Clipless in Coeur d'Alene
Join Date: Mar 2012
Location: Coeur d'Alene, Idaho
Bikes: Calfee Dragonfly S&S Tandem, Specialized Tarmac SL4 S-Works, other misc Road & MTB singles
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This link from TandemGeek's
blog shows Calfee's eccentric at the bottom left, and the Bushnell near the top right.
TandemGeek's use of square taper BB adjusts by applying inward pressure to the BB cups. That does not work very well with Calfee's 2-piece eccentric. Since the Bushnell eccentric has a solid center core, the BB cups will screw into this and any adjustment pressure is applied to the ecc core, not the frame shell, which works better for his case.
Calfee's ecc can be a bit tricky to get the two side to align perfectly when using external BB bearings (think HollowTech or MegaExo, etc) since these BB types do not provide their own cores. It can be especially tricky when trying to set a specific tightness for a Gates belt. The Bushnell BB helps keep everything properly aligned. The Bushnell is also a better option for Gates belt users as it allows the ecc to be setup a little left or right to improve alignment with the rear timing ring.
I have no experience with older and possibly smaller Calfee shells, but only the "newer (+2008?) aluminum sleeved shells which are compatible with either the Calfee two-piece or Bushnell shell.
FWIW, I actually got DaVinci's version of the Bushnell from Mel at Tandems East. This one has some extra gripper notches, etc, and the price was good too. If curious, call Mel and ask about it.
Tip: An added benefit with the Bushnell, is the ability to flip the core and have the ecc tightening screw on the left hand side. This is useful if using right-side drive setups (ours for example).
Last edited by twocicle; 02-09-16 at 02:10 PM.