rexdelmolvo Posted August 28, 2020 Share Posted August 28, 2020 I just got my 16X, riding after 150 miles on the MTen3. I took it for my first ride and I LOVE it, but god is it different. Tonight I took it up to 20mph max, both because I didn't wanna go too far with it on my first night as well as being unable to unlock the speed any higher (it unlocked after I got home). I saw a thread on here, albeit an older one about a cut-out that happened on older 16X firmware where someone was riding at 30mph. The marketed top speed of the 16X is 31mph, is it safe to attempt to hit it on the newer batches/newer firmware? I would love to try it once I get more comfortable in the wheel but I want to make sure their marketed top speed isn't just 'theoretical' (like how the listings for the Nikola+ 100v say you can theoretically hit 40mph but shouldn't ride at that speed) and that I won't go flying off my wheel if I try to reach it. I'm about 220lb with all my gear on, if that matters. Quote Link to comment Share on other sites More sharing options...
Nick McCutcheon Posted August 28, 2020 Share Posted August 28, 2020 For me, I've noticed the motor loses a lot of power above 28mph. It's possible to ride above that speed, but it doesn't feel very safe as the motor feels too weak. This is an issue with the 2200w motor KS uses for the 16X, 18XL, and now the S18. The old 2000w motor didn't really have this issue. So overall I'd say 28 is a safe top speed number but you can go faster as long as you watch out for bumps that could draw a lot of motor power to overcome and possibly lead to an overlean/"cutout". 1 Quote Link to comment Share on other sites More sharing options...
mike_bike_kite Posted August 28, 2020 Share Posted August 28, 2020 Most of the numbers shown for a wheel are for a 70Kg (154lbs) rider riding on perfectly level ground. If you weigh 220lbs then the safe top speed comes down. If there's any dips or bumps in the road then that number comes down again. Then there's how much charge you have in the battery, anything less than 80% will bring the numbers down again. If there's a wind then the numbers change again. Personally I'd be very suspect trying to reach 30mph at your weight on a 16X and, if you do feel the need, then wear full face protection and armour and use very gradual acceleration. 3 Quote Link to comment Share on other sites More sharing options...
Tazarinho Posted August 28, 2020 Share Posted August 28, 2020 (edited) I'm about your weight fully geared, maybe slightly more if I'm wearing my backpack (which is virtually always). I set the upper limit at 40 kmh (25 mph). I believe for my weight that is 100% safe. I think going up to 45 kmh (28 mph) would be ok for my weight 95% of the time. Which is not a risk I'm willing to take. Going any faster than that is just a gamble. But that's just my opinion on the matter. Perhaps I'm overly cautious. Edited August 28, 2020 by Tazarinho 2 Quote Link to comment Share on other sites More sharing options...
Popular Post Chriull Posted August 28, 2020 Popular Post Share Posted August 28, 2020 (edited) On 8/28/2020 at 6:57 AM, rexdelmolvo said: The marketed top speed of the 16X is 31mph, is it safe to attempt to hit it on the newer batches/newer firmware? Just updated my graph from https://forum.electricunicycle.org/topic/16436-ks16x-cutoffoverlean-29-30mph/?do=findComment&comment=329930 Whats to be seen here: - It's battery current (y-axis) versus speed (x-axis). Battery current is not proportional to output torque of the wheel, just at the limit - so it's not a real torque over speed diagram, but the nearer one comes to the limit line the more it gets one - Limit Lines: Red lines for no load battery voltage of 84V (full), 66V(almost empty) and 72V 76V(estimated no load battery voltage at @DjPanJan overlean logged). The area to the right of the limit lines is filled black - these area cannot be reached while driving! The lower the battery voltage, the further this area goes to the left (grey) - "needed Power" Power lines (Yellow): An estimation of the needed power (roughly recalculated to show as battery current in the graph) at a specific speed (air drag, friction). A second "needed Power" line is shown (bright yellow) with additional regard for an acceleration of 1m/s² or an incline of ~10%. So as "riding right to the limit lines" the area below this "needed Power" lines can never be reached (exception: braking) and is also filled in black (grey) In real life additional power will be needed for balancing and as safety margin for "road irregularities". So if one wants to ride "safe" until empty battery something like 45 km/h is a sound limit (were the "needed Power (1m/s² or 10% incline)" line cuts the "Limit 66V 76V" line. From this graph 50 km/h could still be about safe if battery is above 50% and one stays with accelerations below 1m/s² (inclines below 10%). But best for higher speeds is to not accelerate or drive up inclines, but keep the safety margin for "road irregularities" or other unforseen. If one wants to stay safe in as good as any situation (highe accelerations, low battery, etc...) 30 km/h would be some limit PS.: don't trust this graph with your life - i just put some numbers together reported here! ... and i did not even double check anything.. Edit: Was informed that i mixed up lift cut off speed for the KS16X - it's 67 km/h, not 76 km/h. So here the adapted graph, and one see's that what i stated before: "From this graph 50 km/h could still be about safe if battery is above 50% and one stays with accelerations below 1m/s² (inclines below 10%)." is (mostly) not true anymore... Edited September 9, 2020 by Chriull Graph changed - KS16X lift cut off speed is 67 km/h, not 76 km/h.... 6 Quote Link to comment Share on other sites More sharing options...
