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  1. #1
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    Brake rub on pedal stroke only?!

    My setup is a 2008 Trek Fuel EX 8, XT brakes, Mavic 819 wheels, XT hubs, 160mm shimano rear rotor. I am not a small rider at 6' 235 lbs.

    I upgraded brakes from avid juicy's to XTs and I haven't been able to get my rear brake adjusted right. I have gone to the LBS to have them adjusted with rotor true'd without success. Bike leaves bike shop with no rubbing and no sounds coming from rear brake. I get on my bike and pedal hard, my rear brake starts rubbing. If I coast, there is no rubbing. Is the frame flexing? my wheel flexing? Are the clearances on the shimano brakes really that tight?

    Any help is appreciated.

  2. #2
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    Most likely your frame is flexing as you pedal, especially given your weight.

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    I dunno, I never had this problem with the avid juicy's....I read that it could be play in the hub or the skewer isn't tightened enough. Might take it to LBS to get hub looked at.

  4. #4
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    Could also be that the brakes were overfilled during the bleed reducing clearance between pad and rotor.

    Rotate the brake lever so that it is horizontal, pop the cap and diaphragm on the master cylinder reservoir, reset the pistons so that they are flush with the body of the caliper, replace the diaphragm and cap, then wipe up the drips with isopropyl.

  5. #5
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    Thanks for the response. Is there any way of knowing it is overfilled without opening it up? Anything I can see from the caliper operation that would indicate this?

  6. #6
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    You've mentioned that you heard that it could be that the rear skewer may need to be tightened which is what I suggested. So, did you crank it down?

  7. #7
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    Quote Originally Posted by Cable0guy View Post
    Most likely your frame is flexing as you pedal, especially given your weight.
    This and potential flex on your wheels too.
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  8. #8
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    Yes, I cranked down this morning and tried riding again before going to work...still rubbing when I ride it. Worse when I pedal.

  9. #9
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    Quote Originally Posted by drm31078 View Post
    Yes, I cranked down this morning and tried riding again before going to work...still rubbing when I ride it. Worse when I pedal.
    I'm just guessing, but could it be you have gained some weight since you changed the brakes? That could account for some flex in the wheel/ frame, right? I had a bike that used to creak a lot, but when I lost weight, the problem lessened.
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    Zarr, what are you implying!? Haha...although I could probably lose a few (or many) pounds, I gotta think a bike should be designed to accommodate me. I called the shop and I am going to bring it in tomorrow...

    Reading more and more, the XT hubs seem to have some reliability problems with the cones loosening. Perhaps there is some play in the hub under load. With what seems to be a tight tolerance between the caliper/rotor, it probably doesn't take much play to get them to rub. I will let you all know.

  11. #11
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    OK, then perhaps worn rear suspension bushings/bearings/pivots?

    Loose spokes on the rims?

    Worn rear hub bearings?

    Loose rotor?

    Loose cailper mounting?

    Have you taken your bike on a normal long ride to see if the new brake sysem wears in?

  12. #12
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    Quote Originally Posted by drm31078 View Post
    Zarr, what are you implying!? Haha...although I could probably lose a few (or many) pounds, I gotta think a bike should be designed to accommodate me. I called the shop and I am going to bring it in tomorrow...

    Reading more and more, the XT hubs seem to have some reliability problems with the cones loosening. Perhaps there is some play in the hub under load. With what seems to be a tight tolerance between the caliper/rotor, it probably doesn't take much play to get them to rub. I will let you all know.
    Nah partner, I'm not trying to imply anything. I weigh more than you do (260),so far be it from me to imply you are too heavy. But when you are dealing with close tolerances like we do with our bikes, weight can definately be a CONTRIBUTING factor in misalignment issues, could it not? So far all the replies you have got sound good to me. Let's cover all the bases to get you on your way. I am currently building more than one bikes myself right now, so I want to thank you for your thread. You are on the right website to learn, I know that much. Hang in there. Continue to post up & help out when you can. And pay no mind to hecklers and trolls. thanks again.---zarr
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  13. #13
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    Sometimes for me if the rotors get grungy they will start doing what you describe. Most often when I clean the rotors it will stop doing it. Good luck!
    I'm not a vegetarian because I love animals, I just hate vegetables.

