Pinkbike and
BikeCo.com are excited to bring back the mechanical “how-to’s” with the new Tech Spotlight articles that you can expect to see on the last Tuesday of every month. Joe Binatena, BikeCo’s owner and world class mechanic, will help walk riders through a variety of tasks, from basic jobs to more advanced work that you'll be able to read about in the future. We aim to provide readers with a gauge on difficulty and risk for these projects, and also encourage you to post any questions in the comment section below when it comes to things that need more explaining.
How To Perform a Bubble BleedWhat are you doing?This is not a brake bleed, but rather a quick method to solve inconsistent lever feel such as pump-up and long lever throw. At BikeCo we consider this a "brake fluid service bubble bleed", and we utilize this technique to improve brake system feel and performance throughout the lifespan of the system. Essentially, bubbles build up on the inside of the master cylinder bladder over time - think of bubbles in a two liter bottle on the plastic walls - creating performance issues, and this process will remove those bubbles and restore the performance of your brakes. What this won't remedy is air deep in the brake line or caliper, contaminated fluid, or leaky fittings and sticky pistons. We are not here to articulate exactly how the air ends up inside a close system - simply that it does. If you are interested in the physics, there are many great articles around the talk about brake boil, fluid contamination, diffusion coefficient, absorption coefficient, etc from motorcycle, automotive and aerospace engineers.
BikeCo’s Joe Binatena began utilizing this technique while traveling as a mechanic with some of the world’s fastest gravity racers, and he would perform this service in between runs on brakes that saw extreme heat cycles on the race circuit. This service can also be done at the end of each race day on bikes that don't see as much heat put through their brakes. Our personal bikes tend to have this service performed on them every month or so depending on how often they are ridden, and that experience indicates that these steps help to extend overall fluid service life, meaning we have to do full bleeds less often. Whether you have a hand-me-down rig or a dream build, consistent brake performance is essential to your riding enjoyment. Don’t tolerate poor performance because you see your bike as “so-so” or “not worth it”. Service like this stretches the life span of your components, allowing you to get the most out of your spent dollar and possibly increase the time to budget for your next purchase.
This is not a brake bleed. This service
WILL NOT ADDRESSPiston stick
Air in slave cylinder
Air deep in brake line
Leaky fittings
Contaminated fluid
This service MAY ADDRESS
Inconsistent lever feel – pump up, hard lever, long throw, etc.
This service takes an experienced mechanic five to ten minutes, meaning that with some practice you can have terrific brake performance with minimal pain and suffering. To illustrate this, watch Joe complete the entire service, while narrating, in less than 5 minutes
Difficulty:
medium - proper technique is vital to ensure your brakes function well Risk: medium - it's your brakes, so don't mess it upThe tools you need for this service are very simple. We keep them in the shop, as well as a small vehicle tool box in case we need them at the trail head before a ride.
• Torx or Allen to remove the bleed screw
• A small bottle of the appropriate brake fluid (
it goes without saying do not mix them, do not use the wrong fluid, etc – this will cause brake failure). If you are uncomfortable with the risk to your master cylinder bladder a Shimano bleed cup or equivalent may be used.
• Rag and Windex to clean up
Disclaimer: Brakes are critical to safety, so work with an expert service center it you are uncomfortable with this job. • Step 1 - Carefully remove the bleed screw and associated o-ring. Do not pump the brake lever at this point to avoid air ingress. Remember to treat all brake fluid as damaging to finishes, contaminating to brake pads and rotors, and not super good for your body.
• Step 2 - Gently screw the bottle into the bleed fitting - it's only plastic, so it just needs to be finger tight. You may also need to trim the tip down to allow the nozzle to form a tight seal on the threaded port without bottoming out in the internals. The bottle should ideally will be able to easily support its own mass throughout the procedure, thereby freeing your hands for the other steps. If it doesn't, having a friend lend a hand will be very helpful.
• Step 3 - This service can be performed with the brake levers on or off the bars. For speed - which also equates to motivation to do the work - we leave the bike assembled. It is important that you understand the basics of your brake system's layout. You will want to begin and end the service with the bleed port at the systems highest point.
With the bottle inserted as an additional reservoir, gently squeeze the brake lever. Your first few lever strokes should be with the port at the systems highest point to maximize the air release. Slowly rotate the handlebars side to side while pumping the brake lever a few times to insure that you have released any bubbles that maybe caught at different points in the system.
