B-Tension adjustment on Shimano derailer doesn't change angle

Dan Musicant wrote:
To me it appears that the rear changer is not vertical but tilted so
that the bottom is closer to the wheel than the top.The angle off
vertical I'd estimate at 3 degrees. I have tried changing this angle to
acheive vertical with the "B Tension" adjustment screw on the Shimano
rear derailer. However, from the tightest adjustment to the loosest I
detect no effect on the aforementioned angle. Am I wrong in thinking
that this adjustment screw affects that angle? What am I missing?
Thanks for any help.
Dan



Yes, you're wrong - the B screw changes the gap between the top of the
jockey pulley and the bottom of the cogs - you usually need to adjust it
when you're changing to a cassette with different gearing. There are no
adjustments to the angle the derailleur cage makes with the vertical -
except for bending.



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It sounds like to me, that from your description, you may need the
derailleur hanger bracket aligned.

Hope this helps.

Lewis.

***********************

Dan Musicant wrote in message . ..
To me it appears that the rear changer is not vertical but tilted so
that the bottom is closer to the wheel than the top.The angle off
vertical I'd estimate at 3 degrees. I have tried changing this angle to
acheive vertical with the "B Tension" adjustment screw on the Shimano
rear derailer. However, from the tightest adjustment to the loosest I
detect no effect on the aforementioned angle. Am I wrong in thinking
that this adjustment screw affects that angle? What am I missing?

Thanks for any help.

Dan

On 9 Sep 2003 08:43:05 +0950, DiabloScott
wrote:

an Musicant wrote:
: To me it appears that the rear changer is not vertical but tilted so
: that the bottom is closer to the wheel than the top.The angle off
: vertical I'd estimate at 3 degrees. I have tried changing this angle to
: acheive vertical with the "B Tension" adjustment screw on the Shimano
: rear derailer. However, from the tightest adjustment to the loosest I
: detect no effect on the aforementioned angle. Am I wrong in thinking
: that this adjustment screw affects that angle? What am I missing?
: Thanks for any help.
: Dan
:
:
:
:Yes, you're wrong - the B screw changes the gap between the top of the
:jockey pulley and the bottom of the cogs - you usually need to adjust it
:when you're changing to a cassette with different gearing. There are no
:adjustments to the angle the derailleur cage makes with the vertical -
:except for bending.

Yep. I figured I had the wrong concept. Thanks, and to Mike too! I will
make the angle adjustment with a large crescent wrench, and carefully so
as not to hurt any threads. I figure the pullies should dangle vertical
to the ground, no?

Dan

"Dan Musicant" wrote in message
...
On 9 Sep 2003 08:43:05 +0950, DiabloScott
wrote:

an Musicant wrote:
: To me it appears that the rear changer is not vertical but tilted so
: that the bottom is closer to the wheel than the top.The angle off
: vertical I'd estimate at 3 degrees. I have tried changing this angle
to
: acheive vertical with the "B Tension" adjustment screw on the Shimano
: rear derailer. However, from the tightest adjustment to the loosest I
: detect no effect on the aforementioned angle. Am I wrong in thinking
: that this adjustment screw affects that angle? What am I missing?
: Thanks for any help.
: Dan
:
:
:
:Yes, you're wrong - the B screw changes the gap between the top of the
:jockey pulley and the bottom of the cogs - you usually need to adjust it
:when you're changing to a cassette with different gearing. There are no
:adjustments to the angle the derailleur cage makes with the vertical -
:except for bending.

Yep. I figured I had the wrong concept. Thanks, and to Mike too! I will
make the angle adjustment with a large crescent wrench, and carefully so
as not to hurt any threads. I figure the pullies should dangle vertical
to the ground, no?

Dan


Yes, more correctly parallel to the rear wheel (assuming properly dished and
true). Which is what the derailleur alignment gauge checks for. If you are
in good with your LBS it shouldn't cost much to have it sorted out. I have
my own tool because I have a downhill bike that gets bent frequently and I
can't be arse'd with going to the LBS every time.

Mike

On Tue, 9 Sep 2003 13:23:50 -0400, "Michael Dart"
wrote:

:
:"Dan Musicant" wrote in message
.. .
: On 9 Sep 2003 08:43:05 +0950, DiabloScott
: wrote:
:
: an Musicant wrote:
: : To me it appears that the rear changer is not vertical but tilted so
: : that the bottom is closer to the wheel than the top.The angle off
: : vertical I'd estimate at 3 degrees. I have tried changing this angle
:to
: : acheive vertical with the "B Tension" adjustment screw on the Shimano
: : rear derailer. However, from the tightest adjustment to the loosest I
: : detect no effect on the aforementioned angle. Am I wrong in thinking
: : that this adjustment screw affects that angle? What am I missing?
: : Thanks for any help.
: : Dan
: :
: :
: :
: :Yes, you're wrong - the B screw changes the gap between the top of the
: :jockey pulley and the bottom of the cogs - you usually need to adjust it
: :when you're changing to a cassette with different gearing. There are no
: :adjustments to the angle the derailleur cage makes with the vertical -
: :except for bending.
:
: Yep. I figured I had the wrong concept. Thanks, and to Mike too! I will
: make the angle adjustment with a large crescent wrench, and carefully so
: as not to hurt any threads. I figure the pullies should dangle vertical
: to the ground, no?
:
: Dan
:
:
:Yes, more correctly parallel to the rear wheel (assuming properly dished and
:true). Which is what the derailleur alignment gauge checks for. If you are
:in good with your LBS it shouldn't cost much to have it sorted out. I have
:my own tool because I have a downhill bike that gets bent frequently and I
:can't be arse'd with going to the LBS every time.
:
:Mike
:
I wouldn't say I have a good working relationship with any LBS. I've
always done my own maintenance and repair but a lot of stuff I've never
done or done so infrequently that intervening years have blurred or
erased the knowledge I had to gain in order to do the job the time
before! I have a couple of books that discuss bike repair, but one is
almost 20 years old and the other has bike repair as a sub-theme. I
should maybe get another book. However, nowadays I can find out things
online, it has been pointed out.

Why would your downhill bike get bent frequently?

Downhill is the thing that scares me the most on a bike, easily. I'm a
very safe city rider, having sorted out the mischief, but downhill is
something that I figure is always dangerous. The only thing you can do,
other than be very alert and sensible in the way you ride, is to make
sure your equipment is OK as much as possible.

Dan