Your company bike, lease bike and cycling allowance can be added up. But this is only possible if you complete part of your journey by bike and part by public transport.
If you use your own bike, the maximum allowance is 0.24 euros per kilometre (in 2021). If more is awarded, tax and social security contributions are due on the extra amount.
If your employer grants you a bike allowance and a public transport contribution for the same journey, there are no exemptions for withholding tax and social security contributions.