Disc brake performance

dinyull

Fenix wrote:

I do find it crazy that in order to get them to work properly you have to go out and slam on repeatedly. Why is that acceptable in a braking system ? Imagine if cars were like that ? Or am I misunderstanding some of the instructions I've seen for discs ?

This is the problem, they shouldn't need that. Which is why I'm asking if anyone else has suffered with this and knows a solution.

apreading

I do agree with you about standards UGO. But not about any of the other stuff here.

Thing is, you dont see people on MTB boards saying disc brakes dont work, arent as good as rim brakes, are hard to set up etc. In the main, they just work and people get on with it. Earlier Avids had ALOT of problems and other brands arent as good as Shimano but if ever you see the very occasional post about someone having issues with disc brakes there, the advice is universally telling them to buy any Shimano hydraulic, even the cheapest, and they just work with no faff.

You only see the stuff you are saying on road bike boards and I think it is a) resistance to change coupled with definsiveness of the system people have got used to and b) early versions were not very good and they are only recently reaching maturity with the advent of hydraulic systems. Too many people refuse to embrace them for silly reasons, too many people took against them because they tried early versions that werent sorted yet. I think you fall into mainly the latter category because I recall that you havent and now refuse to try proper hydraulic versions - so you are not in a position to judge.

The advantages are not increased stopping power - that misses the point.

They key advantages are that they get up to heat and clear water much more quickly - so they respond pretty much immediately and that you can modulate the power easily, with one finger, with much better leverage from the hoods. Quick to respond, very fine control from both hand positions and easy to use. No adjustment needed, just replace the pads when they wear out in a few thousand miles. Thats what hydraulics give you. They just work, very well, all the time. Then add to that increased stopping power if, when you need it.

The biggest problem with disc brakes has been excessive heat buildup - something pretty much cured now with better rotor design (shimano ice-tec) and cooling fins on rotors and pads.

Something is wrong with the OP's report here - that should not be hapenning. Doesnt happen to anyone else and doesnt happen on cars for example.

When you changed the pads, did you clean the rotors thoroughly with isopropyl alcohol? It the rotors got contaminated then they could contaminate the new set of pads too. Only thing I can think of.

mamba80

meanredspider wrote:

ugo.santalucia wrote:

The wet braking is a bit of a myth,

Utter bollox. You might have had bad discs but that statement is total nonsense and flies in the face of just about everybody's experience.

I ve ridden 3 different hydraulic shimano disc braked road bikes and its not the braking at all, its the tyre grip or lack of that's the problem.
tbh on shitty little used farm lanes, i m over braked with discs, this is also the opinion of a mate who runs his own cycle business, has extensive use of loads of different bikes and also believes disc is over the top... the rim wear argument is a given.

I ve just come back from the Pyrenees and used Vitt carbon tubs with campag red pads, the wet weather braking was absolutely amazing, no lag, great modulation, downside was pad wear, disc's would last an age.

i use a 29 er HT as my winter bike now, hardly any slower, i ve big fat soft tires under me and i dont need a new set of wheels every year!!!
But just because our exp is different, it doesnt mean yours is the only the only one that matters does it?

to the OP I ve never ever had an issue with hydraulic braking after any sort of lay-off, fit some new and dif manufacturer pads and start again.

apreading

Fenix wrote:

I do find it crazy that in order to get them to work properly you have to go out and slam on repeatedly. Why is that acceptable in a braking system ? Imagine if cars were like that ? Or am I misunderstanding some of the instructions I've seen for discs ?

Cars are the same - if you get new pads or rotors, you are told to go easy for a distance while they bed in. You dont have to emergency brake to get them to bed in because the extra weight of the car means it is easier to get them up to the required temp to bed them in. But it still takes a bit of braking to do it - you just dont realise.

Slamming the brakes is simply the easiest way to be sure they are fully bedded in on a bike before you go ride. You dont have to do it that many times, once or twice might be enough - drip a couple of drops of water on the rotor to check - if the water fizzes then you got them hot enough and you are bedded in. You could just ride normally without slamming on brakes and they would bed themselves in, it would just take them a bit longer and be a bit less predictable for a few miles.

meanredspider

I'm sorry that they're not as great as you thought they'd be - maybe it was you that fell for the hype. I'm not on a crusade but totally accept that it might look like I am - and that solely for the reason that so much nonsense has been posted on here that is simply factually wrong or totally misunderstands the physics of braking. I've often listed where rim brakes are perfectly adequate and I've also said that if fettling isn't your talent, some discs won't be good. I hear what you say about bike mechanics but, honestly, fettling a bike is a pretty basic form of mechanical fitting. My first years of work were managing time-served mechanical fitters in an industrial setting and these guys were properly competent. The highly rated LBS in AMS managed to set my HyRds up wrong - in a way that clearly showed that they hadn't bothered to understand how they work. That's just incompetence.

