I will be finding out very soon. I just bought a rear rack and am waiting for it to come in. Ive been commuting with a backpack for about 2 years and its finally getting to me. Light loads are okay but heavier loads put a strain on me and my backpack smells heavily of back sweat haha.

I have a cycle computer that I got for Christmas and have been timing my rides with it so I have good data with a backpack just need to see what its like for a rack. With backpack average moving time is about 35min for 9.2 miles with an average speed around 16mph based on my cycle computer. Wind is the biggest factor for me when it comes to speed, with 20-25mph sustained for most days. I ride in the drops if that counts for anything..

Ill chime back in when I get more data riding with the rack when it comes in.