Mtracer

The rotor looks like overheating to me. But some of that color seems to be flaking off. So, I'm thinking some residue was left on the rotor that has turned that color. You might try cleaning it. If it comes off, then it's not the discoloration of the rotor metal from overheating. If there was some residue left on the rotor, perhaps this also contaminated the pads and explains the lack of braking power you expect.

You bought it new, so you could ask the shop about it.

As for brake rub, disc brakes are finicky and it can take some adjustments to finally get the things centered and not rub. Also, some rotors just seem to be bad. Get them set with no rubbing, do a ride, now rubbing for no good reason. I think you can get some with various stresses built into them and they just do weird things every time they get thermal cycled from use.

As for your saddle tilt, do what works for you. I'm 100% certain your saddle tilt has nothing to do with your brake discoloration and also nothing to do with the topic of this thread.

njkayaker

The fitter has less patience than people here. He’s not going to earn more income arguing against Larry’s nonsense.

genejockey 

This may help. The color is an oxide that is only on the outside of the metal, so it's easily removed, say by abrasion.

genejockey 

Interesting. However, I ordered 250 business cards when I got promoted. I still had 230 of them left when we moved our offices, and I ordered 250 more. Then they changed our main phone number, so they ordered us another 250.

So, I have several lifetimes' supply!!

genejockey 

Now that I think a bit more about it, the bike doesn't have to have travelled far for the rotors to have been hot enough for the steel to start turning color. It only needs to have gotten that hot ONCE, which a 250# guy coming down long hill could do.

LarrySellerz

I ageee that the discoloration is an artifact from heating. What I disagree with is the contention that this discoloration is all over the disc and is being weared away by the rotor. It’s a very interesting Idea, but I don’t think it is happening I think the discoloration is local to that area. My gut tells me there not uniform discoloration on the rotor.

guys I would know if my saddle tilt doesnt work/is a mistake. I ride a lot, like 100 miles a week minimum just living my life on top of any recreational riding I might do. I don’t wear padded bike shorts, so it is less slippery.

datlas 

fooferdoggie 

I have found Shimano hydro's are too tight of a tolerance for that.

jadmt

2600 miles so far and some fast down hills and no discoloration on mine. knock on wood zero rub.

fooferdoggie 

ut e tandem weighs about 420 pounds with us and our stuff. and 9 seconds ob braking on a 18% grade will do the discoloration. had to go back to the ice-tech rotor as those short breaking sessions are too much for regular rotors.

genejockey 

That's funny, because Shimano hydros are the only disc brakes I have, and it works just fine.

LarrySellerz

Yeah my hill maxes out at just over 18% so it could just be a few seconds of hard braking.

fooferdoggie 

well your pushing the pads in while doing it they make a u shaped feeler gage for the job like this. its wont fit between the rotor and pads on any of my Shimano setups. worked fine on my maguras. but that's flat bar maybe the pads are farther away on road setups?
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

LarrySellerz

he didn’t have problems with putting standard flat pedals with no straps on the bike either.

also: open invitation to anyone who has issue with my bike’s setup to race me. Canada road and highway 92. If you’re in the area and want to talk smack, give me a time and I will be there.

genejockey 

Please feel free to suggest a reason, apart from being abraded off, why a piece of steel heated to the right temperature in normal air would not change color, which is such a reliable process that it has been used to color watch hands (for example) for more than 150 years.

LarrySellerz

I think the discoloration is from heat. What I’m pushing back against is the idea that the whole thing or much of it is being heated up and discolored, and most of the discoloration is being abraded off and we are only left with the pictured stuff on the inside. I suspect that only the inside is heating.

what is the rotor made of, stainless? Very low thermal transfer in that material compared to other metals, it makes sense to me that only part of it could get hot.

njkayaker

Don't you complain regularly about being dropped?

Your reputation here would be greatly enhanced by you saying less.

LarrySellerz

I gave a place, give me a time or keep it to yourself. Don’t want to argue about my bike’s setup in this thread, want to brainstorm about the rotor.

tomato coupe

Standard procedure -- that's what they give you if you don't buy pedals with the bike.

njkayaker

This is not saying less.

Regarding the rotor, we have a well-known brand with simple components that thousands of people are using versus you, who has provided numerous examples of cluelessness. Ask yourself: which one is likely to be right?

Russ Roth

Does the other rotor have the same coloration? Might have been a result of the final heat treatment of the rotor or just meant to add an effect. It is unlikely to have this develop from a slight rub that's so small it doesn't effect the effort needed to maintain speed. So either the rub is worse than you're claiming or something else did it and you need to watch how much you're dragging the brake on steep descents.

jaxgtr

If the bike is brand new, I would take it back to the shop to make sure the brakes are adjusted correctly if you are concerned.

genejockey 

Well, I never said the whole thing would be heated up and discolored. But the braking surface is where the heat is generated so THAT part would be the hottest. It's also subject to frequent abrasion, wearing both the pads and the rotors.

LarrySellerz

my comment on the rub was suggesting that since there is a slight misalignment, maybe when braking only the inner part of the rotor is engaged or maybe that part engages first. I don’t think the constant minor rubbing generated the heat. Also, my hill is very steep and very long, I cannot reasonably use the front brake less than I am doing.

LarrySellerz

i suppose that another way of phrasing my question is “is this discoloration indicative of the braking surface being more on the inside of the rotor than it is supposed to be.” Where the actual braking surface is the key to my quandary