Quoted message said:Boy do I feel silly! I took the mech off to try and find GS or SGS
serial code and then replaced it to take it to the shop. Only when I
replaced it I noticed the deray housing was now touching the drop out
and the chain cage was angled back much further - fitted the chain did
the H/L/Index settings - works a treat. At least I found it out
before returning it to the shop.
Glad you solved your problem. There are some significant differences
in the new Shadow derailleurs though. Besides the low profile, there
are three other major changes: a more direct cable pull (reduced loop
in the cable housing), removal of the B tension spring, and centering
of the guide pulley on the cage pivot. The direct cable routing is
clearly better. The next two changes are only an advantage for Horst
link bikes as they prevent the derailleur from hitting the chainstay.
This issue is clearly demonstrated by the infamous videos of SRAM
versus Shimano rear derailleurs:
I talked to a senior Shimano guy at the show and he said that shifting
is not improved by these changes. Most customers with OE drivetrains
will not be able to notice any difference other than reduced ability
to misadjust cable tension (for example good shifting will occur only
within one turn of the barrel adjuster rather then two turns). I can
only assume that Specialized is a large enough customer to make this
reduction in shifting quality worthwhile enough to raise eyebrows at
apparent adoption of SRAM derailleur design.
As the B pivot is now essentially fixed, this required two other
changes in this derailleur design. Because the derailleur can no
longer "float", it cannot follow the change in cog size as accurately.
This is exacerbated by the lack of an offset guide pulley. Thus the
cage angle has been significantly increased compared to help it track
the cogs better. This makes it less flexible for a variety of cog sets
and indeed Shimano specs this derailleur as being for 11-32/34t
clusters only.
For a similar reason, it does not have the inherent chain wrap
capacity of derailleurs with B tension springs. Thus you will notice
that the cage is significantly longer than the old design to
compensate. In fact, the long cage version is probably the longest
cage I have ever seen.
Because of the lack of the B spring, tension of the pulley spring had
to be increased. The Shimano rep told me that this translates into a
15 percent higher force required on the cable (probably unnoticeable
but still significant).
I purchased the XT Shadow long cage before I went to Interbike based
on what I thought were real design improvements at the time. After
Interbike I wished I hadn't, particularly after my trial last week of
two very different derailleurs. As background, I have a non OE very
wide range (9-34t) cogset with custom cog selection (Shimano). As
such, my setup is ideal for testing derailleur's abilities on marginal
systems.
I'd been using a SRAM X-O derailleur for some months. Switching to an
older XT derailleur (and appropriate shifter) brought about
significant gains. While subjective, I would say shifting improved
about 20 percent.
In addition, one thing often noted about SRAM derailleurs is that
upshifting (to a smaller cog) is done with a noticeable clunk, both
audible and tactile. Because of the way my XT B spring derailleur
follows the cogs closer, upshifts are much smoother. If performance
was otherwise the same, this one factor would be enough for me to
switch.
As a result of this, I don't even see the point of trialing my new
Shadow XT for my purposes (I'll probably sell it on eBay). For others,
you would have to consider carefully your choices. Horst link owner?
That is a no brainer. Often hit your derailleur on protrusions? Maybe.
I looked at my older derailleurs and noticed a number of dings. Don't
have a wide cluster? Then no. I wish Shimano would put the more direct
cable routing on all their derailleurs but unless you are unwilling to
go the Avid Rollamajig route, that shouldn't be a major factor. SRAM
versus the Shadow? The increased cable pull of the SRAM is a minor
technical advantage.
One other thing to consider when switching from standard Shimano to
SRAM or the new Shadow if you have a full suspension bike is proper
chain length. You will likely need to add a chain link or two. SRAM
derailleurs have a reputation for self destruction on the trail. I'm
convinced this happens because of chain growth at full bump.
Derailleurs with a B tension spring have much better wrap and ability
to shrug off poor chain length selection.
On other thing noteworthy I've discovered with my less than optimal
setup is that Shimano chains shift better on Shimano clusters than
SRAM chains. It was very minor but noticeable. I was very surprised by
this and almost didn't bother trialing the Shimano chain because I
could not see a visual difference in inner plate profile - they looked
absolutely identical.
