Nerding out on Brakes shall we? Not another tech deraliment

I have hubs with center lock so I skipped Hayes rotors (only 6 bolt) and tried few options:

- shimano icetech freeza discs (1.85mm): lacks power and preatty noisy 

- swisstop catalyst pro (1.90mm back/1.95 front) decent braking performance but warped and deformed a lot! Had to re-center the calipers after nearly every ride when with new brake pads. 

- Galfer shark centerlock (2mm): these are really good! Braking performance is outstanding, they stay true and are quiet. No rubbing issues even with new brake pads. Only cons imho is they cost a lot. 
 

All discs are 203 mm front and 180 mm back and yes, at 63 kg I am pretty light. I generally ride steep techy  stuff 

Piston retraction is always set off the rotor surface. It doesn't matter how wide a rotor is as long as it fits in the slot through the caliper. I've got set of Dominions sitting on my desk right in front of me. The slot in the caliper measures 3.25 mm. If you run a 2 mm rotor, you've got 0.625 mm of clearance per side. Does your rotor run out this much? It's possible for a rotor to be perfectly straight, but it's also possible for a rotor to be worse than this. If you go run a rotor that is 2.05 mm, you're sitting at 0.6 mm of clearance per side. The 0.025 mm difference is less than the thickness of a sheet of paper. About 1/5 to 1/8 depending on your paper. Is that enough to matter? Almost certainly not. The tolerance on rotor thickness is potentially wider than that. 

Somehow deleted the bit about the Trickstuff Dachle HD 203mm rotor I run on my front Cominion brake setup when I edited this. Basically boiled down to the Dachle HD works great with the Dominion A4 caliper. It actually had more grip/pad interface for friction than the 200mm HS2 rotor I run on the rear. Same brake setup and pads front/rear.

I also finally swapped out the rear brake line and the supposed Hayes compatible banjos and bolt are not at all. Bolt definitely does not work with Dominions although it claimed to on the website. Ended up reusing the existing bolt with new orings but with a new banjo that came with an Aliexpress SRAM hose kit. No leaks still, but left enough hose so I can search out a certified Dominion A4 compatible banjo and bolt at a later date. I'll edit my previous post for those parts as they are a no-go.

Edit: Something didn't sit right with me so today I revisited the Alligator banjo and bolt, and it worked after I cleaned out the caliper bolt hole. No idea why it failed yesterday but it went on today. The only thing is that I was so relieved/happy it worked is that I forgot to remove the old banjo nut bit. Doh! Well, that'll be taped to the new banjo nut until I need it or replace the line again. 

Thanks - these are helpful data points. I'll stick with the Dachle HDs. Any issues with them coming out of true?

I've only noticed it after shuttling with large groups on a single vehicle where there's lots of carelessness. I'll be riding a day or two later and hear the shish-shish-shish of the rotor glancing against the pad, but haven't had any issues with heat or long braking periods resulting in warping. 

not sure what my issue is: 
at anything over approx 20km The front rotor resonates/vibrates & it rubs, When i turn it rubs.
There is heaps of room on each side of the disc and is pretty bang on true, rotor isnt near adapter etc
New Ebike build on a fox 38, parts:
dtswiss 350 hybrid hub(front)
Shimano m8120 XT 4 piston caliper
Shimano 220 rt66 rotor
Galfer Purple ebike pads

Anyone got any idea whats going on, axle is at torque etc

your discs are super soft, true them as good as possible. will change again with heat, repeat

May not resolve the issue, but it never, ever hurts to order some good, 4-bolt adapters like NSB and get fork and caliper faced.

Having replaced the olive end of my Cominion setup, I think there's a bit more power as there isn't the o-ring expanding/bulging at the olive bolt. Will find out more tomorrow riding but that made me curious about "better" hoses. I'm currently using/have always used whatever hose comes with the brake kits or bikes.

Is there any benefit to getting hoses that are "Kevlar reinforced" or some other type of reinforcement?

Thanks for any input!

First thing I'd try is longer brake mount bolts, 25mm instead of 18mm.

Other thing I'd ask is if you're riding a Levo.  When I had one, the rear had awful resonance, which I believe now is due to the rear end being pretty flexy.

It's just the front.
Im currently using a shimano 4 bolt +40. The adapter isnt the issue.

I’ve been running them with the TRP rotors that are 2.3mm 

No issues, they do pretty well at staying straight and big fan of the gel style coating on the arms to prevent rusting 

Can anyone here explain what is going on with Fox 40 brake mount geometry? It's driving me insane.

Running a 223 rotor. Fox 40 is PM203 so a +20 adapter should work fine right? Wrong.

With my Dominions I've now tried adapters from : TRP, Hope, Magura, NSB, Intend, and pretty much anything else I can get my hands on. All of them are very different and none of them provide proper pad alignment (as in, the caliper is rotated too much and the rotor either doesn't fully contact the pad on the high side, or the rotor hits the caliper body on the low side). I ended up making my own adapter based on PVD's drawings which was very tight on clearance but worked better than the other options. 

Then I put Mavens on the same adapter and the rotor is touching the caliper again. No problem, SRAM provide a +20 adapter that specifically caters to big rotors right? With that adapter it's even worse, and the rotor contacts the caliper so much the wheel won't even turn.

So what's the deal? Never had this issue with Rockshox or EXT, and the rear brakes on my bikes have no alignment issues either. Fox seem to be using a slightly different PM geometry to everyone else, but who are they catering to? 

When Weird sh1t like that starts to happen I go looking for bike checks of Pro's...  usally sorts issues out quick, if you cant match their setup, something is defective.

