Yeah, that's actually a problem. Those levers pull more cable than typical drop bar brake levers, and that means they don't pull as hard. If you've used levers like that with mountain bike brakes, you may be questioning my claim because when paired with something like a V-brake or even well adjusted cantilevers these levers will produce great stopping power, but paired with a brake designed for short pull they won't work as well.

I'm not sure how much cable pull a vintage brake like the Modolo Speedy was designed for, but I know modern dual pivot brakes like the Veloces you mentioned won't work well with these levers. I'd recommend a flat bar lever that's designed for short cable pull, something like this Shimano BL-R3000: https://www.universalcycles.com/shop...0&category=669