"Yes, I am able to cycle."
Translation:Ydw, dw i'n gallu seiclo.
We don't cover that particular short form on this course - it is a more formal form of Welsh, although you have mixed two different patterns If you were to use galla i..., you would use a matching form for 'Yes...': in this particular case:
- Galla, galla i seiclo.. (or Medra, medra i seiclo.)
Oh of course! Silly mistake as I was sidetracked by the main sentence structure. Thank you.