lithium power adult mountain bike external lithium power student mountain electric power power endurance

orange aluminum alloy frame [suitable for 160-188cm]] black aluminum alloy frame [suitable for 160-188cm]] green aluminum alloy frame [suitable for 160-188cm]] blue aluminum alloy frame [suitable for 160-188cm]]

21-speed 7.8a battery life 40-50km 21-speed 10.4a battery life 50-60km 21-speed 13.6a battery life 60-70km 24-speed 7.8a battery life 40-50km 24-speed 10.4a battery life 50-60km 24-speed 13.6a battery life 60-70km 27-speed 7.8a battery life 40-50km 27-speed 10.4a battery life 50-60km 27-speed 13.6a battery life 60-70km