I setup my old classic (1973 Schwinn Varsity) road bike on my Tacx Vortex trainer so I could spin when the weather’s bad. I’m used to averaging 3.2 w/kg during the winter with my Felt Z5 and I struggled to get half that power with the Schwinn setup on the trainer. I calibrated the bike on the trainer and not sure what else could effect it that much. I doubt the Schwinn is 1/2 as efficient as the Felt especially on the trainer where the weight of the bike is not a factor (granted the Schwinn is a tank). I’m not using a trainer tire on the Schwinn and did smell a slight burning rubber smell but don’t think that was really an issue. I’ll also note I had to modify things on the rear axle nuts/bolts to get the rear wheel to align with the trainer.
So in short, have other people had similar issues where different bikes on the same trainer yield significantly different performance readings (in particular power)??