I too wanted this and have achieved it.
From what I understand the next activity you record inherits the last activity. So before you record you next activity change the activity type to cycling from then on every activity will inherit cycling.
This usually defaults back to something else after an update so it not permanent.
You should be able to test this by simply recording a short test activity as cycling whilst at home, then having saved that, record another, the subsequent activity should inherit cycling.
As a fellow cyclist you might find this doc I previously upload useful to trigger the device to record without using the app, simply the button on the device.

Hi Matt, The device defaults the activity type to the previously recorded activity type. You can follow the below steps to default it to cycling , going forward:- 1) Connect the device to the app 2) Choose activity type as ‘Cycle’ 3) Start an activity From then on the activity type will default to cycle until you wish to change it and do so manually. Once the activity type is set, it will not matter whether the device is connected to the mobile app or not, while starting an activity.