Road Bike, Cycling Forums banner

1 - 20 of 30 Posts

·
Registered
Joined
·
91 Posts
Discussion Starter #1
How often should I bleed/flush my Shimano brakes? What's a good bleed kit?
 

·
'brifter' is f'ing stupid
Joined
·
15,349 Posts
Once a year unless you ride tons w/ lots of descending. Shimano or Park bleed kit.
 

·
Banned Sock Puppet
Joined
·
13,030 Posts
Once a year unless you ride tons w/ lots of descending. Shimano or Park bleed kit.
Hmmm. So I guess my 4-year old gravel bike is long overdue even though it only has 1,500 miles?
 

·
'brifter' is f'ing stupid
Joined
·
15,349 Posts
Definitely wouldn't hurt to do it more often but I generally always see contamination after a year w/ Shimano and DOT really absorbs water so for sure every year. I know race car/moto guys that bleed after every track session.
 

·
Banned Sock Puppet
Joined
·
13,030 Posts
Definitely wouldn't hurt to do it more often but I generally always see contamination after a year w/ Shimano and DOT really absorbs water so for sure every year. I know race car/moto guys that bleed after every track session.
Hmmm, OK. So I'm on borrowed time. I guess I'd rather not learn about brake line contamination on the next steep downhill. :eek:
 

·
Registered
Joined
·
1,356 Posts
I know race car/moto guys that bleed after every track session.
I know a couple of guys that do that as well, but they're really pushing the envelope on track days. They'll also completely flush the brake fluid every 5k miles or so in their daily drivers, whether a car or moto.
 

·
Registered
Joined
·
91 Posts
Discussion Starter #8
I bought the Shimano kit, but what's the point of the funnel? I'm used to a tube and bottle arrangement from the lever to watch for bubbles and catch fluid when I bleed my Hayes mountain bike brakes.
 

·
'brifter' is f'ing stupid
Joined
·
15,349 Posts
I bought the Shimano kit, but what's the point of the funnel? I'm used to a tube and bottle arrangement from the lever to watch for bubbles and catch fluid when I bleed my Hayes mountain bike brakes.
RTFM.
 

·
Registered
Joined
·
6,659 Posts
Hmmm, OK. So I'm on borrowed time. I guess I'd rather not learn about brake line contamination on the next steep downhill. :eek:
you got that right! With contamination and/or water in the fluid, you can be riding normally and you wouldn't notice.. until you need to use the brakes long and hard in a long and steep descent. On my long mtb shuttle-up descent, I could be doing 25+ miles of descent, and I always flood the fluid before such a ride and bring a spare pair of pads.
 

·
Registered
Joined
·
91 Posts
Discussion Starter #11
I watched the Park Tool video. Yikes! What an involved process! First you use the syringe to push the fluid up through the lever, but you have to orient the lever into multiple angles, which means loosening the handlebar clamp so the bars can be rotated. Then you have to run the fluid down through the lever and out the caliper into a bottle or plastic bag. That last part seems dumb. I'm sure I've left a few things out like stroking the lever.

CX, do you do all these steps or is there an easier way?
 

·
'brifter' is f'ing stupid
Joined
·
15,349 Posts
No, I push the fluid up from the caliper to the lever. I change the angle of the bike in the stand rather than loosening the bars. When I think I've got fresh fluid all the way through and don't see any more bubbles I'll take the syringe off and pull on the lever to see how it feels. I will usually finish up by pumping the lever a bunch to make sure I've got all the small bubbles out (you'll see them go into the cup) and that's it. I never seem to need to go from the lever to the caliper.
 

·
Registered
Joined
·
6,659 Posts
I bought the Shimano kit, but what's the point of the funnel? I'm used to a tube and bottle arrangement from the lever to watch for bubbles and catch fluid when I bleed my Hayes mountain bike brakes.
on brake levers (usaully small XC or roadie brakes) that have no reservoir space, the funnel acts as a reservoir containing brake fluid so that when you pump the lever, you'll have fluid to pump. Otherwise, how else are you going to have fluid to pump?

On (big) brake levers (burly downhill brakes) that have a built-in reservoir, then you don't need a funnel. But you would still need to keep an eye on the reservoir so that the fluid won't run out as you pump the lever.
 

·
Registered
Joined
·
6,659 Posts
I watched the Park Tool video. Yikes! What an involved process! First you use the syringe to push the fluid up through the lever, but you have to orient the lever into multiple angles, which means loosening the handlebar clamp so the bars can be rotated. Then you have to run the fluid down through the lever and out the caliper into a bottle or plastic bag. That last part seems dumb. I'm sure I've left a few things out like stroking the lever.

