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  1. #1
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    help. Disc brakes only rub when riding

    Like the title says. I can spin my rear wheel for days and it won't touch, but as soon as I get on the bike and start pedaling it's rubbing hard. I had to walk my bike back from class because I didn't want to damage the disc or pas it was rubbing that bad. Also, it stop rubbing if, when I am riding, I lean the bike to the left. Any fixes? Brakes are tektro novela.

  2. #2
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    Re: help. Disc brakes only rub when riding

    There is play in your wheel. Either loose skewer/nut or loose bearings. Grab your wheel it should NOT have any side to side play.

  3. #3
    because GIANT
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    yeah, something is loose or bearings have too much play

    normally, sometimes rub will happen anyway with discs, but just a tiny amount...
    should be possible to tune out all rub [except on floating rotors]

  4. #4
    Fat-tired Roadie
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    What bike? Quick release axles or one of the new kinds?
    "Don't buy upgrades; ride up grades." -Eddy Merckx

  5. #5
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    Wheels mounted loosely and/or slack bearings are the usual causes.

    But there's also the possibility of adjusting them to "ride spec" instead of "bench spec", just like you fine-tune your shifter cable tension based on riding instead of free spins on the bench. Mechanical brakes allow this.

    Here's how to do it: back out one pad to see if the brake still rubs while riding. If it does, adjust the pad back to its initial position and back out another pad. Repeat until you've figured out which pads rub while you ride, and back them out just enough to make rubbing go away. (Very slight rubs at one or two points may be acceptable: if you can't get it perfect, at least the situation will improve.) Once you've done that, move the opposing pads gradually closer until you have a bite point you prefer.

    Long story short: adjust the pad positions based on riding instead of free spinning.

    As a result the brakes may rub a bit when you're off the bike, but not while you're riding and that's what counts.

  6. #6
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    Also spoke tension. worth a check. Not as common, but I've seen it on one of my bikes that the disc drags when corner/leaning, and after tensioning the spokes, it goes away.

  7. #7
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    Spoke tension shouldn't affect the rotor orientation at all. Most likely you just torqued down the wheel on the bike better than before, after it was off the bike.

  8. #8
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    I have a similar issue... my rear wheel has a constant rub sound whenever it spins without me even applying the brakes. The guy at the bike shop told me it just needs a new brake pad, but they didn't carry any brake pads that would fit my brakes. He assured me it would be fine in the meantime until I was able to get a replacement, so I haven't worried too much about it.

    Although now after reading this thread, I thought I'd maybe just get a 2nd opinion as to whether that's actually the cause. Not intending to hijack the thread, but I figured this was relevant enough to justify not starting a new thread about a similar issue.
    2010 Specialized Stumpjumper Comp Hardtail

  9. #9
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    Quote Originally Posted by Saul Lumikko View Post
    Spoke tension shouldn't affect the rotor orientation at all.
    Normally, I'd agree. For some reason, it did. I tried re-seating the wheel, adjusting QR tension, pad adjustment, removing & re-installing the brakes calipers, etc. Only went away after I adjusted spoke tension at a DIY night at the LBS. The spoke tension was really loose though.

    South-of-Nowhere,
    Kinda sounds like you're LBS is trying to sell you something. Are they mechanical or hydraulic? If mechanical, have you adjusted pad clearance (bolt on the back of the caliper and adjustment ferule at the brake lever)?

  10. #10
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    Pad clearance on mechanical brakes should be adjusted by dedicated knobs. Using a ferule to effectively shorten the cable (actually extend the cable housing) affects mechanical advantage.

    In any case, when a pad wears down it should not start to rub. If anything, a worn pad has more rotor clearance and a later bite point (if the brakes are mechanical).

  11. #11
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    My bike has Avid Elixer hydraulic brakes, only the rear wheel has the rubbing sound/issue. He wasn't actually trying to sell me anything, he'd just finished tuning it up to replace my old bike that had been stolen out of their shop. (long-ish story) He'd been working to get the rubbing noise gone, but concluded that it was just that it needed new pads, but that they didn't carry any brake pads that would fit and that I could easily find some new ones someplace like Performance Bike. Knowing next to nothing about hydraulic disc brakes, I just figured that was the case until I came across this thread today.

    All in all, they still work just fine, just a bit of noise and maybe some slight added resistance from the constant friction. Is there an easy way to adjust these, or would I be better served taking my bike to a different bike shop for a second opinion/adjustment?
    2010 Specialized Stumpjumper Comp Hardtail

  12. #12
    since 4/10/2009
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    Only two instances should you need new pads.

    1. The pads are worn. This kind of wear is visible if you remove the pads from the caliper, and there is absolutely no reason you should need to replace the pads just because they rub.
    2. The pads are contaminated. You will notice this by having little to no power when braking, and/or lots of noise when braking.

