Please take this the right way..."the "search" button is your friend.
Short version, yeah, about 38 is common as a compromise between leg shake and tube life. Higher generally means more shake. Lower appears to come with anecdotal evidence of tube pinch and scuff problems. I run 50 in an 8, but I don't have to deal with leg shake.
Last edited by DanH : 09-07-2018 at 09:42 AM.