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Anyone take brakes off bike to bleed them?

April 19, 2024, 7:54 a.m.
Posts: 514
Joined: May 11, 2022

I don’t have a bike stand but have a vice and spare bars so think I could just do a gravity bleed with the Shimano cup and a tube on the caliper nipple.  

I have a bleed block too so I’m good yes?

I ask because there’s so much info on brake bleeds but there’s so many different methods it’s overwhelming this gal.

Diddy can dieddy

April 19, 2024, 8:41 a.m.
Posts: 1564
Joined: Sept. 30, 2006

You definitely wont want to be doing that if you have internal routing on the rear brake :) I'd say taking them off is completely unnecessary. The lever is automatically higher than the caliper, so gravity will do its think even if the bike is sitting on its tires. If you want to help out the rear brake gravity bleed, then just prop the front of the bike up on something. There are lots of theories on what works best for a bleed on Shimano brakes. Some say let it bleed from the cup down and out the caliper until it completely flushed. Other say to push from the caliper up into the cup, followed by a gravity bleed down to the caliper. Personally, if its just a bleed, and not a fluid change, I just do the quick bleed technique at the lever with the cup.

April 19, 2024, 9:13 a.m.
Posts: 638
Joined: Feb. 24, 2017

Posted by: shoreboy

You definitely wont want to be doing that if you have internal routing on the rear brake :) I'd say taking them off is completely unnecessary. The lever is automatically higher than the caliper, so gravity will do its think even if the bike is sitting on its tires. If you want to help out the rear brake gravity bleed, then just prop the front of the bike up on something. There are lots of theories on what works best for a bleed on Shimano brakes. Some say let it bleed from the cup down and out the caliper until it completely flushed. Other say to push from the caliper up into the cup, followed by a gravity bleed down to the caliper. Personally, if its just a bleed, and not a fluid change, I just do the quick bleed technique at the lever with the cup.

Same here.

April 19, 2024, 9:14 a.m.
Posts: 16011
Joined: Nov. 20, 2002

I don't think you need to take the caliper or lever off, for Shimano I counted 7 you-tubes per page & 10 pages before I quit counting, there must be just as many for SRAM and we havent even talked about Hayes or Hope so which one do you pick cuz these are all credible sources of info but each one is slightly different so I watched a bunch of them to understand what is really going on and came up with what worked for me

I got the universal bleed kit from TBS the way I seen it a cup and or syringe with a level of fluid in it that will stop air going into the system, I force fluid in from caliper up with the cup on the lever


 Last edited by: XXX_er on April 19, 2024, 9:15 a.m., edited 1 time in total.
April 19, 2024, 9:17 a.m.
Posts: 514
Joined: May 11, 2022

Good points.  All routing is external but I guess there's other ways to keep the bars and bike still besides using a stand.  They haven't been bled for a year at least so I think I'll just flush out the old and replace with the new.  I believe the gravity bleed prevents all the crud in the calipers from getting shot up into the hose and levers?

Trying to wrap my head around the bleed block.  How come some people don't use them?  Are they not necessary?  Wouldn't squeezing the lever cause the pistons to come out of the calipers?  I'm even seeing stuff about making sure the pistons aren't fully pushed back into the caliper.  And other stuff about lubing the pistons with the brake fluid.  FFS.  It's voodoo.

Anyway I guess I'll use the bleed block and see what happens.

April 19, 2024, 9:56 a.m.
Posts: 16011
Joined: Nov. 20, 2002

I think we have all grabbed a lever with nothing in the caliper and had to deal with pistons and fluid splooging everywhere which won't happen if you got a bleed block in there whenever the wheel and/ or padz are not in the brake so even if you are just transporting with no wheel you want something between those bake padz even if its just some ripped up pieces of carboard

So consider if you do a bleed with half worn padz you will be putting extra fluid in the system to make up for the pad material that has worn off which is fine until you wana replace padz and then the pistons won't retract enough to get a new set of padz in the calipers with the rotor so then you gotta wank around with talking some fluid out which is more or less doing another bleed, so the bleed block gives the right starting point from which to do the bleed and ensures you will get the right amount of fluid in the system to have enough room for new brake padz

I only do bleeds when the lever starts to feel flacid and i only do full bleeds


 Last edited by: XXX_er on April 19, 2024, 9:57 a.m., edited 1 time in total.
April 19, 2024, 10:01 a.m.
Posts: 1564
Joined: Sept. 30, 2006

I think the 'official' Shimano procedure has you pushing old fluid up to the lever from the caliper and into the cup until fresh fluid comes through. This is followed by filling the cup with fresh fluid, and allowing it to gravity bleed down to the caliper. The final step is to do a quick bleed at the lever. You definitely need a bleed block for the final steps, and please make sure to take out your pads :) There is something to be said for letting the pistons poke out a bit (by gently pumping the lever with the pads removed and no bleed block in place) and then lubing/cleaning the edge of the pistons with some fluid. I used dental floss soaked in fluid, and it works well. Once the pistons are lubed and cleaned, gently press them back into the bores (but make sure you have put the cup on at this point so you dont force fluid past the seals) and install the blocks and do the bleed.

