You want a ‘fast’ road bike that will let you bolt on a giant air brake? Have you thought this through?
Yes, what Scot said. Ride/train to hotel on Monday with computer/weeks’ clothes, check in, leave panniers at home go riding during the week, then pack the bags and ride home.
It really needs to be panniers or a trailer, because when putting my bike on the train I remove the panniers in seconds to bring them with me – not leaving them in the guard’s carriage. Also very handy when stopping off to grab food or something similar.
If I’m planning to do off-road riding during the week then it’s already covered by the El Mariachi, but not so easy with road.
I’ve long fancied a trailer, like a Burley Travoy – this is another option and would work with whatever bike I choose.