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Is there another crank standard that would be better than ISIS?

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  • #16
    I use PVC pipe for my spacer it work very well
    Roses are red, violets are blue, may I procreate with you so I can ride a g32!! - Alan hogan


    • #17
      @ nurseben- The picture of KH's prototype was in the 'pictures of your latest ride' thread, with some searching you might be able to find it.

      Find out about my latest Enduro XC rides and races at my blog.


      • #18
        I don't understand how that would be any different than what we have now with a spacer that fits between the crank and inner race of the bearing.
        Yeah, in a sense it would be no different, BUT, how much side load can the bearings take ,AND, what happend if the bearing pressure cause the spindle to move in the hub? They are just pressed into the hub.

        The idea I'm getting at is that this "washer" would be a hard stop, as if it were machined onto the spindle.

        If KH is making his cranks with pinch bolts, then I'm not the only one who has worked this out. I wonder when his cranks will be available...
        I dream of hamsters and elderberries


        • #19
          There isn't any side load on the bearings as the inner bearing race is pressed against the step on the hub before the spoke flange and the spacer then pushes onto the other side of the inner race, there is no side load onto the ball bearings / retainer itself.

          The spacer solution works but as has been said the alternative solution would be larger bearings to facilitate a machined stop in the correct place on the axle for the crank to be torqued against as per the ISIS specs. Although unlike spacers you would/could still get bearing so again we go back to the current setup which with correctly sized spacers is actually probably the best solution?

          I always loctite my crank bolts on once the crank has settled as I have trashed too many expensive cranks on my bikes from a lose bolt and literally one hard up hill slog (I ride single speed). Uni parts are so cheap compared to what I used to spend on my MTB that I am not to fussed if I have to change "stretched" cranks a few times a year


          • #20
            ok, I think I can answer some of the things here with reasonable authority.

            First I will say that I believe that the ISIS standard is great for unicycles. Here are some of the reasons why it does work for us.

            1. the shaft size is relatively small, so this keeps the bearings down in size, hence reducing the weight without major loss in the bearing properties.
            2. It is tolerant to the shock treatment that is common on unicycles.
            3. The use of spacers has 2 functions, it not only gives a hard stop for the cranks but also holds the bearings in place.
            4. The standard is established with unicycle manufacturers and this gives considerably greater choice to the users.

            Here is the ISIS standard (it looks like the main site is down).
            The Unicycle manufacturers actually work together on this (this would be unheard of in the bike industry). They follow the standard for the tolerances on the splines and all its basic principals. Although if you do the calculations on the tolerances you will find that the ISIS does not work as written (and never has); so they agreed to tighten the standard, working to less than half the specification tolerance! The "male cranks stop" is replaced with our spacers and are critical to the design, but even with our tighter tolerances, we have found that we need to supply different size spacers with different products and allow for creep if cranks are taken on and off regularly.

            I can not say why Nurse Ben is having so many problems with his fitting of the ISIS cranks. It is not the norm, by any means. The vast majority of riders have no problems with creep or creaking.

            Lets clears some things up.
            1. There is no torque setting in the ISIS standard.
            2. Venture 2 cranks are the same material and harness as the Moment cranks, it is also the same material and speciation used by some of the best of the mountain bike cranks... it is also considerably harder than most.
            3. Using a pinch bolt on deep splines as ISIS is not a standard solution.
            Roger Davies
   in the UK
            The UK's Unicycle Source


            • #21
              On my ungeared unis I use spacers and don't get these problems but with the Schlumpf hub one is not supposed to use spacers so the cranks creep inwards slowly. I had the first gen ventures on my G26 for some time but at some point they couldn't be tightened anymore. The tensiles seem to last longer.
              So for Schlumpf hubs it would probably be a good idea to have some other kind of stopper. Maybe one could make the splined part as a steel insert to minimize the creeping?
              Last edited by munirocks; 2012-02-13, 11:38 PM.


              • #22
                Thanks Roger, that's some good information.

                There is quite a bit of difference in how the cranks fit on the same hub(s). I have various lengths of KH (Al), Koxx (al), and QuAx (steel and Al) cranks.

                The Ventures and Moments fit furthest onto the new Nimbus hub splines, the Koxx and QuAx have the most crank spline remaining and seem to fit the spindle splines best..