Yup - there are different standards - show me a part of any bike that doesn't have different standards - it's the one thing you can be sure of. And, as I pointed out in the TdF thread, even Canyon are running DA surface mount calipers on an eTap bike because SRAM don't make them - so discs are no different to rims.

apreading

Oh, and get a rim brake wheel that is buckled, has broken a spoke or maybe just (significantly) out of true and your only option to keep riding is to disable all braking on one of your two wheels.

ugo.santalucia

apreading wrote:

Thing is, you dont see people on MTB boards saying disc brakes dont work, arent as good as rim brakes, are hard to set up etc. In the main, they just work and people get on with it.

They started from a lower point... both V brakes and cantis are not as good as modern dual pivot calipers... the diference was meant to be night and day. Add to that the superior grip of MTBike tyres and the fact that these systems are now cheap and awesome and why would anyone complain? My wife's XT were probably 10 pounds more expensive than rim brakes.

That said, when I had a 2004 Stumpjumper with V brakes it was much much lighter than the equivalent with discs that came out the following year and I never felt short of brakes

dinyull

Will give IPA a go and probably include it in my weekly cleaning regime from now on.

Actually thinking back to Friday on the commute home I went through a big patch of diesel. So much so I barely made it up the hill as there was so much wheel slip.

Although brakes were fine on the rest of the journey (was about 3 miles into 8 mile commute), it could have taken hold this weekend as this morning seemed worse than normal.

meanredspider

Fenix wrote:

I do find it crazy that in order to get them to work properly you have to go out and slam on repeatedly. Why is that acceptable in a braking system ? Imagine if cars were like that ? Or am I misunderstanding some of the instructions I've seen for discs ?

That's exactly what you do with car pads - especially so with race pads. I was given a hard time by a farmer in the wilds of the Black Isle because I was accelerating and braking hard on a remote road. If you don't want to do it, stick with the rubber blocks and buy new rims and live with the quality of braking that you get. It's all good with me.

ugo.santalucia

apreading wrote:

Oh, and get a rim brake wheel that is buckled, has broken a spoke or maybe just (significantly) out of true and your only option to keep riding is to disable all braking on one of your two wheels.

Bend your rotor in a crash and you are even worse off

apreading

Dinyull wrote:

Will give IPA a go and probably include it in my weekly cleaning regime from now on.

Actually thinking back to Friday on the commute home I went through a big patch of diesel. So much so I barely made it up the hill as there was so much wheel slip.

Although brakes were fine on the rest of the journey (was about 3 miles into 8 mile commute), it could have taken hold this weekend as this morning seemed worse than normal.

Dont do it every week - you will have to bed the discs in again after cleaning it like this so you are going over the top and creating hassle for yourself if you do.

Something is wrong somewhere with yours - decent disc brakes need ZERO regular, ongoing maintenance unless something unusual happens.

meanredspider

ugo.santalucia wrote:

apreading wrote:

Oh, and get a rim brake wheel that is buckled, has broken a spoke or maybe just (significantly) out of true and your only option to keep riding is to disable all braking on one of your two wheels.

Bend your rotor in a crash and you are even worse off

Yeah, because if you run matched rotors front and rear, you might have to swap the rear to the front before continuing

Vslowpace

Have you possibly got a bit of air in the system. Try storing the bike overnight with the levers pressed in.

dinyull

Vslowpace wrote:

Have you possibly got a bit of air in the system. Try storing the bike overnight with the levers pressed in.

Spyres are mechanical, not hydraulic.

ugo.santalucia

meanredspider wrote:

Yeah, because if you run matched rotors front and rear, you might have to swap the rear to the front before continuing

you can't let go, can you?

So assuming you are happy to continue with one brake only, how are you going to remove a centrelock rotor on the road?

meanredspider

ugo.santalucia wrote:

meanredspider wrote:

Yeah, because if you run matched rotors front and rear, you might have to swap the rear to the front before continuing

you can't let go, can you?

So assuming you are happy to continue with one brake only, how are you going to remove a centrelock rotor on the road?

Why do you think I did the two winkies? :roll:

I don't think I'm the one having trouble letting it go...

fat daddy

ugo.santalucia wrote:

you can't let go, can you?

:shock: wow !!!! ..... pot - kettle - black !

veronese68

apreading wrote:

Dinyull wrote:

Will give IPA a go and probably include it in my weekly cleaning regime from now on.

Dont do it every week - you will have to bed the discs in again after cleaning it like this so you are going over the top and creating hassle for yourself if you do.

Something is wrong somewhere with yours - decent disc brakes need ZERO regular, ongoing maintenance unless something unusual happens.

Have to agree with APR here. I don't think I did any maintenance to my discs for a year other than occasionally using the back brake harder than was strictly necessary to stop it glazing.
As others have said it does sound like some sort of contamination getting to your discs. Not sure how it is getting there but if it happens every week it could be something you are doing.
You normally clean the bike, this week you didn't but did have the large amount of diesel incident. Either could cause contamination. Next week don't wash your bike, just relube the chain carefully with a dropper bottle. See if it happens then.

apreading

Better still - dont clean it and dont do any maintenance whatsoever this weekend. Hopefully the bike will learn its lesson and not want to be neglected like that all the time and will decide to behave properly in the future!

