Pad wear in wet conditions…
Its something that has been debated a good few times on here and in other places. its complex, multifactorial and there is no conseusus
IMO its all to do with heat or lack of it. disc brakes work by depositing a layer of pad material on the disc and thus you get a boundary layer effect of adherent friction not abrasive friction. remove this boundary layer faster than it can form you get the very rapid wear as the brakes go into abrasive friction not adherent ( its actually always a mix of the two)
Brakes need to be at hundreds of degrees C to work properly
So – to prevent it you need to get and keep the pads and disc hotter or only use the brake hard so its hot. So fast riders who only use the brakes occasionally but when they do its a hard stop don’t get the wear, real mincers who drag the brakes don’t – cos in both cases the brakes are only used when they are hot
Average rider who in these conditions us the brakes gently a bit do – cos the discs never get hot.
smaller disc, sintered pads, use the brakes hard.
Its not just the local grit as where ever some folk get the rapid wear others do not
We get fantastic life out of the tandem brakes – cos they get worked really hard with all the weight so the pads and disc get a nice baking every ride.Posted 6 years agomolgripsSubscriber
My experience is as follows:
When it’s really wet, there’ll be a film of water suspended between the pad and disc, which collects grit. THIS is what causes the wear. If it’s not wet enough for this film to form (or the mud is too thick and gloopy), you’ll not have problems.
This is why people say ‘oh well I ride in mud all the time and never have problems’. You need lots of water being splashed around, and/or wet runny gritty mud.
You can help matters by stopping and blowing the water away from the pads before a descent or just periodically. You can also wash it clean with more water if you like. Just make sure you don’t burn your lips on a hot disc when blowing the water away 🙂Posted 6 years ago
Molgrips – sorry that is just not so. applay the brakes and One turn of the wheel or less and that water film has gone – thats what the drillings are there for. OIr if you mean when the brake is not applied then there is no pressure on the pad to create the wear
I ride in very wet and gritty conditions and do not get the wearPosted 6 years agonickfMember
Dalby is notorious for pad wear though, and I’d say it’s the grit/sand that is causing most of your issues.
My understanding is that although heat is necessary, if the disc/pad gets too hot, the pad material cooks and becomes brittle, so that eventually it’ll just crack and fall away. And you end up with just a backing plate slowing you down…squeaky bum time.
So the idea that using smaller discs and sintered pads (which don’t conduct heat away so effectively) may make some sense in the UK, but none whatsoever for, say, Alpine descents, when you want the maximum cooling. Large discs and organic pads are what you need there.Posted 6 years agoElfinsafetyMember
Wow, great answer TandemJeremy!
It is actually, and would explain why I managed to destroy a set of pads at Swinley once, in the wet, as the sandy soil was basically just sanding the pad material off. They would have bin cold cos of the water, so TJ’s theory makes perfect sense. I never worked out why they wore down so quickly until now.
Cheers Teej! 🙂Posted 6 years agojonbaMember
You’d struggle to get your pads hot at Dalby anyway, I seem to remember it being pretty flat. 😉
For me it seems variable depending on so many factors. Kielder seems to eat pads in very wet conditions as well. I generally run sintered pads and 180/160mm discs for reference.
I use superstarcomponents sintered pads and they are cheap enough that it doesn’t matter. Very occasionally a ride will kill a set but normally I get long enough out of them that I forget when I put them in.Posted 6 years agorucknarMember
After a recent day biking at Dalby in very heavy rain with some friends we came home to realise that all of the brake pads on all the bikes have worn out completely! Now it seems like the puddles and grit they use to keep the trails rideable in the wet have got on the disc and caused the wear.
Are there any tips on how to reduce this?Posted 6 years agobrakesMember
why then can I do a whole day at Afan in the dry and not wear the pads at all, then do one loop of Whites in the wet and wear through a whole set of pads?
I don’t believe this can be attributed to just heat – these are the factors I think will come into play in the wet:
1) braking more because it’s wet
2) discs cooling because it’s wet
3) watery grit/ sand wearing pads down quicker
I think 3 has to be the most contributing factor!Posted 6 years ago
I agree with TJ.
As an experiment I swaped my gnarrr 180/160mm disks for 160/140mm.
They’re tiny, and you need to re-adjust to braking hard rather than the gentle pressure that big disks need. I’m 15stone and never had too much of an issue though once I was used to them,
But, I’ve not changed pads since last summer, despite riding more off road this autumn/winter/spring than any other year!
On the downside, they get hot enough to boil the fluid far more regulalry, I’ve needed to bleed them with fresh fluid 3 times, expensive fluid helps, but only marginaly.Posted 6 years ago
Footnote: organic pads are insulating, sintered pads conduct. So organic pads would solve the boiling issue and provide more power, but at the expense of longevity. You certainly dont want the pads to conduct heat as it would result in boiling the fluid, if you want heat dissipation use bigger rotors, but heat in general is good, upto the point where it causes brake fade (components in the pad material lose their friction at very high temeratures) or the pads glaze over (the surface melts and forms a solid block rather than a sinter)Posted 6 years ago
interesting elfin that you went through a set of pads at swinley, were they a new set? i’ve still got the cheap pads halfords put in before they sold me the bike over a year ago and i’ve ridden 30-45off road miles in swinley a week, every week apart from 2 months recovering from injury.
juicy3’s, 180mm/160mm.Posted 6 years ago
Thats a part of the conundrum. clearly there are multiple factors at play from riding style to pad make to disc drilling pattern to type of soil and many others.
However I remain convinced heat is the key – get your brakes hot then you will not get the premature wear no matter what he other factors are, don’t get them hot then the other factors might conspire against you to get massive wearPosted 6 years ago
Just as a second footnote:
My rotors are more air than rotor (‘aligator’ I think the brand was called, they were the cheapest and lighest that I could find without spending a fortune on them) which possibly helps by not having any material to conduct heat into whilst allowing mud/water to pass though easily?Posted 6 years ago
whilst everyone is adding footnotes, swinley was a foot deep in snow for a fair amount of time in the winter and we continued to go play… edging towards the 30miles a week instead of 45 but still out there 3 times a week.
i might need to change my rear pad soon… but i thought that before winter and they’re still going strongPosted 6 years agohilldodgerMember
I’ve just taken out a set of red SS pads that are almost a year old, used almost daily, average about 150 miles/week just to see how far they’d worn, more than half the pad thickness remained.
I’m not a particularly heavy or draggy braker, certainly never blued my rotors and mostly ride over typical Surrey sandy loam with regular trips to various other parts of SW/SE.Posted 6 years ago
Rotors are Hope AM4’s 180/160 (sawtooth), calipers Hope TechX2.
Never had an issue with braking performance in either wet/dry, summer/winter use……..
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