In this case, id start at bike checking to see if I can find a similar setup and compare, this usually comes in the way of measuring stuff aswell, just to see if the rotor is correct etc

I've only really experienced those problems when putting the adapter the wrong way around. 

Sounds like companies should get on the 20 mm step bandwagon to not have these issues?

(Yeah, I'm not helping, but any time I see either 203, 223 or 246 mm, I get annoyed.)

I actually tried this and checked what the Commencal Muc-Off guys are running in Les Gets since it's the exact same fork / rotor / caliper combo - the adapter was unmarked (custom?). Not the standard SRAM one that comes with the Maven anyway. 

id be measuring that rotor, does the caliper/rotor line up correctly with a 203 rotor?

What year model Fox 40 is it?

face the mounting points on the fork, Fox are terrible for the post mount been wonky.

The way the caliper is contacting the rotor, refacing the mounts wouldn't help since I'd actually need to add material to the lower mount to stop the rotor hitting the caliper with certain adapters. Effectively the rotor edge is too close to the caliper bridge on "entry" and too far on "exit", as if the whole thing is rotated a couple of degrees off from where it should be. Adding spacers under the caliper fixes the clearance on entry but then means the rotor misses the very top corner of the pad on exit. This problem exists to varying degrees across multiple adapters, two different 223 rotors and two different brake manufacturers... very curious if anyone else has noticed this issue. 

As you go up in rotor size, the angle the caliper needs to shift gets smaller. That’s why a +20 adapter for 160-180 won’t work for a 200-220, they rotate the caliper too much.

Mavens have two +20 adapters, are you sure you used the right one? I think it should be the 20P-2.

Have you tried a Hope “P” adapter or the North shore Billet 200-220 adapter?

That explains why the +20 adapter doesn't work on my zeb with a 220 rotor, it was grinding on the caliper and I had to use some washers to make it fit

Yes I'm aware of this, that's why I ended up making my own adapter specifically for 203-223, but even then with the Mavens the rotor justttt touches the inside of the caliper unless I run washers under the caliper. 
My Mavens actually only came with the 20P-2 adapter, but the rotor contact was even worse and the wheel wouldn't even turn. 
I also tried the Hope P adapter, better than the SRAM 20P-2 adapter, but still grinds.

I tried tracking down this adapter that the Commencal guys were running with their TRP brakes but the serial number doesn't find anything online. Also worth noting the adapter specifies "Fox 40" on it, which makes me think Fox might be running a different geo than other fork manufacturers. 

Is it possible your rotors are the issue? It seems like the issue persists with a bunch of caliper and adapter combinations that should work.

I just found that Galfer lists an adapter specifically for a 223 rotor on the 40, and they list is as a +23 for some reason.

https://galfer.eu/bike/new-caliper-adapter-sb005/

Sounds like maybe there is something a bit fishy with the mount.

For sale here: https://gripandpedal.co/product/galfer-disc-brake-adaptor-23mm-fox-40-49/

Definitely not the rotors since the issue has persisted with both the Galfer Waves and Sharks. Plus the issue is more that the caliper angle is wrong which is causing contact, rather than overall clearance - if that makes sense? 

Good find with that adapter! Weird it's listed as +23... I'll give that a try and see if it improves alignment over my own adapter.  

Any pad rattle on dominions? Just tried some deores with d02s and the noise was unreal. Previously silent bike sounded like it was falling apart with them on

I've not experienced pad rattle with Dominions, but I always spread out the retaining spring when installing new pads. 

Just picked up a set of Radic Kaha’s after 2 years with Dominions and I wanted to post my initial impressions for anyone that might have these on their radar. FWIW I have, prior to the A4’s, been a Shimano fanboy for 10ish years?  But I’ve been fortunate enough to have ridden some MT7’s and a few different versions of codes as well. The first thing I want to point out about the radic’s is that next to Maximas (only squeezed, never ridden), they have the best fit and finish of any brake ever I’ve seen, for the price it’s pretty remarkable what you get, granted I know they are made overseas but whoever is making them knows what they are doing. 

The bite point is brutal with how quick it arrives. Near zero free stroke yet pretty easy to get aligned, meaning there is still sufficient pad clearance, something I appreciate since these don’t have the Hayes alignment screw (another game changer). That being said the lever action is not nearly as light as I was expecting. New or refreshed set of A4’s are much lighter, I don’t remember exactly how the Maximas felt but I do remember when getting the A4’s that they were better feeling than anything I had ever felt (maybe I have a outlier set?). I was thinking about seeing if we have a digital pull scale at work that I could use to quantify this because it’s noticeable, I have another bike with XT’s on it that are much heavier feeling than the Kaha’s but having numbers is always fun. I will say that the Dominions require regular maintenance to keep that light lever feel. Cleaning and greasing the ball and socket at the lever as well as keeping the pistons clean is the trick that I’ve found to keeping the lever feeling like you can blow on it to get engagement… Being that leverage ratio/shape is probably the biggest lever, no pun intended, that a company can use to influence brake feel it makes sense In my min that the Kahas have a heavier feel. If you want zero free stroke you need to have more leverage to get more lever piston travel at the initial part of the stroke. The A4’s have much more dead stroke but gain a really, really light and smooth lever. 

I’m waiting on some sinter green pads to arrive, as well at the frame that these will ultimately be bolted to before I actually will put some serious miles on them. For the time being it’s just garage nerding as I don’t want to run the lines inside my stumpy evo right now. Hopefully within the next week I’ll be able to do some back to back comparisons with the same pads and rotors setup on two bikes with I’m pretty stoked about. Even if they aren’t any better they shure do look sweet!