Originally Posted by
soul05
troll?
Newbie.
39/15 = 2.6
48/18 = 2.666
2.6666/2.6 = 1.025, 2.5% faster
So if you're going 25kph at a good cadence now you'll only be going 25.6 with the new gearing.
43/15 will put you at 2.86666 which is a 10% improvement.
This is assuming you are spinning out your gear. If you're not then you need to find some hills to make your legs bigger.