I've put a DC on my bucket list for next year. When you're mid-60's you can have a bucket list: in fact you need a bucket list.
Background: Took up cycling 4+ years ago. Have ridden combined 15,000 miles tandem and single. Typical "long" rides are 100K (tandem). Have only done a few centuries on the single. I'm 6', 200 lbs and should probably weigh 185 to be really fit. Seems heavy for a cyclist, but my Cat 2 son is exactly the same build and weighs 190.
If I retire at the end of this year I'll have plenty of time to train. If not, I'll have to make time around one long tandem ride each weekend. I might be able to do one 40 mile ride during the week even if I'm working (work out of my house).
My plan such as it is: ride 150 miles/week consistently hoping that business travel doesn't make too much of a dent. Ride one century a month and find a doable 200K before year's end with 1 or 2 more in the spring. Build up to doing a 70 mile hill training ride a couple of times per month. I have three dead-end ranch roads near my house which would give me 6000'+ of climbing in 70 miles. Biggest problem with this ride is absolutely no water for the first 60 miles with all the climbing. Also, these roads are in terrible condition with steep descents so cannot be ridden at night.
Assuming I can get comfortable enough on my bike (Volagi) does this seem like sufficient training? As far as gearing I've got a compact with 11-32 that I'll be changing to an 11-36 for big climbing rides. As the months roll on I'll consider a triple, but I don't believe I'll need it with a 36t in the back.