Shimano DA7800 RD question

In article 09440412-c751-44ac-8abf-
,
says...


On Mar 26, 12:29*pm, Nick L Plate wrote:
On 26 Mar, 00:39, RS wrote:



In article 25c76e6e-b9dd-46dd-8839-
,

says...

On Mar 25, 12:22*pm, RS wrote:
In article 72481d88-a31b-4cbe-a4ec-
,

says...

On Mar 22, 4:22*pm, RS wrote:
I use a Shimnao Compact Crank 50/34 w/ 9 speed setup, 11
-28 in
rear.
*I'm
currently using a DA7700SS RD. *I know the max. capacity of
this
derailleur
is 27 and there is minor contact even with the B screw set in
all the
way and
I even exchanged the B screw for another one with 1mm
longer
reach.
*Will
going to the GS version of this Derailleur solve the problem,
though
I
only
hear the contact when I have the bike on my workstand,
riding it
never
seems to be a problem. *I believe the GS version also states
27T
max.
in
rear but has a larger overall capacity.

And yes at my age and weight and local steep hills the 34-28
is nice
and
needed. *Thanks.

I put a B screw with about 4 mm greater length in a 7700GS RD
and
it
was used with a 50/34 and 11-32 10s rear cassette (IRD, not
ShimaNO).
Works like a champ, shifts perfectly. *I would suspect that you
could
do the same with the 7700SS.

As a side note, I used the same setup (50/34 with 11-32
cassette)
with
campy gear and the rear der (Centaur long cage) worked fine
without
touching the B screw or having to severely reduce the chain
length to
get the top jockey wheel to clear the cassette.

Reason #764 why campy road gear is the clear choice for road
use.

D'ohBoy

With a longer B screw screwed out the angle of the 7700 SS
becomes
too
horizontal and won't hit the stop on my frame. *But I'll revisit
that
solution,
possible I can get another millimeter or two out of it which may
just do
it.

Sorry - that was a 7800GS Rder i did that with. *But the geometry
and
cage are the same.

D'ohBoy

OK, thanks. *The Longer cage of the GS probably makes a difference.
*I
have another bike with an Ultegra RD6500GS and it works fine in an
8-
speed setup with a 50/34 crank and 11-28 in back. *Guess I'm stuck
on the
50-11 high to the 34-28 low, seems to suit all situations. *50-12 just
isn't
high enough but I will admit to occasionally wishing I had a bail-out
34-30

If there is no other way, grind the tips off a 34, it's not as if you
willl be using it often, *plus the wear rate of a large sprocket is
much much slower than say a sprocket half its size. *If you think wear
would be a problem with this large sprocket, use an older, thicker
sprocket with the tips ground off.

TJ

Do you understand bicycles at all? Grind the teeth off the cog so the
upper pulley doesn't hit it? YGBSM. How about making the chain the
right length or a longer b limit screw, instead of asking for a chain
slip, while going up hill, to take one's front teeth out.

I would agree with Peter, I will not be grinding teeth off.
Ride a well used cassette and haveing chain slip is not pleasan or an
option I would want to create.

On 27 Mar, 11:31, "P. Chisholm" wrote:
On Mar 26, 12:29*pm, Nick L Plate wrote:



On 26 Mar, 00:39, RS wrote:

In article 25c76e6e-b9dd-46dd-8839-
,
says...

On Mar 25, 12:22*pm, RS wrote:
In article 72481d88-a31b-4cbe-a4ec-
,
says...

On Mar 22, 4:22*pm, RS wrote:
I use a Shimnao Compact Crank 50/34 w/ 9 speed setup, 11-28 in
rear.
*I'm
currently using a DA7700SS RD. *I know the max. capacity of this
derailleur
is 27 and there is minor contact even with the B screw set in all the
way and
I even exchanged the B screw for another one with 1mm longer
reach.
*Will
going to the GS version of this Derailleur solve the problem, though
I
only
hear the contact when I have the bike on my workstand, riding it
never
seems to be a problem. *I believe the GS version also states 27T
max.
in
rear but has a larger overall capacity.

And yes at my age and weight and local steep hills the 34-28 is nice
and
needed. *Thanks.

I put a B screw with about 4 mm greater length in a 7700GS RD and
it
was used with a 50/34 and 11-32 10s rear cassette (IRD, not
ShimaNO).
Works like a champ, shifts perfectly. *I would suspect that you could
do the same with the 7700SS.

As a side note, I used the same setup (50/34 with 11-32 cassette)
with
campy gear and the rear der (Centaur long cage) worked fine without
touching the B screw or having to severely reduce the chain length to
get the top jockey wheel to clear the cassette.

Reason #764 why campy road gear is the clear choice for road use.

D'ohBoy

With a longer B screw screwed out the angle of the 7700 SS becomes
too
horizontal and won't hit the stop on my frame. *But I'll revisit that
solution,
possible I can get another millimeter or two out of it which may just do
it.

Sorry - that was a 7800GS Rder i did that with. *But the geometry and
cage are the same.

D'ohBoy

OK, thanks. *The Longer cage of the GS probably makes a difference. *I
have another bike with an Ultegra RD6500GS and it works fine in an 8-
speed setup with a 50/34 crank and 11-28 in back. *Guess I'm stuck on the
50-11 high to the 34-28 low, seems to suit all situations. *50-12 just isn't
high enough but I will admit to occasionally wishing I had a bail-out 34-30

If there is no other way, grind the tips off a 34, it's not as if you
willl be using it often, *plus the wear rate of a large sprocket is
much much slower than say a sprocket half its size. *If you think wear
would be a problem with this large sprocket, use an older, thicker
sprocket with the tips ground off.

TJ

Do you understand bicycles at all? Grind the teeth off the cog so the
upper pulley doesn't hit it? YGBSM. How about making the chain the
right length or a longer b limit screw, instead of asking for a chain
slip, while going up hill, to take one's front teeth out.

A 34 is large for a racing mech. usual 'limit' at 28, but can be
pushed to 31 or 32. I've not heard of a 34 being used on a racing
mech. Like I said "If there is no other way" grind the tips off a
34. It is the bottom of the tooth that does the work, not the tip.
The tip guides the chain into position and prevents the chain from
tipping sideways when the chain is severley skewed. Leaving the
height of the tip so that it is no more than 5/8 of the roller
diameter I hope would be sufficient. It should at least enable an
easy shift away from it i f not necessarily onto it.

TJ