In all seriousness, just do nothing. Nothing at all. That way you can be sure if it is something that you are doing or the bike being left unused for a couple of days that causes it.

apreading

ugo.santalucia wrote:

apreading wrote:

Oh, and get a rim brake wheel that is buckled, has broken a spoke or maybe just (significantly) out of true and your only option to keep riding is to disable all braking on one of your two wheels.

Bend your rotor in a crash and you are even worse off

Oh year, I forgot that. It happens all the time so I dont know why I didnt think of it... :roll:

ugo.santalucia

I should really really put into practice my resolve to leave this forum for good... fuc-king sh-ithole

mamil314

Come now, ugo, everyone appreciate you sharing your experience here, as long as you disclaim it as such ^_^

orraloon

There might be something with the Spyres. Have a similar issue with my road bike, new in April, still not happy with the braking efficiency. Ongoing conversation with LBS, others have similar experience. Been repeating the cleaning / resurfacing discs and pads cycle, braking efficiency remains poor especially compared with my other disc bike.

Alternative pad type is next step.

dinyull

Cheers for all the input.

On getting home last night I tried a few things:

1) Re centred pads, and adjusted cables so tensions, lever reach etc were all good. Made no difference at all.
2) Tried to bed in the pads again. Still no difference.
3) Cleaned the rotors with baby wipes, which seemed to remove loads of sh*te judging the baby wipes. Fronts immediately improved, rears worked for for a few tries and then stopped working.
4) Removed the rear pads for inspection to find they're badly glazed. Have sanded them down, but although the glazing is removed you can still make out where they were glazed. This improved things again, but still not as good as they should be so going to replace pads. Considering the rears don't get used too heavily I'm shocked at how badly glazed they were, so will avoid these pads from now on.

Much better braking performance this morning in the wet, but doesn't explain poor performance following a weekend so will keep an eye on things for the next few weeks.

fat daddy

don't baby wipes have moisturiser in them ??? .... I use them religiously to clean my bikes .... butnever plucked up the courage to use one on a rotor ?

veronese68

I think APR has worked out my bike cleaning regime, or non-cleaning.
Interesting if Orraloon has a similar issue. The mechanics of the caliper can't be any different after being stood so that can be ruled out. So, there must be something going on with the pad material. Does seem odd.
I tend to glaze my rear pads if I don't think about them. I think this is caused by only braking gently with the rear. If I make a conscious effort to use the back brake harder every now and then it's not an issue. I just pull the back brake on and off a bit harder when rolling to a stop if there is no one behind me every now and then.

dinyull

fat daddy wrote:

don't baby wipes have moisturiser in them ??? .... I use them religiously to clean my bikes .... butnever plucked up the courage to use one on a rotor ?

Not sure, although these are budget wipes for the sole intention to clean the bike. I'd imagine Nivea or the like might have some sort of moisturiser in them.

I did check t'interwebs before using and they were recommended on a few MTB forums.

meanredspider

Dinyull wrote:

Considering the rears don't get used too heavily I'm shocked at how badly glazed they were,

They get glazed BECAUSE they are not used heavily. Disc brakes benefit from heavy use and I suspect many of the poor braking issues we see on here are because people drag brakes or simply don't bed them in properly to begin with.

I, too, am surprised baby wipes didn't make things worse. Probably indicates how bad things had got. Some sort of alcohol wipe (computer screen cleaner or similar) would be more appropriate if you have one.

Like others, I just don't touch my brakes between pad changes. I think people often overdo bike maintenance and create problems (I speak as someone who used to be an industrial maintenance specialist). Bikes are inherently simple machines - that's their beauty - and we have refined their design over a century or more. Yet some people seem to treat them more like an F1 racing car - pulling them to bits too frequently. Leave them alone as much as possible. If you're OCD, find something else to obsess over.

fat daddy

Dinyull wrote:

[ I'd imagine Nivea or the like might have some sort of moisturiser in them.
.

yeah I use the expensive, hypo allergenic ones with natural fragrance of medow flora .. only best for my baby

DeVlaeminck

cougie wrote:

Not had discs but mate got a bike with them. The originals were worse than my crappy cantilevers. He upgraded them and still not happy. Sold the bike and bought a rim braked bike.

They must be decent I guess but from plenty of threads on here it's a bit of a dark art to set up.

Yes mine haven't lived up to the hype. I've got the rear working well in that it is powerful and it does work better in the wet than a rim brake but I'm not sold on the better modulation argument I actually prefer the feel of a rim brake, it may just be a case of what we are more used to. The front disc works well when I'm into a long ride but similar to the OP at the start of a ride it is poor, I suspect the pads are either glazed or slightly contaminated and when I get round to it I'll replace them and see if that works. Even working "well" though when I got my best bike out the other day I found decent rim brakes with clean rims better.

I know some say how come mountain bikers don't have this problem. Thing is I'm sure most of us do have mountain bikes with discs and don't have these issues - I've found discs on my MTB fine, powerful, low maintenance etc - for whatever reason road disc brakes just don't seem to be as satisfactory for a lot of people. I'd only get discs on another road bike if I could test ride first, I'm fine that others have a different experience but there are enough that seem to share mine.