Speaking hypothetically, is there any reason why eg. Hope levers wouldn’t work with Shimano calipers?

Andy

I would say that any DOT system component would be compatible with any other DOT system component, and incompatible with and mineral oil system component.

DOT fluid will make the seals swell in a system designed for use with mineral oil; and vice versa. This would of course mean that, as per your example, a Hope caliper could not be used with a Shimano lever.

YOu could run a hope lever with a caliper from another system that used DOT fluid. You could run into issues with them being incompatible because of the piston size.

How would piston size be an issue other than altering the lever stroke required?

Andy

That’s about the extent of it. Given the tiny size of bike brakes, I’d reckon it would be quite unlikely to run into any significant issues.

Andy – by altering stroke til it was ridiculous – I don’t know ‘cos I dont know bore sizes but if you alter the ratio of master cylinder to piston bore size you could end up either with a lever like an on off switch that you had to pull very hard to get any braking or the lever that comes back tot eh barwithout much pressure needed – like using canti levers with Vs or vice versa

Edit – quite probably threefish.