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About tudordewolf

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  • EUC
    Msuper 3S+ "T"

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  1. I believe something like this converter from aliexpress should do it, it offers current limiting and the appropriate voltage ranges. It's a little overspec'd but that's good for something like this, and the input current would still be up to 10 amps. I've been messing around with the idea of using old packs as power banks for a unicycle, and converting them directly rather than going through the charger.
  2. That's definitely too high- It sounds like the seller thinks they can upgrade themselves to one of the latest flagships for under $500 out of pocket, while unloading their old wheel on someone else in the process. Even if it was pampered its entire life, that's at least the first 50 charge cycles on the battery and around a year of daily use; the tire has either been changed once, meaning the case has been dismantled and put back together after leaving the factory, or else you'll need to change it yourself, soon. I get about 3500km per tire before the grooves are gone. For a 3000km Msuper, I think $500 would be reasonable; that would be plenty to help someone upgrade/replace their main wheel. They don't hold value like cars, the money you get from selling one is a sort of consolation prize, not a chance to recoup your investment. They recouped that investment several times over already in the miles they put on that wheel. I think some people massively over-value the re-sale value of their wheels because it's still worth a lot to them- it's not that they've depreciated in value to the owner, but to anyone else. Someone else's used wheel is too much of an unknown to pay 80% MSRP for. I wouldn't pay more than half price for a used wheel, especially not one with a thousand+ miles on it. I've put >8500 km on my 84V MS3, and hope to get another couple thousand out of it - to me, it's still worth at least $1000, and I'd have to spend almost twice that to replace it. But I couldn't imagine asking more than a couple hundred bucks from someone else for it, when new wheels are just... new.
  3. Good write-up, useful pictures. I use an i5 as a backup wheel and am reassured as to it's reliability. I'm impressed you ride your's in anything other than dry, sunny weather, I'm paranoid enough about the exposed motor. Would you happen to know how many total miles ridden the wheel reports? ~3 miles per day is very impressive for an i5, mine still only has ~100 on it. Interesting about the 288wh battery, mine was sold marked 245, and I think the only other size option on my pack was the 18650-powered 167wh version. I wonder if your's a more recent model from when they'd begun producing the s5; I believe it uses two identical packs, but with slightly higher-capacity cells. When did you get your's? I can get the iamips app to work as-is on an older android phone. It's really too bad you can't buy them anymore, it was years ahead of the competition in 2017, gliding around when other wheels still had noticeable cogging and whiny PMW, and nobody else has tried an "axle-less" form factor.
  4. The i5 was ahead of its time in 2017, and is still a gorgeous wheel today, I wish more manufacturers explored tall slim wheels instead of just making them wider. The entire i5 is thinner than the tire on most wheels being released this year. I like wheels where form follows function; I think trim and lighting looks cool in concept, but too much winds up kind of cheap when the plastic has worn and faded. I don't like glossy shells in general, I think they wear poorly compared to matte. Boxy? Let's not forget where the Msuper line came from
  5. When the BMS is refusing a charge, it has a reason. In my experience, "battery too low to charge" actually means 1 dead cell, that the BMS is aware of, and preventing charging. The reduced voltage you're detecting is from the remaining good cells. The pack is worth more as individual salvaged cells and (maybe) a salvage bms now (often they'll be so taped up they're not reusable) now; even replacing the dead cell, you don't know how soon until its siblings start going bad too and what state of degradation they might be in. I've tried charging these packs by going straight to the connections on the battery, and it takes a charge, but the result is that you overcharge the good cells since they have to come up to the same voltage as they did before, and the pack is still useless (they'll all charge to 4.35 or 4.4, I've even seen 4.5 which is why the BMS is refusing a charge)
  6. I think a lot of that might boil down to experience. When you first get into it, it's like you just learned to fly, it's exhilarating. It took me a few spills to mellow out that enthusiasm for maximum speed. I'd say I went through 3 stages - first, tentative excitement with occasional falls that keep you careful. Once I was comfortable controlling the wheel, I started riding everywhere pretty aggressively, got both cocky and complacent, and broke my right radius falling in the street. Now I probably max out at 20mph and even then find myself cruising slower if it's nice out. I got a big gotway for the specs, but it also feels safer at low speeds - the torque overhead to handle an unseen divot or missing cobblestone means it bounces fairly aggressively, but doesn't tip you off the way smaller wheels would, and there's lots you can do with its acceleration and braking while staying below 20mph. Just going fast in a straight line is one of the less interesting things an EUC offers to me.
