straight take off leg

[noobar]

could any one tell me if bending the taking off leg later could be a problem and how should I avoid it? I tried several times,when my grip is low,my leg remains straight but when I gradually raise my grip I lose the straight leg.I tried to compare my videos with the videos of the beginner jumpers in the CD of From Beginner to Bubka, but unfortunately I couldn't be able to recognise the reason
In my opinion, I've good free take off with forward speed and driving right arm and I'm landing in these jumps in the middle

Here are the two links,there are three jumps from 2 steps in each link.
http://www.youtube.com/watch?v=XEYQ2DS1ASY
http://www.youtube.com/watch?v=NOuQTo93keE

[altius]

You are leaning forward as you come in to plant the pole . Get the trunk upright. Do straight leg claws and then try to execute the same action with your take off leg. The leg will then bend slightly - but backwards -IE slightly hyperextend. Should improve rapidly because despite your problem you do the drill well.