If I use a 48/36 chainring double combo and prob a 12-25 cassette will I need a short or long cage rear mech?

I'm guessing short as there isn't a wide spread of ratios?

Thanks for any advice.

I've got a short road (SS) mech with 22-36 and 11-25, and you have less spread than that, so go as short as you like.

max spread of 25 teeth with a max size of 25. I'd imagine a short mech would be your best bet on that but a long would still work.

Thanks both

have a look at the shimano tech documents. Look at the mech you want and it will tell you the total capacity of the mech and the maximum sprocket size it will handle. Some road mechs might actually suit what you're after.

Yeah prob gonna get a road mech.