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  1. #1
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    Why are my disc brakes so bad?

    Summary: even after several months, the mechanical disc brakes are very ineffective.
    Their braking behaviour is "on par" with something I last experienced about 15 years
    ago with "single pivot" rim brakes.

    Details: Fuji Tread 1.0, Shimano 105, mechanical TRP Spyre disc brakes.
    The brakes were really bad at the beginning and I was told they need some time to work well.
    However, that never happened. I still can't get the bike to stop without braking from the drops
    (in contrast to my rim brakes where I only need one or two fingers applied from the top of the shifters).


    Is that problem just "inherent" in this disc brake model?
    Based on "reviews" I found online these TRP Spyre disc brakes are supposed to be "good".

  2. #2
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    Quote Originally Posted by Got Time View Post
    Summary: even after several months, the mechanical disc brakes are very ineffective.
    Their braking behaviour is "on par" with something I last experienced about 15 years
    ago with "single pivot" rim brakes.

    Details: Fuji Tread 1.0, Shimano 105, mechanical TRP Spyre disc brakes.
    The brakes were really bad at the beginning and I was told they need some time to work well.
    However, that never happened. I still can't get the bike to stop without braking from the drops
    (in contrast to my rim brakes where I only need one or two fingers applied from the top of the shifters).


    Is that problem just "inherent" in this disc brake model?
    Based on "reviews" I found online these TRP Spyre disc brakes are supposed to be "good".
    Ineffective, as in they will not lock your wheel?

    No, they don't. Sounds like they need adjusted, and probably did originally.
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  3. #3
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    "ineffective" as in "they require a lot of force on the lever to work",
    i.e., way more than I need for my other brakes.

  4. #4
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    Sounds like these are either:

    1) Improperly installed
    2) Improperly adjusted
    3) Improperly maintained

    Are the calipers properly aligned? Are the pad/rotor gaps correct? Are the rotors properly maintained? Is compressionless brake cable housing used?
    Also, mechanical disc brakes require more adjustments as they wear, is this being done?

    Small adjustments can make a big difference with disc brakes, much more so than rim brakes, IMO.

  5. #5
    Rub it............
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    The Spyres are probably the best road disc mechanical brake on the market right now. So I doubt it's the actual brake.

    My guess is that the pads and rotors are glazed. The front brake is probably not going to lock up with a 140mm rotor, but the rear should get close to lock up when panic braking.

    Pull the pads a take a picture. Post it up and lets take a gander.
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  6. #6
    'brifter' is a lame word.
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    I'm betting someone 'adjusted' them by pulling the cable tighter. This reduces the leverage that the actuating arm develops to basically zero. You have to adjust mechanic disc brakes by moving the pads closer to the rotor NOT pulling the cable.
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  7. #7
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    what size rotor?

  8. #8
    'brifter' is a lame word.
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    Quote Originally Posted by reptilezs View Post
    what size rotor?
    That would be absolutely the last thing that could be the OP's problem.
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  9. #9
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    I'm wondering if pad material might be part of the problem? Good metallic pads give great grip, but wear rotors out quicker. Softer pads don't wear rotors as quickly (and also don't squeal as much), but kinda suck at braking.

    Also, there was some bonehead who had this same problem because.......after every wet ride, he used to spray his rotors with WD-40!
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  10. #10
    'brifter' is a lame word.
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    Quote Originally Posted by No Time Toulouse View Post
    I'm wondering if pad material might be part of the problem? Good metallic pads give great grip, but wear rotors out quicker. Softer pads don't wear rotors as quickly (and also don't squeal as much), but kinda suck at braking.

    Also, there was some bonehead who had this same problem because.......after every wet ride, he used to spray his rotors with WD-40!
    Funny...Shimano and SRAM supply pretty much all of their disc brake systems w/ resin (organic) pads.
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  11. #11
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    Thanks for the comments, based on this feedback I took the bike to the store and the mechanic told me there seems to be some "glazing" and he fixed that -- now the braking is "acceptable".
    The brakes are barely used, so there shouldn't be any "glazing" from braking (no real descending, no prolonged braking), correct?
    Maybe the rotor/pads have been that way from the start when I bought it new from a Performance store and the "braking in" period didn't change that? (which would explain why braking never got better)

  12. #12
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    Disk brakes have to be 'used' to effective. New disk brake pads are not very good until seated in. If you get a disk bike, and just tool around the compound, they will never seat in.
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  13. #13
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    How much do they "have to be 'used' to effective"?
    I rode probably 200-300km with the bike.
    Moreover, back when I bought it I also rode a few kms while slightly pulling the brakes (nice workout :-) because the sales guy told me it would take only about 20 minutes of braking to get things settled.

  14. #14
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    >>I also rode a few kms while slightly pulling the brakes...

    This may explain the glazing, avoid "dragging" the brakes, especially on long descents. I typically seat new pads with few good hard but controlled tug on the levers. Also, I recommend routinely clean the rotors with isopropyl alcohol.

