Modify option field and store value before pipe

<?php
// http://www.gravityhelp.com/forums/topic/change-option-value?replies=19#post-103945
// change the 241 here to your form ID
add_action('gform_pre_submission_filter_241', 'strip_pricing');
function strip_pricing($form) {

        // split input_1 on the pipe symbol and use the first part
        $haystack = $_POST['input_1'];
        $needle   = '|';
        $result   = substr($haystack, 0, strpos($haystack, $needle));

        // assign the result to the hidden field in the form
        // update the 58 here to the ID of your hidden field
        $_POST['input_58'] = $result;

        // return the form
        return $form;
}