS they used another method: They put
one side of the rim between the open jaws of a vise, with the rim
vertical as when riding, and then pushed back on the rim. Surprisingly
for me, rather than bending the rim broke cleanly. The LBS uses this to
break discarded rims into several pieces, which makes recycling the old
metal more convenient. It also let me quickly see how thin the rim walls
had become.

Ned
  #66  
Old February 14th 19, 04:47 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
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Posts: 10,538
Default Disk brakes might be useful

On 2/14/2019 4:57 AM, Ned Mantei wrote:
On 14-02-19 05:10, Frank Miles wrote:
My wheels seem to stay true until the sidewalls get really thin (I build
my own).Â* Once they start getting flakey I've cut them with a hacksaw and
examine the cross-section.Â* It's been amazing to see how thin the
sidewalls have become before they are no longer serviceable.


Instead of using a hacksaw, at my LBS they used another method: They put
one side of the rim between the open jaws of a vise, with the rim
vertical as when riding, and then pushed back on the rim. Surprisingly
for me, rather than bending the rim broke cleanly. The LBS uses this to
break discarded rims into several pieces, which makes recycling the old
metal more convenient. It also let me quickly see how thin the rim walls
had become.


For both Frank and Ned: I'd be really interested in measurements. How
thin were those sidewalls when they are no longer serviceable?

--
- Frank Krygowski
  #67  
Old February 15th 19, 05:37 AM posted to rec.bicycles.tech
Frank Miles
external usenet poster
 
Posts: 40
Default Disk brakes might be useful

On Thu, 14 Feb 2019 10:47:45 -0500, Frank Krygowski wrote:

On 2/14/2019 4:57 AM, Ned Mantei wrote:
On 14-02-19 05:10, Frank Miles wrote:
My wheels seem to stay true until the sidewalls get really thin (I
build my own).Â* Once they start getting flakey I've cut them with a
hacksaw and examine the cross-section.Â* It's been amazing to see how
thin the sidewalls have become before they are no longer serviceable.


Instead of using a hacksaw, at my LBS they used another method: They
put one side of the rim between the open jaws of a vise, with the rim
vertical as when riding, and then pushed back on the rim. Surprisingly
for me, rather than bending the rim broke cleanly. The LBS uses this to
break discarded rims into several pieces, which makes recycling the old
metal more convenient. It also let me quickly see how thin the rim
walls had become.


For both Frank and Ned: I'd be really interested in measurements. How
thin were those sidewalls when they are no longer serviceable?


I didn't keep any of them, and didn't measure, sorry...
  #68  
Old February 15th 19, 08:48 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 1,261
Default Disk brakes might be useful

On Thursday, February 14, 2019 at 8:37:04 PM UTC-8, cassiope wrote:
On Thu, 14 Feb 2019 10:47:45 -0500, Frank Krygowski wrote:

On 2/14/2019 4:57 AM, Ned Mantei wrote:
On 14-02-19 05:10, Frank Miles wrote:
My wheels seem to stay true until the sidewalls get really thin (I
build my own).Â* Once they start getting flakey I've cut them with a
hacksaw and examine the cross-section.Â* It's been amazing to see how
thin the sidewalls have become before they are no longer serviceable.

Instead of using a hacksaw, at my LBS they used another method: They
put one side of the rim between the open jaws of a vise, with the rim
vertical as when riding, and then pushed back on the rim. Surprisingly
for me, rather than bending the rim broke cleanly. The LBS uses this to
break discarded rims into several pieces, which makes recycling the old
metal more convenient. It also let me quickly see how thin the rim
walls had become.


For both Frank and Ned: I'd be really interested in measurements. How
thin were those sidewalls when they are no longer serviceable?


I didn't keep any of them, and didn't measure, sorry...


I have actually worn through the sidewalls of Mavic MA-2's. Luckily I caught it before the next ride. The rim did not peel apart but I'm positive it would have the first hard bump.
 




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