• Step 4 - You have an additional option which helps eliminate the remainder of air trapped in the system, but there is a risk to understand here. Too much pressure in this step WILL cause your master cylinder bladder to fail, and this step requires a delicate touch to protect your brake system. This is NOT a hand strength exercise. The sealed bottle allows you to gently flush fluid into the bladder system compared to the open Shimano reservoir which does not provide this capacity. If you question your small motor skills, the open ended system has much less risk of damaging a bladder. Gently pushing a little fluid into the bladder releases the last bit of air, generally much smaller bubbles than your initial lever strokes, in the system. Think of it as softly inflating the bladder with fluid flow, which displaces the tiny air bubbles on the bladder walls which are sucked back into the bottle through the vacuum as you release the pressure.
Rotate the bar while softly pumping the system as you did with the lever procedure. Again, over inflating the bladder will cause it to fail. This is generally illustrated by brake fluid leaking out from the lever system upon completion. DO NOT pressurize your brake system! The goal is to fill the system without air bubbles. This step is designed to flush bubbles out, displacing the bubbles with fluid.
• Step 5 - Return the bleed port to the highest point and remove the reservoir bottle. Refit the bleed screw while making sure any O-rings you may have removed are correctly replaced to insure your seal integrity.
• Step 6 - Remember to thoroughly clean any excess fluid from your bike. Windex, or even water, and a clean rag get you handled. Your brake lever should offer greatly improved feel and consistency. If you correctly completed this service and lever feel has not improved, or worsened, you should complete a full brake service and bleed to identify the area of failure.
IMPORTANT NOTE: This service will “top off” fluid during brake pad life. When replacing your brake pads you MUST remove the bleed port prior to resetting pistons to clear the new pads. Opening the system will minimize stress on the bladder system and may purge a bit of excess fluid.
Disclaimer: Many of our tech tips ARE NOT factory approved service techniques. Riders should evaluate their skills prior to attempting any published tips. Knowledge base is needed to define success or failure after any tip procedure – if you doubt your understanding of any system described in our tech spotlight work with a professional resource. All systems on a bicycle should be considered critical – riders risk injury or possibly death with improper service or application. Be safe and enjoy your riding.
We hope that you found tips in this that will help you better maintain your ride. We will look forward to future instalment of Tech Spotlight here on Pinkbike on the last Tuesday of each month. If you have an idea that you would like to see covered, please e-mail Nate@BikeCo.com to let us know what issues you’ve had that can’t seem to be solved and we will put Joe on the task.www.bikeco.com
My boxxers need some care, my chain is dirty... can youtake care of my bike?
when handling DOT or even Mineral Oil (which is not as benign as they would have you believe) you want to be wearing workshop gloves and eye protection
its not uncommon to get brake fluid on your hands, and on occasion for something to leak / squirt out which can hit you in the eye
Am I wrong for saying this , it's seems to work but I wouldn't want to compromise the full system buy pulling in unwanted air
And what about the degassing of the fluid (ex for Avid: when u get the bubbles out of the fluid in syringe by decompressing it, when full bleeding). Or should u degas it before u put it in the bottle?
Wouldn't this bottle-technique create more bubbles faster in time rather than air tight full bleeding?
Would be great if u address this.
And will this system work by having a threaded filled open/closed syringe instead of the bottle?
Cheers.
That was the exact problem i was having with my old juicy 7's maybe it's time to get them new life...
Avid Pro bleed kit. That's the shit right there.
Difficulty = very easy
Risk = no risk
This bottles solution seems amazingly simple and a plastic bottle shouldn't cost more than a few cents. This would be perfect for bleeding Avid brakes, as they need bleeding quite often. You'll still need to fully bleed brakes, when it's time to change the brake fluid, but this is not a job you do often.
As for the fittings, all you need is to find the right fitting that can be screwed in and some o-ring. Both costs almost nothing as the syringes do cost nothing, as the hoses cost nothing. Asking 50 euros for these thing is the best joke bike industry is making with us.
And people who do pay 50 euros for couple of syringes deserve to pay 10000+ euros for bikes and 200+ euros for bike shorts.
