Originally Posted by
nfmisso
Given the above, the only thing left for initial acceleration is inertia. ->> which leads to gearing as mentioned by @
FastJake and @
Reynolds above.
And me, just sayin...
If OP is really conducting tests with the same gear ratio (dude, go count teeth and let us know), then I think suspicion reverts back to this mysteriously-clicking bottom-bracket. New BB should not click. Maybe it's faulty and adding a lot of friction to the system.