If you grab it in the 12 and 6 o'clock positions, you are typically checking for play in wheel bearings and ball joints. If you grab it in the 9 and 3 o'clock positions you are typically checking for tie rod ends or wheel bearings. But you are not totally limited to these although the most common.
A knocking noise when pedaling a bike could be caused by loose pedals, a loose crank arm, worn bottom bracket bearings, or a misaligned chain.
A hole in the muffler would cause a knocking sound in your muffler. A loose exhaust pipe can also cause a knocking noise.
Tie rod
A knocking noise in the front wheels can be a very serious problem. The knocking noise could be caused by bad ball joints. Bad ball joints can slip off the tie rods and cause the wheel assembly to collapse. This problem should be looked at as soon as possible.
Worn front axle and/or front end component.
Bad fuel pump, loose fuel pump, loose baffle or foreign matter in the tank.
loose CV joint. The CV joint(s) need to be replaced, the transmission is probably fine.
The knocking noise could be one of several things. The wheel bearing, a worn steering or suspension part, or road debris could be causing the noise.
Can be a loose shock, or loose suspension parts. Can also be loose exhaust system parts. I had a car that made a front-end knocking sound on bumps. Any little bump would do it. Turned out to be bad struts.
you may have a rod knocking and you need to take it to a shop asap
many many things, Loose lug nuts which lets wheel make knocking noise. Engine will make a knocking noise if it is really low on oil. Some timing belts make a knocking, slapping noise just before they break.These are just a few examples . Have someone ride in car with you as you duplcate the noise and see if they can determine which part of the vehicle it is coming from.
I found my noise wasn't something loose. It was the rear strut was bad. Was more of a load squeak that sounded like something knocking.