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Old March 4th 19, 03:20 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 6,016
Default Coaster Brake Failure

On 2019-03-03 10:00, wrote:
On Saturday, March 2, 2019 at 6:24:14 PM UTC-8, Radey Shouman wrote:
Ralph Barone writes:

Joerg wrote:
On 2019-03-02 08:28, Mark J. wrote:
On 3/2/2019 8:04 AM, Joerg wrote:
On 2019-02-28 18:31, AMuzi wrote:
On 2/28/2019 6:49 PM, Joerg wrote:
On 2019-02-27 14:47, John B. Slocomb wrote:
On Wed, 27 Feb 2019 08:09:04 -0800, Joerg
wrote:

On 2019-02-25 11:42, Tosspot wrote:
On 2/25/19 5:06 PM, Joerg wrote:
On 2019-02-25 07:29, Ralph Barone wrote:
AMuzi wrote:
https://www.bicycleretailer.com/reca...nd-aftermarket









Mysterious. How the hell did that happen in a design
100+ years old?

They must have improved it.


In German there is the inofficial word
"verschlimmbessern". It sums up the action of
"Here we have a working design but let's
optimize it anyhow" and then it all goes to
pots. A very common scenario in software
design.

https://www.youtube.com/watch?v=gp_D8r-2hwk


Sometimes those things happen for reasons Tom
mentioned. People using library modules that others
have written, assuming everything in those we be
just fine. And then things aren't.

This is one of the reasons why I prefer gear with
the least amount of electronics and software in
there and, for example, will never be caught with
electronic shifters on a bicycle.

True, but then people also have had the metal shift
cables break and been restricted to a single gear. It
appears that everything is subject to failure :-)


That is very rare, more so than a derailer ripped away
by a rock.

Main thing is, with batteries the number of available
shifts per charge is finite. I was told that front
shifts are especially hard on the battery and on
mountainous singletrack that's used a lot.

If I had north of $1k burning in my pocket I'd rather
spend that on a Rohloff. That one allows shifts across
the complete gear range at very low or zero speed which
is very useful in MTB riding. To heck with the extra
weight.


Old fashioned junk. Try to keep up:

https://bikerumor.com/2019/02/24/rot...pset-at-1785g/





13-speed, yikes. When that has run it's course they'll offer 14-speed.
When will we have CVT for bicycles?

I recently installed a longer rear derailer, a hanger
extender and a 11-40T cassette. I hacked it to fit the old
6-speed road bike, now 7-speed. For a guy getting older and
having moved into hill country that makes a major
difference. The only downside with such a large cassette
for me is when I stop pedaling too suddenly or pedal
backwards a little to level the cranks for a water
crossing. Then the chain slaps violently and hits the right
chainstay. Happens only when on the smaller sprockets, due
to the flywheel effect. So now there is a piece of slit
pool sweep hose on top of that as "sacrificial material".

They make modern rear derailleurs with a "clutch" in/on the
jockey pulley to avoid just this chain-slap problem.
Example:
https://bike.shimano.com/en-EU/produ...-RX800-GS.html



The described "on-off switch" is for the clutch.


Interesting! However, that derailer retails north of $100. My
solution with a $20 derailer and a chunk of plastic hose with
three cable ties leaves $80 to spend at bicycle gas stations,
a.k.a. brewpubs :-)

An upside is that such kludges along with mud caked onto the
frame and a hose clamp fix on the steerer greatly reduce the
chance of this bike being stolen while in a city.

http://www.analogconsultants.com/ng/bike/Hoseclamp.JPG


If you ever decide to fix it in a similarly cheap, but more
aesthetically pleasing fashion, cut a strip out of an old inner
tube, then wrap it around the chainstay and super glue it to
itself on the inside of the chainstay.


Or just buy a roll of helicopter tape, enough for several dozen
bikes.

--


While that keeps chain grease off of the stay it doesn't prevent it
from being slapped hard enough to damage the paint or even dent the
stay. When you peel the take off the paint comes with it. The best
idea if you can call it that is to have the proper chain length and
gear selections so that you don't have chain slap. Also you can learn
to shift only one gear at a time so that you get less chain length
variation and almost no chain slap at all. Not that I'm not guilty of
shifting at the last second and going down 5 gears.


On my road bike it mostly happens when I am in high gear, small cog,
high speed and suddenly a deer or whatever jumps out of the bushes. When
I then stop pedaling immediately and brake hard ... SLAP. It's because
of the large 40T cog and the 36-32-28 next to it. Their rotating mass
drives the cassette to want to turn some more. As Mark pointed out
that's because my derailer doesn't have an "anti-slap" clutch.

--
Regards, Joerg

http://www.analogconsultants.com/
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