I dont know how you can say 10-20 miles is just a warm up for a fit cyclist, What if a fit cyclist was doing 15 mile maximum effort? Is it still a warm up then?
I've come from running so dont fully understand, but in terms of running, so correct me if its totaly different is like saying.
3 mile run is a warm up run for a fit runner, but if they are doing tempo work its not, you get me?
TITS training (Time in The Saddle) is regarded as a bit old fashioned these days, there are loads more ways to increase your cycling performance, but there's actually a lot to be said for just spending time on the bike pedalling out the miles. If you start to try anything new, it's always going to be difficult initially but then get easier over time. And I'm not talking days, I'm talking months and years. Performance improvement is gradual to the point where you barely notice it. The only way I do is because I log all my journey times and average speeds. I don't feel stronger because I'm always exerting the same effort. I just go faster.
There aren't any short cuts unfortunately. When I first started commuting 18 miles every day I was falling asleep at my desk around 3 in the afternoon and struggling to do anything active in the evenings. I've now added club rides of 80 miles on a Sunday to my regular schedule as well as cycling to football and playing 90 minutes before cycling home again and riding to work the next morning. Sometimes that morning after I'd feel stiff as a board and crawl to work, but now, for the most part it just feels like any other day on the bike.
I've recently started to time trial on a Tuesday night, so I have to take that into consideration now too... I used to think that I should give myself a rest to make sure I'm not jaded, but the more you cycle, the more you come to realise that once your body gets used to it, the days off can make things worse not better. Keeping the legs going, even if it's just gently will help you go better in the long run. Your body will always tell you if you need a break, but unless you're struggling with an injury, the rides where you feel like you're struggling are the ones which make you stronger.
As far as you're concerned, I wouldn't worry. If I go out on my own (apart from the commute) I really push myself, no matter what the distance. The longer rides I go on are usually with the club and these will all be a little gentler because it's easier to ride in a group. Variation is essential. Long and slow is very good for general fitness as well as short quick rides for speed improvement.
The most important thing though is just to enjoy it. Don't feel like you have to force yourself to ride a certain way to improve.
