First thought: you're on to a loser -- forcing a left turn creates
a situation without a clean solution for bikes.

Second thought: well back from the junction create two on-road
advisory cycle lanes, one on the left and one on the right (up
against the centre line). Paint them red or whatever so they are
conspicuous. The one on the left should start earlier, and have
arrows indicating "left turn only", the one on the right should
have "straight ahead only" arrows and should continue past the
junction, a little clear of the stop line. The two cycle lanes may take
up 50% of the lane, but that's okay if they're advisory.

Brendan
--
Brendan Halpin, Department of Sociology, University of Limerick, Ireland
Tel: w +353-61-213147 f +353-61-202569 h +353-61-338562; Room F2-025 x 3147
http://www.ul.ie/sociology/brendan.halpin.html