The honest answer most cyclists don't want to hear: there is no universal number. Joe Friel sets it cleanly in The Cyclist's Training Bible — your weekly volume should be the most you can absorb while still adapting and still living the rest of your life. For the audience reading this, that almost always lands between 6 and 12 hours. Below 6 you can hold fitness but rarely lift it; above 12 the marginal gain shrinks unless you've got the recovery infrastructure of a full-time athlete.
Anthony has dug into this on the podcast with John Wakefield, Dan Lorang, and the Bora coaching team. Their consistent message: a structured 8 hours a week beats an unstructured 12 every time. Two genuinely easy zone 2 rides, one threshold or VO2max session, one strength session, and one moderate weekend ride will move FTP further in twelve weeks than a random 12-hour week of group rides and sweet spot. The reason is simple — randomness produces fatigue without specificity, and the body adapts to the stimulus you actually deliver, not the hours on Strava.
Practical targets by goal: to finish a 100-mile sportive comfortably, 5-7 structured hours a week for 12 weeks is enough. To lift FTP from 3.0 to 3.5 W/kg, 7-9 hours with proper periodisation usually does it inside 16-20 weeks. To race Cat 3 with a chance of staying in the bunch, 8-12 hours. To compete in Cat 2 or finish a Marmotte/Étape strongly, 10-14 hours plus strength. Above 14 hours you're in serious-amateur or elite-amateur territory and most of the gain comes from recovery and structure, not more saddle time.
Two warnings from inside the coaching community. First, the hours figure on Strava lies. A 60-minute zone 2 ride and a 60-minute group ride that touches threshold are not the same training stress. Stop counting hours; start counting load with intent. Second, more hours added to a system that's recovery-broken makes things worse, not better. If you're already 8 hours a week and tired all the time, the answer is rarely 'go to 10'. It's 'recover properly for two weeks, then come back to 8 with cleaner zones'. Roadman's masters cohort sees this play out every block.