  14. #14
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    Might not help, but I bled my brakes in the cold and when the temps went up they would get a little tight and rubbed easy. Got the rubbing when mashing hard, rebled them while hot and problem went away.

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    Quote Originally Posted by drm31078 View Post
    Thanks for the response. Is there any way of knowing it is overfilled without opening it up? Anything I can see from the caliper operation that would indicate this?
    Symptoms would be:

    -Reduced clearance between pad and rotor (duh, I know)

    -Weeping oil from somewhere in the brake system: around the pistons, around the MC reservoir, or the lever plunger (all of these are very unhappy things requiring replacement of parts)

    -Difficulty in resetting pistons "all the way." If it is, DON'T try and force them back in with the reservoir cap on as it strains the seals. Shimano makes their seals out of tissue paper, in my experience.

    -"Tight" brake levers. Rear brakes will often feel less tight than the front, because the fluid travels through more line (which may expand under pressure). That is the normal condition. If it is the case that your rear lever feels tighter than the front, it is a sign of overfill.

  16. #16
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    You might get some answers by posting up some threads in the Clydesdale/Tall Riders forum which is dedicated to heavier and tall riders. someone there might even have the same bike/ problem you have. You will get less responses there though, because the forum is mainly meant for those riders.but it is very helpful for heavy/tall riders.
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  17. #17
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    Well, I took it to my LBS, which is a Trek store. They spent a better part of the day doing the following:

    Check caliper alignment
    True slight wobble in rotor
    Serviced hub (tightened slightly)
    Checked spoke tension
    Checked brake fluid
    Checked rear triangle for cracks
    Checked sprocket tightness

    Result = they said that it doesn't sound as bad, but the rub is still there on a hard pedal.

    Basically, they could not figure it out and are attributing it to frame flex. Keep in mind these are not big guys riding the bike. They also said if this was a new bike, that amount of frame flex would not be acceptable. However, since it's an older bike, Trek will not warranty the frame for some noise from the brakes.

    WTF. Try another bike shop?

  18. #18
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    Quote Originally Posted by drm31078 View Post
    Well, I took it to my LBS, which is a Trek store. They spent a better part of the day doing the following:

    Check caliper alignment
    True slight wobble in rotor
    Serviced hub (tightened slightly)
    Checked spoke tension
    Checked brake fluid
    Checked rear triangle for cracks
    Checked sprocket tightness

    Result = they said that it doesn't sound as bad, but the rub is still there on a hard pedal.

    Basically, they could not figure it out and are attributing it to frame flex. Keep in mind these are not big guys riding the bike. They also said if this was a new bike, that amount of frame flex would not be acceptable. However, since it's an older bike, Trek will not warranty the frame for some noise from the brakes.

    WTF. Try another bike shop?
    Either that or take one less bite off that hamburger.
    hahahaha
    Hey, i'm sorry man. I just couldn't resist the moment.
    I'm sorry.
    Nah, but seriously, if you did all that, maybe you can get a brakeset that permits more pad adjustment. I am beginning a couple of builds using avd BB7 mechanicals, which have ability to adjust both the inner & outer pads independently. Not sure how they work yet though.Come to think of it, maybe there's ways to shim or file down some part of the mounting process to allow enough space between the pads to keep them from rubbing.Take a good look at the way everything lines up. Twweking might help.
    Either that or Slim-Slow.
    Ask around in the Clydesdale furum. Might help.
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  19. #19
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    Find out which way the calipar moves when pushing hard and adjust the gap accordingly.
    lean forward

  20. #20
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    Quote Originally Posted by drm31078 View Post
    Well, I took it to my LBS, which is a Trek store. They spent a better part of the day doing the following:

    Check caliper alignment
    True slight wobble in rotor
    Serviced hub (tightened slightly)
    Checked spoke tension
    Checked brake fluid
    Checked rear triangle for cracks
    Checked sprocket tightness

    Result = they said that it doesn't sound as bad, but the rub is still there on a hard pedal.