They work great though.
www.amazon.com/Vestil-BTL-RC-4-Polyethylene-Dispensing-Removable/dp/B00B51367M/ref=pd_sim_hg_6?ie=UTF8&refRID=06BE9DRNRXW26027PVVG
My wife has free access to all sizes of syringes, but none compare to those in the Pro kit...much better results when compared to bleeds done w/regular Avid kit.
the same kit and can confidently say it's worth any penny so far, to bleed AVID properly there is nothing better than a Pro Bleed Kit
indeed. I do understand the message of the cheep option but come on give me a break this is like emergency case only if you are in the middle of the desert
If you want to have flawless working Shimano brakes use genuine Shimanos Mineral Oil. It more expensive but it's much better.
Another thing, and I'm not joking about this one: where to get squeeze bottles?
I do NOT miss those closed systems. The other 2 brands I rode, needed a bleed every couple months, usually like the above. Yeah, don't miss it at all, as it seemed to happen over night. Ready to ride, grab your bike, pull the lever, "Damn it, not now"...
Our bottles are a collection over the years from Hayes Brake Kits. I would assume a hobby store would have a very similar offering too. Here is a link to the Hayes setup for review (of if you want to have your shop order it for you)
bti-usa.com/public/item/HY8072?track=true
MSRP is $18.00 for the kit. The key to the bottle is having the nipple wide enough to engage the bleed hole diameter - but not so deep to hit the internals
Profit margins on bulk plastic bottles is crazy. I'm in the wrong business. You can't sell drugs and turn $35 of bulk product into $220 of single servings, but these little bottles? $220 is cutting them a deal, internet price, while some craft supply store is moving it for $550.
Seems to me this "trick" is 80% of the work of a full bleed and has some shitty consequences if done wrong (blown seals) I'd rather just fully bleed my brakes every spring and fall.
Then I just carefully open the caliper bleed port a little and let the fluid come out a drip at a time and give the lever a squeeze between each drip. As soon as the pads move back enough to clear the disc after I release the lever, that's it, i'm done. I dial in my bite point adjustment and lever reach adjustment to my preferred setting and bingo, rock solid brakes.
If you have mushy feel, this won't fix it for you, you need to purge all the air first, it's just a way of polishing up a fresh bleed if you prefer rock hard lever feel.
I can't believe they are showing this guy drip a bit of fluid into the system from what looks to be his 'goto' bottle. Any fluid going in there should be brand new and you should have sucked the shit out of it in a syringe to remove any and all dissolved gas. When I wrenched at Kawasaki they would have kicked my arse out the door if I topped up a system like he shows. No wonder he's talking about regular bleeds....
I'm with Oldschool below, I've bled my Hopes once and don't expect to do them again for years.
this article is about bike-style brakes that usually need 8 arms like a Hindi goddess, 9 injectors, and 3 hours of pumping and sucking break fluid around repeating and repeating in reverse procedures in exact order like a Japanese tee ceremony... not hopes
Of course with hope the only way to actually need longer than 5 minutes to fully bleed a brake with not more tools than a 8mm wrench and a T10 driver is if you happen to not find one of them in your tool bag...
that is if you ever have to bleed them in the first place...
This guy is meant to be a pro? ha ha ha...
Anyone just flush from the syringe out and cap the reservoir? It seems this would be better since you're going bottom up, just like air wants to do.
Or, you know, just ignore the evidence and believe in your own individual and unfounded conclusions. I mean, this process "definitely" blows the bladder and introduces air right? They've just been ignoring the obvious, and going ahead with this "pointless" process and destroying brakes without a care at pinkbike for years. It's not like they have had thousands of bikes, brakesets, drivetrains, not to mention probably billions of words in data aquired from us readers and forum posters, come their way over the years. I'm sure they're entirely ignorant.
Or maybe thinking you're an expert based on your own limited experience and non-existent is working for you, ymmv.
TL;DR idiots
Super genius.
Tbh as someone else has already mentioned in a comment above, shimano are so easy and quick to bleed that you may as well do a full bleed on them rather than this method.
www.jensonusa.com/Shimano-Disc-Brake-Bleed-FunnelStopper
Also the best way to bleed (at least for shimanos) is with two syringes & a piece of rubber tube..fill the big syringe with oil, fit the tube to it and place it to the caliper nipple, squeeze the syringe and with the other syringe remove excess oil from the reservoir until you see no bubbles coming out of the reservoir. Not more than 5 minute job!
www.epicbleedsolutions.com/products/bleed-kits/universal
www.mcmaster.com/#bottles/=r91bwv
Amazon has all kinds of useful syringes and graduated cylinders also