I change discs when they reach minimum thickness. If you go past minimum, be sure to not let your pads also go to minimum, the caliper pistons may extend out too much.

 

Good point about the piston lengths, I hadn’t thought of that.

My main line of thought is that the kinetic energy of the bike (incl. rider/luggage etc.) pre-braking, minus the kinetic energy of the bike post-braking, is dumped into the discs and converted into heat (not withstanding any engine braking or other frictional losses). The lower the mass in the disc, the lower its capacity to dissipate the heat, and the greater the likelihood of the disc being damaged / warped. However I’m not on a race track – the wear is down to all-weather commuting in the UK which includes a lot of wet and gritty conditions. Overheating isn’t really a problem and there’s no sign yet of any runout on the discs.

Interestingly, the UK government mandatory annual vehicle check (MOT Test) is a lot more forgiving on disc thickness/condition than motorcycle manufacturer recommendations.

 

I dunno, engine braking is usually more than enough (I am religious about 3 seconds separation), still on original pads & rotors @ 95k

 

3 seconds separation is a very rare luxury in dense rush-hour traffic in the London area. I do a lot of filtering close-range through traffic (about an hour daily), then about the same amount of time on open roads covering four times the distance.

95k on original pads and rotors tells of relaxing rides I can only dream of. Great care-taking of the machine.

 

I’m approaching the wear limit recommend in the Service Manual, i.e. 4.5mm, after nearly 29,000 miles of mixed motorway/urban commuting in all weathers. Are Suzuki (and bike manufacturer’s generally) being a little cautious with this wear limit number, which represents only 0.5mm of wear, given they charge £300 (nearly US$400) per OE disc from Suzuki UK? Yes, that’s OE cost for each disc!!

Any thoughts from those of you with high mileages? Have you run them a bit thinner without issues?

I've worn the front disc down to 4.2 mm without excess piston extension. Do keep an eye on it because they wear faster and glaze easier after the wear limit. The discs might not be the same hardness throughout (my guess).

I wore the rear disc to 3.9 mm because I was an idiot and it overheated and glazed very easy. Thankfully these are much cheaper.

New Suzuki OEM discs (Sunstar brand) are SUPER EXPENSIVE. I gambled with used ebay front discs, they turned out to be 4.9 mm for $ 130 CAD delivered. Very happy. Otherwise check carpimoto for Brembo serie oro discs which seem reasonably priced and good quality. Beware the 2004-2006 models take a different front disc than 2007 onwards (ABS or non-ABS) models.

 

I tend not to wear out my own rotors but I am "easy" on them as are many of us as we use more engine braking and are gentle on stops. Of course it is very rare that I ever go into urban areas so I don't work the brakes a lot. Another consideration I noted while working in the trade; some like those super brake pads that stop so much better than the OEM pads. Well, no such thing as a free lunch. Often those pads wear out the brake rotors at an accelerated rate. YMMV on that but its something I saw a lot of.

 

@Linus
Kinetic energy? You sound like an engineer.

 

@Linus
Kinetic energy? You sound like an engineer.

I am, but I mostly work currently in the construction and civil engineering sector. Yes, I bore my children with stuff like this too.

 

I've worn my '06 fronts far under the recommended minimum thickness, they now have 188k miles on them. They still perform, though surely don't shed heat as when new. Will probably replace them at some point.

I don't think warping should be a significant concern, considering they're floating.

Keep some grease on the slide pins and where the pads meet the brackets and you'll be less likely to see accelerated wear.

 

I’m approaching the wear limit recommend in the Service Manual, i.e. 4.5mm, after nearly 29,000 miles of mixed motorway/urban commuting in all weathers. Are Suzuki (and bike manufacturer’s generally) being a little cautious with this wear limit number, which represents only 0.5mm of wear, given they charge £300 (nearly US$400) per OE disc from Suzuki UK? Yes, that’s OE cost for each disc!!

Any thoughts from those of you with high mileages? Have you run them a bit thinner without issues?

My 1050 discs at 31,500 miles are at 4.6mm. I’m planning on replacing them at next tire or pad change, whichever comes first. The rear is still at 4.9mm. I don’t use the rear brake. It should go more than 100,000!