Been out for a cracking 2 hour night ride. Brilliant fun except for one thing – I’ve worn out a brand new pair of pads and one two rides old pair of pads. FFS!

Set up is Avid BB7 mechanicals, 160mm rotors, red ceramic pads.

Are there any brake/pad combos out there that can survive wet gritty rides.

Help me out here, it’s screwing my noodle!

try bedding them in before riding?

Bed them in properly.

I don’t get this – I have changed one set of pads in 8 months of mostly gritty, wet, dirty riding.

The Avid sintered pads seem to last quite well on my BB7’s.

Front was bedded in, rear not. But how the **** can the pads just disappear in one ride?

I’ve never bedded in a set of pads in my life and they always seem to last for yonks.

dont brake

Kona – because they have never got hot enough to cure properly – that is a part of bedding in.

cooogan – some pads need it more than others and some combinations of pads and riding styles mean they get bedded in in normal riding

>Kona – because they have never got hot enough to cure properly – that is a >part of bedding in.

Tell me more, my noodle is still screwed…

when you first use them you are meant to brake repeatedly at lowish speeds till the discs are so hot that water would evaportae on them. the pads are then hot and bedded in.
Some people oven bake them to achieve this effect if internet forums are to be believed

Bedding in is a 3 part process. Conforming the pads to the disc, smearing a thin layer of pad material onto the disc and curing them under heat and pressure. Different formulations require more or less heat. |If you don’t bed them in and the first ride is wet and gritty then the boundary layer will never form thus instead of adherent friction you get abrasive friction and the pads wear quickly.

Adherent friction is the forming and breaking of molecular bonds in a semi fluid boundary layer. Abrasive friction causes far more wear than adherent

mind you Avid pads are shite though….I used to go through them like the OP on winter rides. Seen them disappear in the peaks in 2 hours.

smearing a thin layer of pad material onto the disc

Which wears off at the first sign of grit, good to hear TJ hasn’t given up with his old wives tales of bedding in pads, they really make me laugh 😆

How old are the discs?
If the disc is badly worn it will accelerate the wear rate of the pads.
Though one ride seems a bit strange.

I’ve never bedded in a set of pads and they have always lasted for ages (i.e. years). My guess is that the pads were duff.

get some sintered pads, get them hot by braking on the road, do it again. Job done. Report back with your findings. Superstar sintered seem fine and cheap, if you wear them out too quick you should get your money back. I’m on my second set this winter which I think is fine.

Dibbs – go check the science on it. I have. You get the premature wear when that boundary layer wears off but I get thousands of miles from a set of pads. Just because you cannot understand it does not mean it does not happen.

Discs do not work solely on abrasive friction. They work with a mix of adherant and abrasive friction.

“there are two very different sorts of braking friction – abrasive friction and adherent friction. Abrasive friction involves the breaking of the crystalline bonds of both the pad material and the cast iron of the disc. The breaking of these bonds generates the heat of friction. In abrasive friction, the bonds between crystals of the pad material (and, to a lesser extent, the disc material) are permanently broken. The harder material wears the softer away (hopefully the disc wears the pad). Pads that function primarily by abrasion have a high wear rate and tend to fade at high temperatures. .”

From “http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml”

“There are two basic types of brake pad friction mechanisms: abrasive friction and adherent friction . In general, all pads display a bit of each, with abrasive mechanisms dominating the lower temperature ranges while adherent mechanisms come more into play as pad temperature increases. Both mechanisms allow for friction or the conversion of Kinetic energy to Thermal energy, which is the function of a brake system, by the breaking of molecular bonds in vastly different ways. “

“The abrasive mechanism generates friction or energy conversion by the mechanical rubbing of the brake pad material directly on the rotor disc. In a crystalline sense, the weaker of the bonds in the two different materials is broken. This obviously results in mechanical wear of both the pad and the rotor. Consequently, both pads and rotors are replaced when they are physically worn to their limit and are too thin to endure further service.

