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Disc brake rotors
Well after still having problems with excessive pad wear I'm now contemplating changing disc rotors.
See my previous post for details on the pad wear problems http://nobmob.com/node/8818
A 10km ride this week on a wet track has worn through 50% of my sintered metal pads. And I certainly wasn't dragging the brakes or using them a great deal. By the end of the ride the pads had worn so much that the brake lever was squeezing all the way to the bars before the pads were engaging.
What I've noticed though is that there was a continuous grinding noise coming from the brakes. I could stop and flush the dirt out with water but within 50m they had picked up enough sand again to be grinding away. Pad wear on the rear was more than the front, and there was more noise from the rear than the front too. I believe this due to the rear being exposed to more sand whilst riding.
I'm wondering whether the rotor design is not clearing the sand adequately? Looking at the pads I took out after the ride I see grooves across the pads and they're quite rough. Certainly not smooth like they are after riding in dry conditions.
I have a Shimano brake system. M486 callipers, RT53 rotors.
Would changing to a different rotor make any difference? Perhaps changing to an XT rotor? They seem to have more 'waves' and cutouts that may help clear the sand out.
Or perhaps even changing to a different brand or aftermarket rotor? The rotors are centerlock, however you can easily get a centerlock to 6 bolt adaptor tht would allow me to fit any rotor to the hubs.
Pad wear in the dry is great. It is absolutely pathetic in the wet! I doubt I'd even make 20km in the wet/sand with our without touching the brake lever 
Maybe I should install the Fred Flinstone braking system 
Any suggestions or recommendations please? Someone with experience riding in wet/muddy/sandy conditions that has a good experience with a brake combination.
many thanks
Loki
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I ride through a lot of sand and water, brakes are always making grinding noises and i don't notice anywhere near this amount of wear.
I think you have a problem with your setup and i doubt its the rotor.
I have Hayes HFX-9 brakes, semi metallic pads and wear is not a problem, in fact I wore a set of crank rings out before a set of pads!
on 2 of my bikes (front only on the NORCO) and new ones on the Viper 29er (new) and have Hayes Strocker on the FAT (since Oct. 2008 with the first set still well over 50%), even after 3 races (Fling, 8 1/4h and Dirtworks). maybe the rotor's are the reason?
Bernd
A group of us had an eye-opener at the Sydney24 earlier this year with really wet conditions. (read the blog entries here: http://nobmob.com/node/7053 ).
Pad wear was going ok in the beginning (wearing steadily but not crazy), until the night laps when the conditions changed for the worse. Pretty much everyone was going through a set of pads every two laps. This was about 18km from memory! I kid you not!!!
I personally had never seen anything like it, my hope pads have lasted up to a year in drier conditions, with the average life about 6 months for the front and 9 months'ish for the rear. I've tried both std and sintered pads, with the sintered ones lasting a bit longer as a rule. My commuter has hayes hfx-9 and I go through front pads in a year, and 18months for the rear just riding on the road (but in all conditions).
I have seen shimano pads wear out at a much faster rate, probably cos the standard ones are organic (softer for better grip/control/modulation).
The rotor type probably won't make a 'huge' difference when conditions are bad. I stand corrected on that one btw. If we want to split hairs and look at nuances, the wavy rotors are probably clear crud better in poor conditions, but generally don't offer as linear feel - I've heard there can be some pulsing as the wavy shape passes between the pads. Perforated rotors can hold crud in the holes, and that is definitely going to add to the wear.
All that said, find a cheap source of pads for wet conditions and keep a few sets in your toolbox. We have some of the most effective sandstone based grinding paste in the world (unfortunately) on the Sydney trails, and in this weather the drivetrain attrition brings tears to your eyes and a gaping hole in your pocket....
This is a site for cheap pads if you are interested (i've not used them but am tempted): http://www.discobrakes.com/
Whisperer
i would think that the clearance between the disk and pad when your brakes are not applied might be the problem... ( well duh
)
Perhaps this could be caused by something such as warped rotor or too much pressure in the system; like riding with your fingers resting on the leaver or just a bad brake system design?
If your disks are not warped and you don't ride with your fingers on the brakes, I'd look at a trying a different brake system.
You could mess around and try to find a system that would allow you to try the rotors first if they are compatible with the old calipers.. sounds like too much hassle, so I'd bite the bullet and go with something that's recommended by people that ride very sandy places in the wet ( no one here... because that's stupid and selfish right? )
I've had a very similar problem, although the wear is no where near as bad. But the pad has lost alot of stopping power after a few damp sessions.
