Disc brake performance

dinyull

I commute 5 days a week on a disc brake bike with TRP Spyres.

I've started to notice that when the bike isn't used over the weekend - or for a couple of days - the brakes are terrible, and don't start working properly until half way into my commute after VERY heavy braking.

For eg, I grabbed the brakes at the bottom of my road this morning and was convinced I was going to die.

It's like they accumulate a layer of crap over the weekend in the garage - is this the norm or is does something sound off?

I can't remember if they've always been like this (been using them for 2,500 miles) or if I'm just noticing how inadequate they are in the dry because I'm able to use the summer rim brake bike more and more often thanks to the weather*.

I should add that in all of the rain last week they worked fine, was quite thankful for them, but in the dry especially at the start of the week they are dreadful.



*Not unusual to be locking up the rear/almost flying over the handlebars on the summer bike at the start of a ride as I'm accustomed to the discs and the 105 calipers with koolstop salmon are fantastic in the dry.

meanredspider

Sounds really unusual to me. My Volagi can be unridden for weeks and works just fine from the off. You don't have a particularly damp storage for the bike do you? A fine layer of corrosion would do it.

k-dog

I do the same but I've never had that - the first pull of the brakes usually takes a second to bite (I always just assumed condensation on a cool morning) but they're fine after that.

I'd be tempted to change the pads and give the discs a good clean and see what that does.

dinyull

Rear pads were changed recently and just like the front fail to perform after the weekend.

Bike is stored in a garage and wouldn't have thought damp would have been a problem as it's been mid to high teens all weekend.

meanredspider

Dinyull wrote:

Bike is stored in a garage and wouldn't have thought damp would have been a problem as it's been mid to high teens all weekend.

Rust forms faster in warm conditions and it has been pretty wet. I doubt it's the cause though.

dinyull

No visible signs. Bike is cleaned and inspected on Sunday evening's and have never noticed any rust before.

mamil314

Got to stop using your ceramic pads!

Seriously, though, i reckon the cheapest way would be to do a few repeats of speeding up and brake slamming to burn some pad off and see if that does the trick for you. That's after making sure rotors are free of any lubricant residue, of course

dinyull

mamil314 wrote:

Seriously, though, i reckon the cheapest way would be to do a few repeats of speeding up and brake slamming to burn some pad off and see if that does the trick for you. That's after making sure rotors are free of any lubricant residue, of course

Yeah, but then why does the same happen again after the weekend?

Over the first half of the commute I was brake slamming and they finally started to bite. They will probably be fine for the rest of the week now....until next Monday morning.

meanredspider

Dinyull wrote:

No visible signs. Bike is cleaned and inspected on Sunday evening's and have never noticed any rust before.

What do you clean it with? Are you sure that's not contaminating the discs/pads somehow? Try not cleaning it next weekend and see what happens on Monday.

dinyull

meanredspider wrote:

Dinyull wrote:

No visible signs. Bike is cleaned and inspected on Sunday evening's and have never noticed any rust before.

What do you clean it with? Are you sure that's not contaminating the discs/pads somehow? Try not cleaning it next weekend and see what happens on Monday.

It didn't get cleaned this weekend....haha

Just hot water, with a cloth that I don't use elsewhere on the bike. Whilst cleaning cassette I cover up rear disc with cardboard and make sure no GT85 or lube etc goes anywhere near discs or pads.

fat daddy

my hybrid with hydraulic discs does this ...... my MTBs and SS road bike with mech discs don't !!!!

I "think" the rotors might be to blame with build up of crap in the teeny scores all over the disc in the line of rotation .... I spent the weekend, resurfacing the rotors with some 80 grit ...... lets see what this week brings

dinyull

Yeah, let me know how you get on.

Keep thinking about just binning off the disc experiment, as they're more hassle than worth. But then last week in the wet they reminded me just why I use them on the commuter.

ugo.santalucia

fat daddy wrote:

my hybrid with hydraulic discs does this ...... my MTBs and SS road bike with mech discs don't !!!!

I "think" the rotors might be to blame with build up of crap in the teeny scores all over the disc in the line of rotation .... I spent the weekend, resurfacing the rotors with some 80 grit ...... lets see what this week brings

Waste of time...

meanredspider

What pads are you using and when were they last changed?

cycleclinic

you may not think GT85 is not getting on the disc but it might.

