Increasing 'snappy' response of hydraulic brakes

N

nmw

Likes Bikes
StuartO said:
To the OP. Have you tried resin pads? They usually offer more initial bite over their sintered friends. Also give the rotors and pads a clean. I find when i wash my bikes, they tend to get a film which causes what you describe.
Same as everyone else though. I've only ridden shimano because i know they work.
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Hey mate, don't believe so, just the "organic" standard sram pads... after a bleed and a pad change, I re-bedded, including an iso clean, sand and iso clean again to the rotors, plus the riding around like a demon, braking to walking speed etc etc.
 
Alo661

Alo661

Likes Bikes and Dirt
moorey said:
Yeah, but with shimano, you don't remove bleed nipple, just loosen half a turn. Removing bleed screw is surely dumbest idea ever. Must have done 50+ bleeds for self and others in 15 years running shimano discs. Never stripped a bleed screw, and never botched a bleed. I'm not a smart man, but I knows what I likes.
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The lever bleed port screw, you need to remove that for the funnel. I've seen two bikes with that stripped, just random ones that have come into work. Still no-where near as common as a tri-athelete with a broken stem bolt cause "I was just doing them up with my torque wrench"
 
moorey

moorey

call me Mia
Alo661 said:
The lever bleed port screw, you need to remove that for the funnel. I've seen two bikes with that stripped, just random ones that have come into work. Still no-where near as common as a tri-athelete with a broken stem bolt cause "I was just doing them up with my torque wrench"
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Hey! I'm no triathlete!

people strip out that little bleed port with a plastic funnel? The fuck? It's metal, isn't it?
 
pharmaboy

pharmaboy

Eats Squid
BigHair said:
You are brilliant. So not only does it not matter if there is air in your calipers (not a common occurrence, but an occurrence none the less) but you are never going to replace the shitty old fluid in your lines (I bet its blacker than skin cancer). Cool man, but there is a bleed port on the caliper of Shimano brakes for a reason.

I think I'm gonna continue to bleed mine regularly. Don't do yours. Thats fine.
I've seen seals blow. If it happens you'll probably crash, but hey, they're easy to 'bleed' right?
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What's with the uppity?

Bleeding a brake is removing air.

Purging a brake is replacing the old fluid for new.

Look it up and edumacate yourself before going off like an old granny, else you look like a big airhead
 
The Duckmeister

The Duckmeister

Has a juicy midrange
Alo661 said:
Just bleed avids the gravity way, remove the plunger from the lever syringe. Don't like the vacuum idea, it works in theory but not in practice. Requires the clean rubber hose to be replaced regularly to get a solid seal to achieve the vacuum., otherwise you'll be pulling on the syringe and getting bubbles, but those bubbles are not necessarily coming out of the brake. Not to mention pressurizing the system means the when removing the syringe it'll either spit dot4 fluid out or suck air back in.
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I use a bottom-to-top positive pressure bleed method for all hydros. air is buoyant you see, so pushing new fluid up pushes any air up with it. Just draw off the excess fluid from the top until you get clean juice. For Avids, after disconnecting the lower syringe, very gently push a tiny bit of fluid back down from the top; this stops air entering the caliper while the plug is out. Tilt the lever so the reservoir port is at the highest point, which will also minimise air entry when the syringe is removed. Clean thoroughly afterwards (not that it should be necessary to mention this point, but you never know with some people....).

Never have a problem with this method.
 
Alo661

Alo661

Likes Bikes and Dirt
The Duckmeister said:
I use a bottom-to-top positive pressure bleed method for all hydros. air is buoyant you see, so pushing new fluid up pushes any air up with it. Just draw off the excess fluid from the top until you get clean juice. For Avids, after disconnecting the lower syringe, very gently push a tiny bit of fluid back down from the top; this stops air entering the caliper while the plug is out. Tilt the lever so the reservoir port is at the highest point, which will also minimise air entry when the syringe is removed. Clean thoroughly afterwards (not that it should be necessary to mention this point, but you never know with some people....).

Never have a problem with this method.
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Pretty much the same idea, just push new fluid from the caliper and the pressure of the fluid pushes the air along with it rather than just getting trapped which can occur in a vacuum even when cycling the syringes. Just didn't understand why Avid insist on using a vacuum, yet no-one else does....

moorey said:
Ahhhh, with the plug, thought he meant that the funnel stripped out the bleed port. I'm a fuck wit. As you were
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In my mind, if it's got thread, it's a screw, not a plug. Can't wait for someone to take that out of context.
 
udi

udi

swiss cheese
moorey said:
Do they still use the shitty screw in bleed port, where unlike shimano (for one), you can't close off the bleed nipple...but rather have to rush to replace bleed port screw after removing syringe? Please say no, it's been a couple of years since last doing one.
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The Avid bleed system is functionally superior because you can draw a vacuum on the system at the caliper, which makes actually bleeding (i.e. removing air) much easier. If you try to do the same on the Shimano system, you just pull air from the atmosphere past the nipple's threads and into your syringe. The grub screw system is also cleaner after bleeding whereas the nipples retain fluid and drip it out over a few rides (usually all over your caliper) unless you're pedantic about cleaning it with alcohol.

