[Closed] bedding in pads - is this bollox?

Bigyinn, I quoted you because in fact that's pretty much what Mike Hall says. I think people are misunderstanding the heat treating thing, it's not intended as a substitute for bedding in, but an additional thing.

TJ, I'm not even going to begin discussing anything with you. There's a perfectly good brick wall out there if I want to beat my head against something, thanks.

lol @ BWD. Dont do that, you may dislodge some mortar.

Sadly TJ only knows Hopes, therefore everyone else must be using the wrong brakes or doing it wrong. The only way to silence him would be to [s]fit his tandem with an alternative make of disc brake and let him run it for a year[/s] beat him to death with a black rubber dildo (12" pref).

I have used other brakes. I have also been following the debate on pad wear for a long time. Some folk me included can ride in areas where the short pad life is common but still not get the short life.

never understood anyone wearing out a set of disc pads in less than a year, never mind one lap of an XC course with any make of brake.
If I ever got anywhere close to that sort of wear I'd be switching back to V-brakes pronto.

So you can wear out your rims in a year instead? No thanks, I'd rather replace pads and or discs than rims anytime!

Are brake pads not made by pressing the brake material at high pressures onto the backing plate while at high temperatures?

TandemJeremy - Member
I have used other brakes. I have also been following the debate on pad wear for a long time. Some folk me included can ride in areas where the short pad life is common but still not get the short life.

Can you post your data so we can all analyse it?

captjon - unfortunately its scattered around and mainly in my head so not of a great deal of use apart from for my interest

Lots of threads on here about it and lots of folks experiences on there Scienceofficer did some good analysis as well

The biggest factor in pad life is a. how much you brake and if you are not braking then if your pads are rubbing or not.

TandemJeremy - Member
captjon - unfortunately its scattered around and mainly in my head so not of a great deal of use apart from for my interest

So we're stuck with your assertions based on your memory of posters self reporting..? How do you account for the myriad factors which affect pad wear and the variability between riders? And what about confounding variables?

Capt - plus the reading I have done and the discussions with the manufactures of brakes. Are yo really interested in what I have found =or are you looking to slag me off? Its unfortunate I have not collated the info well. The only thing I can be really sure of is that its a multi factorial conundrum when two riders using the same equipent doing the same rides in the same weather get dramatically different pad wear rates
If you are really interested I will spend some time typing out what I have found

Geda - the crucial thing I believe is the the formation of the boundary boundary layer and getting adherent friction - which requires heat in the pads. I brake a lot on the tandem and pads last thousands of miles - because they get very hot indeed even when ridden for multiple miles full of abrasive grit

TandemJeremy - Member
Capt - plus the reading I have done and the discussions with the manufactures of brakes. Are yo really interested in what I have found =or are you looking to slag me off?

I'm interested in how you came to your conclusion because i hate it when people declare things but don't back up their claims with evidence. It is even worse when they say they have data but can't/won't share it, or don't explain their methodology. I think multifactorial is one word btw.

Sorry - my spellchecker splits multifactorial 🙂 its a real shame I have not kept all the data so all I really have is whats in my memory and the various threads on here. I did not realise it would get so complex and interesting

I am about to have dinner - I will write up what I have found out and post it later on ad I'll find as many sources as I can

good stuff

Ok - capt asked me to put down what I had found out . as above I have not kept most of the source material as I did not realise it would get so complex or interesting. I do not mean to be patronising but am trying to make this complete. I have looked at the wear that many different riders get and tryed to gain some understanding of how they ride

[b]basics of how they work. [/b]
There are two types of friction generated between the pad and disc - abrasive and adherent friction. Abrasive is what we all know - like dragging your hand across sandpaper. Adherent is a little different as it only occurs when there is a microscopically thin layer of pad material on the disc and you get chemical bonds created and broken in a semi fluid boundary layer. as an analogy think about a layer of treacle between the sandpaper and your hand - still resistant to movement but its differnt and you don't wear the skin off your hand.

Abrasive friction occurs more at low temps, adherent at high temps. Abrasive friction creates more pad wear. Abrasive friction is more with sintered pads and less with organic - sintered pads are much harder hence even tho they have more abrasive friction they last longer.

disc brakes have a temperature range under which they work effectively and at the interface this will be hundreds of degrees C

[b]Bedding in.[/b]

does 3 things - cures the pad under pressure and heat, puts thin layer of molten pad material on the disc and conforms the pad to the disc.

