Timing with ornamentations (Bh. Op.49 No.2)

[prometheus]

In measure four and eight there is a C with a tremelo and a B-C grace note onto B. I have a hard time playing this correctly in time. In the fourth measure it isn't that hard but in the eight the part for the left hand gets more complex.

I can't seem to think both the rhytms at the same time. I am new to the piano. I used to play guitar and that requires perfect left and right hand synchronisation. It seems that my brain has this locked in tightly. The rhythm in the left hand has to be the same as the one in the right. Or is this a natural difficulty? How do I practice this effectively?

I am also unable to tap four against three or other polyrhythms.

[pianonut]

you could try different rhythms when practicing your tremolos.  say three, accenting slightly every other third note.  and, try pairing up (by drawing lines down to each main beat) the exact amount of tremolos you are going for for each eighth note or quarter note.  once you have everything mathematically figured out, it's just a matter of practicing it.  try them slow and then gradually work faster.

on the polyrhythms, try playing hands separate at the same tempo with a metronome.  then gradually add just the quarter notes in the right hand (if you are playing left hand) or visa versa.  often, after much practice, your hands start doing what you want them to without having to 'think.'  i still draw lines to show how closely or far away one beat is from another.  this helps me gauge when  playing hands together until i can play smoothly.