OP It's not cycling per se, it's the fact that (usually) men have a time consuming hobby that means they are away from their kids/ responsibilities at home for hours and days at a time. Unless the women have an equal amount of time (should they wish) then it is unfair.
You seem to be saying that because you didn't want or need that time for your hobbies, then other women shouldn't either, or shouldn't be resentful of not getting it.
You have martyred yourself, congratulations. Other women don't want to do this, and would prefer their husbands to be more available to their children/ take up more of the slack.
Also, you stated that your husband never had the kids on his own for the day because you didn't ask. But why should you have to ask - surely he should have offered sometimes, to allow you go off and do something fun for yourself? That's what a partnership is about.
Also, you said that it's about 'quality of time not quantity', I don't agree - for many mothers, they don't have the choice of quality over quantity when it comes to small children. Somebody HAS to be there with them, doing the grunt work, which usually isn't quality time.
The fact that if falls to the mother because the father is unavailable (doing his hobby) is not a coincidence.