    If you have hydros and you have rubbing like that, there are very few problems that can cause it. First would be the caliper alignment. Simple. It's an adjustment. The second one is a larger problem. You might have sticky pistons. This can happen with any hydro brake. Sometimes you can clean/lube things up (google it) and get them moving again. Sometimes not.

    I had sticky pistons on a set of Magura brakes. I cleaned/lubed them until the frequency of doing that was just a bit too much (once every couple of months). The brakes were not rebuildable, so I replaced them.

    I dunno what kind of shop doesn't carry replacement pads for a pretty common brake. I work at a roadie shop and we have pads for Elixir brakes.

  13. #13
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    I had my bike in the shop several times to be tuned. The brakes have almost always rubbed a little. Few days ago I was working on my brakes to try again to rid myself of the rub. After cleaning & sanding & inspection of everything I could think of, as I was mounting the caliper I noticed the holes to mount the caliper were slotted. Ding ding ding, the lights came on! I mounted the caliper lightly tightening the bolts. I slid the caliper around lightly tapping the caliper with my knuckles til the rub stopped. Finished tighten the bolts & voila, no rub for the first time in a long long time.
    The bike doesn't make you go fast.
    You make the bike go fast.

  14. #14
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    Quote Originally Posted by South_of_Nowhere View Post
    I have a similar issue... my rear wheel has a constant rub sound whenever it spins without me even applying the brakes. The guy at the bike shop told me it just needs a new brake pad, but they didn't carry any brake pads that would fit my brakes.
    BS. bad pads don't cause constant rub. maybe you needs new pads for some other reason that the mechanic saw, but constant rub is caused by something else. I don't know why the bike shop didn't offer to order the correct pads for you if he didn't have them in stock, but that's another matter.

    I find that frame and fork mounting points for disc brakes often have uneven surfaces that make it impossible to properly mount a disc caliper. the surface needs to have all the crap scraped off it and and a flat, even surface "machined" into it. the LBS should have the tools for that if that's and issue. I often preempt this whole scenario by facing the brake tabs on new bikes that I build if I think they might be a problem.

  15. #15
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    Quote Originally Posted by mack_turtle View Post
    BS. bad pads don't cause constant rub. maybe you needs new pads for some other reason that the mechanic saw, but constant rub is caused by something else. I don't know why the bike shop didn't offer to order the correct pads for you if he didn't have them in stock, but that's another matter.

    I find that frame and fork mounting points for disc brakes often have uneven surfaces that make it impossible to properly mount a disc caliper. the surface needs to have all the crap scraped off it and and a flat, even surface "machined" into it. the LBS should have the tools for that if that's and issue. I often preempt this whole scenario by facing the brake tabs on new bikes that I build if I think they might be a problem.

    yeah sort of this...

    I had some avids on my monkey with monkeynuts, and they were perfect for a long time...one day after a simple flat repair back end started rubbin while riding. OK so I reseat wheel, no dice...checked my mounting and bolts and I set everything back correctly...stumped why it would rub when just before it did not.

    even loosened and recentered caliper. no rub off bike, thought it was OK, get on bike...rub rub rub...GAHHHH!


    anyhow....got out my alien knife and scraped off all the paint where mount is attached, bolted it down, good to go. odd that it changed but whatever... removing paint fixed it

  16. #16
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    Riding home from work last night, I had a long stretch of quiet road where I had my right side next to a concrete barrier, so I could much more clearly hear the noise from my rear brake. It's a near constant rub, but there is definitely a point that the rub is very noticeable, so it may be closer to the problem experienced by the OP, although the sound is the same whether I'm riding or not.

    The LBS I got my bike from is a non-profit, and usually only has parts that are donated. They sell a few brand new items, but mostly just accessories and not actual parts, which is why they didn't have a compatible brake pad. I originally had a Diamondback Response that I'd taken in for service, but it was stolen out of their shop when the mechanic stepped into the back. They had a 2010 Stumpjumper that had just been donated to them, so they gave me that in place of my stolen bike. (No complaints about the upgrade!)

    From what I'm gathering, it sounds like maybe the guy who was working on my bike maybe isn't too keen on disc brakes. He was trying to get the rubbing issue fixed for a solid 15 minutes before telling me that the pads were wearing out and that would probably fix the issue. There's another LBS that's much closer to me, and their lead mechanics have 20+ years experience each, so my faith that they might be a little more mechanically inclined is greater. Plus, they even have some special tool for facing the caliper mounting surfaces that they mention on their website, so it sounds like they are probably better equipped in general for whatever the cause may be.

    I'll try and see if I can find time to take a look and maybe try to see if I can make any adjustments on my own.
    2010 Specialized Stumpjumper Comp Hardtail

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