[Closed] Nearly had a massive off today

Not sure about the rotors sorry. What size are they? You must have been pretty heavy on the brakes to get them like that

Sounds like you need to replace the oil completely: Old oil tends to be more susceptible to heat than new, I believe. I doubt you would need to replace the rotors unless they are warped, but even then you should be able to bend them back.

You may have cooked the pads, in which case you would need to replace them.

Sounds nasty - suppose it's a good job it happened on the road rather than on narrow, wooded singletrack 😯

My M4's survived a few weeks in the Alps which would put Walna Scar to shame so you must have water in the system. Rebleed them and they'll be fine.

You must have been braking with a death grip in order to have overheated them on a road section.

Mikey what do you mean by 'cooked the pads'?

You won`t need to replace the disc they surface will come back to normal after a few muddy brakes

i am 6'2 and 15.5 stone,that takes some stopping power.

Cooked pads are what i am worried about, is it true that the high heat may have altered the performance?

Heated them to a point where they harden and lose their bite. You can also glaze the surface, which also reduces stopping power.

I used to have Hope M4s and suffered from the same problems when I went on holiday to the big mountains. Since I switched to Shimano I have had no such issues, including trips to Whistler.

Were the levers coming back to the bars or were the pads hitting the disc but not doing anything ?

Suck it and see. In my view, brake pads are brake pads - you can get soft ones, you can get hard ones, but the technology is all fairly similar whether you're talking bikes, cars, or motorbikes. If you overheat the pads, you get white smoke, a very noticeable smell and a loss of braking power. I've done it a few times in cars, and never ruined a set of pads, even when I've had glowing discs.

On the other hand, if you overheat the fluid (the boiling temperature of which is reduced by water absorption - DOT4 and 5.1 are hygroscopic) then you lose braking power but don't have smoking pads...

how hot do they have to get to cook? (I'm not taking the p1ss, as an *ahem* clydesdale rider, I'm genuinely interested)

Levers were not coming back to the bars, and i could seriously smell the pads when i eventually stopped.

Are M4s easy to bleed (never bled brakes in my life before)

IME you do not ruin pads by overheating - at the very worst you get a bit of glazing.

this to me sounds clearly like old fluid. Bleeed thru with new fluid and they will be fine. Don't do anything to the discs o pads.

Are M4s easy to bleed (never bled brakes in my life before)

Very easy - Dot fluid should be bled thru every year - herein might be the issue

M4's are dead easy to bleed. You must remove the pads when you bleed them though to stop potential contamination of the pads - you'll need to place something between the pistons to keep them retracted while you bleed.

yeti guy, glad you didnt hurt yourself mate! that must of been terryfiying. Did you have to change your ubderpants?? haha

Mates brakes failed a few years back when were out in the dales. He ended up hitting a dry stone wall, flew through the air before resting face down on the road. The rear tyre exploded as the bike hit the wall. Really nasty ankle/leg break. Airlifted out. Still has loads of metal work in place.

i cooked a set of M4's at Fort Bill world cup track. they were never the same again....

Scotchbrite the discs - should remove any discolouration. It's probably just a bit of blueing from where they've got a bit hot. 🙂

Agree with TJ, pads should be fine, just glazed, roughening them up with a (clean) file should help.

brake less!

[i]Are M4s easy to bleed (never bled brakes in my life before) [/i]

And what other maintenance tasks are you now going to learn...

TBH if the levers weren't coming back to the bars, you weren't squeezing hard enough.

Yeti Man, do you have a black Yeti, did we (Group of 10 that became 7 after a crash)speak to you by the road near Torver? I was on a blue/green Santa Cruz Bullit with green wheels.

Cheers

Had total brake failure (old Hope Mini's) in the Alps as i was braking into a hairpin bend with a sheer drop the other side. How TF i got round that corner without coming off i will never know.

Nowt wrong with the brakes either before or after this.

Get orf the ****ers though. Dragging on long descents shows Hopes weakness (sorry Hope fans, I think they're gash brakes).

