Bicycle Mechanics - Just how crappy are disc brakes?

...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.

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?

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?

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.

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

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

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

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.

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, grimmy conditions.
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.

IM(very)HO, the only reason to run rim brakes anymore is if you can't afford discs, or your bike isn't compatable.

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

http://www.velonews.com/images/mtn/6918.9209.f.jpg
http://www.velonews.com/images/mtn/6918.9215.f.jpg
http://www.velonews.com/images/mtn/6918.9218.f.jpg
http://www.velonews.com/images/mtn/6918.9221.f.jpg
http://www.velonews.com/images/mtn/6918.9222.f.jpg

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.

Yeah weight weenies hate discs.

Yeah weight weenies hate discs.

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.

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.

Wrong forum, Khoun, with the chicks. ;)

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.

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

Rims are just giant disks you know.

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

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...

Rims are just giant disks you know.

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?

Wrong forum, Khoun, with the chicks. ;)

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

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.

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

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.

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.

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.

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.

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.

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.

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.

Sorry, I know pretty much nothing about this, but on a car aren't they enclosed?

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

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

Here is a great faq I found about disc brakes.

http://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.

Here is a great faq I found about disc brakes.

http://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.

Good link; thanks! I've heard from time to time (but never seen in an owner's manual) that you should not hang or carry a bike with hydralic brakes upside down. I've been doing that (hanging the bike by the wheels in my garage) with no bad effects that I've noticed. Any truth to that advise?

WEll i have not had any issue with them, sure you dont want to get them contaminated, I dont see why not being able to touch them is bad, is there any reason unless your clleaning it? All your going to do is burn yourself. I never noticed any difference really if i ever touched them (i was fascinated by them when i just got them) but they say your not supposed to so i have no issue its hjust habit now. i dont thinkt hey are THAT heavy anyway.

WEll i have not had any issue with them, sure you dont want to get them contaminated, I dont see why not being able to touch them is bad, is there any reason unless your clleaning it? All your going to do is burn yourself. I never noticed any difference really if i ever touched them (i was fascinated by them when i just got them) but they say your not supposed to so i have no issue its hjust habit now. i dont thinkt hey are THAT heavy anyway.

The main issue, as I understand it, with touching the pads or rotors (in additon to them being super hot after braking) is simply transfering something (oil, grease, ...) from one place, like your chain or peddles, to the pads or rotors via your fingers. I've never been concerned about the small amount of natural oil on my fingertips; it's the chain lube and other stuff that might be there that I watch out for.

Here is a great faq I found about disc brakes.

http://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.
Yeah that's the link I posted in the fourth reply. Good stuff

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.

Hot brake pads become hot gas as you use them... any oil would be quickly burnt away. Unless we're talking gobs here.

Hot brake pads become hot gas as you use them... any oil would be quickly burnt away. Unless we're talking gobs here.

Oils are used in high temp applications all the time. It won't necessarily just burn away.

Ok, a little common sense here.

When working on your bike, avoid the brake area to keep the grease away, because a good sized gob of grase or oil will cause the pad to glaze and decrease braking for some time, the same with automotive brakes.

The small amount of natural oil that you have naturally on your skin, will not ruin your brakes, or decrease braking power. How do I know this?......I have done it. Once your pads are glazed they work less efficiently until the glaze wears off.

Ok, a little common sense here.

When working on your bike, avoid the brake area to keep the grease away, because a good sized gob of grase or oil will cause the pad to glaze and decrease braking for some time, the same with automotive brakes.

The small amount of natural oil that you have naturally on your skin, will not ruin your brakes, or decrease braking power. How do I know this?......I have done it. Once your pads are glazed they work less efficiently until the glaze wears off.

Thanks for clearing that up, I guess people are just being cautious when everyone tells me not to touch brake discs with my bare hands.

touch away, ive had hayes forever. i ride in and around chicago thru all types of stuff. been a mechanic for 7 years. the great thing about discs are that theres very little loss of power in these conditions. rims are horible when you get them wet cuz the mosture has no where to go. disc force it away. id go tow to tow with your bike shop on this. must be a roadie shop lol.

Rims are just giant disks you know.
maybe...not as effective though, also the disks grip better. I mean when you have wet rims, that is bad for grip, i say disks have more gripping power unlesss....like everybody is talking about....are touched with greasy hands.

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...

Yes, you don't know much about "practical" stuff. Rather than talking about it, go to your car and look under it; better yet, pull a wheel. Ever done that? You must not have. Get some hands-on experience. You'l be amazed how exposed the disc's are. Also, why would almost all vehicles have disc's? They must work or there's a lot of idiots out there with bad brakes.

Al

We say don't touch them because after use they are really hot and can burn your hand quite badly.
Thats the only real reason I can think of, other than some fool with gobs of lube on his grungy paws.