    Basically, they could not figure it out and are attributing it to frame flex. Keep in mind these are not big guys riding the bike. They also said if this was a new bike, that amount of frame flex would not be acceptable. However, since it's an older bike, Trek will not warranty the frame for some noise from the brakes.

    WTF. Try another bike shop?
    I hate bike shops almost as bad as I hate car shops.all they are is pocket Drano. But if it wasn't for them, I never would have got so interested in building bikes.it's because of their shyster rip-off actions a lot of folks learn about bikes I guess. one thing I know...if you keep trying you WILL solve your problem and any other bike problem.. without them. Just keep posting up... the guys on this site won't let you down.
    Hang in there.
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  21. #21
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    As I mentioned earlier, go for a long, hard ride and work the Hell out of the brakes. They may self adjust or wear in.

    If not, then it looks like it's time for a brand new, late model frame.

  22. #22
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    Quote Originally Posted by ambassadorhawg View Post
    As I mentioned earlier, go for a long, hard ride and work the Hell out of the brakes. They may self adjust or wear in.
    That may definitely be the problem and I would not be surprised if it solved your issue.
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  23. #23
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    Let me show you how wack the Local Bike Shop is...and how a good nap helps me (a old dude ).Well, not that old. to think.
    Why didn't the LBS have the sense enough to put a different wheel/tire on your bike so you could test ride and find out if your frame is flexing? Boy, they're a big help, aren't they? that's why I try to learn as much as I can from other sources. I get sick just looking at the bike shops where I live.Every single one of them has tried to rip me off...exept one and he went out of business. he was a nice guy too.(Sad).Try to get e hold of a different wheel at least long enough to try to find out what the problem might be.
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  24. #24
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    What kind of quick release do you have??

    Good ol shimano xt hold things very well.

  25. #25
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    I really think you should try letting some fluid out of the system. Make sure the pistons are flush with the caliper body before you put the res cap back on. Microliters of fluid can be pretty significant in pad clearance issues.

  26. #26
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    Quote Originally Posted by zarr View Post
    ................Why didn't the LBS have the sense enough to put a different wheel/tire on your bike so you could test ride and find out if your frame is flexing?.....................
    that makes the most sense...
    with it happening mostly when you are pedaling it's giving the clue that when you add tension the chain is pulling the cassette and hub forward and twisting the rotor inside the caliper....

    OK, there is only really three "parts" that could be the issue.
    1. Hub, including skewer (the rest of the wheel has no bearing on the brakes)
    2. Frame
    3. Brake caliper it's self or new (thicker) pads.


    My first guess would be the Hub especially since you mentioned it was a Shimano hub. They are famous for getting the cup slightly out and having the bearings come loose when inserting into the frame. Hit up a ride buddy who has a different wheel/hub combo and ask to switch out the wheel for 10 minutes and see it it's still an issue. You can also just shine a flash light in front of the brakes, grab the wheel and frame and try pushing side to side pretty hard while watching through the brake caliper.. if the hub is moving/loose you're likely see it.

    I did once see yrs ago when a frame had worn where the bolt hit the dropout (didn't have quick release back then) and would slip forward under pressure, when you'd pedal, not likely with a fairly new frame like a 2008

    I highly doubt it's frame flex as it didn't happen before with the other brakes, the tolerances might be a tad tighter with the new calipers but most are about the same, I certainly wouldn't rule it out as all frames have some flex, and you're not exactly on the light side. But that area of the frame is about the stiffest there is on the whole bike because of the brakes and what the manufacture has to do in that area of the rear triangle to support the forces applied to that section of the rear triangle when you hit the brakes hard for a quick stop.

    I would try the "go out and ride" everyone is saying, could just be that the new brakes have thicker pads and tighter tolerances so a good beating could bed everything into place, but I still think the underlying problem is still there,.. hub is moving apart/different than the frame... I keep going back to loose/bad bearings or all around hub issue.

