My suspicion is that for what I will probably do with the bike , a Raven would maybe suit me better and I like them , but i also like the nomad and the heavy duty and even overbuilt ness of it . I’m about 16 stone and could get heavier (hope not!) so a big tank of a big that can go anywhere I might want appeals to me. Obviously the Ravens are no more which means I’m looking at a used bike.
You are not wrong to consider your own weight when choosing the right bike. I don't know how it is done in the UK, but in Germany new bike info generally shows the total authorized weight INCLUDING rider, baggage and bicycle to help you select the right bike for you. It is not just about your height and inside leg measurement- but a frame that can carry you and your luggage.
I once bought a 'discounter' bike that otherwise had reasonable looking components on it- and with a 14 days no quibble return. Bike details was total weight including rider of 100kg. I think I was around 100kg (approx 16 stone) at time of purchase- and quickly discovered that the bike was not nice to ride. The chain skipped under duress and the frame didn't feel that solid. Bike was returned. If I had kept bike, I just wouldn't have cycled as it was not a nice experience.
I then went to a real bike shop with knowledgeable staff and spent double the price on a similar looking bike- but made to carry up to 115kg. I probably should have gone a tad higher on the rating as with me+bike+bike bag I'd have been topping 120-125kg. But 20 years later, I still have that bike frame and forks in use and they still perform fine. Most of the components have worn out during that time and been replaced though. I am in no doubt that components will wear quicker with a heavier rider too as they will get more stress applied as you ride.
Although above mentioned bike is still great, and works fine, my Rohloff journey began 2 years ago when I was 49, 5'9 tall and my weight had crept up to 19 stone and suffered a stroke cause by a thrombosis. I've been a keen cyclist since my mid 20s, but had dropped from around 5000-8000km a year down to less than 100km- always putting off starting a fitness/weight loss program 'until tomorrow'. Those extra kg didn't appear overnight, but gradually as my lifestyle became more sedentary but my appetite for food had not changed since I cut down on cycling so frequently. Simple maths. If calories in exceed calories out, your weight will climb. As will your health risks.
I wasn't fit enough to cycle after my stroke. In fact I was 6 months off work. Post convalescence, my GP encouraged me to walk every day, rain or shine. I was so proud to wear the soles out on my trainers. I set a target to walk 10,000 steps/day. Then I upped my game to 16,000 every day- on average, but often way higher. I started to ride my (old) bike about 18 months ago and set myself a target that if I could get 1000 miles on my bike before my birthday, then I would reward myself with a Rohloff hubbed bike for my 50th birthday to encourage me with something new and shiny to keep my cycling. I got my birthday present 2 months early and I have made myself ride that bike every day (and I've enjoyed it too) rain or shine since then.
Back to bikes and total approved weight. The Rohloff hub is the perfect hub for tandems. And these are often with total approved weight of 200kg+. So a heavier person riding such a bike is not a problem for the hub. Chains/sprockets might wear a little quicker than a lighter person would manage- but the hubs are very reliable and highly suited to such demands.
Don't just invest in your bike purchase. You've asked a lot of questions about various aspects of getting yourself this new bike. Keep that enthusiasm once you pull the trigger and purchase- and start to ride your bike regularly. Make sure your bike is suitably sized even if not custom made (e.g. 2nd hand) for carrying you today and for the future.
16 months after purchasing my non-Thorn Rohloff hubbed bike, I've ridden almost 9000km. The cycling combined with a healthier lifestyle means my weight has dropped by around 5 stones since my stroke. But having a bike that is enjoyable and comfortable to ride because it is designed to carry someone of your stature will encourage you to use it, and perhaps help you maintain or even lose weight in the process, rather than letting it creep up over the years as it did with me- until almost too late.
In my opinion, better to take your time and find the right bike for you, and make it your 'forever bike' than to just purchase and then regret down the line that you did not do your due diligence before parting with a not-unsubstantial amount of money for this steed if something was not quite how you wanted it. And if you do go 2nd hand (which I think you have mentioned in a couple of threads) decide on what factors you will compromise on if not exactly the specification you want. I really wanted disc brakes, but have learned to really love the HS11/HS33 Magura rim brakes that came on my bike that I know longer pine for discs.