I currently run the Silver XT calipers. The front rotor is a 8" Avid and the rear is a generic 6" shimano rotor from a cheap Giant. I got immensly harsh grinding whilst on a couple of rides and the rear disc has some bad grazing along with the pad. The front is perfect. It would start to grind a little and a light brake application for a few rotations cleared it all out. But the rear just wouldn't clear out.
I suspect that the rotor design may impact on it's ability to get rid of the grit. I am getting a 7" adapter to install my other Avid disc of the same design. As soon as I've given it a run I'll let you know if it makes a difference.
I wonder if anyone makes a sort of crud cover for the front of the rear brake setup. Basicly to stop sandy water being splashed/sprayed up onto the rotor/caliper from the front wheel. It'd need just a half moon shaped U channel cover. just to protect the front half of the rotor, with the top flaring out to sheild the caliper.
I might make one up out of glass if I get a chance, and test it out. Might make cooling a little less efficient, but it shouldn't make that much of a difference.
Thanks for the help and suggestions.
It seems that there are variations in the pad wear for different brake system setups. However once it gets very wet and sandy then all seem to suffer excessive pad wear.
My dilemma now is whether to just accept that the pads will wear out if they get wet and sandy, or whether to pursue an alternative setup or perhaps a design flaw that is giving me such poor pad wear characteristics.
However I guess what I don't understand is why everyone puts up with this pad wear. Whisperer - you mention everyone having to replace pads every two laps in the recent 24hr race. I also read that some riders were taken out of the race from running out of brakes!
I find this ridiculous and in a sport that can be very competitive why is it allowed to continue? With all the technology and money spent on braking components there should be something better. What's the use of saving a few grams in weight if the device will prematurely fail and end your race?
Can you imaging motorbikes in the Dakar rally having to stop every 100km to change brake pads just because it rained whilst they were riding through the desert?
Obmal - you mention the pad to rotor clearance. Perhaps a greater gap between pad and rotor would prevent sand from getting caught between the two and grinding away? Or pehaps a smaller gap would prevent sand getting caught in there in the first place? BTW my rotors aren't warped and I'm not riding pulling on the brake lever.
Perhaps rotor design does have something to do with it? Do perforated rotors trap sand in the holes and cause continuous wear?
Muvro - we have a similar characteristic in not minding a ride in the rain. I too get the same greater amount of noise from the rear brakes, and the noise from the front is easily cleared by applying the brakes for a few wheel rotations. Interesting to hear the apparent difference the two rotor designs make between front and rear too. Can you tell me what model rotors you have please?
I'm also very interested to hear the result when you replace the rear Shimano rotor with the Avid rotor. (Although it'll probably stop raining now for months and we'll never get to see if it makes a difference
The mud cover could be an interesting development too. Give it a go and let us know the result please.
Many thanks for everyone's help and suggestions - very much appreciated
Best Regards,
Loki
Loki, I replaced the rear rotor during the week with the same design Avid rotor as the front. I went for a ride today on my usual wet weather loop. As would be expected it was very sloppy out there.
The rear rotor was miles ahead in getting rid of sand etc. Normally, I'd have to put up with grinding the entire way. But this time it'd grind for a few rotaions, just like the front and it'd be all quiet again. It was bliss! hahah
Here's a pic of the rotors. I don't know what model they are, but they are made by Avid.
Front rotor - 8" Avid
Rear rotor - 7" Avid
The rotor I was running that is now back on my old bike(6" shimano generic)
I also sanded back the pads with 180 grit paper. Here's a before and after;
Before
After
If I were you, I'd be trying at least these rotors. It might not fix your problem, but aorst case senario, you'll have a spare set of rotors.
Takis
Hi Takis
Thanks for the photos and taking the time to reply. Your results seem to have confirmed my suspicion about the rotor design and I'll give it a try myself. The Shimano rotor in your picture looks the same as mine too.
I've found some "wavey" rotors with slotted cutouts that look to me like they will work well at clearing mud and sand so will order them today.
I notice you're running Shimano callipers with Avid rotors - were there any compatility problems mixing manufacturers? eg rotor thickness, actual diameter or position of braking area the same?
thanks
Loki
Only issues I've heard of is then the rotor is 2 piece kind. You know - lighter alloy or something in the centre attached to steel braking surface.
Gazza was saying when he tried some of these (were they XTR?) with his Juicys they fouled the lugs on the Avid pads. Nothing a grinder didn't fix though from what I recall
Has anyone any experience using a Shimano Centerlock to 6 Bolt adaptor - part number SM-RTAD10?