  27. #27
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    Quote Originally Posted by half_man_half_scab View Post
    I really think you should try letting some fluid out of the system. Make sure the pistons are flush with the caliper body before you put the res cap back on. Microliters of fluid can be pretty significant in pad clearance issues.
    Wow, thanks for all the support. Turns out the Trek store has a parent store in town that I took it to last night. I explained my frustration and they seemed sympathetic and I believe the owner/manager started working on it. AND, he is about 4" taller than me and is probably 260lbs. I asked him about frame flex and he said he gets no rubbing on his bike unless he is cornering hard, so that should not be the problem. He worked on it for about 20 min until he decided he needed to keep it for the day. He says something weird is going on and thinks the rear brake doesn't feel quite right, but it's subtle. Mentioned maybe bleeding it, but wanted to check a few other things first. I will let you know what I find out.

  28. #28
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    Just got a call from the 2nd LBS and the head technician said that he went through every part of the rear end and could not find a problem that would result in rubbing (which is still happening). So he thinks there is a problem with too much flex in the rear triangle (same result as 1st LBS) perhaps due to faulty heat treatment. They spoke to their Trek rep and they are putting in a warranty claim for a new rear triangle with new pivot hardware. Should be here in a week. Sounds odd to me, but LBS said they can't find any other symptom causing it. He said the rear triangle may just come painted black without any of the detail on it (ie. red stripe, etc.). Kinda disappointing, but if it fixes the problem its okay by me. If it doesn't fix the problem, I won't be too happy. We shall see....to be continued...

    Thoughts?

  29. #29
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    I'm starting to worry with all the talk about shimano hubs loosening up. I just ordered a set of wheels today with XT disc hubs (29er).I heard from someone to put some locktite on the axle threads to keep everything in place. I will try that if I have any problems.I'd rather do that than stop eating Pizza. With a capital P.
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  30. #30
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    Quote Originally Posted by zarr View Post
    I'm starting to worry with all the talk about shimano hubs loosening up. I just ordered a set of wheels today with XT disc hubs (29er).I heard from someone to put some locktite on the axle threads to keep everything in place. I will try that if I have any problems.I'd rather do that than stop eating Pizza. With a capital P.
    get yourself some cone wrenches now, you'll be using them!!

    Honestly i HATE shimano hubs, but... if you can get that just perfect sit they are about the sweetest rolling wheel there is, problem is that the chances you get it just perfect are slim, very slim.

    the biggest thing is to actually have them JUST a tad loose, as the cup and cone style bearings tighten just a tad when you crank down the quick release. then add the stupid 2 bolt locking system, which doesn't work as the two bolt in all reality,.. just become one. And when you slide the wheel into the frame one bolt always catches the frame and spins a bit and then your bearings are all out of whack.

    not worth the trouble. Sealed bearings work FAR better than cup and cone that aren't set right.

  31. #31
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    To the OP-Don't forget to play your Trump card if you have one if it's necessary. I googled up "recent mountain bike recalls" and cliked on "sports & recreaton related recalls". There is a list of recalls for various bike related stuff handed down by the CPSC there. Check that site and as many others as you can find to see if there is anything you need to know. ALWAYS check for recalls for ANYTHING you buy. Don't know where that thought came from... Must be the Angels...
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  32. #32
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    There are pads adjustment on the XT brakes right? Try playing with that. It might be that your new XT brake pads are a little closer to the rotor than your old Avids, causing the rub?

  33. #33
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    Quote Originally Posted by thomllama View Post
    get yourself some cone wrenches now, you'll be using them!!

    Honestly i HATE shimano hubs, but... if you can get that just perfect sit they are about the sweetest rolling wheel there is, problem is that the chances you get it just perfect are slim, very slim.

    the biggest thing is to actually have them JUST a tad loose, as the cup and cone style bearings tighten just a tad when you crank down the quick release. then add the stupid 2 bolt locking system, which doesn't work as the two bolt in all reality,.. just become one. And when you slide the wheel into the frame one bolt always catches the frame and spins a bit and then your bearings are all out of whack.

