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Totally aware, but using it as an example to show why I switch rotors if I switch pad compounds. The like size grit/ grain structure analogy is legit when it comes to the discussion at hand, providing context to what happens between a bedded in rotor and pad set and why simply swapping pad compounds may not provide the desired results. The pad material grabbing at each other as contact made is not significantly dissimilar to what occurs during galling.
Side, that AvE cat is one of our own. Highly entertaining fellow that one.
Hopefully you've all been being careful when performing maintenance on your brakes, but a couple new studies just dropped reinforcing that inhaling brake dust is bad, mmmkay. No types of dust were good for you, but interestingly one study showed that metallics were less damaging than organics when exposing lung tissue to dust. Either way, I'd encourage everyone to clean their stuff using a wet method to avoid dust generation, and ideally catch the majority of the liquid in a garbage can for proper disposal, because if you just let it dry on the floor of your workshop it can get kicked back up if you use the air compressor, sweep, etc...
From: https://particleandfibretoxicology.biomedcentral.com/articles/10.1186/s…
"The scientists examined the effects on lung health of particulate matter from four different types of brake pad with differing chemical compositions; low metallic, semi-metallic, non-asbestos organic and hybrid-ceramic.
Results showed that of the four types of brake pads, non-asbestos organic pads were the most potent at inducing inflammation and other markers of toxicity, and were found to be more toxic to human lung cells than diesel exhaust particles. Ceramic pads were the second most toxic."
And from: https://www.sciencedirect.com/science/article/abs/pii/S0300483X25000113
•Exposure to brake pad particles induced lung inflammation and a tendency towards fibrosis.
•Notable alterations in pulmonary function parameters, indicating compromised respiratory health.
•Significant changes in plasma metabolites, implicating KEGG pathways of purine metabolism and caffeine metabolism.
•Alterations in intestinal microbiota, with implications for the gut-lung axis.
Ok I'll try bring this convo over here and reply to this comment-
I really hate to derail this conversation but I must talk about those maven cups. I've always been a fan of the Shimano overnight cup bleed rubber band thing and I thought these cups would help me do the same things to my mavens.
Needless to say, it did not work, in fact it made my mavens feel terrible. So I've never used them again and suck with syringes. I think having a bit of positive pressure in the system and "overfilling" it a bit by pushing a little bit of oil from the caliper up with the bleed port on the lever closed makes them feel the best.
Though I'd be really interested in your thoughts.
I've never relied on the rubber band to the bar method (now or 20 years ago) - it might help if small air bubbles have been mixed in and trapped in tight corners of the brake but generally I try to flush degassed fluid through the whole system and that carries a lot of the air with it.
Theres 2 things which seem obvious but manufacturer bleed methods seem to forget -
Gravity - air will always travel upwards so if there is a local high point then a vacuum won't be able to pull it unless the path to the bleed port is roughly vertical. Some brakes have more spots to trap air than others so if you're having trouble you might need to experiment with orientation of the whole system*
The reason a vacuum helps is because it changes the ratio of bouyancy vs friction (archimedes principle). Small bubbles have a relatively high surface area compared to their mass so the friction on the bubble prevents them from floating. Pulling a vacuum causes the bubbles to expand, greatly reducing their density and if there are multiple bubbles that can join together they will now be much more likely to travel up to the lever.
Tapping the brake gently also breaks the friction between the hose which helps it get moving, and once moving will be more likely to continue travelling upwards. Too much agitation will break up the bubbles and create a foam which is harder to move though. Personally I like to fill a sysringe and pull a vacuum to degas it before gently pushing it in to the brake from the bottom. That makes for far less air to remove later on. Holding pressure on the bubbles shrinks them and might help it squeeze through small gaps but might not be a lot of help getting it all out.
*I really want a workstand that somehow clamps in the middle of the bike and makes it easy to spin 360 degrees for this exact thing. EVT had an offset clamp on their stand for the reason too, but it held the seatpost which I would like to be able to remove in the stand as well
Yup I do it a very similar way - the the inital bleed nipple opening at the caliper involves drawing the air out, as well as any crud that might be stuck there. I'll often hold the lever closed so its not sucking the bladder back or if you have already installed a cup/top syringe. But leaving the top plug in place works too
And yeah i've had bleed blocks fall out too - I'll always hold it with a pin or rubber band now!
@Digit Bikes mentioned that pulling a vacuum might make the bubble too big for them to be able to move through the hose. I'd say pulling a vacuum with the other syringe opened (there's enough restriction in the line or complete system that there still will be a vacuum) will enable the oil to flow under a vacuum, so pulled through the system, thus the bubbles will enlarge and flow together with the oil.
