Most of my training is limited to a gym-bike at lunchtime, and I get to ride a sportive say once every 3 weeks. These often involve a lot of climbing (2000 - 3500m).
When these climbs get near the 10% mark I find that I cannot maintain the cadence that I would like, so I drop to to ~70 RPM.
Does this mean that my training @FTP done on a stationary trainer should also be done at a cadence of around 70 RPM ?
I train for a mountain time trial with typical 12% gradients and parts that go up to 18% and even with compact gearing it can be hard to maintain high cadence. As part of my training I do some lower cadence intervals. You said below you run 34x27 so there isn't much option to improve the gearing.