“What’s the point of it?”
I think:
+ shift without the need to pedal
+ shifter doesn’t have to set up very finely to work
+ instant shifting from/to overdrive at the click of the lever
+ shifts under whatever pedalling load (think going up a steep uphill)
+ ‘better’ chainline as set up for one ring, meaning don’t have to worry about having a diagonal chainline (eg. both little rings, or both big rings)
+ Increased clearance (is the size of a 24T ring)
+ a single ring means the chain should be run shorter (and with a short cage mech) means less chain slack (to deal with less change in ring sizes), and so should stay on better
+ has a built-in upper chainguide
However:
– a lot of bikes are designed to pedal without bobbing in the middle ring. Because it uses a 22 or 24T tooth ring, a lot of frames won’t pedal very well with it, whether in normal 22T, or overdirve (22T ring spinning 1.6 times faster than the cranks)
– Heavier than an equivalent AM/FR setup (despite what they say)
– Expensive
– Internal drag (especially in overdrive mode)
– needs ISCG frame mounts (few non-FR/DH/DJ frames have them)
Something like that
According to a review in the mag from a year or two ago I seem to remember A rohloff doesn’t shift well under load, has a twist grip shifter, aren’t indexxed ever so well in some ratios, are a bit weighty (all in the wheel throws the bike balance out a fair bit), require a wheelbuild, cost £700 as well as a few other issues that I can’t remember