I went with a 43 Tooth rear. I REALLY like the difference. I ended up taking out 4 links. I went with a steel Supersprox . Love the black vs the stock shiney
I had this from an old search
For ideal wear both sprockets must be odd in contrast to the even number of links on the chain (don't use half-links!). Bike Bandit carries 13-16 tooth fronts and 39-46 tooth rears. Here is a partial list of combinations near the 15/44 ratio that don't result in poor wear. Ideal wear numbers match sprocket teeth, above half is good, below is poor.
~ Front/Rear-Chain ~ Ratio ~ Length Difference ~ Wear #s ~ Comments
~ 15/46-114 ~ 3.06 ~ .000 ~ 5/23 ~ Stock, ratio little a high, poor front wear
~ 16/46-114 ~ 2.88 ~ -.150 ~ 8/23 ~ 15/43-112 is better
~ 15/45-112 ~ 3.00 ~ -.460 ~ 15/45 ~ May not fit, ratio one step down from stock
~ 15/45-114 ~ 3.00 ~ +.170 ~ 5/15 ~ Poor wear
~ 15/44-112 ~ 2.93 ~ -.290 ~ 15/11 ~ Poor rear wear
~ 15/44-114 ~ 2.93 ~ +.340 ~ 5/22 ~ Good choice, stock wear
~ 15/43-112 ~ 2.86 ~ -.120 ~ 15/43 ~ Excellent choice
~ 15/41-112 ~ 2.73 ~ +.210 ~ 15/41 ~ Ratio a little low
~ 14/41-110 ~ 2.93 ~ -.270 ~ 7/41 ~ Good choice, Better wear than 15/44-114
~ 13/39-110 ~ 3.00 ~ +.210 ~ 13/39 ~ Front sprocket small, one step down from stock
For a 2.93 (15/44) ratio I'd use 14/114-110 instead just move the chain up one link on the front when you clean it. For a 2.86 ratio 15/43-112 is the way to go for highway riding. Other ratios are possible but this seems to be what most people find to be the right ratio for this bike.
and this is the old thread