TT bike / Road bike swap on trainer

Hi, I’ve set up my TT bike on the trainer for the off season. It’s got 165mm cranks and ratio 39-53 / 25-11 whereas my road bike (which has been on the trainer) is on 170mm cranks and 34-50 on the front. Do I need to recalibrate the trainer or do something on zwift to ensure things are still accurate? Are erg mode etc affected by these sorts of things?

If you have a trainer that needs calibration you should do so regularly regardless of which bike you are using. The different gearing will of course make things more difficult in sim mode, however, ERG mode also seems to respond better when starting in a lower gear but just switching out a bike shouldn’t affect the calibration of your trainer.