Bleed process for Shimano 12 speed is far easier than 11 speed. Shimanos process says to draw fluid though and then bleed levers at three different angles in a work stand. The 3 angles correspond to internal shapes in calipers to ensure no bubbles are lodged anywhere. All of this basically means the process is simpler (no need for a drip bottle at the caliper) and it is super reliable.
Great video though I differ on two points which might be helpful for some to note ... Brake oil contamination is more likely to be at the bottom of the circuit - grime introduced by retracting pistons and sinking with gravity - so you are better to start with oil in the funnel and pushing it down with the lever to empty the old oil at the bottom first until clear. Do not use grease on the brake pad bolt threads, use anti-seize.
I think this way might be better to prevent bubbles to be trapped in the process, though? I would set the bike level, the higher rear might be the reason the level of the fluid of the rear brake is higher...
@@DR_1_1 clearing air is a separate issue to clearing contaminant - start with flushing old oil out at the bottom - once you are happy based on volume extracted and the oil colour then you can reverse the flow and pump new oil from the bottom. Basically from the bottom you have hydraulic pressure + air rising and from the top you have hydraulic pressure and yes it is harder to get the air out of the rear circuit
19:10 is excellent advice for those of us that like to work on our own bikes. Getting the “pad axle” through the pads and spring is so much easier this way.
To avoid getting any air extra air in the system I like to put a small amount of fluid in the funnel, then I pull a small amount of fluid (with any air) back out, flick the hose to get the bubbles to go up in the syringe before pushing the fresh fluid in. Any air bubbles end up in the top of the syringe, and not into the system.
Illustrative video, but there are more details to considerate about purge brake systems. One of them (and maybe the most important to me) is first remove brake calipers and clean pistons after purge them. Caliper has to be vertical. This ensures that the air is removed.
Thanks for this video, I learned a lot and remembered a lot that I had forgotten like my 6 year old rotors!! um I didn't need fancy digital vernier calipers to see that the disc was visibly thinner 😳🚴♀🚴🚴 Safe to say they are now in the bin and replacements on the way.
Shimano hydraulic disc brakes are fortunately easy and straightforward to work on and in most conditions they work really well. However, this winter has been really cold here in Finland with temperatures dropping below -20 degrees Celsius for several weeks. I find Shimano disc brakes (both road and MTB) don't work very optimally any more at those temperatures. There is no more lever free stroke, the brakes bite almost immediately as you throw the lever. I guess this is because of fluid viscosity. The bigger problem is that the pistons don't retract back enough after a few lever pulls and the brakes start dragging. The pistons don't even retract back when you bring the bike inside to warm up. The only thing you can do is to take out the pads and push the pistons back in. This kind of behaviour also happens with almost brand-new brakes, not just old and dirty. Do you or Scott have experience about this and what could be done to prevent the brakes from dragging in the coldest of temps?
Because using different tightening torques affects the brake alignment and could potentially cause rubbing, its precisely why you SHOULD use a torque wrench to get the same tightness and disc spacing every time. If you undo any bolt on the roadside you should always be re-checking when you get home. He mentions 20 Nm but that seems way to high, thats probably why he has had the issue.
What causes brakes to lock up? I have a Specialized Stumpjumper & my rear wheel has locked up on me twice in 2.5 years. I don't even ride this bike as much. Can it be from sitting in garage? Heat? I had it tuned up a 2 years ago and addressed this issue at the time as well.
Am i a massive hack for bleeding with my wheel in? i like really short lever throw and on a setup with no freestroke adjustment it just doesnt feel right otherwise.
@@davidarthur Fair enough. It's worth pointing out that dabblers should pop open the lever bleed port (to which the funnel is attached) BEFORE pushing the pistons. Otherwise, it is possible to perforate the rubber bladder in the lever if there is too much brake fluid in the system. Thought could be a costly mistake that is easy to avoid!
Nice video but I am a certified Shimano Service Center PROFESSIONAL mechanic and have been for donkeys years...... bleed my own brakes(on the car) and prefer RIM BRAKES FOREVER!!!
@@rogercmerriman Same, I don't do it enough to always remember the process but the way Scott showed made it look far easier than I thought, but yeah the cost of learning and buying all the kit for once a year max probably isn't worth it
@@davidarthur the other problem personally is my ability do diy etc unless very simple has fallen off a cliff since the brain injury the posh term is executive function lucky to have a good bike shop 5 mins walk away. Only down side is well makes maintenance more expensive!