Also I use the spyres and I have no braking issues when I dont use it for a few days. The problem you have is contanination of some kind.

What pads also. I have found the RWD pads not be that great, the sintered RWD pads might actually need to get warm before they really bite. EBC organic pads are long lasting and are superior for bite.

ugo.santalucia

Dinyull wrote:

Yeah, let me know how you get on.

Keep thinking about just binning off the disc experiment, as they're more hassle than worth. But then last week in the wet they reminded me just why I use them on the commuter.

When it came to "upgrading" the bike to one with more relaxed geometry and suitable for long distance cycling, I did just that. Swimming against the current, as more and more Audaxers choose discs... but most of them don't build their own wheels, so they see rim wear as a problem...
The wet braking is a bit of a myth, I've had good braking as well as bad braking with both systems. Besides, when it's wet something triggers in my mind and I lean less, I go slower and I brake earlier... I do paly it a lot safer

meanredspider

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.

dinyull

Rear pads are TRP pads that came standard with Spyre's - done approx 2500 miles.

Front pads were changed to Uberbikes Race Matrix at end of April and have done just over 700 miles.

Still plenty of life left in both.

ugo.santalucia

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.

The censor is back... the Torquemada of braking

dinyull

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.

Sorry Ugo, I'm with MRS on that.

I commuted and rode weekends for years with 5800 105 calipers and kool stop salmon pads. Had 1 emergency when someone pulled out on me in the wet and went into the side of the car. I wouldn't have been anywhere near them with (even my poor) discs.

meanredspider

ugo.santalucia wrote:

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.

The censor is back... the Torquemada of braking

Somebody needs to balance some of the "stuff" you come out with. Just because you've (on your own admission) decided to swim against the tide, it doesn't mean you're right. There are plenty of scenarios where I believe rim brakes are perfectly adequate (I do, after all, own a rim-braked bike) but claiming that superior braking with discs in the wet is a "myth" is just nonsense...

dinyull

thecycleclinic wrote:

you may not think GT85 is not getting on the disc but it might.

Also I use the spyres and I have no braking issues when I dont use it for a few days. The problem you have is contanination of some kind.

What pads also. I have found the RWD pads not be that great, the sintered RWD pads might actually need to get warm before they really bite. EBC organic pads are long lasting and are superior for bite.

Only thing with that is....it happens even when I haven't cleaned the bike, like this morning. But yes, it must be some sort of contamination.

Annoyingly, they seem to work better in the wet...could lock the rear up at will last week in the rain and I can't remember the last time I locked it up in the dry?!

timothyw

I simply won't commute in the wet on rim brakes, too much unnecessary added risk when the disks work so much better.

ugo.santalucia

Dinyull wrote:

I commuted and rode weekends for years with 5800 105 calipers and kool stop salmon pads. Had 1 emergency when someone pulled out on me in the wet and went into the side of the car. I wouldn't have been anywhere near them with (even my poor) discs.

Well, you don't know... you are just assuming...

I find that wet discs are just as bad... they do dry quicker that rims as you brake and they don't get wet again while you brake, so on balance they are marginally better, but they are still worse than they are in the dry, so you still have to be extra careful.

What I am trying to say is that while folks make it sound it's night and day, I find that it's much much more marginal

cougie

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.

ugo.santalucia

meanredspider wrote:

Somebody needs to balance some of the "stuff" you come out with. Just because you've (on your own admission) decided to swim against the tide, it doesn't mean you're right. There are plenty of scenarios where I believe rim brakes are perfectly adequate (I do, after all, own a rim-braked bike) but claiming that superior braking with discs in the wet is a "myth" is just nonsense...

I am likely the most objective on here, having tried extensively and coming to my own conclusions. I worked out that the hype is a bit excessive and the downsides often brushed under the carpet... it's the same for tubeless, that I keep using... a fine balance between pros and cons... I swing for the pros, but I might change my mind on that too.

You buy them because you want reliable, predictable braking... then you find out that a drop of diesel spilled on the road can kill the pads instantly... is that reliable? I've never managed to get consistend pad wear, both in the way the pads wear and in the time it takes to wear them... a set would go in one year, another would go in 3 weeks. Then of course I've had to deal with faulty products that attempted to murder me on two separate occasions and that is AFTER the recall, not before.