If you're worried ditch em for Hayes or Shimano. But learning to brake would be a good start.

Having said that - glad you're not dead 🙂

Coming down walna scar on the road section towards coniston

but [b]why[/b] ?? That's a rubbish way to go! There's a parallel bridleway drops from near the car park to Spoon Hall 🙂

Paul, that was me, yes, hows your mate?

I think most brakes would suffer serious fade if they were dragged all the way down a very long steep decent. I have the latest generation Hope Tech V2s(for DH) and X2s (for XC) and have had no such issues. Sorry if this sounds obvious but maybe braking for short bursts just before a feature to scrub speed is the better option but easier said than done!!

Undoubtedly, i was braking like a plonker ! Learning curves and all that !

Simon, didnt know about that route mate, was following a route from the MTB in the lakes book, will look out for it next time

was following a route from the MTB in the lakes book

ask me next time 🙂 I may be a rubbish rider but after riding the area for 13 years I know a lot of stuff 🙂

Lol...I did that a few years ago Yeti Guy and had to bail at the bottom. I kind of managed to eject and I slammed into the low wall of the house at the bottom of the steep bit as the road turns right. I was pretty lucky as I took most the blow with my fullish rucksack. 😆

You can't ride that road without dragging your brakes a bit surely? It's bloody steep! We did the same run off Walna Scar and after doing that road bit I've just looked at the map and was wondering about that other bridleway as a better option? What's it like to ride?

Yeti, Ian is ok, had both cuts glued up and should be ok. He has a very black eye too.

*gets worried about Fort Bill on M4's in a few weeks*

I've never had problems with my brakes overheating because i've got Avid BB7s 🙂

I really feel sorry for all you fashionistas with sketchy hydraulics 😉

*gets worried about Fort Bill on M4's in a few weeks*

Don't be if they are bled proper, they'll be fine. I've done FB on M4's many times.

Bomberman - some of the tandem boys have cooked avid BBs - the plastic bits melted and fell off. You can still overheat the pad surface

There are two types of brake overheating failure - the fluid boils or the pad surface overheats. Both are caused by prolonged dragging of the brakes. In the first simply maintaining the brakes and replacing the fluid every year, in the second either more heat resistant pads or alternate / brake in bursts are the cures

Edit - yetiman - glad you are OK - did you get no warning? - I have done this a couple of times and both times the lever feel changed and gave me enough time to come to a halt.

as jordie says
[b]You won`t need to replace the disc the surface will come back to normal after a few muddy rides or brakes [/b]
same goes for the pads too!!

dragged my small rotored maguras loads on a ht on the alps. One ( single occasion) front brake brake fade in 2 weeks.

yetiman - glad you are OK - did you get no warning? - I have done this a couple of times and both times the lever feel changed and gave me enough time to come to a halt.

Earlier on in the ride i started noticing that i had to pump my back brake to get power?

Considering changing to V2 brakes now!

yeti guy - Member

never bled brakes in my life before

i think you've identified the problem.

DOT fluid brakes will love you if you give them some new fluid every year or so.

DOT 5 is meant to be less faffy, but not IME.

>Considering changing to V2 brakes now!

As above, maintain your existing ones and they'll be fine. Replacing brakes ever time they need bleeding could get expensive.

this makes me glad I put in all those hours perfecting my "foot on the back wheel to brake" skills on my old BMX...

Sounds like you glazed the pads and then they overheated badly. The fluid is probably fine if the lever didn't come back to the bar but if you've never bleed them I'd consider doing it anyway. If you are a big rider you will benefit from running soft organic pads. I used A2Z blue pads all year and they get reasonable life in the mud but work very well on hard long descents.

I've had cheap sintered pads do similar to the OP.

this makes me glad I put in all those hours perfecting my "foot on the back wheel to brake" skills on my old BMX...

Lol this is what I was thinking it beats crashing any day.

Strangely enough that's one of the few descents where i've ever had trouble with my Hopes when they needed bleeding. Not sure what you can do - it's super steep road but you need to keep your speed down. I wasn't dragging them either - brake and release - but still enough to cook them.

