Does anyone make a frame bag for a road bike that would take a laptop?

Looks to be room in the frame, though it’ll be tight, and yes it might act like a sail, but…

Alternatively which of the bespoke manufacturers would you recommend? (Remember they’d need to be amenable to silly ideas.)

Contact Beerbabe for a custom bag if you fancy some re-cycled inner tube action.

https://www.beerbabe.co.uk/

no damping on the frame…

Alpkit will make custom frame bags.
I have one, it’s fine.
Remember to allow room for an appropriate amount of padding, even if you have large volume tyres, I doubt a laptop will put up with the vibration for long otherwise.
Consider a rear rack and pannier, by far the best option, although not trendy.

I considered the same to get away from big pannier bags, but I was put off by the vibration, not wanting to lose the water bottle cages and the cost (cheapskate).

I bought a 12L heavy duty Lomo drybag and some ortleib spare parts. £20 for the lot and some time with a screwdriver, and bob’s your dad. Dinky lightweight pannier, enough space for a toolroll, laptop, notepad and a spare layer.

Pannier or rucksack.

I know people like to proclaim the world will end in a spine aching sweaty mess if you ride with a rucksack, but I (in)frequently do my 25mile each way commute with my laptop in my bag along with a big heavy kryptonite d-lock and change of clothes.

Obviously the advantage of panniers is they’re not on your back. The disadvantage is they’re a faff off the bike. I’ve ditched panniers and now have a trailer for carrying more than a backpack full of kit. It’s big enough to leave outside the supermarket and just load bags into it, rather than needing to carry the panniers round in a second basket to load stuff directly into at the till.

Thanks all. I suspect you’re confirming my suspicions – that there’s a reason no-one’s done this.
Currently using panniers just looking to see if I could reduce the bike count by one.

Solid-state drive in the laptop though, so maybe, just maybe…

Obviously the advantage of panniers is they’re not on your back. The disadvantage is they’re a faff off the bike.

Most people can get away with one pannier for commuting. Off the bike you can just carry a pannier using the shoulder strap.

Get a Carradice Nelson with the SQR mount, I’ve got a laptop in mine a fair few times.
When not in use you end up with a small plastic block on the seat post.

I’ve done what the OP suggested, taken a canvas laptop bag, fixed three short sections of inner tube with pop-rivets to attach to (=around) the frame (2 around top-top, 1 around seat-tube), but I also have a longer solid fabric strap (like a shoulder bag strap) around the bag and top-tube as a back-up. The thinking was that hanging the bag off the top tube using sections of inner tube would allow for some damping, but the laptop has a SSD, so I *hope* that’s not too much of an issue.
In a 58 or 60cm CX frame, I even have space for a water bottle, but also managed to attach the laptop bag to the bottle cage with a zip tie to avoid it moving left/right.
For the occassional 35km commute, I prefer not to arrive with too sweaty a back, hence no rucksack, and I am paranoid that even one pannier – which I occasionally use – slows me down a little (more aero without 🙂 )
Sven