내일 오전에 라이딩좀 해봐야겠다.
http://bike.shimano.com.sg/publish/content/global_cycle/en/sg/index/products/road/di2_flash.html#/site/product/detail/RD-7900-SS
http://bike.shimano.com.sg/publish/content/global_cycle/en/sg/index/products/road/di2_flash.html#/site/product/detail/CS-7900
EV-CS-7900-2869A_v1_m56577569830728250.pdf