The adherent mechanism is altogether different. In an adherent system, a thin layer of brake pad material actually transfers and sticks (adheres) on to the rotor face. The layer of pad material, once evenly established on the rotor, is what actually rubs on the brake pad. The bonds that are broken, for the conversion of Kinetic to Thermal energy, are formed instantaneously before being broken again. It is this brake pad-on-transferred brake pad material interaction on a molecular level that yields the conversion process. “

From “https://www.minimaniauk.co.uk/web/SCatagory/BRAKES/DisplayType/Technical%20Information/DisplayID/2167/ArticleV.cfm”

The first two reference I can find on this – there are also peer reviewed papers on this and so on. It is a fact.

I’ve just taken off a set of juicys from my bike and after 12 months there’s still have the pads left! I’d suggest bedding them in properly and braking a lot less, that may sound obvious but are you controlling your speed before the corners or are you “grabbing handfuls of anchor” and going from very fast to stop? try and ride smoothly and fast, any nutter can barrel towards the unknown then grab the brakes, think, dare I say it, “flowing” 😀

I get this lots if the ground is proper wet. Doesn’t matter what brakes or pads – they just fall to pieces. I’ve wrecked sets in less than 5 miles, bedded in or not, sintered, organic, whatever. Pads that have done some big Alpine descents with absolutely no issues and are 75% good will disintegrate in the wet in under 2 hours.

think, dare I say it, “flowing”

“flowing” to me = not braking, and I think therein lies the problem. When its wet and shitty I barely actually use the brakes – stopping pedalling is usually enough to modulate speed – so the rotors get covered in this wet grey sludge that just soaks the pads, then the first time you actually try and use the brakes you can literally feel the pad grind down through the lever over a distance of about 20ft.

I’ve had the same trouble with Avid pads twice in the past, both times in extremely wet conditions, including one set which had been fine for several months without any problems but dissolved in a single lap of a soaking wet Thetford Winter Series race.

I’ve since switched to Fibrax sintered pads and have had no further trouble for over a year.

TJ is correct.

there were loads of people at HtN last year, putting in new pads out the packet, and wondering why they wernt lasting more than a lap or 2.
(which also didnt do superstar any favours)

youll be wanting a nice long steep hill, and then big ringing down it with the brakes on as hard as you can while still allowing you to maintain enough speed.

then douse the pads in water (this is a scary thought, as it can warp or even crack the rotors, but its what needs to be done)
last time i did this, a few weeks ago, the caliper body itself was sizzling, the water barely got chance to hit the rotor it was that hot.

repeat, the more the better.

compare bedded pads to new out the packet pads and you should see a massive difference.

im happy to recommend superstar sintered pads.
last aaaaaaages if treated properly

[edit:] having just read that article TJ put up, might also be worth noting that ive found my XT brakes run hotter than my Hayes 9s, but once they are up to temperature they seem to work loooads better than when they are cold.
i havent overheated them yet, the only brakes ive ever had overheating problems with were hope minis…. (fade tastic)

Its fascinating to see the pads need heating, considering the material they’re made from is heated in a furnace and compressed at the factory! But it is true, and my other half has gone through a set of pads in 2 rides due to this 🙁 Problem I always find is that after bedding the braking is worse 🙁

and curing them under heat and pressure

utter, utter blarney :o)
I use sintered pads, which are made by heating the constituents very close to their melting point, so the particles bond. If you ever got near this temperature in use the pads would disintegrate

coffee king, the initial bite of new packet pads is abrasive friction (if TJs article is anything to go by) as the surface is sandpapery.
Bedding them in should give a smooth glassy finish, with bugger all “grip”

i hypothisise?

I don’t get this – I have changed one set of pads in 8 months of mostly gritty, wet, dirty riding.

It’s a specific set of circumstances which causes dramatic pad wear. Which is why some people get through pads in a ride and some don’t despite riding in the wet.

It’s to do with the pad clearance in your brakes, the amount of water in the air and on the ground, the drainage, the soil composition etc etc.

Never bedded in Hope pads and they last ages.

EBC Pads – i’ve used others and they just don’t cut the mustard.

