With her aerobic sport background, she can probably handle TB1HV. It’s 2-2:30 rides of mid Z2 and only 4x per week. She likely wouldn’t need to fuel LV, so it’s a good way for her to learn to fuel properly those first four weeks with little chance of blowing up if she follows the plan and rests between rides.
1 Like
I don’t think she should jump in the deep end right away.
Last time I did a long run, conditions were perfect: late summer in Zürich, and my hotel was at the fringe of Zürichberg. I hadn’t run in pretty much a year. But thanks to my aerobic engine I did about 16 km with a little over 500 m of elevation. The first 14 km were easy. The last kilometer was terrible. I literally couldn’t walk properly for a day-and-a-half, because my muscles were so tense (and I mean literally when I write literally, not figuratively).
Point is, cycling isn’t the same as running, you use different muscle groups in different ways. Your aerobic engine helps, yes, you’ll probably gain fitness rather quickly. But you should approach this sensibly and wait until your body gets accustomed to it. Specifically, you shouldn’t just start training 10–13 hours per week, because that’s what you did as a runner.
@Isobel_Thomas wrote she had problems with consistency, sticking to power targets because she got overly enthusiastic and problems with fueling. TB has roughly the same caloric demands as other training plans, and with her weight, not fueling correctly could dig her into a hole quick. I weigh roughly double (currently 75 kg), and I can lose 1 kg quickly when I want to. Losing 1 kg when you weigh 40 kg (and don’t have a lot of fat to begin with) could dig you into a dangerous hole very, very quickly. So my recommendation is the same independently of which plan she chooses: start with the stock low volume plans, after a month or two start adding some endurance workouts, but don’t overdo it. Consistency is king.
Where we disagree is viewing TBHV as “the deep end”. TBHV1 is anything but the deep end, IMO. Frankly, it’s more appropriate for what she says she needs and injury recovery than SSBLV.
4 rides per week, ranging between 7:45 and 10hrs total, peaking at .72IF. If I were coaching her, I’d prescribe basically that (with lower power targets, probably all under 0.65IF), and use those rides to teach her to fuel properly and recover.
Based on what she says, I don’t think there’s any chance she would stick to TBLV nor be happy if she did, and that part matters. Sorry, can’t get on board with that recommendation.
1 Like
I understand your need to train a lot 
and I also understand your silly decisions because I am similar. My advice is maybe give TrainNow a go - it looks at unstructured rides and factors that into its recommendations. I typically go day to day, open up the app put the amount of time I have in there and have it provide a recommendation - typically ride outside to send it to my head unit and away I go. You may find that this will often be endurance type rides if you are anything like me but take a rest day here and there and you’ll get a climbing or attacking recommendation.