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So far I've had issues with Avid (who hasn't).....given up on them and now use XT and XTR after recurring back to bar events mid ride and numerous LBS bleeding sessions.......they still sort of work but very late in the travel, almost to the bars then locking. Is it me???? I'm an old XC mincer and am 13stone and not very fast or rad at all
Help
Yes it is you. Sounds like your LBS can't bleed brakes. No real reason for that to happen.
My brakes, of all types, also resort to the same mode...
Back brake pulls to the bar. Front has no / little travel at all...
Oh, and the rears all seem to get pistons that pump out unevenly / stick so its nigh on impossible to stop the brakes rubbing 😡
There must be something you are doing. Ma be storing bikes upside down, or cleaning with odd stuff, or cheap brake fluid etc.
I have slightly faff Avid's on my bike, but Shimano and Hope on other bikes, and for the last 15 years have never been an issue.
if there's a little air in the reservoir once they're bled and you store them hanging from the back wheel it'll tend to migrate down to the caliper?
Easiest way to check is to bleed them and see whether the air comes out quickly from the caliper or not once you start moving fluid through.
This may sound odd but what rotors are you using?
The reason I ask is I was told (some time ago) that IF your lbs is bleeding them using the supplied Shimano 'bleed block' in the caliper they are setting them up on the assumption that you're using ice-tech rotors which are thicker than the standard ones. Whilst it's only .5mm or so it can make a difference once the pads & wheel are fitted, especially if the caliper is not absolutely centred over the rotor. The longer the brake hose the more exaggerated the impact (more fluid to compress per mm of movement) so the rear is usually where it's noticed.
I use 2 sets of wheels with the same XTR brakes & there is a noticeable difference between them - the only difference on the wheels being the rotors.
The reason I ask is I was told (some time ago) that IF your lbs is bleeding them using the supplied Shimano 'bleed block' in the caliper they are setting them up on the assumption that you're using ice-tech rotors which are thicker than the standard ones.
These brakes (like pretty much all others) have self adjusting pads. The size of the gap between pad and rotor is set by the design of the piston seals.
The simple answer is that whoever bled the brakes didn't do it properly, or there is a leak (which might be too small to be visible).
p.s. a properly bled brake won't care if it's hung upside down as there won't be any air to migrate out of reservoir.
These brakes (like pretty much all others) have self adjusting pads. The size of the gap between pad and rotor is set by the design of the piston seals.
As has been mentioned on [url= http://singletrackmag.com/forum/topic/xt-brakes-lots-of-dead-stroke ]another brake thread running[/url], this isn't particularly effective on some Shimano brakes which is why people take wheels out & pump the levers a few times to adjust the pistons' position. If the spacing is too wide to start then it's much more likely the 'self-adjustment' won't make up the difference.
I've heard of this self adjustment of the pads, but I can't for the life of me figure out how that could be. But I'm not a brake engineer! However, I tend to bleed with some gash pads rather than the yellow spacing block for the reasons mentioned above. Bled on hose trimming 3 years ago, still solid. Year round peak riding and uplift days!
Do you boil them? If not then it's bad parts or bad bleeding.
Are you using Shimano hoses?
Goodrich etc are a much larger bore (XTR is even smaller again)which require more fluid transfer than the lever is designed to give, which can cause this problem, also as the pads wear the reservoir in the lever is not big enough so you effectively run the reservior dry
Hose bore has no effect on how much fluid is needed to operate the brake. If you put a fixed volume of fluid into a hose that same volume will come out the other end regardless of the bore size.
Yes you are right.
I'm confusing myself with my set up where I use XTR levers with Saint claipers. So my problem is that the caliper needs a greater volume to mover the pistons
Leak from seals?
matt_outandabout - MemberMa be storing bikes upside down
If the brakes are bled right, this isn't a problem... Just a symptom of a bad bleed, but very common for all that.
The rotors are whatever comes with XTR.........our LBS's top man is the only on I let touch my bikes...he maintains our island MTB champ's bikes (Elliot Baxter...probably not as famous as we think he is) I am crap so can't/don't/won't touch my own brakes....I do sometimes get the burning smell but we have some gnarly long descents to cope with any everybody's brakes smell...I am however thinking along these lines a bit now.....don't know how to change things .on..shitty rocky hills i need to control speed...
Anyway Magura MT8s on the Carbine to come..????
From my experience with Shimano brakes especially the newer ones is that they pull in a lot then hit a bite point where you need very little modulation to get full power. On mine if your reach adjustment is wound out then they will pull to the bars at about the same time as they hit the bite point.
Pump the pads out a bit before you do a bleed. It's fairly trial and error to get the 'bit' just right - too far and you get rotor rub with new pads. I had the same problem, but the brake bites instantly now.