OK, Hayes 9’s aren’t the world greatest uber brake, but they do what they’re supposed to, but it seems the EBC pads dont require bedding in, just fitting and off we go.

simon – its a combination of heat and pressure – go read the science. Some bed in at lower temps than others. Some compositions need it more than others. I don’t know why you feel you know better than people who manufacture brakes and research them. The heat curing may well be of lesser importance with sintered but during manufacture they are not heated under pressure.

“When a system has both new rotors and pads, there are two different objectives for bedding-in a performance brake system: heating up the brake rotors and pads in a prescribed manner, so as to transfer pad material evenly onto the rotors; and maturing the pad material, so that resins which are used to bind and form it are ‘cooked’ out of the pad. “

From https://www.minimaniauk.co.uk/web/SCatagory/BRAKES/DisplayType/Technical%20Information/DisplayID/2168/ArticleV.cfm who are quoting experts.

Molgrips – plus pad composition and riding style I think.

Crikey! Thanks guys, food for thought. What a faff bedding in appears to be.

What was wrong with v brakes, and sqare taper bb’s and rigid forks…?

Whether you believe it or not I followed TJs advice a couple of years back and i’m still running the same set of pads on my full susser which must have done almost 20 laps of the infamous HtN over 4 months last year.

By the way, proper bedding in is very difficult if you ride somewhere without big steep hills. It also won’t work as easily off road as you won’t be able to brake hard enough repeatedly.

I always try to do mine on a big steep road downhill before going anywhere near dirt. On the occasions I haven’t, my pads have disappeared rather rapidly (and had crap performance).

I never bother bedding in pads and mine last for ages.

waves at teejay….

Always got plenty of wear out of Avid sintered pads and I’ve never done any sort of bedding in.

Agree broadly with TJ and Olly. The process with sintered pads is mostly in the category of work-hardening and doesn’t need the hot brakes to be quenched. Olly, the science says that drenching the hot brakes with water achieves nothing for bedding in. If you are achieving good results with your method I won’t argue against you continuing with it.

Jambo – you blew my last theory on this out of the water. Hope brakes? Sintered?

Harry – ta muchly

i use magura pads and do what magura tell me to regards bedding in.
they last for ages, regardless of conditions and i brake like a mincing tart all the time.

Hi TJ.

Interesting, and I’m sure this may have some validity in clean conditions where most car brakes would work.
Do your articles suggest what happens to “adherant friction” when samples in question are sprayed with wet sand throughout their lifetime?

Oh, and TJ. On the few occasions I go road biking with my family I do a lot of hard downhill braking (trailer bike in tow). Brakes thereafter do feel smoother – like indeed the friction material has worn to a gloss, they also often begin to squeal after these rides which they never normally do, indicating something has altered.

I’m sure pads like this would last me a long time if I could keep this up. (Is this your Adherent stuff?)

It doesn’t last. First rainstorm on Surrey sand, and it’s straight back to grinding pad demolition 🙁

Mountaincarrot – I believe but have no proof that its when the adherant friction no longer occurs because the boundary layer has worn faster than it is replenished that the excessive wear occurs.

One turn of the wheel will clean the disc of grit if the design of the disc and calliper is suitable.

There is some other factor here or some complex interplay of factors that is not fully known for sure. I ride my bikes in all sorts of conditions and get thousands of miles out of pads. The last set I changed on the tandem were above half thickness after well over a thousand miles. Now on the tandem the brakes get worked really hard – enough to smell hot and blue the discs. They had been in mud up to the axles many times – and sometimes gritty mud as well. Used hard in the quantocks on a filthy wet weekend where the folk I was riding with said they get rapid wear – no measureable wear. ( I measured them)

The description you give is of glazed pads – not the same thing. Glossy pads that squeal are glazed. Properly bedding in pads are a sort of matt / satin finish and don’t squeal.

I don’t pretend I know all the answers to this but I have read widely about it and have asked manufacturers and experienced mechanics about it.

some pads are formulated to give differing amounts of adherent and abrasive friction, this will also alter in different conditions and at different temperatures. Hopes seem to give long life for sure.