In a way, the only advantage I cannot deny is rim life, which is the reason folks doing distance like them... new wheels every year is not economical. I happen to like building wheels and buying myself a new set of rims, so that spoils it for me, unfortunately... :?

meanredspider

ugo.santalucia wrote:

I am likely the most objective on here, having tried extensively and coming to my own conclusions.

And you're different from me in that respect just how? Because, of course, I've not ridden both extensively and I've just read the hype and believed all of that....? :roll: I ride a cable disc bike, a rim-braked bike, and a hydro disc bike. As it happens, the Foil is the highest spec of the three. Yet you're more objective?

Except I don't build wheels. Nor do most people. So who is the more objective in this instance?

And how many sets of pads have I had ruined by diesel? Um, that'll be zero. I've crashed on diesel 3 or 4 times so there's plenty of the stuff about.

And it's not as if disc brakes are the only brakes to be affected by a recall :roll:

Please feel free to ride your rim brakes and to praise their qualities - I've absolutely no beef with that. But I will probably respond when you claim stuff that me and most people know to be shaky.

ugo.santalucia

meanredspider wrote:

Please feel free to ride your rim brakes and to praise their qualities - I've absolutely no beef with that. But I will probably respond when you claim stuff that me and most people know to be shaky.

The problem is that you seem to be on a crusade, as if you made a penny every time Shimano sell a disc brake unit. I am not denying the benefits, I just think they are not as great as I thought initially and as great as the industry want us to believe. They are not a God send.
Also, you brush off a vast number of people who cannot get them to work satisfactorily as incompetent every time you have the opportunity, including mechanics with years of experience fixing bikes and I think there might be a way to make them to work faultlessly, but it is indeed a fine art, as someone mentioned above. Every time I did manage to get them to work well, I made sure I didn't touch them, in fear of losing my magic moment.

IF frames mounts were perfectly machined and IF the two independent pistons were working perfectly, I am sure they would be great all the time... but out of two frames with post mounts, both of them didn't want the caliper to sit perfectly. Now someone will tell me that flat mounts are all the rage and have solved all the problems... maybe, but do I have to constantly run to the latest standard in order to have brakes that work?

Finally, the increasing number of standards make them unpalatable for someone like me, who enjoys building his own bikes out of components... I buy flat mounts now, but then two years down the road there will be a new standard and a new standard of dropouts and a new width of the rear triangle and whatnot... and I have to replace everything, rather than just what I want to replace

First.Aspect

meanredspider wrote:

ugo.santalucia wrote:

I am likely the most objective on here, having tried extensively and coming to my own conclusions.

And you're different from me in that respect just how? Because, of course, I've not ridden both extensively and I've just read the hype and believed all of that....? :roll: I ride a cable disc bike, a rim-braked bike, and a hydro disc bike. As it happens, the Foil is the highest spec of the three. Yet you're more objective?

Except I don't build wheels. Nor do most people. So who is the more objective in this instance?

And how many sets of pads have I had ruined by diesel? Um, that'll be zero. I've crashed on diesel 3 or 4 times so there's plenty of the stuff about.

And it's not as if disc brakes are the only brakes to be affected by a recall :roll:

Please feel free to ride your rim brakes and to praise their qualities - I've absolutely no beef with that. But I will probably respond when you claim stuff that me and most people know to be shaky.

You've got too many bikes, MRS, that's the problem.

I'm with you though - its nonsense to suggest that the problems with discs are downplayed. If anything its the opposite - there is a lot of technobabble going around about their problems.

I've managed to contaminate my own discs or pads cleaning the bike, and just like rim brakes occasionally I have to brake hard a few times to restore optimum performance (possibly from an accumulation of crap thrown up from the road), but the notion that the pads are so easy to contaminate doesn't tally with my experience.

Like any more complex system, when they do go wrong they are a more complex to fix, compared to cable operated rim brakes. That much is true.

Personally, I much prefer riding a bike with conventional brakes. But I commute and so do most of my riding on a disc equipped bike (have done since 2009), because they work best for year round all weather riding.

fenix

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 ?

k-dog

Cars are like that when you get new discs - they have to bed in the same way.

They're a bit less prone to dirt though - partly because they're bigger and partly because they're sheltered out of the way. A lot of systems have an auto check where the brakes come on gently when you first start moving - just to clean the discs. Not enough so you would feel it but it's the same as me pulling my brakes on just as I've started off.