Craigs

As said I do not want to change the gears at either end, also because I find 25km/h too fast on a wobbly 20" folding bike. The 20km/h are very comfy for my old age and non-existing excercise level. I have no clue why anyone wants to 'hack' these bikes to run 20mph (32km/h); ridiculous. That's why I was happy as a clam when it ran only 20km/h 'out of the box', until it changed its mind after the suprising "run-in" phase... For the fun of it (sun was out, 20C) I did a last test ride on my slightly hilly 'home track' near my home: - PAS disengaged, manual power control as needed: 32Wh for 9km on a semi hilly track, avg=18km/h - with PAS active (i.e. full power whenever moving pedals): 67Wh for the same trip, avg=21km/h Since the motor kicks in about 3sec after starting to pedal and opens 'full throttle' (350W and more) this is extremely inefficient, and accelerates above 20km/h each time so I need to stop pedaling to ´get the motor "off my back". Crazy. I also clocked the steep incline to my home after doing these two countryside laps: for the 300m uphill the motor 'eats' a whopping 7Wh, the voltage dropping almost 3V during this load cycle (37.5->34.7V), power peaking around 440W; probably limited by the max amperage of 13A and the already depleted battery voltage. Had I started around 34V the system may as well have shut down halfway up. Thanks for the charting tool! Mkes perfect sense, torque and all, matches my GTmeter quite well under the various conditions. I am suprised that the Chinese are FOR ONCE honest and specify the true OUTPUT rating of their hub motors. Usually they exaggerate capacities, speeds, powers and sizes by a factor 2 or more... I might as well ride a '500W' bike based on my own meter readings 8-) I think it is a good idea to store the semi-charged battery (1/3 down after these tests) for the upcoming winter. One should NOT leave them fully charged for long periods of time, right? Spring is far, far away..

[mention=19726]sjpt[/mention]: None of the documented tweaks for setting changes (brakes, buttons, switches) seems to work. At least I feel vindicated that my original observation (higher speed after 3 charges) was NOT accidental, but a planned run-in by the manufacturer. I did find several similar comments in reviews at the dealer's site. Someone is counting 1-2-3-GO! somewhere in this funny bike. It does not tell HOW TO RESET this counter though. I wish I had another battery canister to see whether the controller would 'sense' the change and start all over. As said in my final report I am set, my 'solution' is better than the manufacturer's. My bike runs longer ranges than any other JG20, thanks to the PAS on/off-modification.

Sorry, I have not updated this topic for a while, was too busy fiddling and riding... Here is how I solved my issue with this ONE-POWER-MODE controller, as I could not reset it to the factory mode of Vmax=20km/h: As the PAS would always trigger the full power mode whenever pedaling I made it optional, adding a switch to the handle bar. This way I can disengage the PAS and control the electric power manually at will and ANY level, using the handle bar gas grip. Meaning I can adjust the power output for any desired speed up to Vmax, but have to hold the gas grip, like on a motorcycle, while pedaling along. Range of the 288Wh pack is now back to 55-60km for a single charge (from around 40km with PAS active), around 5Wh/km, cool! I did some very nice trips with the modified bike, at avg speed of 20km/h, perfect for the 20inch wheels and high cadence gearing. I also invested into a GTC power meter to watch over power output, true battery voltage, power consumption etc. It allows to see the actual wattage, the accumulated Wh consumed, the battery voltage and amps under load etc. The cheap meter (which is usually bought and installed for solar panel monitoring) is very accurate (home bench testing) and very useful for this bike with its anemic 3LED power display. But I found a few very surprising facts when observing the readings during my rides: - a 36V battery really has around 42V when fully charged, so it contains TEN elements of 4.2V? - even during regular rides the battery operates way above 36V - under load the battery on this 250W bike is drained with up to 13Amps, around 480W! Why a 250W bike will operate at almost twice the power (at regular speeds below 25km/h) I cannot explain, but it is a fact for my JG20. Does the full power get to the motor, or is it partly consumed by the controller FETs? Cannot say. Also interesting is the significant voltage drop of the battery under load, a typical effect of these Li ion packs: at full throttle and power the voltage may drop from 39V to 36V or lower, recovering quickly when the load is released. This behavior is very unfortunate for folks like me who live on TOP of a steep hill. After a trip the battery may be down to 35V already, still containing 'juice' for another 10km or so. But a steep hill climb will squeeze the voltage below the shut off trigger point (around 33V?) and will NOT allow to restart the motor afterwards, bummer. I ended up pushing the bike uphill more than once.. The season is over; I rode about 550km with this weird Samebike JG20. It IS fun and WAS cheap, it DOES work, but needed the special TLC and mods to become a useful vehicle. Would I buy it again? Not with the simple and poor controller and display it uses, not with the bad gearing ratio of the Shimano set. A conversion of all controller electronics or the Shimano sprocket sets would cost more than the bike is probably worth. My own solution set me back by 7Euro for the PAS shut-off switch and the GTC power meter - well spent! Thanks for reading and your suggestions; I learned a lot about pedelecs this year!

