Wow problems in a list for my builds , first would be the online wait for parts takes days and thears no shop around my area that I can walk into and buy parts big problem when your patience is limited, as for mechanical breakdowns, always the chain weather miss align or faulty links, my brakes go out all the time the disk break in front vibrates loose backes out the bolt that's holding the pad in place, also the tires will go fast especially mtbike tires knobby tires wear fast go bald then your in the area of a tube bulging out the weakest spot in the bald tire , very important to remember the bearings in the rims and the axles must be greased whatever is used hi temp bearing grease, or tractor grease no matter them bearings will go fast if left dry and if the axle is loose and neglected the rim will grind down loose bearings in about a block distance stay on top of that, and a bunch of other wear and tear that's normal , I'd list more but I'm burning day light I gotta ride the weather is nice here in the bay area ca I'm taking advantage of it ,RIDE TO LIVE ,LIVE TO RIDE , even if it is a motorized bike