Hello, Steve,
If I adjust the start/end range in RadRangeSelector at design time and associate it with a RadChartView at design time as well, the range gets adjusted in correspondence with the chart.
Design time:


Please refer to the below screenshots demonstrating the InitializeComponents method and its workflow:
Initially, you have the default range [30,70]:

Associating a chart will adjust the range:

You manipulate only the StartRange at design time and it would affect only the start, but not the end:

Shown form:

I would recommend you either to update both start/end range at design time or associate the chart and specify the range at run time:
this.radRangeSelector1.AssociatedControl = this.radChartView1;
this.radRangeSelector1.StartRange = 10;
this.radRangeSelector1.EndRange = 70;
Should you have further questions please let me know.
Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik
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