Sorry for the late response (I was too busy riding and fiddling..): No, that does not work, as the bike only knows ONE power setting (FULL) and only one mode (kick power in whenever pedals are mov ing). So it will always push to 25km/h when pedaling. See my final 'exam' below for details.

Chapeau, Andy! But IMHO foldable bikes are not really made for speeds above 20km/h. Even back in the 1970s when they became popular. 'Duomatic' was their biggest feature, a simple 2 speed hub. Even if I change the overall ratio of the gearset I'd still feel rather unsafe on this el-cheapo pedelec. The disk brakes are rather soft (need to tighten all after 200km or so), the front fork is 'so lala'. It IS great for field trips around my area, for shopping during the summer. It easily fits into my car's trunk, one of the reasons I opted for this 'old school' design, with a practical and sturdy rack in the rear. I was quite pleased on my first trips (50km non-stop on a 20" foldable bike IS an adventure, trust me!). Power assist DOES work neatly, a great improvement in hilly areas like mine. One can feel the extra punch, especially if removing the drive for a moment. Just this stupid self-tuning to Vmax=25km/h is still nagging me. If there is any trick to reset the controller to the original 'slo mo' mode with lower power output, I'd be 'happy as a clam' as you would say. Or if I could get my hands on a complete set for the Samebike XMZ1214. A bike with too tiny wheels and a too large battery - but with a reasonable 'multi power' control and LCD unit with extra features. I guess that's 'life' - you get what you pay for..

[mention=490]Andy[/mention]: thanks for your various thoughts! To clarify: the bike has RWD, the black box under the crank contains the controller. PAS is actually a nuisance on this bike: it overrides any (lower) handle grip setting and will push the speed up to the new limit anyways. That's why I decided to remove PAS sensing altogether. Now I can pedal at 5...25km/h WITH motor support, holding the grip in place.. As hard as it is to believe; it seems to be a SINGLE power output design (in pedal assist mode), aimed at 25km/h resp US: 20mph, by design. Rather unusual, no? With 46teeth:14-28teeth and 20" wheels there is little room left for extending the 6spd gear ratio. It would be costly, and the limited battery range issue would remain anyways. Changing the handle controls alone would probably NOT solve the issue, unless someone can confirm that my controller -AA004 is supporting power stepping like version -AA006 on other bike models with a LCD and powerstep display.

Cool idea!! YES, that sounds rather reasonable, thank you! Nobody brought this up in the German forum. I do not know much about "BMS" (must study!), but understand that packs of batteries must be 'in sync' to operate efficiently. Maybe my cheap controller does a 'run-in' like balance load control after all; and I was right all the time? The BMS theory raises a few questions: 1) Can I re-invoke this mode somehow, without damaging the battery pack, the motor or the six power transistors? How? 2) Wouid the unbalanced battery pack deliver full capacity at a LOWER power output level as it did for me? Would such a pack have the full voltage of 36V, as visible on the 'voltage' LEDs on the flimsy Saxin display? Three steps is coarse, the upper LED disappeared around 27km in the 'broken' mode, now around 20km due to the higher power output. As said, I am a newbie, trying to learn, looking for other owners of these odd Chine thingies. I did not expect much, did not pay a lot (ca. US$450), was quite pleased in its presumed 'defective' state. And do not want to dump money and parts into this JG20, not knowing how long it may last. Thanks for any clarification and idea, especially about the mentioned controller and totally obscure 'Saxin' handgrip!

Hou is (according to the internet ) the main rep on Samebike's site, the only person and email I could find. China is not really known for customer/warranty support, so I am not that surprised. Yes, I'd LOVE to see where on the circuit board such a thing is - can you point to it? But: the 'wrong' initial speed was 20km/h, now it healed itself and runs the specified 25km/h. The only optional speed (for US markets etc)is 32km/h, even FASTER than my one can run. This does not explain the behavior, from my point of view.

There are none, that's what I tried to explain. It would not have bothered me if the bike had maintained the original, comfy top speed.

