Ok so riding season is upon us here in ole Tennessee. I'm pretty sure I need a new rotor, but before I order some wanted to hear from y'all about when is a good time to replace them. Better yet what are u looking for when checking to see if a rotor needs replaced.
its not warped from what I can tell but it's not pretty an smooth. Old bike so needs em anyway but not sure if I can get another season out of em.

TIA

 

Not “pretty or smooth” ? Has she been sat for a while and does it look the same after some usage? Are you brakes working perfectly?
If there’s any warp you’ll get a pulsing sensation on your foot. It could be very subtle. Another thing you could try using just the rear as you come to a stop, the braking should be smooth to the stop, no snatchiness ( is that a word ?) it might only be subtle but if you trail your rear sometimes then you need a smooth operation or you could end up in a ditch. Not what you need.
Front discs have a wear limit that’s around the 3.5mm mark if I remember correctly (sure someone will put me right lol) so I imagine rears will have a measurement also. It’s late and zzzzzz time for me so hope someone comes along to help you some more.
Best of luck mate

 

Ok, we are talking about a rear rotor here right?
There are only 2 reason to replace a rotor.

1. It's passed the wear limit. This never happens as the rear brake isn't used much if at all.
If you are using the rear enough to get to the wear limit, then you need to either
A) learn how to ride properly or
B) just sell the bike cause you are a rolling road hazard.

2. It's warped significantly. It is possible to bend them in a crash. Check with dial indicator.
But in general this is extremely unlikely as the rear brake isn't used much if at all.
If you are using the rear enough to warp it, then you need to either
A) learn how to ride properly or
B) just sell the bike cause you are a rolling road hazard.

If the rotor has minor warping (couple thousandths) it can be tapped back to straight with a hammer and block of wood.
If the rotor has minor surface rust, use a scotch brite pad to shine it up. A scotch disc on a 1/4 air grinder makes it quick work.

Service limit for front and rear rotors is 4mm. Front rotors can wear out but it takes a very long time.
Mine were at 2.8mm and looked like DirectTv dishes when I replaced them.
They are more likely to warp before wearing out. If they warp, you will know it from the feel.

Personally, I'd be FAR more concerned with having 2 front rotors on the bike, but that's just me.

 

Thanks you guys. I am pretty sure they are not warped as I don't feel anything unusual when I press the brake, no "snatchyness" either lol. I'll probably measure for wear limit later on.
was just writing up things I'm gonna need before I start riding more often this season. Didn't wanna buy a new one unless I needed it.
but thanks again, love this forum!