Hmmm thanks for the reminder. My Saint brakes (I think they were new when they first came out years ago?) anyway- Ive never bled them 😯

Stupidly i was dragging them all the way down !!

Brakes and bike only 3 mnths old, didn't think they would need bleeding.

yeti guy I ALWAYS trail my rear brake. That doesnt make sense if they are only 3months old. sounds like the rotors/pads are contaminated. Hence the 'funny rotor colour' IMO.

Lot of people posting that know jack about brakes, why you would need to bleed them and how to use them.
Seems to be a universal answer when brakes dont work as you expect
"Bleed Them"
Why FFS ?

Could it be contamination on the pads? GT85, or a bit of fluid?

This does remind me to bleed my hopes. Do any of the hive mind know how much fluid is in a typical brake on average? How do you know when all the old fluid is out?

This does remind me to bleed my hopes. D

How do you know when all the old fluid is out?

So you crashed through bushes and flew off a drop and made it . Amazing what you can ride if you don't think about it and just let your body react. Cool.

Dales_rider, what's your problem? Why are you such an angry man?

Hmmm Grum "Angry man" is not really the word I had in mind 😆

Why bleed them - because dot fluid absorbs water and as it does so its boiling point lowers - until you overheat the brakes, the fluid boils and the brakes fail.

However if the lever did not come back to the bar this might not have been the cause - it might have been overheated pads. Its still might have been the fluid tho - but with the brakes only 3 months old that is less likely.

How do you know when all the old fluid is out? You can see the colour change usually - or about 4 master cylinders full for me.

Thanks TJ!

Earlier on in the ride i started noticing that i had to pump my back brake to get power?

Sounds like air in the system to me.

I had an old set of hayes that had some weird issue.. every now and again the levers would feel completely lifeless, it was almost as if there was no fluid in the system.. i'd let the levers go, grab them again and all of a sudden the brakes worked just fine. It was probably 1 in 5 brake applications that would fail.
No amount of bleeding would fix the problem (even at the hayes service tent).. i ran these brakes on whistler's bike park for far too long before making the sensible decision and ditching them... taught me better braking though I guess 😉
Magura or Shimano are the only brakes i'd consider now.

IME new, or 1 yr+ brakes tend to have the most fluid issues.

New ones, as they're sometimes not right from the factory, and old ones as the fluid needs replacing.

Dales_rider, what's your problem? Why are you such an angry man?

Why bleed them - because dot fluid absorbs water and as it does so its boiling point lowers - until you overheat the brakes, the fluid boils and the brakes fail.

Its much easier just to bleed the system thru with fresh fluid top down that do as you describe. You still get a complete fluid change. air can get in from the top if fluid levels drop. water gets in thru the top as vapour from the air

Not always will boiling fluid mean the lever comes back to the bar - if it boils when the brake is on then the lever bite point pushs out from the bar ( there is nowhere for the vapour expansion to go if the brake is on). Usually tho they boil as you release the brake and the pressure drops - then the lever will come back to the bar next time you apply it.

I have had both happen on the tandem

Buy Shimano Saints? Cowards around the country swear by them. Simples. 😆

just buy BB7's 😉

We 've had the same thing happen on the tandem a few times.(on a long fast descent from the top of the longminge)

The lever feel stays the same but the pads overheat and can't get enough grip on the disc to stop you.
I've put a vented rotor on the rear now (Hope V2's)so we need to go back and try it again. Something tells me that we're going to need to do the same to the front aswell though.

Solamanda.

Your the second person that's said to try the AtoZ blue pads (first being K)so i think we'll give them a go too.
You want to jump on the back while i test them out? 😉

*Waits for someone to tell me i don't know how to brake* 🙄

TandemJeremy - Member

Its much easier just to bleed the system thru with fresh fluid top down that do as you describe. You still get a complete fluid change. air can get in from the top if fluid levels drop. water gets in thru the top as vapour from the air