This is really one of those 'it depends' answers!

The best advice is to speak to your coach and let them know how much time you have available to dedicate to your training. Be aware that it is not necessarily a case of "more = better". Many top class athletes competing at an international level have achieved success on 10 to 12 hours of training. Indeed, one national champion time triallist hardly raises volume above 10 hours a week!

Of course, if you are targeting longer events (races over 4 hours for example) there will be times in your year that you need to get a bit more endurance work under your belt, and this will impact on your weekly total.