Here's how you can resize your image for your used bike listing page when submitting your info here: https://form.jotform.com/50238139717962
First, go to https://picresize.com
Upload your image
Click "Continue To Edit Picture" - blue button
Scroll all the way down to "Save As" section and enter "300" under "JPG Max Filesize"
Lastly, Select "Save to Disk" option to save to your browser downloads folder.
Use this new file to upload to your form here: https://form.jotform.com/50238139717962