Welcome to my store. Note: During installation, the two transmission wheels need to be adjusted to a straight line. The deviation of flywheel angle will tilt the flywheel stress point to one side, causing flywheel damage. The flywheel angle is generally adjusted through the mounting bracket of the motor. This item is for the bike that uses the hub diameter less than 36mm. This item doesn’t include battery or charger. This is our newest kit for electric common bike, this kit mounts the sprocket on the wheel spokes, so it fits most of bicycle wheel. Motor use freewheel so when wheel rotating, the motor will not rotate, just like a normal bike, this can reduce resistance. The twist kit includes. 1x brush motor with freewheel. 1x Customized sprocket & components. 1x Mounting plate + bolts. 1x Twist throttle (with battery indicator & key switch). Note:This type of railing is not suitable for installation in coastal areas, and it can rust quickly. France, Germany, spain, Italy. Feedback is very important to us. It is impossible to address issues if we do not know about them! Please keep the original box or packaging within 15days since item received. Your satisfaction is our ultimate goal. We work hard to earn your trust and future business. A If you receive a defective item, you may return it or ask for a discount. Due to time zones, our reply to your questions may not be immediately. If it’s non-workdays, please kindly be patient and wait till Monday.