That's why I was saying here about using a vacuum machine connected to both ends of the brake system with a Y plumbing system and pulling a vacuum on a reservoir then maybe even having a pump or something flowing the oil from the caliper to the lever (and back towards the caliper through the external plumbing) to promote this flow of bubbles. The only reason for this is to a) be able to tune the level of vacuum (0,9 to 0,8 bar absolute pressure, so 0,1 to 0,2 bar vacuum might be enough and prevent ingress of air past the master seals) vs. how you're able to control it with a syringe and to be able to plug the system and have the machine run instead of standing there and handle the two syringes back and forth, pulling vacuum, holding it there, holding your hands up above your head, etc. etc.
Re a work stand clamping in the middle of the bike without using the seat post, could you use the Silca ‘Hirobel Frame Clamp’ or something similar? Seems designed for aero road bikes but a very brief web search shows people using it on mtbs.
The vacuum machine makes me think of the Unior rotor/pad bedding machine. It's a $2,000 piece of equipment to replace pedaling up a hill a few times. But sometimes it's raining, sometimes it's snowing, it takes employees time to go do the pedaling (assuming the shop actually does a bed-in procedure), maybe the shop is located where it's hard to do the bedding procedure.
The vacuum bleeding machine seems similar, although standing there with a syringe in each hand seems like a lot less trouble than bedding in brakes.
Saying all that to ask the industry folks on here if they are seeing or hearing about the Unior machine getting purchased by larger shops. I would think that would be a useful data point on the commercial viability of a vacuum bleeding machine for brakes.
I suppose shops could also use the vacuum machine to get more business be claiming that their brake bleed with the machine is superior to a home bleed with syringes, but I'm not sure I'd buy that argument.
It's actually Sinter's machine, not Uniors. COmpletely different company, but they both sponsored the now defunct team
Apparently they made it to have consistency in bedding in brakes vs. the variability when shop employees pedalled up the hill.
As for better or not, if it frees up a service tech to do other things, any machine will pay itself off VERY quickly if it actually works. As for me asking it, I'd use it at home and I'm just lazy
As someone who went from bleeding shocks by hand to using a vacuum pump about 10 years ago, a brake bleeding and pad bedding machine are 2 things I would immediately buy if I was running a general workshop. The time saved plus consistency (which saves even more time on parts coming back to be redone) is crucial for a sustainable workshop. I only occasionally do brakes but I'm still planning on building more tools for pad bedding when I get the time.
Actually the same goes for wheel building - I used to do about as many wheels as I do shocks but the reason I stopped is I couldn't invest in dedicated machines for both jobs. Look at Wheelworks in Wellington, NZ for the kinds of stuff I mean. https://www.wheelworks.co.nz/?srsltid=AfmBOooE6xOR6S3PT9hMztNxJQiCKBytlFTaQxgyXLGz_M1V2wYOaGln
In my opinion if a shop is hoping to do technical work like brakes, suspension and wheels they absolutely need to invest in modern tools. The productivity rapidly pays for itself, making life better for customers and the workshop more sustainable/profitable. The trend I see is if bleeding brakes is too much of a hassle then a mechanic will convince themselves its "fine" and doesn't need to be done, whereas if the service is super easy you'll be much more likely to get it sorted then and there without much thought
Couldn't a cheap treadmill be used to bed brakes? Sure the size is a bit of an issue in a small shop but it'd get some better use out of them that way instead of as a clothes rack they typically become.
https://www.wheelworks.co.nz/what-makes-us-unique/
Pretty cool read for anyone who's curious. A lot of very expensive, very cool tools and machines.
I hadn't thought of the Hirobel but those are pretty cool - and might actually do a pretty good job. My dream stand would be able to spin an ebike right around the centre of gravity but with shocks and wildly different frame shapes in the way that could be overly ambitious! Might have to get one to try, and possibly use my new 3D printer to make some custom pulleys for different shapes.....
Probably - apparently the motors in treadmills are super robust and torquey so are perfect for re purposing in to stuff like that
IDK about the whole expensive tools necessity spiel. If you have good pitch perception, you can tension wheels like a champ. I understand that an amateur like me has infinite time to fine tune their wheels unlike a shop that has to optimize time budget to make a profit. But like in many other crafts, a talented and skilled wheel builder likely doesn't need fancy technology for superb results.
That makes sense to me. Thanks for taking the time to reply.
If you could wave a magic wand, would the brake bleeding machine also be able to pressurize the system at a consistent and repeatable pressure - like the trick of pressurizing Codes from the bleeding edge fitting at the caliper before closing it off. Sometimes I do end up letting a touch of fluid out of one or the other. I can definitely see the value of doing that consistently and quickly in a shop setting.
Any extra pressure in brakes will go somewhere. Either inflate the bladder (and could cause problems once water is ingested and the volume increases, see option two) or the caliper pistons will push out and advance towards the rotor to take up the slack. The timing of the port will stay the same and the brakes will grab at the same time. Maybe the bite point will be quicker because the pads are advanced more, but you don't need to overfill the system to achieve that, just advance the pistons.