This adaptor lets you fit standard 6 bolt rotors to hubs designed for centerlock rotors.
I could replace my rotors with centelock XT or XTR, however if I buy a couple of these adaptors I will be free to try any other rotor on the market.
It's a Shimano part so should be ok.
Hey, I use them and they work just fine. I actually really like the idea of centre lock hubs. No more swearing at that last rotor bolt that wont come out...
Just make sure you do them up nice and tight!
No probs.
NO compatability problems at all. Everything lined up perfectly. I couldn't say that any mix-matching would be fine, but I had no probs with this combo.
I have the same pads shown in the pictures above and i often ride is wet muddy conditions. there is occasionnaly a bit of scraping, but a few taps on the levers clears it all very easily. I've had my bike since Aug 2007 and am only now thinking about changing pads.
Still wandering whether i should get the resign, sintered or ceramic?. I love the red pads of the ceramic 3x from discobrakes.com, but that is purely asthetic. I might give them a try though.
I just put a set of Serfas Metal pads in and they are great! Haven't really given them a hard time yet, but they feel great so far. I'm heading out tonight, so I'll report back with the results.
I've been runing the disco brakes red ceramic pads on the rear of my bike for two (?) years. I bought 4 sets of pads and the first set are still only half worn.
Running Shimano generic discs, 8" on the front and 6" on the back. Front pads are shimano XTR, Ti backing plate with sintered metal compund. The first one lasted about 300km but did some serious wet weather work in Cascades, then I put the good one on the front and the discos on the rear as a trial. Have not touched the brakes, except to free a sticky piston and bleed the lines once.
Discs are hardly worn either.
One thing I noticed, never ever had noisy brakes wet or dry. Just the occasional scratchy sound when really sandy/muddy, but a quick jab or two generally cleared that.
Maybe I'm just too slow to wear out my brakes?
I bought two new rotors, along with a couple of centrelock to 6-bolt adaptors.
The rotors have a much more aggressive set of slots and holes in them than the standard Shimano.
I've had them on for almost a month now and about 150km. Some rides earlier in July were on quite wet tracks with many unavoiodable puddles. Brake pad wear has been minimal.
I also notice I no longer hear the constant grinding noise from the rear brakes. After going through a puddle the rear is silent pretty much immediately. The front grinds for a few seconds and then stops.
Time will tell I guess, however so far it seems to have made a huge improvement.
BTW stopping power hasn't changed, nor has the brake "feel". I also bought some adaptors that will let me upgrade to 8" front and 7" rear at a later stage if I want to.
Rear rotor:
Front rotor:
cheers
Loki
Glad to see it all worked out for you.
I just upgraded my front rotor, more for the bling factor than anything else. I went to a Hope 6Ti (I think it's the Ti ?) rotor with an alloy center, and floating rotor. After a lengthy run-in it bites noticably harder than the Avid rotors I had on.
Hi Loki, just checking to see how this is working for you. Have read the other threads and hope I've got this in sequence and is where you have ended up?
Yes the new rotors helped, but I'm still not entirely satisfied with the brakes and am looking to replace them soon.
With the new rotors I hear a lot less "grinding" noise from the brakes after riding through a puddle or some mud, and that I believe has resulted in less pad wear.
)
However I recently went through one set of pads after just one lap of Sparrow Hill and one of Mt Stromlo in wet conditions. In hindsight I didn't have the calliper centred on the rotor properly and this resulted in constant rubbing of the pad on the rotor and subsequent wear.
In comparison to other bikes I do wear through pads a lot quicker! This includes other bikes with identical brake components. (I have noted though that I am always the "dirtiest" after a ride than the others so perhaps the mud is just attracted to me
cheers
Jon
Try JetBlack sintered pads it's all I ever use and they last for ages, even in very wet conditions like the pouring rain at the Sydney 24 hour the last 2 years. When a lot of people were getting 1-2 laps from a set I was doing about 5-6 and won the over 40's solo. Sure they sponsor me but I'll only use gear that I'm very happy with.
John
Am interested as I have the same bike and I have, after the wet weather, just raced through a set of rear pads from new.
The grinding noise was quite annoying however I did manage to get over 1000km out of them but most of that was dry and it's only the past few months in the wet which killed them.
I have just bought a set of the std pads and will go with those for the moment, but I might look into it a bit more when these are gone.
@John, thanks for the info.