LarrySellerz

Hey guys, I just bought my first dentist bike a couple days ago, so I want to take better care of it than most of my bikes because it’s 10x more than I’ve ever paid for a bike. The front disc brake has some discoloration on it, and I wonder if that is normal. I am very paranoid about disc brakes rubbing and getting out of alignment, almost didn’t buy the bike because of ‘em but the owner was convincing that I wouldn’t have issues like I do with cheap disc brakes. Needed something to get to work the next day so I pulled the trigger.

I’ve ridden it a couple times, and the disc brake is rubbing slightly (wtf!) but it’s not slowing the bike down much. I think most people wouldn’t care or even notice the amount of disc rub, but I am intolerant of any. I wonder if this very slight misalignment could be responsible for the photo.

my buddy says the discoloration is some paint or something, but I think it’s heat. The bike is brand spanking new though. I live on the top of a hill and am like 240-250 lbs now. Kind of unhappy with the stopping power too, but I tend to ask a lot from my front brake

Koyote

Your bigger concern should be sliding right off that saddle and over the handlebar.

Kai Winters

meh, no longer care...

Kai Winters

really ! slide right off it or his arms and shoulders are going to be sore...

LarrySellerz

My thoughts exactly.

aliasfox

Did you buy new, or used? If it’s new, have the shop take care of it. If it’s used and it’s bothering you, a fresh rotor is about $60.

Mind you, a fresh rotor is no guarantee. I have Shimano XT rotors on my bike, and the front rotor not only came slightly out of true, but one of the floating rivets occasionally gets stuck after prolonged braking, resulting in more rotor noise until I soft-press the brakes again to get the rotor to realign. I’ve mitigated the warping using a big pair of pliers to bend it into place (so no more rotor rub under normal circumstances), but that may have aggravated the sticky rivet. It’s not enough to be bothersome, but definitely enough to be noticeable.

Btw, if you do decide to use pliers to correct any warping, make sure to clean them with rubbing alcohol first to prevent contamination.

TiHabanero

A discolored rotor usually indicates heavy use, such as hard braking for a longer period of time as when descending a mountain pass. It is possible the dragging brake will cause this, but it needs to be dragging fairly heavily on the rotor.

genejockey 

I have discoloration just like that on my front rotor. Mind you, the bike's got >2500 road miles on it and I weigh just North of 200#.The braking surface doesn't get discolored because you keep wearing off the surface

I'm also a little confused - you say it's "brand spanking new", but then refer to "the owner", which sounds more like you bought it used. Compared to your other bikes, any bike less than 10 years old. This bike could easily have a thousand or two miles on it and still look pretty new. And if the owner does much climbing (and thus descending), there's no reason the rotor wouldn't have gotten heated up a bit.

choddo

That post above by Kai is outstanding. Often amazed by the effort people on here will go to to help other cyclists.

The bike and brakes are both excellent so I don’t think you’ll have any long term problems. Take a look down the face of the rotor between the calipers with a light or white paper behind, as you rotate fhe front wheel and you should be able to see whats causing that rub. it’s fairly easy to realign the calipers if they are a little out of whack. I also don’t tolerate any brake rub at all.

I didn’t know Wilier made rotors. Suspect they get someone else to make them and put their logo on.

and yeah, your saddle needs to be horizontal

If that heat effect is from heavy sustained braking, perhaps intermittent, earlier braking down your hill from home will help. Gives the rotor a chance to cool slightly between pulls on the brake rather than constantly building heat.

Polaris OBark

If it over-heats, it will discolor. Try an XT/Ultegra rotor for better heat dissipation.

Congratulations on the new (even if just to you) bike. Don't let the pessimistic naysayers and incorrigible vultures of ill-omen be off-putting.

Some people advocate aiming the nose at the center of the handlebars, exactly as it seems to be done on that bike. If it creates problems, or you just want cheap effective birth control, tip it up.

genejockey 

Easiest way to stop brake rub: get one of those thick business cards. Fold it in half. Take the wheel out, put the folded card over the disc. Re-install the wheel, sliding the card and rotor in between the pads. Loosen the caliper mounting screws enough that the caliper moves freely. Squeeze the brake lever and hold it while you tighten the caliper mounting bolts down. Remove the wheel and card and tighten the mounting bolts to spec (usually 5-6 Nm). Reinstall wheel and spin. Rub should be gone. If you do choddo's paper trick you should see white on either side of the rotor.

LarrySellerz

I bought the bike brand new from gebhard (bike store)

LarrySellerz

Y’all don’t micromanage my saddle tilt, it’s like that deliberately, and I ride a lot. Don’t own a car.

bike has like 15 miles on it I’ve had it for like 2 days

LarrySellerz

Are you suggesting that the discoloration is an oxide layer or something similar, and the reason it is only on the inside is because it’s being worn away by the braking? I think you are wrong, but that is an interesting idea that I hadn’t considered.

tomato coupe

That saddle tilt won't benefit from micromanagement -- it requires a complete corporate shake up.

Kai Winters

And it's smart ass comments, especially the 'Y'all' crap that make me not want to comment.
I'm done here...

LarrySellerz

it’s just obnoxious to hear “your saddle is angled wrong” as if I didn’t deliberately set it there. Said y’all because there were 3 commenters. The guy who fit my bike didn’t complain when I asked for it to be angled down twice.

I do appreciate your post btw, might reference it if I get around to fixing a couple of bikes whose disc brakes are useless and shops keep fixing them and the adjustment going bad quickly.

LarrySellerz

this is petty lol

choddo

For a small amount of cash, you can get a metal version of this

https://cyclepal.co.uk/products/cycl...41198340800675

There are cheaper versions too.

shelbyfv

There's no way to spin that saddle misalignment. It's just wrong. Ride a century or even a metric like that and report back.

PeteHski

I’ve never heard of a bike fitter advocating that approach to setting saddle tilt! 😂

spclark 

I think genejocky's correct; the discoloration is an artifact of heating, the friction of pads against the metal along the disc rim keeps it from remaining there. Inside the pad path the heat leaves the telltale discoloration.

https://www.bikeforums.net/15364878-post8.html

I'd look for warp in the discs showing this coloration, may be why pads are rubbing. Heat could also come from pad friction if they're improperly adjusted, something you have some control over. If they're warped from excessive heating you may want to source replacements before riding – and braking hard – over too many more miles.

choddo

Do you not find it affects your arms?

Some problems tend to only show up after fatigue sets in a bit. I did 65 miles this morning (151 this week) and the load that saddle tilt would put on my shoulders holding me from sliding forward would definitely be painful over that kind of distance.

njkayaker

Sounds like a “you” problem. You do all sort of nonsense “deliberately”.

tomato coupe

I suspect the fitter was willing to do anything to end the fitting session. "Sure, dude, whatever you like. Looks perfect to me!"