I don't run Avids, but Shimanos do have a bunch of issues (very common seal leaks on the ceramic piston calipers - eg. current XT and SLX, which people mistake for accidental contamination but is actually a design/mfg fault), and excessive lever throw on both Zee and Saint brakes due to the servo wave geometry not being calibrated to compensate for the increased hydraulic leverage ratio and resultant increased lever throw with these calipers.

They used to be the peak of reliability and performance but that's changed, and I think they actually need to sort out a few issues before they deserve the relentless praise some are bestowing upon them here.
 
moorey

moorey

call me Mia
udi said:
The Avid bleed system is functionally superior because you can draw a vacuum on the system at the caliper, which makes actually bleeding (i.e. removing air) much easier. If you try to do the same on the Shimano system, you just pull air from the atmosphere past the nipple's threads and into your syringe. The grub screw system is also cleaner after bleeding whereas the nipples retain fluid and drip it out over a few rides (usually all over your caliper) unless you're pedantic about cleaning it with alcohol.

I don't run Avids, but Shimanos do have a bunch of issues (very common seal leaks on the ceramic piston calipers - eg. current XT and SLX, which people mistake for accidental contamination but is actually a design/mfg fault), and excessive lever throw on both Zee and Saint brakes due to the servo wave geometry not being calibrated to compensate for the increased hydraulic leverage ratio and resultant increased lever throw with these calipers.

They used to be the peak of reliability and performance but that's changed, and I think they actually need to sort out a few issues before they deserve the relentless praise some are bestowing upon them here.
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Who sucks? Always push up from the bottom with shimano. :noidea:
 
S

schred

Likes Bikes and Dirt
moorey said:
Who sucks? Always push up from the bottom with shimano. :noidea:
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Maybe, but that's because they dont have an MC nipple you can bleed properly I'm guessing. On a real bike you'd bleed the MC first and then the caliper.

Pushing from the caliper in my exp pushes air either further into the caliper or up into potentially the whole length of the line.
 
M

Mitch243

Likes Bikes and Dirt
pharmaboy said:
What's with the uppity?

Bleeding a brake is removing air.

Purging a brake is replacing the old fluid for new.

Look it up and edumacate yourself before going off like an old granny, else you look like a big airhead
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Nice pun. That's all cool, but then you better update the rest of the thread that they're comparing a 'purge' to a 'bleed' which achieve different things.

moorey said:
Who sucks? Always push up from the bottom with shimano. :noidea:
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Air rises, bottom up no matter the brake. The reason why a vacuum bleed is far superior at removing air is because it reduced the brake line pressure, gas bubbles expand (dissolved gasses may come out of solution) and have greater effective bouyancy and then end up at the top.

schred said:
Maybe, but that's because they dont have an MC nipple you can bleed properly I'm guessing. On a real bike you'd bleed the MC first and then the caliper.

Pushing from the caliper in my exp pushes air either further into the caliper or up into potentially the whole length of the line.
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Schred, most calipers and MCs are designed so that the bleed point sits at the top of the volume anyway, reducing (if not removing) the risk of air getting caught.
The Shimano MC bleed philosophy is that pressurizing the line decreases the volume of gas, with the shock increase in pressure breaking the wall friction that holds gas bubbles.

So seeing as I've now been corrected on what kind of 'bleed' we're all talking about here (btw, apparently you're not allowed to push up from the bottom to bleed Shimano, Moorey, because then you're not doing a 'bleed', its a purge, learn the difference!) then you certainly can bleed Shimano MCs perfectly fine with their bucket (or without, just open up the reservoir and squeeze the lever and add a few drops of mineral oil, its what I do on my Shimanos when I don't have a bucket handy).

Anyway, aside from the fact that a good bleed will firm up the feel of a brake, this is all getting remarkably off topic.
I feel like there should be a permanent Sram vs Shimano thread on every MTB webpage for people to have an e-war over.
 
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udi

udi

swiss cheese
moorey said:
Who sucks? Always push up from the bottom with shimano. :noidea:
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You shouldn't need to bleed a brake at all unless it's seen a seal change or hose change - and that means you need to actually get air out of the system.

This is a very fast process on anything that uses the Avid system (eg. Formula), but takes forever on a Shimano because you can't draw on them. Pushing up from the bottom on an empty system won't remove much air apart from what is in the flow path of the fluid (not the contents of the entire caliper).

I agree with you on the method when doing Shimano, but that's because there's no choice.
 
moorey

moorey

call me Mia
udi said:
You shouldn't need to bleed a brake at all unless it's seen a seal change or hose change - and that means you need to actually get air out of the system.

This is a very fast process on anything that uses the Avid system (eg. Formula), but takes forever on a Shimano because you can't draw on them. Pushing up from the bottom on an empty system won't remove much air apart from what is in the flow path of the fluid (not the contents of the entire caliper).

I agree with you on the method when doing Shimano, but that's because there's no choice.
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Yet people have issues galore with bleeding avids and spongy brakes......but rarely shimano. Makes sense.
 
Flow-Rider

Flow-Rider

Burner
I have been using an automotive vacuum bleeder to bleed my avids for years, fuck that avid bleed kit and my brakes have been perfect.
 
udi

udi

swiss cheese
moorey said:
Yet people have issues galore with bleeding avids and spongy brakes......but rarely shimano. Makes sense.
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The problems with Avid brakes have absolutely nothing to do with the design of the bleed port system. You're making a connection that doesn't exist.
 
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