Yes you are right - most cyclists in the UK will say 'I did 10k' today but it is also correct to say 'I rode 10km today/ I'm going to ride 10km tomorrow' It is technically correct to say 'I'm going to ride FOR 10km tomorrow' but in practise you never hear this. Motorcycles are never referred to as bicycles. Both bicycles and motorbikes can (and usually are) referred to as bikes though. Usually the context tells us which one we mean - if there is likely to be confusion we would say the full word, either bicycle or motorbike, to clarify. Hope that helps :)

Informal: I did 10 miles today. [A runner might also say this.] Better: I rode 10 miles today. "Bicycle" only means the non-motorized vehicle. "Bike" can mean either, and I can remember being confused as to whether the speaker was interested in bicycles or motorcycles. https://www.dictionary.com/browse/bike

Or you could say 'I cycled ten miles today'; that would also be correct and would imply only a bicycle, not a motorbike