Hope this helps!

April 19, 2024, 10:09 a.m.
Posts: 2165
Joined: Nov. 8, 2003

Bleed cup and angles? 60% of the time it works everytime! Spending 15 minutes on the 5 minute bleed I always find some extra micro bubbles. Unless your fluid is properly toasted, then bottom up method. Though I'm so lazy it's probably 10 to 1 bleed cup to bottom up for me.

I've done a bottom up bleed without the bleed block many times, and accidentally pushed out a piston many times haha. Could just be I channel Mr. Bean when doing anything mechanical though. 

Lubing the pistons by pushing them out a little definitely is real and prevents stuck pistons though, makes a difference in lever feel too. I've had a few stuck pistons over the years before I started doing that each bleed, and it's the worst. I think it's why the Marshy method is so good.

I don't know if taking the whole brake off is worth it tbh. When Shimano starting having wandering bite point issues I'd pull the whole brake off each time to bleed it. Eventually I switched to bleeding on the (very elevated front end) bike, and I got the exact same bleed. With the front end up the hoses had a clean uphill run the whole way.

Makes a mess (and Marshy seems like he doesn't know wtf he's doing lol), but this odd bleed is the most effective I've encountered:

https://youtu.be/piWBVDh1pTE?si=hIQ2_0z4TDrvUOga

The Syndicate- pit tips- brake bleeding.


 Last edited by: Hepcat on April 19, 2024, 12:51 p.m., edited 3 times in total.
April 19, 2024, 10:12 a.m.
Posts: 1124
Joined: March 15, 2013

This is what I do whenever I need to do a more comprehensive bleed on my Shimano brakes.

Edit - lol beaten to the punch 

https://youtu.be/piWBVDh1pTE?si=GUAfYjwsQ3iXbwWC


 Last edited by: thaaad on April 19, 2024, 10:13 a.m., edited 1 time in total.
April 19, 2024, 10:25 a.m.
Posts: 16011
Joined: Nov. 20, 2002

" Bleed cup and angles? 60% of the time it works everytime! "

oxymoron
/ˌɒksɪˈmɔːrɒn/

noun

1. a figure of speech in which apparently contradictory terms appear in conjunction (e.g. faith unfaithful kept him falsely true): "that fashionable rhetorical novelty, the humblebrag, is itself an oxymoron"

April 19, 2024, 10:29 a.m.
Posts: 2165
Joined: Nov. 8, 2003

I don't know about that at all, the moron part, yes. 

@Thaad My man! 👊

I will add that Marshy makes a mess, and all (some I guess, lucky fuckers) of us at home don't have a whole drawer full of Shimano pads from our sponsor.

Even after cleaning the caliper spick and span I've still managed to foul a couple of pads using his method. Have no idea where the fluid came from, but maybe clean and then get ridiculous and clean a couple more times when doing the Marshy.

https://youtu.be/m9iXlOHtzV4?si=RJX0Ws254DIGhP-v

April 19, 2024, 10:41 a.m.
Posts: 74
Joined: Oct. 7, 2020

I don't use the block for a simple bleed, but I do for a flush to make sure pads don't get contaminated. Also allows a better clean of the caliper with pads out. 

A stand isn't essential if you have a way of keeping the bike upright. I also find that for a rear brake, hanging the bike by the front wheel overnight can get a few more bubbles out. 

I don't gravity flush, the fluid in the lever is usually dirty anyway. I think this is one of those things where the details of the procedure are the last 5%, 95% is flushing regularly in the first place.

April 19, 2024, 10:46 a.m.
Posts: 16011
Joined: Nov. 20, 2002

when I was reasearching SRAM bleeds i watched at least a doz youtubes while eating breakfast, a bunch of guys that all had the logo'ed golf shirts so which one?

I settled on the DH mechanic ( they are all DH mechanics) guy with hair like Lyle Lovett ( I like lyle lovett) who said " yeah you don't need to do all that stuff in those other youtubes just do it like this " and it works

hitting the brake system with a screwdriver helps dislodge the bubbles, using thesyringe to  suck the fluid in - out whilst marveling at the phalic symbolism seems to get the bubbles out for me


 Last edited by: XXX_er on April 19, 2024, 10:49 a.m., edited 1 time in total.
April 19, 2024, 11:27 a.m.
Posts: 514
Joined: May 11, 2022

Thanks for all the great advice.  I guess I will pop the pistons out a bit and lube em up with mineral oil first.  Toothbrush work well for this?

I think I have enough of the mineral oil to do a full flush of front and back.

April 19, 2024, 12:59 p.m.
Posts: 2165
Joined: Nov. 8, 2003

I like a q-tip. I can replace them as they get dirty cleaning the pistons. And use a *very* tiny amount of fluid to avoid pad contamination.

Tooth brush I felt like I might be flinging microscopic droplets about.

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