gistfile1.txt

public class SliderViewModel : INotifyPropertyChanged
		{
			public event PropertyChangedEventHandler PropertyChanged;

			private double limitedValue = 10;

			public double LimitedValue
			{
				get { return limitedValue; }
				set
				{
					value = Math.Min (value, 50);

					limitedValue = value;
					Debug.WriteLine (limitedValue);
					OnPropertyChanged ();
				}
			}

			protected virtual void OnPropertyChanged ([CallerMemberName] string propertyName = null)
			{
				var handler = PropertyChanged;
				if (handler != null)
					handler (this, new PropertyChangedEventArgs (propertyName));
			}
		}


			var contentPage = new ContentPage ();
			contentPage.BindingContext = new SliderViewModel ();

			var slider = new Slider {
				Minimum = 0,
				Maximum = 100,
				VerticalOptions = LayoutOptions.CenterAndExpand
			};
			slider.SetBinding (Slider.ValueProperty, "LimitedValue");

			contentPage.Content = slider;
			MainPage = contentPage;