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  • #16
    John, I think you missed something. The cranks they're currently using come in both square and ISIS, in a large variety of sizes. http://www.sinz-racing.com/drivetrain_home.html
    There is nothing worse than a gross exaggeration.

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    • #17
      Originally posted by johnfoss View Post
      The biggest drawback on your current model is the square taper cranks. As a disc brake is kind of a high-end add-on, it would seem much more likely to appeal to the users of splined hubs these days. Hopefully you have an ISIS version in the works.
      Originally posted by Mountainuni1
      wide range in sizes from 115-180mm square taper & 135-180mm ISIS lengths at an affordable cost
      Sounds like they've tried it with both.
      "Hedgehogs - why can't they just share the hedge?" (Dan Antopolski)

      "I would absolutely recommend a 29er to anyone who didn't prefer a larger or small wheel." (Mikefule)

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      • #18
        Looks interesting, but I'm wondering if this braking system is better than the magura hydraulic rim brake, or just another equally good option. For me the HS33 provides an extremely powerful and sure stopping force, and you can modulate the braking very precisely. It also seems that if the wheel became tweaked, the disk would "wobble" just as the wheel would, making it less effective with the high/low spots.
        Last edited by MuniAddict; 2010-03-01, 06:34 PM.
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        • #19
          Originally posted by MuniAddict View Post
          Looks interesting, but I'm wondering if this braking system is better than the magura hydraulic rim brake, or just another equally good option. For me the HS33 provides an extremely powerful and sure stopping force, and you can modulate the braking very precisely. It also seems that if the wheel became tweaked, the disk would "wobble" just as the wheel would, making it less effective with the high/low spots.
          Wouldn't the same be true for rim brakes? If the wheel is not true.... I get rubbing of my pads.

          Plus.... I'm pretty sure the axle would have to be bent for it to affect the rotor as it is attached to the cranks, not the wheel specifically. Maybe I'm seeing this wrong but for the rotor to wobble, the crank would also have to wobble..... right?

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          • #20
            Other than some occassional rubbing with a rim brake, it's hard to see an advantage to a disc, but as a gear whore I feel the call...

            One thing, I don't want to weld anthing onto my Ti frame that won't be relevant down the road. However, I do have a Nimbus frame kicking around that would be okay for a little weld.

            Why not a bolt on bracket? More saleable for sure.

            As to abuse, the location of the disc is likely a safer place than all the brake hose and such on a rim brake, as my recent bent steel braided hose can attest.

            Heat will be insignificant with a steel disc, maybe with aluminum it might be an issue. Keeping in mind that we're not doing emergency stops or traveling at bicycling speeds, there should be a lot less heat build up than on a bike. Socks and shoes should be fine protection.

            I wondering how much sensitivity you can get from the disc, that's a lot more braking power than a rim brake
            I dream of hamsters and elderberries

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            • #21
              schlumpf....

              Originally posted by munirocks View Post
              I would love to test these but my main unis are KH, so they would require another brake mount. I do have a nightrider too, though.
              Schlumpf compatibility would be awesome. Will that be possible?
              if Schlumpf uses conventional isis cranks, then yeah. its the whole idea of using cranks for the brakes, you don't have to modify wide hubs or geared hubs.
              Retrofit Disc Brakes to your existing unicycle today!

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              • #22
                I think it makes perfect sense for a road going uni. There seems to be a lot of worry about hitting the disc with you foot/ankle, but in all of the time I've ridden bikes I can't remember ever hitting my foot/ankle against the chainwheel. I like the idea of a mount that bolts on, or maybe an endless band like the way road bike brake levers mount.

                I think you could expect better modulation with a disc brake on a 36'er than a rim brake. If you think about it there is more leverage between the rim and the disc, and so you should be able to get finer control; although, not stop as quickly. I also like the idea of using a cable brake rather than a hydraulic. The cable brake would allow for a simple drag lever in line with a standard brake lever so that you could have the best of both worlds.
                "A properly ridden unicycle is like an object in orbit: constantly falling but never landing." -Diogenes

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                • #23
                  I was thinking of having an adaptor made that would screw onto the crank arm like a freewheel on a trials bike crank. It would then allow you to use standard 6 bolt rotors.

                  My fist thought was that people would rather have a standard disk rather than a oddball disk that may or may not work properly with various calipers. You loose a point there

                  But

                  You found a readily available crank in almost all usable sizes for unicycling where you would need a brake and allow the use of other (bike) cranks without modification to be used. +1

                  Are you planning on making various sized rotors? I would be curious to see if 203mm rotor would feel similar on a 36er as a 160 would feel on a 26.


                  One suggestion I would make right away though would be to make the rotors compatible with Hayes, Magura, and Avid calipers, as far as I understand it they need a slightly wider braking surface than the Shimano calipers but the braking surface looks very wide so those calipers you mentioned might just be the ones tested and confirmed to work with the disk. Am I right?[/QUOTE]

                  when we modified a cheap crank for the prototype and bolted on a 160mm 6 bolt rotor, the bolts were 1mm away from the bearing holders -too close. when we decided to use 104mm bcd cranks with 160mm rotors, the bcd was too close. we're using 180mm rotor, and may also make a 203... but this is a drag brake. this rotor should work with all calipers, as it did with shimano. we need the feedback before we build every option. These are the most common usable standards out there. I'm glad you like the idea.
                  Retrofit Disc Brakes to your existing unicycle today!

