[Closed] When do you replace a rotor?

When I bend them, what did it start at, 1.5mm sounds a bit thin, will also depend if it's a lightweight design. Though simple rules for brakes - replace before you need to (it fails)

They are lightweight to be fair! 🙂

When I can see through the metal

dont they have the minimum width stamped on them?

When i notice an obvious lip.

When they get to thin just double them up.

I'd probably replace when I got too nervous about the width. Often the pads overhang onto the spider a bit, that's where I reckon it'd fail, so when it looks a bit dodgy there. 1.5mm doesn't sound overly spendy a thickness to replace.

With the older style Hope floating rotors --- When they rattle
With Shimano when they start to deform and the braking surface isn't flat anymore or they shudder under hard braking..

I notice mine are worn when removing/inserting wheels: when the lip of the rotor gets wider than the worn main braking surface, getting the wider lip section out through the narrower pad gap gets to be a pita so thats the time i change them

Hope start at 1.8mm and they recommended replacing at 1.5mm.

Measure a part that would have been the original thickness and not worn by pads and compare.

As an aside, I've found superstar Kevlar pads wear in a concave pattern which I found rather disconcerting.

It looks like the rotor started at 1.8mm thickness 🙂

Onzadog - Member

As an aside, I've found superstar Kevlar pads wear in a concave pattern which I found rather disconcerting.

The pads'll wear to the shape of the rotor unless you've got something really weird going on

when i couldn't get a good "bleed" loads of leaver throw etc....

by chance, i put on a different wheel with a new rotor, and suddenly the lever throw was very short....

inspecting the disc showed noticeable wear

I've never replaced a rotor.

Only when I change colour schemes

After the rotor splits in 2! Mind you I've only done that once, it was enough.

Have never worn one out, I seem to bend them before that.

Had a big piston leak due to a worn disk in the past, a bit more attentive these days. Should probably borrow a micrometer have a check at the moment as one of mine doesn't look healthy at the moment.

I always err on the side of caution with discs and pads after I had brake failure on a big descent, the disc was worn well below the 1.6mm Hope recommended (measured one of the slithers at 1mm!) and the pads were very low too. So far that the pistons popped out 😯

Tend to find the current Shimano discs wear sightly concave so new pads take a while to bed in to them, change them at that point. Usually close to the 1.5mm stamped on them anyway.

So far that the pistons popped out

Along with a little bit of poo I bet!

I didn't check, was more worried about getting all the thorns out of me from the hedge I'd bailed into, was an interesting day at work on that Monday. Was pulling bits out for a good hour or two and stacking them on my desk 😀

I still don't know exactly how the pistons came out as there technically wasn't enough room for them to do so. All I know is that one was MIA and the other was rattling around not doing anything 🙂

Should probably borrow a micrometer have a check at the moment as one of mine doesn't look healthy at the moment.

I bought one off the internet for about a fiver. It looks like something a dentist would use. Good enough for what I use it for! 🙂

[url= https://toolsntoolsuk.co.uk/product/iwanson-spring-wax-calipers-crown-gauge-measuring-1-10-mm-jewellers-dental-etc/ ]One of these bad boys :-)[/url]

A Vernier gauge for measuring thickness of the rotor, internal holes too, micrometers are for measuring outside diameters.

Outside calipers also measure outside diameters, inside calipers measure internal diameters.

This seems reasonably worn..
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[img][URL= http://img.photobucket.com/albums/v633/rickmeister/image.jpg5_zpspfgpvmqv.jp g" target="_blank">http://img.photobucket.com/albums/v633/rickmeister/image.jpg5_zpspfgpvmqv.jp g"/> [/IMG][/URL][/img]

A Vernier gauge for measuring thickness of the rotor, internal holes too, micrometers are for measuring outside diameters.

You would think so, but usually the middle of the brake track wears faster than the extremities, see rickmeister's images above.
A micrometer gives a more accurate estimate for the minimum rotor thickness.

Yup as he says ^ Verniers are pretty much useless here

I replaced the last set after they started playing up. The pad wear was weird and they kept rubbing no matter what I did. Eventually I figured it out and ran my finger down off the arms onto the braking surface (a big step was found). As above, probably something to check once every couple of months, but a better safe than sorry approach is prudent with stuff like brakes.

Feeling the disc with your fingers or looking at it will show uneven wear. Measuring that disc will still work with Vernier gauge.

Looking at disc should be part of a pre ride check like headset play etc.

How are you going to measure the thinnest part of the disc when the caliper has to go across a fatter part to get there?

when the anodized carrier no longer matches my bikes colour scheme

Mine just get replaced when changing disc size or brand/model of brake and happens to come with a new disc.