<telerik:RadCartesianChart x:Name="myChart" HandlerChanged="myChart_HandlerChanged">


private void myChart_HandlerChanged(object sender, EventArgs e)
{
    this.UpdateChart();
}
private void UpdateChart()
{
    var platformView = this.myChart.Handler.PlatformView;
#if ANDROID
    var platformChart = (Com.Telerik.Widget.Chart.Visualization.CartesianChart.RadCartesianChartView)platformView;
    var platformSeries = (Com.Telerik.Widget.Chart.Visualization.CartesianChart.Series.Categorical.BarSeries)platformChart.Series.Get(0);
    platformChart.Grid = new Com.Telerik.Widget.Chart.Visualization.CartesianChart.CartesianChartGrid();
    platformChart.Grid.MajorLinesVisibility = Com.Telerik.Widget.Chart.Visualization.CartesianChart.GridLineVisibility.Xy;
    platformChart.Grid.LineThickness = 3;
    platformChart.Grid.LineColor = Android.Graphics.Color.Gray;
    platformChart.Grid.VerticalLineThickness = 3;
    platformChart.Grid.VerticalLineColor = Android.Graphics.Color.Gray;
#endif   
}