    not worth the trouble. Sealed bearings work FAR better than cup and cone that aren't set right.
    mmmm.I don't doubt what you're saying.I used Shimano hubs exclusively since 1995 and never had any issues- and they were only Alivio level.I always serviced them myself, but they were rim brake hubs.maybe the tolerances for Disc hubs have to be more precise? Well, I'll soon find out.Maybe I just always hit that "sweet spot".Well, at least now I know what to look out for. thanks for the tip. i wonder if solid axles and track nuts would help anything? Prolly depends on the thread count...and the Locktite couldn't hurt...
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  34. #34
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    Quote Originally Posted by Kaizer View Post
    There are pads adjustment on the XT brakes right? Try playing with that. It might be that your new XT brake pads are a little closer to the rotor than your old Avids, causing the rub?
    I asked both bike shops about this and they both said the XT brakes have more clearance than the avids especially with the servo technology.

  35. #35
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    What I'm saying is maybe you can adjust the widen pad adjustment a little to see if it still rubs?

  36. #36
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    LBS had the swing bar and pivot replaced under trek warranty due to it having too much flex. They replaced it with the 2009 champagne/white swing bar and pivot. It fixed the problem, no brake rub!

    Although cosmetic, the colors don't match at all and it looks terrible. I asked the LBS about it and they said it happens often and its beyond their control. I got the claim number and emailed trek about my disappointment hoping that they might help me out by replacing the front triangle (main frame) to match. I am waiting for a response.

    Has anyone had a experience like this? I mean, I paid $2400 for a bike that has a manufacturer defect, I would expect it to be replaced with matching parts? Frustrating.

  37. #37
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    Quote Originally Posted by drm31078 View Post
    Although cosmetic, the colors don't match at all and it looks terrible. I asked the LBS about it and they said it happens often and its beyond their control. I got the claim number and emailed trek about my disappointment hoping that they might help me out by replacing the front triangle (main frame) to match. I am waiting for a response.
    That's good that your problem with the brake rubbing got fixed. Nothing against Trek but don't hold your breath. I think they make a good product and it would make sense that when they cover something on warranty it should be the same or similar to the original because technically it was their mistake, if they do get back to you they will probably tell you that they are limited to stock on hand or something else like that. For your sake I hope I'm wrong but good luck with it.
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  38. #38
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    Quote Originally Posted by mtbnozpikr View Post
    This and potential flex on your wheels too.
    Most of your wheel flex occurs in the spokes and rims, the rotor is mounted on the hub. You'd have to be exerting A LOT of force to get the hub to flex or have a lot of play to get that.

  39. #39
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    I just got off the phone with my LBS's Trek Rep's boss. He didn't have too much sympathy with the mis-matched colors since they were close and it could have been worse. I tried to apply logic to the situation saying that my bike is not in the as-built condition due to Trek's manufacturer defect. But it didn't really work. He gave me two options:

    1) They would repaint my bike in a basic color with basic trek decals that would not say the model of the bike.

    2) They would sell me a matching front triangle (main frame) at a discounted price with installation. Basically it would be the 2009 EX8 front triangle (main frame).

    So I am going to see how much option 2 costs. It would be kinda cool to have a new frame for cheap, but I am not sure how cheap it will be. Anyone have any idea how much a 2009 EX8 front triangle (main frame) costs?

  40. #40
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    Quote Originally Posted by drm31078 View Post
    LBS had the swing bar and pivot replaced under trek warranty due to it having too much flex. They replaced it with the 2009 champagne/white swing bar and pivot. It fixed the problem, no brake rub!

    Although cosmetic, the colors don't match at all and it looks terrible. I asked the LBS about it and they said it happens often and its beyond their control. I got the claim number and emailed trek about my disappointment hoping that they might help me out by replacing the front triangle (main frame) to match. I am waiting for a response.

    Has anyone had a experience like this? I mean, I paid $2400 for a bike that has a manufacturer defect, I would expect it to be replaced with matching parts? Frustrating.
    i hope I helped some for you.Keep all your paperwork, make copies, keep the originals and seek some legal help.I hate to hear about folks getting ripped off. Just ALLWAYS check recall lists, etc. all the time.Just try your best. that's all you can do.
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