Or get contact point adjust brakes...
When we agree, we agree pretty damn well.
@Slavid666 Thanks for the Sinter Green suggestion. I did a big ride in the snow and they were dead quiet the whole time. Even after a nice crash in powder which got the rotors/calipers soaking wet and it only took 5 seconds for the noise to go away. With the Hayes metallic pads, they would be insanely loud for at least 5 minutes if not the rest of the ride. Great modulation and power to boot. Excited to run them on my summer bikes too.
You can definitely build very good wheels just by pitch - I'm basically tone deaf and can still achieve adequately even tension by plucking. The problem becomes after a month of riding - can you verify the pitch is still the same? And theres no way to quantify the absolute tension of each spoke in different wheels - a CX-ray in a carbon rim will sound very different to a thicker round spoke in an alloy rim. if a wheel comes back after a month with a broken spoke, you need some way of confirming that it was built to the correct tension so you can be sure its not your fault that it broke. When people are charging thousands of dollars for a carbon wheelset they need to be doing every possible to make sure its as reliable as it can be.I know for a fact most wheel breakages or spoke breakages are due to the tension being too low, uneven or spokes being the wrong length. The only way to do that consistently every time is with good tools. It's sadly become too common for when someone breaks a spoke they get blamed for doing something wrong or "must have got a stick in it" when actually the wheel wasn't built properly. Thats why I linked to wheelworks - he didn't want to accept that spokes always break so learned how to prevent it and has proven its possible. Another example of how low the bar has gotten is Brian Cahals revent video on ENVE wheels - he seemed genuinely shocked that they lasted a year when really that should be a realistic expectation! Wire spoke bicycle wheels are very good so you shouldn't need to touch them outside of a World Cup DH weekend (DH is a bit of an exception - its pretty tough to be invincible to full blown rock strikes, but the typical enduro rider shouldn't be seeing that)
If you only build the occasional wheel then you don't have to go all out on tools, but if you are regularly doing high end builds then I think its essential, and a shop should at least be aware of its limits and maybe leave the most expensive & lightweight builds to someone better equipped. Or be prepared to suck up the repair cost if it comes back after a month and not put it back on your customer. People got trained to accept things like spokes coming loose after a few rides, or brakes needing a few squeezes to "pump them up" when really that is totally preventable and not really that hard to do!
figure putting brage's latest AK insanity in here is appropriate 🤣
Impossible, Shimano brakes are terrible according to a majority of this thread. 🤠
They still are
Get the job done but they’re nothing special, plus, he could do all that on v brakes
Another way of saying "it's not the bike, it's the rider" 😉
My point being, if Saints are good enough for a rider of the skill of Brage, it will do for most of us mortals.
Different strokes for different folks, i was joking a bit, this is a tech derailment thread in the end.
How is pulling a vacuum supposed to be done?
Clamp the syringe and try to degas the fluid the fluid that you will be bleeding with. Is this useful for both for and mineral fluids?
Attach the syringe to one end of the brakes and pull while leaving the other end closed to pull out small air bubbles. How do you prevent bubbles from going right back into the system ones you release the vacuum?
Correct, close the opposite end of where you're trying to pull a vacuum. With the syringe vertical hold the slight vacuum and you'll see bubbles rise past the "surface" of the fluid in the syringe. Poof, gone forever
My apologies if I'm way late to the party on this one, but I was pretty surprised. Want to make 110% sure I've got it right, and post may be a nice PSA if I do.
SRAM "Dot Grease" is now labeled "hydraulic brake grease," and even though seals only play well will DOT or mineral oil, the hydraulic brake grease is what you us for all of their brakes, DOT and mineral oil.
The formula / chemical makeup of this grease has never changed. SRAM says, "The formula for Hydraulic Brake Grease has remained consistent since it was branded under AVID or PitStop"
The bottom line is that it appears I can use the ancient tub of SRAM brake grease labeled "DOT" on my Maven's and it's just fine. It just seems heretical, given how much everyone freaks out about not using anything DOT with anything mineral oil and vice versa.
Is this right?
I would have to look up the data sheet to be sure but its probably right - mineral oil systems and their seals are fairly tolerant of a wide range of grease/oils so grease made for DOT brakes will usually be fine in mineral oil. Its the dot fluid itself that can be harsh on some rubbers. The biggest issue is using anything mineral oil based (ie 99% of greases) in a DOT system as the seals will rapidly swell and ruin the whole thing
people missing the part that Brage is scrubbing the speed.....
When sponsored... you tend to make do with what you have.
Pretty much every single person i've spoken to who have changed away from shimano to brands from TRP, SRAM to trickstuff all enjoy how much better they are than shimano.
Shimano have the benefit of being easy to setup... perfect for pinkies to say "they are better" because they can lever bleed with a cup.
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