Last month, I replaced my Armadillo 26 x 1.95 tires w/Schwalbe Big Apple 26 x 2.35 oversized tires. As soon as I rolled away, I knew something was very wrong. My motorized bicycle could no longer climb the steep ramp at work and the hill on the way home. The Schwalbes were 27 inches tall; the Armadillos were 26 inches. Although the gear ratios were raised only 4%, it was enough to cause problems. Carb settings had to be adjusted to help compensate. I needed to lower the gear ratios to compensate for taller tires.
Fortunately, I had a new 24t sprocket to replace my 30t bicycle chainring. This would result in a 25% gear reduction, offsetting the large tires' disadvantage. The 24t was installed in the exact position the 30t was in, so there'd be no chain jumping. The bicycle chain can be shortened, if need by.
First gear lowered from 37.09:1 to 46.32:1, a granny gear. The new second gear is now 39.55:1, which is lower than the original first gear. I used to cruise the streets in fifth gear, which was 18.55:1. Methinks I'll be spending time in seventh gear, which is 17.73:1. Eighth gear lowered from 12:1 to 15:1. This is an excellent gear for highway cruising.
The 24t install went quickly, then I rode 5 miles into town. It's the same route I bike to work, only a half-mile shorter. The bike ride was absolutely awesome! With the steep gears, carb response was crisper. Sure enough, seventh gear is where the engine wants to end up in.
The bike's fun factor has doubled; I can tell the engine enjoys it too.