                So maybe a hard stop would only be helpful on the Schlumpf at present, but my thought was to combine a hard stop with a pinch bolt cranks, that way we could adjust for increased tolerances.

                The aluminum spacers are not quite a hard stop, the aluminum can crush and wear, also the bearings can shift the hub on the spindle if you're not careful to snug up one side before torqueing the other side.

                Simply torquing the cranks against the spacers is not enough to prevent wear at the splines, so it's not a matter of the bolt loosening so much as it is the crank shifting on the splines. I have no problems with loose bolts, only loose cranks (creaking) or cranks that will simply no longer snug up on the splines and go so far onto the splines that the crank splines are maxed out.

                Note that when the I say the splines are maxed out, this is where the ISIS bolt "washer" bottoms out on the transition zone (lip)where it changes from splines to threads inside the cranks. I think this was an issue on early Schlumps, which is why the spindle was lengthened on the muni version, yes?
                Last edited by Nurse Ben; 2012-02-14, 04:28 PM.
                I dream of hamsters and elderberries


                • #23
                  Originally posted by scott ttocs View Post
                  Could you clean the crank surfaces and then shim then with a thin sheet of metal to artificially build up the contact surface? I am thinking aluminum foil. It would be a kluge, but if you could securely mount your nice cranks for another year it might be useful. It would be aluminum on aluminum on steel, which does not sound that bad.
                  Has anybody tried building up the contact surface of the ISIS interface with aluminium foil or something else yet? Experiences?


                  • #24
                    That would not work.
                    I built up the axle surface where the bearing sits once because my bearings kept slipping and it was a pain in the ass. I needed minimum 5 tries per side to bring it to a nice fit without wrinkling the foil before. It was hard to wrap the foil without any small wrinkles arount he axle, kept in place by some grease, and even harder, to push the bearing over it without destroing the foil. And this was a perfect round surface.
                    For the complex geometry of the ISIS interface, that would be literally impossible!
                    Einradfahren in Sachsen:
                    07.06.2020: Europamarathon


                    • #25
                      OP title: 'Is there another crank standard that would be better than ISIS?'

                      Square taper, if you (me, idiotically) forget to pack your (my) cranks when travelling.

                      Otherwise, no. Keep the industry standard, so all our parts still fit together. It's environmentally and user friendly.


                      • #26
                        Originally posted by bristlecone View Post
                        OP title: 'Is there another crank standard that would be better than ISIS?'

                        Square taper, if you (me, idiotically) forget to pack your (my) cranks when travelling.

                        Otherwise, no. Keep the industry standard, so all our parts still fit together. It's environmentally and user friendly.
                        The great thing about standards is how many there are to choose from.

                        ISIS hasn't been "the industry standard." for 15 years or more. I don't think you'll find a new bike using it. Unfortunately all the standards are moving targets and their applicability to unicycling varies.

                        ISIS is a pretty big compromise for unicycle cranks since we can't really implement a crank stop properly, which forces us to mess around with spacers. But engineering something new is a pretty big project and I don't know if anyone is working on it.

                        (While we're at it, can we settle on inboard vs. outboard disc rotors as a standard?)


                        • #27
                          Coming back to the original question. There is: Q-axle. Which is actually not a new standard, but a copy of the crank/axle connection used by Shimano since many years in the bike industry.


                          • #28
                            I have been happy with Q-Axle:


                            • #29
                              Originally posted by Aali View Post
                              Me too. I like it. Let's hope they decide to keep this system for a while. I think it's the better system for all disciplines except Flatland/Freestyle. The Q-Axle system makes it a little difficult to design a nice crank for crank rolls. They do offer a thing called Rollmops to add some surface for your feet, but the crank is not round and still shaped a bit like a cam. I don't know how that translates into "rollability" of the cranks. I'd think that a perfectly round ISIS crank would be be better for that.
                              Qu-Ax #rgb 36" (125mm) & #rgb 27,5" (137mm)
                              Impact Gravity/Reagent 19"
                              Qu-Ax Luxus "20


                              • #30
                                Qu-ax should develop a 125 mm wide Q-axle hub with 32 holes so that I could replace my ISIS-based Hatchet wheel with a Q-Axle alternative.