OK, here's the info & torrid details on the Hobby Store-stocked, brass
sleeves with set screws we use for our El-Cheapo Gear Position
Indicators:

WHAT TO LOOK or ASK FOR:

Mfr: DU BRO
Cat No.: 137
Item ID: 1/16" Plated Brass "Dura Collars"
Cost: $1.10 for Four (4) -- comes with 4 allen head set screws
& 1 allen wrench (dont't loose it)

These are actually small collars used to hold control surface pins &
wheels onto the axles of R/C Model Aircraft.

INSTALLATION:

-- You thread each of your derailleur cables through one or two of these
collars as they exit the cable stops on the downtube and then position
them with the set screws where you can best use/see them to gauge your
chain position on the front & back derailleurs from your seated
Captain's position.


-- They stay put, but can be removed or re-positioned without marring the
cables & they really look as nice as any other high-end component on
your tandem. Ask anyone who knows me and they'll tell you, if they
didn't look nice they wouldn't be on our tandem. Our old tandem & our
mountain tandem had/has the ink marks, but for the new tandem I went hog
wild and spent the $1.17.

-- On the new set-up, two collars are used on each side.

a). On the FD cable the collars are positioned at a distance of
16mm & 10mm from the cable stops.

b). On the RD cable, they are positioned at a distance of 16mm and
7mm from the cable stops.


NOTE: Your positioning will most likely be different due to differences
in rider & cable stop positioning and, although not by much, differences
in cable throw distances between Ergo & STI.

HOW THEY WORK:

-- Front Derailleur Indicators: From my seated position on the bike &
looking down at the FD cable stop on the right side of the downtube:

a). If the collars are not visible (i.e., hidden by the cable stop)
then I'm in the big ring.
b). If one collar is visible below the stop then I'm in the middle
ring.
c). If both collars are visible below the stop I'm in the granny
ring.

-- Rear Derailleur Indicators: Again, looking down at the RD cable
stop on the left side of the downtube:

a). If the collars are not visible then I'm in my largest (28t)
cog.
b). If one collar is just visible below the stop then I'm in the
next smaller (25t) cog.
c). If the second collar is visible below the stop I'm in middle
range cogs...
...and so on all the way down to the smallest cog (11t) which
is indicated by the appearance of a 1mm gap
between the stop & the 2nd collar.

ALTERNATIVE USES:

-- Again, if you don't mind putting markings on your downtube, you can
use one collar on each cable and set up all the indexed position reference
marks you want to get the level of accuracy you're looking for -- using
pin stripe tape, small numbers, polka dots, you name it.