[url= http://www.stoptech.com/technical-support/technical-white-papers/bed-in-theory-definitions-and-procedures/brake-pad-bed-in ]all this stuff is known and accepted in the automotive world. [/url] ?Some folk and brakes will need deliberate bedding in, some will bed in in normal usage. the key is you need to get them very hot

[b]Now why do we get the rapid pad wear under some circumstances?
[/b]
From what I have read and pondered it is when for whatever reason the deposit on the disc gets removed faster than it can be recreated and the brake system goes into abrasive not adherent friction which simply wears the pads away. But why does this happen?

If the brake is being used in an abrasive environment the disc transfer layer will get worn off - however if the brake is hot it will get redeposited quickly enough ( its only a few molecules thick) to keep the brake in adherent friction. However if its cold and wet and the brake is not getting hot then it will not be redeposited at all or enough, the brake goes into abrasive friction and the pad wears out.

The braking surface will be completely clear of grit after one revolution of the wheel or less - its not the grit that wears the pad - its the lack of the disc transfer layer that wears the pad if the grit has removed the boundary layer.

some folk say the pad gets worn simply by the gritty disc running thru it with the brake not on - we have all heard the noise that makes. I believe the pad is too hard for this to create any significant wear

Dragging the brakes creates heat so should not cause excessive wear but a very light touch on the brake may allow grit to get between the pad and the disc and create wear by removing the transfer layer
[b]
Factors affecting the wear rates[/b]

Its obviously multifactorial and its when a number of conditions stack up against you that the rapid wear starts

this is where the conundrum starts 'cos every time I think I have found a crucial factor someone comes along with experience that does not fit the theory.

Different pad materials and set ups have different working heat ranges - and it may be that some are better at running cooler than others

different disc drilling patterns may be better at clearing grit off the disc.

different manufactures pads will also be different composition and hardness.

Obviously diffent soil / gravel conditions are a factor but cannot be the only one for even in the areas such as afan and peaks where people get the rapid wear others do not.

Different riding styles clearly play a huge part as people with identical equipment in identical conditions some get the rapid wear some do not. However its not as simple as quick riders don't get the wear or slow riders who brake a lot dont get the wear. I am fairly slow and tend to drag the brakes a lot - but don't get rapid wear even in conditions where others do. Jambo is a quick rider and he does not get the rapid wear even tho he rides in areas where others get rapid wear

I believe a part of it is the number of times you apply the brake on each descent as each time you apply the brake ( when the brake is wet and gritty) for the first turn the transfer layer is getting worn away. I am dragging the brakes the whole way so generating a lot of heat and only one opportunity to remove the transfer layer. Jambo is only using the brakes twice the whole descent and each time he uses them hard - so little opportunity to wear the transfer layer and each time heat generated to replenish it. If you are on and off the brakes the whole descent but only using the brakes gently you are having a lot of opportunities to wear the transfer layer but are not generating enough heat to replenish it.

On the tandem the brakes get used hard the whole time and pad life is many thousands of miles

Smaller discs get hotter more easily so smaller discs should reduce the wear as they get hotter and the transfer layer is replenished more easily. certainly I run 160s only my solo and get long life.

I literally get many thousands of miles of life from my pads and all my discs are discoloured fro the heat. The front on my solo which probably gets the least heat in it wears quickest.

However some people still get short pad life in the alps where brakes get hot indeed. It may be possible that the rapid wear in the alps as well as reflecting a years use in a day is also down to the pads overheating and partly melting or going out of their heat range

[b]conclusion[/b]

its complex and multifactorial. I believe the transfer layer is the key and this needs heat to generate it so it when the transfer layer gets worn away and not replenished quickly enough the rapid wear occurs. If the pad has never got hot it will wear as it will remain soft.

You need to keep the pad in its working temperature range and this varies from manufacturer to manufacturer. some generate heat more easily than others and some requite higher temps to create the transfer layer.

If you are getting the rapid wear try sintered pads obviously. try smaller discs if you have big ones, try dragging one brake rather than using two intermittently, try using the brakes in short hard bursts not gently.

IU shall try to keep note of teh info I collect on this in the future and I am very intersted in peoples experiences to see if they fit the pattern

there is also the issues of high temp glazing and low temp polishing of pads as well. It when this has happens abrading the pads with mud improves performance I beleve but that is a whole other issue.

Links to the other discussion on here

http://singletrackworld.com/forum/topic/natural-gift-for-glazing-pads

http://singletrackworld.com/forum/topic/why-do-my-brakes-keep-going-funny

Thanks for taking the time to write that out TJ. But that doesn't explain your assertion that hope brakes give better pad life.

But that doesn't explain your assertion that hope brakes give better pad life.