Chriull Posted September 1, 2020 Share Posted September 1, 2020 (edited) On 8/28/2020 at 12:01 PM, Chriull said: An estimation of the needed power (roughly recalculated to show as battery current in the graph) at a specific speed (air drag, friction). As this was a real very rough estimation the next better approximation: (Edit: before graph was updated, too) What's the difference to the previous estimation: (Edit: all this points are already in the previous graphs as i changed them to the right lift cut off speeds of 67 km/h) The "needed Power" graphs are now "correctly" calculated via the motor current - for this the internal resistance of the batteries were taken as specified in the datasheet and the coil resistance taken from the steepness of the limit lines. So the "needed Power" lines with burden (acceleration, incline) now do not start at the origin (battery current=0), as they should. By this, a bit more correct calulations the no load battery voltage was now not only guessed (~72V )but approximated - in case of this graph at ~76V . Additionally there are now (the dotted) "isopowerlines" showing the battery current at the different speeds needed for a certain motor output power (1000W & 2000W). The maximum motor output power of roughly 2400W 2850W can be reached at full no load battery voltage (84V) at a bit below 40 km/h. This wattage sounds maybe a bit low - but it is the "real" motor ouput without internal losses. So the reported Wattage is the power supplied from the battery and much power is dissipated in the coils, etc. For example when here the limit line with half empty batteries was hit, the wheel reported 3600W drawn from the battery while the calculated motor output power was only about 2100W 2400W. So around 1500W 1200W are used for heating the motor coils... Imo there are "advanced" motor driving algorithms for lower speeds, so my approximative calculations differ the more the lower the speeds are? (1) For maybe some easier understanding of the above graph, here again the different values reported from the wheel drawn over a time axis: Here the speed and current graph values as reported are shown as dots - if one takes these (speed,current) pairs from left to right and draws them in a diagram with current on the y axis and speed on the x axis this leads exactly to the above shown "I-v" diagram. The main purpose of this are to see ones distance to the limit lines - how much safety margin one has until a overlean happens. Here is also this abovementioned "no load (battery) voltage" shown, were the voltage sag by the burden is "removed" by calculation. Interesting (or maybe a bit disturbing?) is that the inverterload shows 93% in the moment the limit line is hit the first time. Only at the second point along the limit line it reports the 100% == overlean. Could be from the way the firmware measures, calculates and reports the values - some timely lags/mixups happening? Or just more to be learned about this value and/or the motor physics... (1) As the first acceleration seen in the graph should be more in the 2.5-3 m/s² region (but more or less following the 2 m/s² "needed Power" line) and the second acceleration is in the region from a bit below 2m/s² to a bit above and it stays below the line... Some/?much? deviation could also arise from timely and valuewise inaccuracies of the reported data? Edit: Seems to fit by now with the right lift cut off speed PS.: So take everything with a grain of salt - failures and new knowledge is to be found and these considerations will change to something more accurate? Or that's just about what can be done with the data we have... Edited September 9, 2020 by Chriull Changed graph for lift cut off speed of 67 km/h Quote Link to comment Share on other sites More sharing options...
bracky72 Posted September 1, 2020 Share Posted September 1, 2020 I finally got my latest gen 16x up to 30 mph for a 10 mile stretch where I had a powerful tailwind. Wheel didn’t falter. But I think I’ll set my limit at 27 just to be safe. I weight 180 lb all suited up. It was a glorious 10 miles though. 1 Quote Link to comment Share on other sites More sharing options...
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