You need the biggest hugest pitzips, like waist to wrist. I have a great backpacking coat like that, it also folds down to a size that would fit in your pants pocket. Note that it is not breathable at all, it is just truly ventilated in a way that no 'breathable' coat can approach.

For cycling I use an old showers pass coat, some model they don't make any more. It has B+/A- pitzips (if the above coat has A+) Their coats are not cheap but they are on sale right now for like the rest of today. For cycling I really don't want a hood, but that is the only negative to the Lightheart coat linked above. Oh, plus no cellphone pocket. Also, the showers pass coat has a back 'exhaust' vent which works great when I am using panniers but not with a backpack.