Normally a rusty rotor would not make a grinding noise. A grinding noise from the brakes usually indicated that the pads or shoes are worn down.
The grinding noise from your bike could be caused by issues with the chain, gears, or bearings. It is important to inspect and possibly replace these components to resolve the noise.
axle bearing or brakes or pinion bearing
your gears are grinding fu!
Front grinding could be a bad wheel bearing or in the front axle assembly.
it could be belt pulley rubbing on the timing belt cover or it could be the berries in the wheel but if its making grinding noise while ilding then def check your pulley make sure it isn't rubbing on anything or it could be the flywheel theres numbers of things to check over for the grinding noise
Could be, in need of brakes or wheel bearing failure,
They could, yes.
countershaft bearing could be problem
It could be a couple different things. Most obvious would be brakes. If a brake is sticking and worn you could be hearing a grinding noise as you accelerate. Second could be a driveline issue. Worn u-joints or something sticking in the transfercase (4X4) could also cause a grinding noise. Best advise is to find a reputable service shop and have them diagnose the noise properly. Good luck!
It could be the wheel barring hub.
A grinding noise when pedaling your bike could be caused by a misaligned chain, worn-out gears, or a loose bottom bracket. It is important to inspect and possibly replace these components to resolve the issue.