  7. I found them for sale here, they would probably arrive faster than from China if you're willing to spend $20.
  8. A larger battery also means fewer charge cycles over time, and/or lower depth of discharge between charges, both of which will increase the long-term performance of the battery. The only time I'd consider too much battery a con is portability; on an ultralight wheel like the i5, being able to walk around with it like a briefcase without significant fatigue lets it fill use-case scenarios that an Msuper simply couldn't; but for wheels with walking handles, which is every flagship by now, the point is moot. There's one more advantage to oversize battery packs, although it's relatively niche - the ability to use faster chargers. I've caught myself on low battery needing to go somewhere, and the option to top up 20 minutes of ride time with a 20 minute charge only applies to wheels that can absorb 4+ amp charge rates, for which you'd probably want at least a 4p battery.
  9. In my experience, the same obstacle at a higher speed causes a greater disturbance to an EUC. Hitting a bump or pothole gets more violent the faster you're going. at least at speeds between 5 and 30mph. Maybe if you're going fast enough you'd skim over a pothole, but any raised bump or stick could still be an issue. On a normal wheeled vehicle, a bump just costs you a bit of forward motion; you don't really notice if it takes a few seconds to recover that speed. On an EUC, it causes you to lean forward by slowing you down at the wheel; your body keeps moving at the same speed, so the wheel has to replace that lost motion immediately, basically while the bump happens, or else you're falling forwards. I'm really curious what effect wind resistance would have on balancing at that speed. A rider's stance to reach 60mph would have you leaning pretty aggressively off the front of the unicycle already, but that angle would actually give you "lift" like a long-jump skier. Maybe a little parachute / cape could actually be a safety mechanism at that speed, to catch and slow you if you fall past a certain angle!
  10. 60mph over level ground would require 70% more power than 50mph, assuming the torque and current draw increases with the square of speed (for a 44% increase), and voltage increases with RPM (a further 20% increase) for a total of 72.8% more power, and a 20% larger reserve to overcome the same obstacle (for a bump which costs you 1mph, ((602)-(592))/((502)-(492)) = ~1.2
  11. A ebike that hits a bump can ride over it, an EUC has to instantaneously provide enough torque to keep itself level and recover. The amount of energy this "reserve" costs gets higher the faster you're going, whilest from an engineering standpoint the torque overhead you have shrinks the faster you're going. Safely hitting higher speeds requires exponentially more power, not just because of the quadratic nature of air resistance, but of increasing kinetic energy and the amount of potential energy that an EUC needs to have available to recover/maintain equilibrium. The power figure that reflects an ebike topping out is the figure when an EUC drops you on your face, at 60mph.
  12. Interestingly, mine was on the right side too, I wonder if most of them bias that way. The electronics are on that side, which meant I had to tackle the problem from the left side which wound up working out; by leaning it in closer to the tire it pushed the right side out. I really exhausted my other options first, including riding it gently for a few weeks, until I read a post here that the tire would eventually eat through the plastic. I wasn't excited about removing and re-torquing an axle nut - I actually built a little jig out of 2x4's to brace the bracket with my legs while I removed the nut with an 18" socket wrench...
  13. If it's new I would try to get it resolved through the vendor, that's a defect. I see you're in Hawaii so that may not be possible... I had that problem emerge after a couple years/ tire changes on my 84V Msuper, and it was pretty tricky to solve. I figured the shells must have shifted on the pedal brackets, so I loosened them and tried to re-align, but that didn't work. I ultimately had to take off one of the pedal brackets and I sanded the last spacer before the motor down into a slant to correct the tilt; as in I went from "l l" to "/ l", using calipers and a sanding stone to make sure I was keeping it "flat" as I slanted one of the faces. It took some effort, but it worked. Edit: I also added some steel strips behind the axle shims to match the amount of material I removed, so the bracket was held at the adjusted angle by the nut assembly as well as the steel plate that goes between it and the spacer.
  14. This aliexpress listing appears to be for such a tire
  15. 100% same experience on my 84V Msuper, at relatively low PSI too; it's not just the turn but my ability to lean it at all. ~30 psi is the highest I can comfortably go before it feels like it's actively fighting my leans, and over 40 psi it feels like it might go into speed wobble because it's so "stiff." I think it must be something to do with the contact patch, like you say. Maybe it shifts forwards or backwards when you try to turn in a way that produces a negative-feedback loop in regards to tilt; like if the patch shifts off the centerline and forward, then the motor itself would be trying to straighten you out (maybe?) There's more air and therefore more mass around the rim, but I can't imagine it would be enough to make a difference via gyroscopic force.
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