I presume that's probably based on experience, testing and observation of others. I know a lot of people who claim to get better life from Hopes than other makes, which will depend on their pad materials and pad sizes. Whether it's true or not, who knows, but lots of peoples experience seems to fit it, some people's doesn't <shrugs>. It's not really important anyway, as it was a side comment to the point of the thread, which has been roundly answered and very well by TJ.

Right - thats simply from my experience and from what I remember of others experienes - and its a tendenccy not an absolute. No decent data as I have not saved it 🙁 TINAS has the same experience on this thread

I believe it may be to do with heat again. Hopes build up a lot of heat easily and / or have a lower working heat range which is why they have a reputation for overheating in the alps but why they dont get the rapid pad wear as often when its cold wet and gritty.

It may also be pad compound? they presumably got tested in UK conditions including winter use whereas in many other countries people don't use bikes in the cold and wet. could be drilling patterns as well?

A lot of that long post is my theories not hard data but it developed over time looking at what is known and matching it with peoples experience - I want to be a real anorak and get some temp readings from a load of discs sometime

I've ridden on a shitty day in the peak and lived! Further more, my pads lasted that day, another day, and then several months of riding in other gritty areas. My pads lasted 5 laps in the puffer last year. Their replacements lasted 6 and then several months of riding in other gritty areas. I use superstar haloumi pads, I find their feta ones are not as long lasting. Hmmmm haloumi and octopus, I can feel some carb loading coming on.

Pretty sure Hope heat-treat their pads before sale btw (an old magazine feature showed loads of pads going into a kiln), which won't make them last longer than a properly bedded in pad, but will probably make them last a bit better than an untreated, unbedded pad.

Less certain of this, but comparing X2s with OEM pads and with EBC pads, I suspect the OEM ones are a pretty hard compound, they seemed down on power compared to the EBCs and had less initial bite. But o'course there's a lot of other things that could have caused that, so that's mostly supposition.

Devs another one who does notwear out brakes!

Info would be nice ta
- what brakes?
Riding style? fast / slow? Brake dragger or hard use or light use?

I don't bother bedding pads in. I typically get through two or three sets of superstar/clarks pads per year. Rich has had the same sets of Avid pads on his bike for 3 years!

I've experienced very rapid pad wear, e.g. a set every two hours, on rainy, splashy days at trail centres when the brakes are constantly being splashed with water and grit. The other time was an enduro near Andover which was sopping wet XC riding on flinty trails.

So the abrasive v.s. adhesive friction argument works for me.

I always bed them in. The peak and puffer brakes were Hope 4 mono on 203 and 180 rotors but I also use hFX9, Louise and Formula K24s. I think I am a brake dragger but I'm also heavy at 17st so I think it's the heat thing again.

Ta chaps

(an old magazine feature showed loads of pads going into a kiln)

That'll be the sintered ones, it the standard way they're made, hence my thinking sintered pads don't require the heat element of bedding suggested in the article in the OP.

TandemJeremy - Member
Devs another one who does notwear out brakes!

Info would be nice ta
- what brakes?
Riding style? fast / slow? Brake dragger or hard use or light use?

Good, more systematic.

My pads last ages. The pads in my Magura Louises have lasted over a year even with regular riding. I bedded them in, weight 12st, not sure of my braking style, but i'm not one of the faster riders i know.

When I lived in sheffield I used hope C2's, some hayes 9's then shimano XTR's. Being a uni student I'd not ridden in the peaks in summer untill this years summertime pootle! Couldn't say which brake lasted longer as I didnt have them all at the same time.

But the key to getting any life at all from them was to drag the brake all the way from Crookes high street, to the arts tower, basicly every ride started with the brakes getting so hot the levers well and trully pumped up and the pad backing discoloured making a cool pattern showing the airflow arround the piston!

Hope 180/160 calipers, SS red pads, no deliberate "bedding in" just normal hard and late braking.
Type of riding, everything from daily tow path/bridleway commute to singletrack - local conditions are loamy soil with some sandy bits.
I try to brake as lttle and as late as possible and don't drag.

Roughly 500 miles a month, pads changed about once a year and even then there's some left......

Any more want to share their tales of brake life / riding style etc?

