Just to play devil's advocate, just imagine Pace had found the problem described by the OP on that frame.
What would you expect them to say? Anything different from what they did say?
It's not just Pace who do that. Different manufacturer says to me, how odd, we've never had that happen before. My reply, really? It's the second one I've sent back.
Similar with matching frames for me and the wife that had problems.
Must be a one off says bike company. What? On two frames of different sizes?
Looks like an assembly error to me.
I've had flutter induced by the pads overlapping the rotor spokes when not spacing the calliper correctly. or using a 203mm rotor on a 200mm mount. Easily remedied by adding washers/spacers under the calliper.
Being as you've got the cup washers on the wrong side of the calliper (they don't do anything to help align the calliper if fitted above it) I'd say the the pads are probably not sitting in the right place on the face of the rotor and are catching on the rotor spokes. That's be what's causing your vibrations though who knows why it's more noticeable in the wet - it's probably the steep bit that's the main factor.
I’m grateful to the OP. I think they pointed out the issue in as level-handed way as they could.
OP seems entirely reasonable to me.
Looks like a poor design for a brake mount.
I ride where Pace live and I can confirm its usually wet and very steep. Just adding that in case anyone thinks Pace develop their stuff in year round 30 degree heat and sunshine.
Being as you’ve got the cup washers on the wrong side of the calliper (they don’t do anything to help align the calliper if fitted above it)
You say this but I've never seen a calliper fitted with the washers below it.
Eeesh, OP is getting a hard time for a what on the face of it at least, seems to me it was sorted to his satisfaction, he's just raising his issue to a bunch of folk who might be interested to hear about it and be a factor in decided to buy this frame or not, and sounds like pretty good customer service from Pace.
Tough crowd.
crossed
You say this but I’ve never seen a calliper fitted with the washers below it.
It's a bit of a red herring as it may or may not need them. The SRAM Manual say the that set up is correct but it depends what level the mount it welded at as to whether it sits in exactly the right place and it's up to the installer to get the pads in the centre of the rotor. This may take any number of washers. It's well worth some careful set up at build stage.
Imo, cup and cone above is usual now and ensures the bolt sits flat. The mounts still need to be perpendicular to the rotor. Cup and cone below was the old avid set up and was used take up any variance.
Just to play devil’s advocate, just imagine Pace had found the problem described by the OP on that frame.What would you expect them to say? Anything different from what they did say?
Well, we had a frame from a small UK manufacturer. There was an issue with disk rotor clearance to the chainstay with some, but not all hubs. Had a chat, sent it back. Manufacturer agreed and made some modifications to the frame to ensure clearance regardless of the hub and sent it back. Frame now happily in it's 10th year or so and still going strong. Happy outcome.
Some brakes use cup and cone washers below the caliper, the BB7 comes to mind. I think most hydraulic brakes aren't set up like this though.
OP seems reasonable enough to me. The way that post mount is welded to the frame doesn't inspire confidence in me, the only disadvantage I can see to welding it on as per OPs other photo is that it may require more manipulation of the seat stay or the mount itself to make it sit correctly.
@someareset - what makes you think that either of those are correctly set up? They're just tests done by mags not SRAM installations. I do accept they're probably correct as they are fork fitted which is a mass produced item and very likely to be to the exact standards. A frame may not. be.
Was it even considered that something could be set up wrong?
Very much not an engineer, but if it was such a problem, it would do it all the time, no?
No. Can't test every scenario. And outliers get missed. Or it only happened "once or twice in testing" so it was rejected as an issue.
You also find some issues that are particular to a duty cycle and installation, even if the installation is correct and the duty cycle is within range.
Eye is an injeneer.
Also, from a stress/bending load perspective. First look at that makes me think "That's awful". Attaching a brake mount on a tube like that, the whole thing will move around unless the tube is at least a couple of mm thick, probably more. I'd start by doubling (or tripling) the surface area between mount and tube. Would be interesting to see how long they last before the weld starts to crack the tube.
Being as you’ve got the cup washers on the wrong side of the calliper (they don’t do anything to help align the calliper if fitted above it)
AFAIK in that installation they are there to make sure you've got no bending load in the bolt, so go between bolt face and caliper.
Tough crowd
I think it's partly that one person's anecdotal experience - with an additional 'friend of a friend' one - is doing a lot of heavy lifting in a 'I had this issue which I think is down to the brake mount' is extrapolated to 'there is a general issue with the brake mounts on this frame' way.
That might be true. It might not. But it's not unreasonable for people to be skeptical rather than just accepting everything they read on here.
No offence to anyone, not saying the OP is lying or that they're wrong, just that it's basically impossible to tell from anecdotes and people's 'I'm not an engineer, but that mount looks funny' / 'I'm not a fan of Pace' posts.
@Speeder - Absolutely it was considered. I'm no XCO World Cup Mechanic, but I've been doing this long enough to know what to check.
It was fine on my Squatch, not to the RC429 and then fine on my Squatch again. There was only one variable there.
