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Disk Brake Heating Up

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  • #31
    Thanks for pointing that out, Finnspin!!!! (I did not take the time to re-read the entire string before posting and missed your post. Sorry about that.)

    You should read the reviews on the T4. If I remember correctly, they talk a lot about how great the modulation is. I thought modulation would be important because with my old brake I would have to be very careful about not over-breaking when first engaging the brake. With the T4, I can brake hard even when first engaging the brake because it is so forgiving.

    BUT!! I'm guessing that the T4 gives up braking force in order to have improved modulation. The reviews say that the T4 does not have good braking force. (I read the reviews a long time ago, hope I'm remembering correctly...)

    I have to admit that I wonder what the best Shimano four-cylinder caliper would be like! My understanding is that it has great force, but who knows about the modulation.

    I find this topic all very interesting, but frustrating because there is such little data/experience out there with these brakes on unicycles. Thus my motivation for posting about my T4 experience.


    • #32
      If it comes to 4 piston brakes I can recomment the Shimano Saint. It has excellent braking power and great modulation. Very easy to control. Due to he solid caliper design plus ceramic pistons it has also no overheating issues at all.


      • #33
        Yeah, I sort of wish I bought the Saint!

        Does anyone have first-hand experience comparing the difference between ceramic and steel pads on a uni? I'm curious how big of a difference you actually feel on a muni.

        Also, as mentioned above, I have the T4 caliper with steel pads. I was concerned that the steel pads would be too aggressive and cause me to stop too quickly (low modulation). Not the case. I feel I could still use more braking power. I believe the reviews for the T4 caliper say that it does not have as much braking force as other calipers. So, I'm wondering how much of the lack of braking power/force that I feel is due to a single brake on a 29" unicycle while going down a 25% grade, or how much is due to the T4 not having as good of braking force as the Shimano Saint.


        • #34
          On mtb in the past I did compare the original organic vs metal pads on a shimano XT. My feeling was that the modulation is a bit better on organic. The braking power is lower on them. In case of vibration the organic can help, they tend to be quiter. However, I did not have noice with the metal pads as well. As braking power is higher and the wear is much lower on metal, I stayed with them.

          There are other pad makers as well. One of the best tested (high power) were always the trickstuff brake pads (available for most current brakes). I have no first hand experience here.

          On the Muni I never changed the original Saint metal pads.
          Attached Files


          • #35
            Well, I've been on a journey dealing with brake chatter from this 203 mm disk. Before I get into it, I'd like to thank kunstrasen again for sharing the design to stiffen the D'brake adapter's large cantilever arm.

            I copied Kunstrasen's basic design, but since my son has a 3D printer, I thought I'd design a nice (plastic) bracket to clamp onto the KH frame. Also, I noticed that one of the M6 threaded mounting holes on TRP's "disk brake adapter" (a.k.a., the standard mountain bike bracket that fastens to's D' Brake Adapter to position the brake caliper at the correct location for the 203mm disk, phew...) was nicely pointed in the direction of the KH frame.
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            So, I though I could easily lengthen the M6 screw and then hold the extended screw with the 3D printed bracket mounted to the KH frame. The design worked sort of nice. Check out the pic below:
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            The problem was that I did not buy a longer M6 screw. I tried to wedge a rod between the 3D printed bracket and the "disk brake adapter". (Figuring that the rod would always be in compression.) After a few rides, the relatively flimsy 3D printed bracket became lose and the rod fell off.

            So, for the 2nd design attempt, I still used a relatively weak 3D printed bracket, but this time I got rid of the original M6 socket head cap screw and bought a 4" long M6 threaded rod. I then used the threaded rod to mount the Slate T4 caliper while the 3D printed bracket held the other end of the threaded rod (still just used compression between the 3D printed bracket and the threaded rod). Two pics below:
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            This worked great for several weeks. But, I've been braking pretty hard and either from yielding the plastic bracket, or creep, or low cycle fatigue, the 3D printed bracket started to twist on the frame and under really extreme conditions I could hear the brakes start to make noise (I believe this is the precursor to chatter once the bracket became even looser).

            So, I bit the bullet and redesigned the bracket out of aluminum. I know that the bracket is huge, but this 3rd try has got to work! Also, I've threaded the M6 rod into the aluminum bracket. Super stiff... Below is my final design. if this does not work, I'm biting the bullet and buying a 180 mm disk and the Shimano Saint caliper...
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            Look at how little clearance there is between the disk and the bracket. Hope this is OK. It was Ok for ~6 weeks of riding with the plastic bracket (and that bracket had even less clearance because of thicker walls).
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            In a few weeks, I'll let you know how this works. My guess is that it's going to be super solid and I'll be able to brake hard and fast with no chatter!


            • #36
              Wow. Looks like you spend a lot of work and time. Maybe buying a disc frame (e.g. Oracle frames are not too expensive, at least here in Germany) would have been easier. But that is just a boring stock solution.

              Good luck with your latest version. Looks pretty solid to me.


              • #37
                An interesting fix for the poorly desiged D' Brake Adapter. I think a welded bracket on the frame would have been better and it would be a lot easier to remove the wheel when needed. A good tig welder could add a bracket on the frame for a clean solution to the problem.


                • #38
                  Originally posted by JimT View Post
                  An interesting fix for the poorly desiged D' Brake Adapter. I think a welded bracket on the frame would have been better and it would be a lot easier to remove the wheel when needed. A good tig welder could add a bracket on the frame for a clean solution to the problem.
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                  Not as pretty as SanJoseUnicyclists solution though, but it has worked well so far. My next unicycle will get a frame with a proper mounting tab though.

                  Does anyone have first-hand experience comparing the difference between ceramic and steel pads on a uni?
                  I've only had metallic, semi-metallic, and resin/organic. To be quite honest, I didn't feel as much of a difference as many people would say, neither in performance, modulation, noise or wear. From the tests in magazines I've read, they often find that the presumed characteristics of materials often are not reflected in the test results, there are organic pads that last longer than some metal ones, really quiet metal pads, etc. So it's not just a question of material, but the specific compound any manufacturer uses.
                  In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move. -Douglas Adams.


                  • #39
                    Finspin, I love your solution! Simple and like you said, it did not take a lot of time. I'm a product designer. So, I do this type of stuff for a living. I just could not help going overboard on this design (just wish I had the time and machining capabilities to put a little industrial design into it)... Also, like you said, I don't need to remove this extra bracket to take off the wheel.

                    I agree about not being able to tell the difference with the different brake pad materials. I was very surprised that after spending ~$300 on this (somewhat) top of the line disk brake that I could hardly tell the difference when compared to the original $100 brake from UDC. The only difference being that this nicer brake does not overheat. If I was not riding steeper hills, I'd be very happy with the $100 brake.