I ordered a front chromoly steel 18-tooth front sprocket (+ a 45-tooth Drive Systems rear steel sprocket) from sprocketcenter.com. After tax and shipping, they came out to US$88. The OEM front sprocket was 17-tooth but I changed it to 18-tooth. The chain is still 110-link. I use DID ZVM2 110-link chain. The set that I just replaced lasted 30000 miles. I bought the chain from a vendor on cbrxx.com forum for US$130.