I’m looking to build something for a fast (as I can) 100 mile plus, road ride. Wouldn’t I be compromising too much using a cross frame? Wouldn’t think twice about using one for a sunday bike though, it looks spot on.
I think it’s been said before, but 100 miles on a road bike, particularly non-hilly miles, is very doable, you just need to keep eating and drinking and turning the pedals over. If you wanted to, you could happily use a cross bike, maybe with a flipped stem, with slicks on. You’re not riding in the Olympics or anything are you?
Mostly I don’t think you really need discs on the road. They might be nice in the wet, occasionally, though decent pads like Swisstop Greens and Koolstop work fine ime using standard road brakes.
If I were you, I’d buy a standard issue road bike from a proven brand like Giant, Trek, Spesh etc. Spend around a grand and you’ll get something eminently decent. If you find you love riding on the road, you can always upgrade to something ‘nicer’ when you have a firmer idea of what you want.
Mostly what’ll get you through your 100 mile ride will be putting in regular miles in preparation and the right nutrition and hydration, pretty much any bike from entry level upwards will get you round just fine.
As a slightly oblique parallel, I rode the second half of a 24-hour solo on a Blur 4x in the summer, I guess if I were looking for a podium spot it would have been an issue, but for a slow old git who just wanted to finish and have some fun along the way, it was great. I guess I’m saying that if you fancy a no-name Chinese disc-braked cross bike, it’ll do the job, but the safe option would be a competent road bike from an established brand.
And then you can stop window shopping and go riding 🙂