slvoid

...if they can't even be touched by hand?
Every time I ride through rain I ride through pools of disel fuel, motor oil, and some sick slick sludge on the streets here in NYC. If a disc brake can't even handle a little oil on my dry hands, how is it supposed to handle the streets here?
Just wondering.

flaming_burrito

i've handled my disc brakes.............., i think............then again. oh well, anyway. what are you going with a disc brake bike if you don't think they can take it. i've used my brakes this weekend in places where there were loads of sand. then when i was rinsing the bike off the brakes got wet. who makes your brakes, it may just be the manufacture?

slvoid

I don't have disc brakes. But everyone here at bikeforums and everyone at the LBS says don't touch the discs with your hands.

flaming_burrito

well then.....i guess i'm lost...........aaaaahhhhhhh

Raiyn

Touching the rotors in turn contaminates the pads causing a loss of braking power and squealing.

More info https://www.mtbr.com/techtalks/brakes/brakesfaq.shtml

Mtn Mike

So, dont touchem with you hands! You don't have to worry about junk and road grime too much. At least not in my experience. They work MUCH, MUCH, MUCH better than rim brakes when you're talking about wet, sloppy, wintery, grimmy conditions. If you really think you've gotten some kind of oil on the braking surface, just wash it off with rubbing alcohol ASAP. IM(very)HO, the only reason to run rim brakes anymore is if you can't afford discs, or your bike isn't compatable. But, if you're talking about a commuter bike or something for the city, I guess you really don't need to stop that well anyway, so I guess rim brakes are fine.

Raiyn

In all honesty, the chances of oil and junk being thrown off to the side like that is pretty slim as long as you're not a slob with the chain lube, wipe off any loose grease after lubing components, and don't go spraying WD40 on them there's no reason to worry. It's also been my experience that Discs work a LOT better when conditions get nasty as they are (almost) unaffected by the conditions at the tire / rim area that can foul up rim brakes.

khuon

Hmmm... not sure I entirely agree with that. Looks like quite a bit of rimbrake-action going on at the World's XC MTB.







FWIW, I'm still running rimbrakes (Avid ArchRival 50) and find them quite adequate even in muddy conditions. Sure discs would perform better but for my type of riding, high-quality rimbrakes are fine. And yes, part of the reason I have chosen not to upgrade is lack of perceived needs, budget and frame/fork compatibility (would want to go with floating discs and would need to convert front fork since I really like my fork). In the end, I do not feel the advantages justify the expense for me. This may change however.

Raiyn

Yeah weight weenies hate discs.

khuon

I'm not all that certain they're all weight weenies. I'm certainly not a weight weenie. I think some people weigh the tradeoffs (NPI) and feel that for them, rim brakes work fine. I'm not saying this will be universally true for everyone just as I would hesitate to say that discs are appropriate for everyone too.

slvoid

Well I guess the city slime coming off the streets is a little more polluted than just the mud and sludge coming off the forest floor.

slvoid

Wrong forum, Khoun, with the chicks.

Al.canoe

You need to get rid of them on your car. They have the same "problem"; your not to touch the braking surfaces with greassy hands.

Al

capsicum

Rims are just giant disks you know.

HereNT

Sorry, I know pretty much nothing about this, but on a car aren't they enclosed? The original question was in regards to oil and crap that can be thrown up from the road onto the brake...

It's not like I use either style of brake, or brakes at all, but I have been thinking about maybe building up a SS MTB at some point, so I'm kind of curious...

slvoid

So getting back to the point, why do people make such a big deal about touching the disc and "contaminating" the disc with oil when they're just as likely to get contaminated by muck being throw up on the streets?

dafydd

and people wonder why they have their our forum now...

bac

They are only appropriate for those who wish to stop better/faster.

Seriously, the only downside to disc brakes is the extra weight. Racers, like those shown in the pix, are all about weight. Therefore, some still elect to run rim brakes. Those of us who have run both know that discs are FAR superior in terms of stopping power, modulation and rider fatigue.

Homer

The no-touch rule is due to the brake pad dust. You won't harm the disc. It's like your car... The pads are made from really nasty stuff.

dirtyscratches

Actually it's because oil on the pads will destory the pads. Touching the disc transfers oils from your skin to the disc which transfers to the pad.

slvoid

But would motor oil, grease, disel, etc, coming off the ground destroy the pads as well? Cause I know my hubs have a fine layer of it from commuting in the rain.

TandemGeek

Makes you wonder how a motorcycle stops... Good grief folks. This is basic mechanics and product liability.

Don't unintentionally transfer petroleum lubricants onto your rotors or disc brake pads by handling the rotors or brake pads during maintenance procedures. Work on your greasy maintenance tasks, clean your bike, clean you hands with Go-Jo or some other type of mechanics hand cleaner and then work on your brakes. If you have hydraulic brakes, be sure you know what you're doing if you decide to bleed the brakes to prevent contamination of the pads and caliper. Once you've completed your maintenance it's not a bad idea to clean the rotor "just as a precaution". Once you're on the road there are few if any reasons to touch the rotors. If you do, just be sure you don't have grease on your hands. Same precautions apply to motorcycle and cars with disc brake systems.

Water, dirt, grime and all that other stuff that you encounter in the "wild" will usually be wiped-off the rotor by the leading edge of the disc brake pad during normal brake application and does not usually present a problem. If you start to get a lot of brake noise clean your rotors and check your pads for embedded grit, grime or contamination.

By the way, your rim brakes are succeptible to the same problems, i.e., rim (rotor) contamination and junk embedded in the brake pads. Therefore, it could also be said that you shouldn't touch your rims or brake blocks with your greasy fingers eithers.

lt1aggie

You are probably thinking of drum brakes, not disc brakes.

Dannihilator

We say don't touch them because after use they are really hot and can burn your hand quite badly.

dirtyscratches

Here is a great faq I found about disc brakes.

https://www.mtbr.com/techtalks/brakes/brakesfaq.shtml

Specifically they say don't touch the rotors because the oils will decrease braking power. I might be wrong about the oils destroying the pads, but I thought I recall reading that somewhere.