  15. #15
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    There are video's, I usually go to a 'hill' and do a few repeats. It's more than just dragging your brake.
    Your bike, probably never had the disks cleaned with alcohol before riding, probably got some oil or grease on the pads. Once that is done, new pads are required or they may be saved if the oil didn't get too deep into the pad.
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  16. #16
    Rub it............
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    Quote Originally Posted by nova_rider View Post
    >>I also rode a few kms while slightly pulling the brakes...

    This may explain the glazing, avoid "dragging" the brakes, especially on long descents. I typically seat new pads with few good hard but controlled tug on the levers. Also, I recommend routinely clean the rotors with isopropyl alcohol.

    Frequent cleaning of the rotors with alcohol starts the removal process of the brake pad material that you worked to get bedded into the rotor. The only time you should use alcohol on your rotor is if they are contaminated, glazed or brand new.
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  17. #17
    'brifter' is a lame word.
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    I'm still thinking that they're not adjusted properly. It's very easy to screw up cable operated discs. There are hundreds and hundreds of mechanics out there that have no idea how to do it properly, I know because I have to fix them all the time. If the arm that the cable pulls is rotated forward by simply pushing it and then attaching the cable OR using the barrel adjuster to 'tighten the brakes' they won't work. It's entirely possible to move that arm enough that the brakes won't create any power at all...zero. You have to attach the cable w/ the arm as it sits w/ no tension at all and then adjust the pads w/ their adjusting screws. Those brakes should feel just as powerful as any hydraulic system when adjusted properly.
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  18. #18
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    Routine does not mean frequent. Perhaps I could have said rotors need to be routinely checked and cleaned, if needed. But a complete rotor strip-down is a must when replacing pads.

  19. #19
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    Quote Originally Posted by Got Time View Post
    Moreover, back when I bought it I also rode a few kms while slightly pulling the brakes (nice workout :-) because the sales guy told me it would take only about 20 minutes of braking to get things settled.
    Yes, this is how you ended up glazing the original pads.

    The proper brake-in procedure is sort of the opposite of what you did. You actually want to brake VERY hard, from a fairly fast speed (but NOT all the way to a stop). Do that at least half a dozen times and the brakes will work great.
    Last edited by fronesis; 3 Weeks Ago at 03:48 PM. Reason: Fixed my mistake

  20. #20
    'brifter' is a lame word.
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    Quote Originally Posted by fronesis View Post
    Yes, this is how you ended up glazing the original pads.

    The proper brake-in procedure is sort of the opposite of what you did. You actually want to brake VERY hard, from a fairly fast speed all the way to a stop. Do that at least half a dozen times and the brakes will work great.
    NO! All brake pad manufacturers...be it bicycle, car, moto...state specifically do NOT brake to a full stop. Brake hard as you said but let off just before coming to a stop. Never stop fully when bedding pads. Also, you need more than 6 times, I believe Shimano says 15 or 20, can't remember. You'll be able to feel when the pads come in pretty easily.
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  21. #21
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    Quote Originally Posted by fronesis View Post
    Yes, this is how you ended up glazing the original pads.

    The proper brake-in procedure is sort of the opposite of what you did. You actually want to brake VERY hard, from a fairly fast speed all the way to a stop. Do that at least half a dozen times and the brakes will work great.
    This is pretty the similar to the bed-in procedure for just about every 'metallic' automotive brake pad. Specifically, they usually call for 5-6 HARD stops, followed by 5-6 Medium 'slow-downs' NOT ending in a stop, followed by a 5 minute cool-down with no brake usage at all.
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  22. #22
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    Let's be real, nearly every car on the road has disc brakes, yet how many motorist even know what bed-in is? Is this any better with cyclists on a disc bike? I think not. The point is most expect disc brakes to work regardless of whether or not they have been properly bedded-in. I suspect component makers have already factored this into their design.

    While glazing might be a contributor, it is not the root cause with OP's issue.

  23. #23
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    Quote Originally Posted by cxwrench View Post
    NO! All brake pad manufacturers...be it bicycle, car, moto...state specifically do NOT brake to a full stop. Brake hard as you said but let off just before coming to a stop. Never stop fully when bedding pads. Also, you need more than 6 times, I believe Shimano says 15 or 20, can't remember. You'll be able to feel when the pads come in pretty easily.
    I stand corrected.

    And now that cxwrench mentions it, I realize I didn't come to a stop when I bedded in those brakes just hard braking.

    Apologies for any added confusion...

  24. #24
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    Quote Originally Posted by nova_rider View Post
    Let's be real, nearly every car on the road has disc brakes, yet how many motorist even know what bed-in is?
    Most motorists don't service their own brakes, and the mechanic who installs them (if a decent mechanic) will do the bedding on a test drive after the installation.
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  25. #25
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    Oh well, that's what I got for "believing" what the sales guy(s) told me.
    Too bad the information how to "bed-in" the brakes isn't in the manual I got with the bike.

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