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                  • #24
                    Originally posted by GizmoDuck View Post
                    Looks really nice- I think Disc brakes are the way to go especially for bigger wheels. Do you find it gets hot and is there a risk of burning your ankles on the brake? Also, what exactly are you patenting? The concept of attaching a disc brake to a bicycle crank has been discussed before, and at least one other prototype has been made, but this is the nicest I've seen so far.
                    The disk is an inch closer to the leg because it's outside the frame, but it's unlikely to touch the leg while riding. if you rest your leg against it in an other circumstance, after taking it to sunday river... well the risk is your own. how many people have hurt themselves on a chainring while riding their bicycles? you should be fine... but that's the feedback we're after. the last discussion of brakes on a crank was the prototype for this.
                    Retrofit Disc Brakes to your existing unicycle today!

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                    • #25
                      Originally posted by rob.northcott View Post
                      I would think the main problem with that would be that the Schlumpf ISIS axle has no stop for the crank, and apparently because of its design it can't use a spacer as a crank stop like other ISIS uni hubs, so you'd need to choose a crank that goes on just enough to get the disc close to the frame without hitting it. But as the OP says it works with square taper (which of course has no crank stop either) then presumably he's thought of a way round that.

                      - For use as a drag brake on a big wheel, is there enough metal there to disperse the heat on a long descent?

                      - How wide does that setup end up? It's hard to imagine from the side view, but it seems like it would end up with a big Q.

                      - I'd also be afraid of dropping it on a rock and bending the disc like somebody else mentioned, but that's a problem with discs on bikes as well - although unicycles do tend to get dropped more often than bikes. If I go out for a bike ride and drop the bike on the ground, it's pretty unusual. If I go out for a muni ride and DON'T drop it, it's pretty unusual.

                      Rob
                      We haven't thought our way around the lack of a crank stop spacer, just spacers between the mount and caliper as the square taper wears, remove spacers... There is no extra metal to disperse heat on the disk, but the crank seems like a great heat sink. as far as Q, it's the same as a chainring on a bicycle, conventional. Am... the seat and pedal seem to keep the disk away from the ground on crashes, however rocks could reach up and smack the disk, what can be bent can be unbent -kinda. I haven't had to hammer it flat yet, or even bend it yet.
                      Retrofit Disc Brakes to your existing unicycle today!

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                      • #26
                        Originally posted by Max_Dingemans View Post
                        John, I think you missed something.
                        Sorry about that. I seem to be having trouble editing my posts. Sometimes the edits won't "save" and there seem to be coding issues. That previous post should have had paragraph breaks in it, but they didn't get coded in...

                        Anyway, I think what Terry was saying could still apply, but not from wheel tweaking. A bent wheel would screw up rim brakes but not a disc. To do that you'd have to bend the disc, which is also a possibility if you have hard knocks against rocks. But could a disc brake be easier to straighten out?
                        John Foss
                        www.unicycling.com

                        "Who is going to argue with a mom who can ride a unicycle?" -- Forums member "HiMo"

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                        • #27
                          Originally posted by mikepenton View Post
                          Not only that, the centre of the pedals would be offset towards the side of the brake, possibly giving an uneven-feeling ride.
                          I imagine that it is significantly heavier than any rim brake?
                          (sorry, I'm being negative - it's a great idea and a simple solution to the desire for a disc brake)
                          We'll submit one for review! the cranks go on evenly, the part that holds the disk on is slightly outboard of the frame, yet still inboard of the person. hydraulic rim brakes are not light, if any weight penalty for a disk is a trade off for consistency if the rim isn't perfectly true, the rim surface is beat, if the wheel is covered in whatever... smooth, predictable, reliable.

                          a negative opinion to start is the most credible opinion once changed!
                          Retrofit Disc Brakes to your existing unicycle today!

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                          • #28
                            Originally posted by MuniAddict View Post
                            Looks interesting, but I'm wondering if this braking system is better than the magura hydraulic rim brake, or just another equally good option. For me the HS33 provides an extremely powerful and sure stopping force, and you can modulate the braking very precisely. It also seems that if the wheel became tweaked, the disk would "wobble" just as the wheel would, making it less effective with the high/low spots.
                            if you bent the axle, then maybe the disk brakes would be effected, but that's the least of your issues in that event. HS33's are great, but host the same issues that all rim brakes do. when you heat the pads, they glaze the rim, when you wobble the wheel, or goo the rim up with something, or get it wet, it's not as consistent as a disk brake.
                            Retrofit Disc Brakes to your existing unicycle today!

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                            • #29
                              as far as the problem you guys are suggesting, look at your frames. the majority of all nicks and dings on mine are about 8" up from the axle... and the ones that are closer are very small and because i did something completely out of the ordinary. the pedal and crank are like a big guard for the majority of the disc, but i wouldn't suggest crank grabs on that side.

                              it is a very original, simple, and useful idea, i like it, but i do have to question etching the name into the disc. it seems that the disc would be very reasonably priced, and significantly easier to produce without that.
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                              • #30
                                Originally posted by johnfoss View Post
                                Ulikely. For those of us who knock our ankles into cranks (we've all done it, right?), remember the disk is behind that, so probably impossible for actual ankle or leg contact. Except in a crash. That's where heat could be a factor, bringing you closer to the experience of motorcycling! Having the disc on the outside of the frame is of course not the optimum way to do it. You have that problem of possible rock strikes and off-centered-ness. But the reality of the situation is that building a system for inside of the fork would involve a lot more custom work, and would be quite a bit more expensive. The idea here is to bolt and weld something onto an existing unicycle rather than having to buy a whole new one. The biggest drawback on your current model is the square taper cranks. As a disc brake is kind of a high-end add-on, it would seem much more likely to appeal to the users of splined hubs these days. Hopefully you have an ISIS version in the works. From the tone of the OP, it sounds like you're ready to gear up for a major production run once testing is over. Sounds great! Just remember to have a realistic idea of the size of your market.
                                The pictured 29er is an ISIS hub, so we're ready for both versions, and I definitely understand the volumes, and potential market. Thanks for the feedback John, and words of encouragement!

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