Tandem Cycling - can't turn my eccentric bb

hey, i'm having eccentric bb problems. trying to adjust the pinch-bolt bb on my '70s gitane tandem so i can throw on a sync chain but i can't figure out how to turn it.

the side opposite the captain's timing crank looks like this:


no holes for a pin spanner, just little triangular spaces around the interior shell. it also might be rusty, although i drowned it in triflow a few months ago. any ideas on how to turn it? my tension right now really sucks.

Why can't you put a pin spanner in the spaces?

Spray the heck out of it with penetrating oil and hit it with a hammer and punch.

BTW you can also use a ring slightly larger than your timing chainrings to take up the slack. Just place it in the middle of your timing chain so that it catches both the upper and lower run and it should stay in place just fine.

yeah, i tried putting a pin spanner in the spaces but the spaces were large enough that it was hard to apply any torque without a cam out. i thought maybe there was some big secret that i was missing. french bikes are such a pain.

don't think i should hammer. think i'll try what you said, stick another chainring in there then ride it solo to the LBS and see what they can do.

Insert hefty screwdriver blade into the space. Pedal backwards. Crankarm will exert force, usually enough to rotate it.

BTW you can also use a ring slightly larger than your timing chainrings to take up the slack. Just place it in the middle of your timing chain so that it catches both the upper and lower run and it should stay in place just fine.

That's a Magic Chainring.

Magic or Floating chainring. Been there and done that back in the late 70s. Works.
It does get some attention so be prepared to answer the question "Why?"

Magic or Floating chainring. Been there and done that back in the late 70s. Works.
It does get some attention so be prepared to answer the question "Why?"
Pedal on!
Rudy and Kay/zonatandem