As for the century, you can certainly do it, but you may be in pain and you probably won't be as strong throughout as you'd like to be. Cardiovascularly you'd probably be fine because of your running, though. I say train for it and see how you feel as you get closer. Look for other centuries that are after this one and if you don't feel ready for this one, then do one of those. Is there a half or metric option for this first one?
As for riding alone, I have a few thoughts. One is to talk to your husband about giving you at least one day a week, preferably on your long riding day. You might remind him that this is about more than exercise and training. It's also about your marriage and doing things together. Whether its cycling or something else, you really should have something you share together. You might have to both compromise to figure out when you can do that one long ride a week, since the day you want to do it might be on a day he typically does a long mountain bike ride with his buddies. Try to be flexible and hopefully he will too. Also, try not to be irritated during the conversation. Be sweet and tell him you miss riding with him and would love it if he would do this for you.
Another option, of course, is to find another riding buddy. I have both my husband and a good friend of mine who have been riding buddies. My husband is so much stronger than me that I can't do every ride with him. There are some rides he'll do all the pulling on the flats and wait for me at the top of hills. He can stay in his big ring and get a better workout at a slower pace. Sometimes he'll do a lot of standing. And I can do his recovery rides with him, but when he wants to go all out, there's no point. And he's not going to want to ride my pace every time (though for a while there I was at a level where it wasn't such a vast difference.) But we do enjoy riding with each other for certain rides and having that "thing" we share. We have done a lot of events together where we didn't really "ride" together on the event, but we prepared for it the day before, went and ate our pre-event meal, loaded the truck and traveled there and back together, and shared our ride stories.
However, the person I rode the most with was my friend Dawn. (I say "rode" because between my health issues and her new job, we haven't really ridden together in a year . . . but that's about to change drastically!) Anyway, we rode 3 to 5 times a week together for a couple of years, sometimes with our husbands, but mostly just the two of us. We were great training partners and motivated each other to get out on days one of us didn't really feel up to it. I'm the one who got her into cycling. She had been a runner, but after some nagging I convinced her to give cycling a try and she's so glad she did. Maybe you have a friend you could "suck in" to cycling?
If not, I also have a cycling club I ride with. Do you have a cycling club in your area? Mine is all levels. They regroup at the top of climbs, etc. They offer various ride options. On Sundays they have a women's only ride. While the majority of the rides are during typical "non-work" hours (Sat/Sun morning and Tue/Thur evening), a small group formed to start doing rides on Wednesday mornings. I have done those a few times, but since I had my riding buddy, we often just did our own thing. If I didn't have her, I would have certainly done those rides more and may start doing them soon since my buddy now has an 8-5 job (which SUCKS!). Also, I got hooked up with a women's only group that rode on Wednesday nights, different from my cycling club.
There are people out there to ride with. You just have to find them. Search the internet and/or start asking around at your local bike shops. Your husband found people to ride with. So can you!!!![]()