I noted on the tandem weight thread that Calfee had posted on FB an album of pics of a new Dragonfly 24.12 lb, featuring a BB30 Cannondale Hollowgram SL crankset.
BB30 cranks. What BB30 eccentric is available?
Is that an eccentric being used for a stoker's crank BB shell? Note the dremel work on the chainstay to provide clearance for the Gates sync pulley. I'll bet this clearance issue was discovered after the crank install was attempted!
Stoker's crank left side.
Cannondale Hollowgram SL BB30 crank in double (no triple spider available for SL cranks).
How is it that a C'dale Hollowgram SL crankset can be used on a tandem? This is apparently a crossover. The design of the SL is more akin to an ISIS or square taper crank, with both the left and right side pedals and spider removable from the bottom bracket.
A few points:
- Calfee has demonstrated that a Cannondale SL crank can be adopted for a tandem.
- Calfee has apparently sourced a BB30 eccentric (Co-Motion has one, apparently).
- It almost looks like the BB30 eccentric is used as the stoker's crank BB shell.
- There is no triple Cannondale road (130/74 BCD) spider. Cannondale or someone would need produce a triple spider to make the C'dale SL a viable tandem crankset option.
- Sources state that the 2013 Cannondale RT3 tandem will be BB30. Might Cannondale be the source of the BB30 eccentric?
- The Cannondale SL crank is a quite light, and well regarded high-end crank. Having a new tandem crank option is a boon.
- The BB30 standard has mixed reviews. But it is potentially well suited for tandems as the spindle diameter is larger.