@BadlyWiredDog Of course - I can't disagree with anything you've said there. I wasn't expecting to post this without getting flamed by some users. And I certainly hope people are able to form their own opinions without taking everything on the internet a gospel.
As I said - this is all my experience and what I've found riding the frame. That may well differ 99% of the other buyers.
My only thought was whether a non straight through +20mm caliper mount might have made a difference. You can get a +20mm mount that bolts to the frame and then the caliper bolts separately to the mount
@someareset furry muff - I still think there's more than one variable in the 2 builds but being as it's now gone back, there's not way to tell. If you'd posted a "What's wrong with . . . ?" post we could have possibly trouble shot it but now that's impossible so we're just conjecting.
Best for all concerned to chalk it up to experience and carry on.
I want to clarify something. The OP's brake caliper, mount, and washers, are fitted correctly.
I'm reposting their picture on this page for clarity:
And an extract from Srams document "disc-brake-caliper-mounting-specifications-for-road-and-mtb.pdf"available here; https://www.sram.com/en/service/models/db-mthw-a1
The cup and cone washers go outside the bracket.
These brackets use long bolts, that pass through ovalized holes in the bracket. The caliper moves outwards, but also at an angle, relative to where it would be fitted directly to the frame with a 160mm rotor. The post mount brake standard is not radial mount.
You can see clearly from the silhouetted shape in that diagram, the mounting plane of the frame for 160mm rotor is NOT parrallel to the final mounting plane of the caliper for 180mm rotor. Ovalized holes, with cup and cone washers allow this to occur. Otherwise we would have a bent bolt.
I have, quite literally, got a set of these on the desk in front of me as I type.
For what its worth, I also agree that this has been an entirely fair review or sharing of informtation from the OP - it does look exactly like poor design. WhilstI havent done any testing for many years, I'm am quite sure that if this were modelled up and tested you would find that the method PACE have chosen to assemble this brake mount, is indeed going to lead (in some circumstances) to flex - which of course leads to flutter, resonanance, noise etc.
My Trek Superfly (aluminium frame, post mount, but both posts were sturdy square aluminium posts rising up from dropout/seatstay) generated exactly the same horrible, physical resonance that the OP is experiencing, so right off the bat I would suggest that Pace's frame design might not be at fault.
I fought with it for a while, strapped lead wheel-balancing weights to the stay (which helped actually) changed from SRAM Level to Shimano Deore brakes, multiple different pads and rotors, etc. etc. Eventually what cured it (and the horrible squeal the brakes produced whenever wet or cold) was absolutely cooking the brakes on a long ride in the Cairngorms.
This convinced me that all bets are off until a brake is PROPERLY (i.e. not just twenty hard stops on the pavement) bedded in. There are articles out there explaining it in more depth but specifically there is a difference between bedding a brake in, and burnishing the rotor. The latter takes potentially much longer and explains my issues on the road and gravel bikes where I just don't brake hard or often enough to achieve proper burnishing (or gave up and went back to rim brakes before I eventually achieved it). I don't know if it's a heat thing, or an accumulation of pad material thing.
Flippancy aside, if Pace can’t reproduce the issue you’re having, then essentially it’s your word against theirs. Are you particularly heavy OP? I wonder if you’re simply needing/able to apply greater braking forces than the likes of Adrian Carter or Guy K, both of whom are relatively light to medium riders.
Also this. I'm 90kg, ride large frames. It doesn't surprise me that e.g. a pal who weighs 65kg and rides small or medium frames maybe doesn't get the same squeal, less force going through brakes, less resonance through frame etc. I don't think it's fair to say a problem doesn't exist if a different rider can't reproduce it.
My Trek Superfly (aluminium frame, post mount, but both posts were sturdy square aluminium posts rising up from dropout/seatstay) generated exactly the same horrible, physical resonance that the OP is experiencing, so right off the bat I would suggest that Pace’s frame design might not be at fault
You've had a few different bikes though, haven't you? And ride a fair bit? But thought of one specific frame with this issue? Is it not fair to suggest that some frames might be more susceptible to it than others?
And if absolutely cooking the brakes in proper mountains is the only way to have properly set up brakes, it's got to be accepted that 95% of riders won't be doing that. If a bike feels/sounds horrible to ride, it's a bit victim-blamey to say it's the rider's fault for not having driven to Scotland every time they replace their brake pads, when the issue doesn't show up on other frames. 😀
You’ve had a few different bikes though, haven’t you?
Yes, Trek was the only one with the resonance issue, rest have just squealed when wet. My logic though is that the resonance/squeal all come from the same source, i.e. pads stick/slipping over a non-fully-burnished rotor. My thoughts were that this effect for the OP was enough to cause the resonance on the Pace frame, even if it didn't cause squealing on other frames.
And ride a fair bit?
No, I'm actually embarrassed that you're the second person to assume that, I must spend WAAAAAY to much time posting on here 😆 I average just over 5000km a year (although, pertinent to disc brake discussion and bedding in, I spread that over 4 bikes, so 1500km/bike/year, which might explain why I never REALLY got brakes bedded in properly, as a lot of that mileage was gentle road miles or flattish gravel miles, very little death gripping or prolonged braking).