So I got your attention, that's great! First and foremost: this is a TRUE story, as weird as it may sound. I searched the internet, contacted the company (thanks, David Hou @Samebike, for ignoring my support request!), nobody ever mentioned what I experienced. Then I asked for help in a German eBike forum, was ridiculed and flamed by some, got a 'semi' explanation, but no real solution for the core issue. BTW: I am also the author of the only (AFAIK) detailed review and test of this specific Chinese "Samebike JG20", published by a German GadgetWelt forum. Interestingly it was written up BEFORE the weird change occured. I liked it more prior to its weird behavior. In a nutshell: I own one of apparently very few Samebike JG20 foldable eBikes (sometimes sold as XW-20ZC or YSDX20). My unit is the UK version, based on the power plug: 36V, 250W, 8Ah battery pack. I use it in Germany. It is my first (most likely last) pedelec; I have nothing to compare it with. 'Learning by doing'. Out of the box it appeared a little weak for the promised 250W, also it did not reach the advertised speed of 25km/h: in both modes (assist, moped) it would run exactly 20km/h. You could hear the motor throttle "whine" cutting at that speed. As it is a foldable 20" bike with a 6spd Shimano shifter this speed was equivalent to a cadence of about 72rpm at the crank. I quickly got used to this. Actually enjoyed this speed and got an acceptable 50-54km out of the 288Wh/36V battery. Life was good. AND THEN IT HAPPENED: after three full battery charges (ca. 150km total) the bike - on its own - changed its behavior and performance whenever powering it up as usual: it was way more zippy, accelerated with more gusto, and now reached precisely 25km/h! Again both with and without pedal assistance it would accelerate to 25% higher speeds than previously. While this matches the specification, this change came with three major disadvantages: - the range of the battery dropped significantly, from 50+ km to about 40-43km - as this cheap ebike apparently has NO power step control I MUST ride at 25km/h instead of 20km/h. Anything below will engage the motor to accelerate, as long as I move the pedals. It is now a 'hit and miss' bike: pedal a little to reach 22km/h, stop pedaling and wait until the motor stops pushing and the speed drops to 18km/h, pedal again to get so the motor kicks in - a little ridiculous, no? - the gearing ratio of this 20" bike is not tuned to this speed of 25km/h. That's equivalent to around 90rpm at the crank, not 'geezer like' as I want to. Kids may pedal along this way, not me. As a novice and retired engineer I had 1 (and only ONE!) reasonable explanation for this unexpected behavior of my Samebike: apparently it had used and finished a 'run in' phase (conditioning), as most mechanical motorized vehicles (cars, motorcycles) require. To settle tolerances, adjust electronic power controls, learn battery discharge curves etc. So I asked about this in a German pedelec forum: they laughed at me, called me a stupid engineer with no clue about Li batteries (OK, they do NOT require a conditioning, but my ebike DID this!) To cut a long story short: the best explanation I received was: - your bike was broken when it arrived - it magically healed itself after (exactly!) three battery charges - the fix increased the speed (power?) by exactly 25% - the controller must have sensed an error and reset itself to match the bike's parameter on its own - live with it mmh.. I WANT THE ERROR BACK!! Nobody knew how to 'talk' to the rare and cheap China made controller, how to 'fiddle' with it. Apparently these Chinese controllers have a Rx/Tx serial port, but who would know such a protocol and parameter setting - hopeless. Many suggested to buy a better (multistep power) controller and handlebar unit; or throw the entire junker away; great advice.. Out of desperation I dismantled (against my rules) the brandnew bike, opened the installed controller, photos attached. When searching the internet I did find ONE similar model: apparently the Samebike XMZ1214 uses a controller "X863-AA006" (I have "X863-AA004"); with a neat handlebar display AND power control buttons that I do not have - wish I did.. Now to my main questions: - can I 'tweak' this controller back to what it COULD do originally: i.e. assist only to V<=20km/h? - does the built-in controller X863-AA004 allow for power step control (+/- buttons on the handlebar) by replacing the simple 'Saxin' unit without LCD display and buttons? - the 'Saxin' handlebar control has two 'indicator LEDS'; only the left one is ON when turning the power key; the right one flashes shortly, so it IS alive. What 'should' it indicate; maybe the alternate 20mph/32km/h mode as used in the USA? Not that I want this bike to run 32km/h, God forbid.. - has anyone figured out how to 'talk' to this specific controller, e.g. by brake/PAS/horn/light activation sequences during the power up cycle? - Could the 'better' controller/display package for the Samebike XMZ1214 be obtained on the market? Would it fit, probably needing more than the currently installed five wires to the handle bar control? - any other ways to throttle the assistance during pedal assisted rides? My current solution: I unplugged the PAS as it would otherwise override the moped gas control at any speed. Now I use the gas control to set it to my speed and pedal'under load' along with it. This allows for pedal assisted riding at any speed up to Vmax, but I have to hold the gas grip like on my motorcycle, Mileage in this mode has not been checked so far. Ok, it IS a long story, but then: it IS about the most crazy problem a pedelec can have: everyone is asking for advice how to speed it up, I WANT IT TO BE AS SLOW AS IT ONCE WAS!! Attached a few photos of my (customized) Samebike JG20, simple 'Saxin' handle bar control unit and the main controller. I'd LOVE to hear from other owners of this JG20 (or its similar Samebike derivates). I want to know about their experiences, about anything to make this freaky '6 speed pedal, 1 speed motor' pedelec a little more useful! Thanks so much for reading this far! And pardon my 'German English'; I tried my very best to keep it entertaining AND informative at once. Whoever finds spelling errors may keep them - for free!