Joined: Mar 2006
Posts: 360
Likes: 52
From: Pennington, NJ
Bikes: Raleigh Sports, '72, Bianchi Volpe, '97 (no more, it died), Greenspeed GTVS6, '05, Trek 520, '13
You guys are making this too hard. If the cog is changed from 20t to 16t and everything else, including the cadence, stays the same, the speed goes up by the ratio of the teeth: 20t/16t = 5/4. 5/4 x 15.2mph = 19.0 mph.
- Ed