If a bike feels/sounds horrible to ride, it’s a bit victim-blamey to say it’s the rider’s fault for not having driven to Scotland every time they replace their brake pads
100% agreed, and my frustration with disc brakes is that there still seems to be some voodoo about getting them bedded in and set up right. I am the poster boy of people who should really be riding disc brakes (heavy-ish, 'enthusiastic', ride in all weather) but won't because they don't work for me. My idea is that manufacturers should be selling rotor and pad sets, pre-burnished and bedded in, or someone (e.g. Hope) should have a rig for doing so (at a cost, obvs).
The point of all this is that burning my pads in properly cured the exact issue OP is suffering on my Trek, so regardless of the brake mount design of the Pace, it might just be that run-of-the-mill disc brake black magic would eventually have sorted it for him.
someone (e.g. Hope) should have a rig for doing so (at a cost, obvs).
Your dreams answered
https://sinter.si/pages/smart-bedding-machine
Summary of this thread
One owner had a problem with the rear brake on a ex-demo Pace frame. He believes this to be a fault of the frame through what he reports as a thorough process of replication and elimination against other frames / brakes.
Pace quickly engaged with their customer to find a suitable resolution. Despite reporting they were unable to replicate the issue, offered the owner a frame replacement (new for ex-demo? Not clear) or a refund.
Due to lack of confidence in the mount design, the owner took the refund.
My takeaways are that there is potentially a so far unproven issue on the frame model … buyer beware and do your investigations if planning to buy. Balance your purchase with Pace being a customer focussed manufacturer who will seek to support one to one even when they disagree with the complaint.
So by all means buy a Pace, be a little cautious around the RC427. Have thick skin if you post on STW.
Could the bolts be flexing ?
Seems like a fair and informative post to me. That brake mount does look crap and I bet they change it for the next batch.
All that load on a base which narrows on its way to the frame looks like the opposite of what you want. I am obviously not an engineer.
And for those who have never experienced it, "Oh that's strange, we've never seen this problem before and no matter what we try we can't possibly recreate it here in the office." is the standard reply every time you have a problem with anything from any manufacturer. I heard it at least once a month when the Fox X2 came out.
Absolutely nothing wrong with the OPs post, some members just have issues, one in particular just cannot admit when they're blatantly wrong.
Pace stated the bike had been used on a couple of rides, but only by them. Pretty much a photoshoot bike.
The condition backed that up. It could have passed as an ex-display.
Regarding the rotor thickness, I was running SRAM HS2 rotors, which are 2.0mm rather than the standard 1.8mm.
Been thinking about this a bit more - especially OP's two photos showing the same mounting 'braze on' but used in two different styles.
I've also been looking for the 'the frame builders Post Mount attaching guide' but struggled to find much beyond PVD - maybe MickR knows?
http://www.peterverdone.com/disc-brake-mounting-systems/
My initial thoughts on previous pages are that the less substantial leading arm of Pace's design is causing the vibration/oscillation and that the second photo frame builders solution was better.
However! One of the those mounts must be incorrect from an angular position (probably bike/photo #2). The reason being that as larger discs are fitted and adapters required to move the caliper outwards to suit - if the angle of the mount on the frame isn't correct then the spaced away caliper won't be in the correct position relative to the disc.
It's likely the Pace mount is correctly mounted/angled and that 'clocking' it as per photo #2 is incorrect from an angle point (?) although it would result in a more substantial mounted caliper with a longer weld.
I've not been able to find the braze on but my knowledge only extends to stuck in the 1980's Ceeway and Paragon parts porn.
It's worth noting the 2nd picture I posted is from a frame builder that specs that mount as being 180mm only.
So additional mounts won't work because, as you've rightly noted, the angle and position is likely to be off.
That makes sense then - #2 photo has rotated the mount to remove any possibility of chatter at the expense of it only ever working for a 180mm disc.
Pace has fitted it correctly but it's probably not the best design of braze on available - see Paragon.
From what I can tell...that's correct.
But as it's a custom build, not production run, it's likely the customer has specd the frame with that in mind.
I'd have zero issues with any of my bikes being 180mm rear only.
I've got what appears to be the same brake mount on my custom Marino frame.
It's welded on in a far more sensible looking way over a larger area to transfer all the forces over a bigger area of the seat stay.
It runs a 180 rotor with no adaptor but currently got it running a 203 with adaptor.
I live and ride in the Tweed Valley so steep is normal.
No vibrations of any kind with several different brakes on it.
To me I know which one looks like the better way of attaching the mount...
Spread the load and put a brace in the right place to spread it further on to the chainstay.
https://www.flickr.com/photos/stu-b/53532648891/in/dateposted/
My thoughts too.
And then the bridge/stay between the chainstay and seatstay spread that braking load even further. As shown on the Marino.
Surely the bridge/stay between the chainstay and seatstay on the Pace can't be doing anything with the front end of the brake mount up in the air?
Exactly.
Even on a cheap assed Marino.
All the same bits just joined together in a better way.
