If you are using the direct download version of Bike then you can control when to check for updates and what kinds of updates to check for. If you are using the Mac App Store version of Bike then updates are handled by the Mac App Store.
For the direct download version of Bike:
To check for updates:
Use Bike > Check for Updates
To check for updates automatically:
Use Bike > Preferences > Check for Updates: Automatically
To include preview release updates:
Use Bike > Preferences > Check for Updates: Include Preview Releases
Preview releases work in cycles. I will post a series of preview releases and then once things are working well I will mark the last preview release as final.
You can tell if you are using a preview release by looking in the menu bar. If you are running a preview release then instead of seeing "Bike" you will see something similar to "Bike 1.0 Preview (51)".
The "Preview" status of a release is determined by the software update process. If you are running a preview release and I then mark that build as final your Bike install will transition from "Preview" to final next time you check for updates.