CX, do you do all these steps or is there an easier way?
it's definitely not an easy thing to do for a newbie. I hate unmounting the calipers because remounting them involves too much realigning, so I leave them mount (and tilt the bike if I have to). If you have brake lever without reservoir, then the funnel is a must have equipment. All other tools are can be jigged up and optional. After 5-6 times bleeding, you become good at it. My brake levers have a reservoir so I don't even need the funnel. I'm only 5'7" but armspan is long enough that I can pump the lever and work the (rear) bleed-port srew at the same time (aka, pump and release), and have a little bottle of brake fluid nearby to refill the reservoir. If I don't have to unmount the caliper, then just bleeding one caliper takes me about 20 minutes. But if I have to unmount caliper and remount it later (and realigning), then more time will be needed. The cleanup also takes time if you got brake fluid dripping on the floor or all over your caliper (easy to do). I'd say if you're bleeding both brakes, it'll take you a couple hours from start to finish including cleanup. There is no easier way to do this stuff, been like this for 2 decades. But you get better as you do more, because most time is involved in preparation and cleanup and not the actual bleeding part.
 

·
'brifter' is f'ing stupid
Joined
·
15,349 Posts
on brake levers (usaully small XC or roadie brakes) that have no reservoir space, the funnel acts as a reservoir containing brake fluid so that when you pump the lever, you'll have fluid to pump. Otherwise, how else are you going to have fluid to pump?

On (big) brake levers (burly downhill brakes) that have a built-in reservoir, then you don't need a funnel. But you would still need to keep an eye on the reservoir so that the fluid won't run out as you pump the lever.
ALL disc brakes have some reservoir space...they have to to accommodate pad wear. ALL Shimano brakes currently need the funnel to bleed or burp. Old Shimano brakes were bled moto style, but for the last 10 years or so they've all used the syringe/funnel set up.
 

·
Registered
Joined
·
1,000 Posts
After watching the vid about a month ago and pricing the bleed tool, I will this to a LBS. for the amount of time they need work the bike shop won’t cost much more over time.
 

·
Registered
Joined
·
6,659 Posts
ALL disc brakes have some reservoir space...they have to to accommodate pad wear. ALL Shimano brakes currently need the funnel to bleed or burp. Old Shimano brakes were bled moto style, but for the last 10 years or so they've all used the syringe/funnel set up.
yep, i should have said small reservoir rather than no reservoir. My Magura has a bigass reservoir, moto style bleeding!
 

·
Registered
Joined
·
91 Posts
Discussion Starter #18 (Edited)
No, I push the fluid up from the caliper to the lever. I change the angle of the bike in the stand rather than loosening the bars. When I think I've got fresh fluid all the way through and don't see any more bubbles I'll take the syringe off and pull on the lever to see how it feels. I will usually finish up by pumping the lever a bunch to make sure I've got all the small bubbles out (you'll see them go into the cup) and that's it. I never seem to need to go from the lever to the caliper.
Actually, thinking about this, mineral oil doesn't absorb water and water collects at the low point in the system, which is in the caliper, so I think you need to do a gravity bleed through the funnel out through the caliper to remove any water. I don't think pushing fresh fluid through the other direction can effectively remove this water.
 

·
gazing from the shadows
Joined
·
27,174 Posts

WTFY.

Watch the Fn Youtube.

Me? I almost always just RTFM, but for a lot of people they will have an easier time watching the job done before trying to RTFM. Visual learners are pretty common, especially for stuff like this. I'm guessing that happens a lot in the shop, where people are shown how to do a new thing, not told how to do it?

Please note that I said to RTFM after the video, and not just rely on the video. But youtube has made DYI a heck of a lot easier and better, that's for sure.
 

·
Banned Sock Puppet
Joined
·
13,030 Posts
WTFY.

Watch the Fn Youtube.

Me? I almost always just RTFM, but for a lot of people they will have an easier time watching the job done before trying to RTFM. Visual learners are pretty common, especially for stuff like this. I'm guessing that happens a lot in the shop, where people are shown how to do a new thing, not told how to do it?

Please note that I said to RTFM after the video, and not just rely on the video. But youtube has made DYI a heck of a lot easier and better, that's for sure.
There is a saying that goes.........

Tell me, I'll forget.
Show me, I'll remember.
Involve me, I'll understand.
 
1 - 20 of 30 Posts
Top