There has been debate on this topic for as long as I can remember. There are arguments on why you should and why you shouldn’t strength train, but even though scientists and top coaches have spend time on this topic for years, there is still no agreement on what is the most optimal winter training for a road cyclist.
The keywords in this discussion are ”˜lack of evidence’. This is due to small study groups in the scientific projects. When the medical industry develops new medicine to prevent heart attacks, they can make large randomized trials to show even small, but still significant, differences between different medications. They include thousands of persons in the study and follow them through several years. Thus, the statistical power is much, much higher.
Unfortunately that is simply not possibly with trained cyclists and that is why we will never see any randomized trials that conclude whether strength training makes us better cyclists or not.
Btw. Are you visiting the gym this winter?