How often do you need to bleed the hydraulic disc brakes?

Discuss light weight issues concerning mountain bikes & parts.

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bikemaniack
Posts: 331
Joined: Thu Jul 16, 2009 9:33 pm

by bikemaniack

You clean your bike after each ride,lube chain before each ride,checking air pressure once a week,so why you cant change brake fluid once a month or 2months. DOT from Avids,Formulas is more like acid for orings,mineral oil isn't that bad,but both get worked out. Fork service is not only to clean upper lags,hydraulic brake service is something more than changing brake pads.

CGT
Posts: 342
Joined: Fri Jan 05, 2007 5:33 pm
Location: Stockholm, Sweden

by CGT

bikemaniack wrote:You clean your bike after each ride,lube chain before each ride,checking air pressure once a week,so why you cant change brake fluid once a month or 2months. DOT from Avids,Formulas is more like acid for orings,mineral oil isn't that bad,but both get worked out. Fork service is not only to clean upper lags,hydraulic brake service is something more than changing brake pads.

Simply because it isn't needed. Sure, you can do it, just as you can change your whole drivetrain every month. But most people don't, because it just isn't justified in terms of time and money spent versus performance gained.

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wingguy
Posts: 4318
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

bikemaniack wrote:You clean your bike after each ride,lube chain before each ride,checking air pressure once a week,so why you cant change brake fluid once a month or 2months.


You can, but there's no real need to. The chain is on the outside of the bike, brake fluid is on the inside. To suggest that one needs replacing super regularly because the other one needs cleaning is nonsensical.

afalts
Posts: 157
Joined: Thu Mar 08, 2012 3:20 pm

by afalts

mattr wrote:Once a month is called paranoia.


meh. It's not that I think something will go wrong, I'm just in a place where there's no reason not to. And all my bikes have shimano XTR, or XT, and they take no more than 15 mins to bleed both brakes. Though I have let it go out to two, maybe it was 3 months, one winter when there were no races, and I definitely had an issue with loss of power when riding extended long downhills

4 years of over 40 days of mtb racing per year and not a single mechanical in that time other than some chain drops one race due to a clutch that broke on a rear xtr derailleur mid race - I'll stick with my paranoia

bikemaniack
Posts: 331
Joined: Thu Jul 16, 2009 9:33 pm

by bikemaniack

As we can see it's very personal thing.

CGT
Posts: 342
Joined: Fri Jan 05, 2007 5:33 pm
Location: Stockholm, Sweden

by CGT

bikemaniack wrote:As we can see it's very personal thing.

Yeah, but the question is "How often do you need to bleed hydraulic disc brakes" (on a XC bike nonetheless), and the answer is definitely not once a month. Some of you might do so, but it's definitely not needed.

bikemaniack
Posts: 331
Joined: Thu Jul 16, 2009 9:33 pm

by bikemaniack

maybe the question should be "how ofter you should...."

afalts
Posts: 157
Joined: Thu Mar 08, 2012 3:20 pm

by afalts

CGT wrote:Yeah, but the question is "How often do you need to bleed hydraulic disc brakes" (on a XC bike nonetheless), and the answer is definitely not once a month. Some of you might do so, but it's definitely not needed.



Totally agree. Not needed. Just a personal choice.

Things that I think would require a brake to be bled more often:
- sustained descents with heavy braking, i.e. heating brakes up a lot and keeping them at high temps (this is just from personal experience between my trail and DH bike, same brakes, same climate, but my DH bike needs bleeds way more - always a lot of air in there)
- Wet riding (call it a sealed system all you want, I still believe that grime (brake dust??) makes it way into the calipers - Especially after living in a wet climate, and seeing the fluid that comes out of a brake line there, vs in a dry climate)
- I also remember reading that water can seep into the system, and dissolve in DOT, but not mineral oil, which would be reason to bleed brakes more often if in wet/humid climates

Others?

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