What you trying to prove TJ?
I personally think anyone who gets through brake pads at an alarming rate simply either brakes far too much or uses their brakes badly.

currently I have 203, 185 and 160 discs as appropriate for the particular bike in question. brakes are currently Juicys (all sintered)and SLX(organic/resin?). I've only* used sintered pads for well over 10 years (prob closer to 15).
some of the brakes I've lots of experience using are BB7s, Juicys, Hayes, Hopes, Shimano.. there are many many more I've used but it doesn't really matter what brake I have I don't ever go through pads quickly!
Oh.. and I never bed pads in! preferring to just use brakes when they're actually required instead

*the new(ish) SLX I have on my hardtail I believe came with organic/resin (and funnily enough feel underwhelming) but even with those shitty pads after 9mths there are no real signs of wear

to the dick that suggested I'd need new rims every year with V-brakes Don't make me laugh. 😆

Not try to prove anything in particular - trying to get to the reason why some folk get rapid pad wear 'cos its an interesting conundrum as its not as simple as braking more - more wear

I have Hope mono mini's on my Orange 5 - I weigh 90Kg with 183mm disks each end and original Hope organic pads. I had a half worn set when I started a four day trip to the Alps last summer which finished with the Passeporte de soleil. I had no issues with the brakes at all, no overheating, no fade I could discern and at the end I couldn't see any appreciable extra wear. Others on the same trip with Hope M4's seemed to have had some fade at times and have had more wear. Admittedly they were faster than me but I was probably on the brakes longer than them. Could this be that the mini's were running hotter?
I have experienced brake fade with the M960 XTR brakes on my Litespeed locally on the Malverns so I don't think it is technique?
Edit: I always have tried to bed the brakes in every time I change them

running Avid X0 brakes on my bike, with sintered pads

on New Year's day, went and rode for 6 hours on Pitch Hill, Surrey in foul conditions including deep mud and rain storm, lots of slithery braking action but not heat build up to speak of?

lost 3/4 of the material on very new, but bedded-in disc brake pads

(brakes bedded in by doing 30 emergency stops down a steep hill off Highgate, London) and 2 XC rides in NW london on relatively flat ground in dry conditions

Hope disc brake pads are somewhat different to other "manufacturers" in that Hope make the backing plates in-house, and then ship the backing plates to automotive manufacturer EBC who apply the material to the backing plates and then heat treat them

do other cycle brake pad manufacturers bother with this?

GW - Member
to the dick that suggested I'd need new rims every year with V-brakes Don't make me laugh.

I don't believe a long bedding in is necessary. I think it is an 'old wives' tale. I would imagine the compound gets all the pressure it's ever going to be subjected to after a few sharp stops.

I think bedding in is just the short period of time it takes to get the pad to conform optimally to the surface of the disc.

From a mountain biker in the early 90s who used to ride in a lot of muddy & gritty conditions, i can concur that i became pretty good at swapping rims 😀

Due to the massive splits in the sidewall of the rim, I was typically swapping the rear rim every 3 months during autumn and winter

How i love disc brakes!!

boltonjon, clearly we are both dicks then! I rode a lot in the '90s in central scotland and a Mavic 231CD would last about a year before being so worn the sidewalls would crack and split.
GW who's the dick now? You are clearly in need of some love from somewhere......

I used to get through a lot of rims from brake wear, it must have been noticeable in mavic's profits when evveryone switched to discs and stopped having to replace their rims every few months.

I think bedding in is just the short period of time it takes to get the pad to conform optimally to the surface of the disc.

Have to say I err on the side of this too.

Might be interesting for a magazine to do a test of 'bedded in' vs out of the packet pads in a controlled environment, if any magaziney types are reading this and haven't died of boredom yet.

bigjim - read the link I put up about it. the layer of disc material on the pad is crucial

curing them under heat and pressure is more relevant to organic pads but still occurs with sintered

Bedding waste of time huh? Whilst some were swapping pads every lap I did 14 laps of a very gritty muddy puffer without a single pad change. Read it and weep Princesses.

I only put new pads in the front so you can really cook them up, you cannot get much into the rear, whatever you do. I live on the side of an over 300m hill, mind.

GW who's the dick now?

FWIW - I have a pair of Hope XC4s from ~99/2000

They use tiny rotors (150mm front, 130mm rear) and to this day I have only changed the pads in the rear once, and the front twice.

They don't get a huge amount of use these days as not on main bike but they did get several XC rides per week for the first 5 years of their life, and they have done 4 x mountain mayhems and 3 x bontrager 24/12s plus 1 season of local XC races and some local riding too on the pair of pads that are in there currently...and they are about 1/3 worn

I'm not the most brake happy rider i'll admit, but from personal experience I can support the small rotor/high heat = long long pad life argument.

(using hope OEM sintered pads)

GW

[i]"clearly you!
What are you so scared of that you're wearing out braking surfaces on rims?"[/i]

you were clearly a fair weather rider!!

amedias - i agree, my old 98/99 Hope mini pads lasted for 5 years