I agree with trying it on. I just bought a speedy 25 today
but I went to the store yesterday to try the sizes. The speedy 30 didn't look big on me 5'2'' but there was so much room I didn't need. I usually carry a wallet, makeup case, cell phone, checkbook and the speedy 25 seem to fit it all with lots of extra room so I went with the 25. Hope this helps you.
