Bafang G510/M620 (Bafang Ultra) thread

Hi all bafang G510/M620 owners,

This thread is to summarize and share knowledge about Bafang's most powerful mid drive (and possibly most powerful mid drive commonly available). Below information summary:

Manufacturer's website and specs
https://bafang-e.com/oem-area/drive-systems/drive-system/mid/m620-drive-system/

Programming UART version (till end of 2020):
http://frey-bafang.patransformers.com/2020/10/09/bafang-ultra-programming/
https://support.biktrix.com/hc/en-us/articles/360042301971-Stock-Ultra-settings-and-Programming-guide
https://endless-sphere.com/forums/viewtopic.php?t=99669
https://electricbike-blog.com/2017/11/23/i-void-warranties-hacking-the-bafang-ultra-max-mid-drive-ebike-drive/
Programming CAN version (2021 onwards)
https://lunacycle.com/bafang-besst-service-tool/
https://endless-sphere.com/forums/viewtopic.php?f=28&t=110876

Updated controller threads:
best available option, FOC controller - with efficiency close to Bosch and Yamaha, requires sending motor for upgrade (due to calibration)
https://innotrace-shop.de/produkt/motorenset-x1/
also known as
https://wattwagons.com/products/archon-x1-controller-only-upgrade-for-your-bafang-ultra

other:
https://endless-sphere.com/forums/viewtopic.php?t=95671

Spare part sources:

https://lunacycle.com/ultra-parts/
https://california-ebike.com/product-category/parts/bafang-ultra/
https://www.greenbikekit.com/bafang-8fun-spare-parts/ultra-g510-mid-motor-parts.html
https://mayebikes.en.alibaba.com/productgrouplist-814430431/Bafang_mid_motor_parts.html?spm=a2700.icbuShop.88.49.7f063b59p0Aid2

The last shop - I managed to purchase there small parts not listed on their website.

Most interesting applications:
http://www.frey.bike/
- AM1000 is one of best Ultra applications ever 21Ah Battery
- EX (sorry for being cruel) big dissapointment, serious design failures (details require a different article) 14/28Ah battery
- CC - brilliant idea - fast commuter with simmilar errors as EX, 14Ah battery

Ansbern Old - 21Ah battery, failed seat tube angle

Ansbern New - 17Ah battery


EXESS HP 180 - top of the linne, but is it discontinued?
https://endless-sphere.com/forums/viewtopic.php?t=94997

Luna Apex - sorry too ugly to add link,

others - many Fat bike projects - more ore less successful, I'm not a fan of fatbikes, especially if there are 3" tyres on std ebikes available.

I wrote the above to my best knowledge, to save others research time and hopefully start gathering all knowledge on the subject in the thread below. I had no intention to favour or discredit any brand/shop, producer, however if any statement is wrong from technical perspective or to harsh, pls let me know and I will gladly imrpoove the post.

I feel like a dozen threads must already exist summarizing this motor, it's very mature tech by now... Did you give the search function a try?

Glad to add info to the thread if not


Some quick tidbits:

- Q-factor is approx 200mm with standard offset crank arms (16mm), can be reduced to about 185mm with aftermarket options (+8,0 offset combo)

- Actual torque output can be in excess of 200 Nm with 52V+ packs and full designed amps (30A). This high torque invalidates most IGH solutions except the heavy, clunky shifting Rohloff. Sturmey Archers will literally self destruct before your eyes, It isn't pretty.

- Aftermarket ESCs can bump the max power beyond 2300W, but results may vary integrating the Torque PAS

- The Excess/Archon controllers claim the highest efficiency values, but they are gutless programming, turning your Mustang into a Prius, basically. Their peak wattage claims are optimistic at best. not very sporty

- Ultra motor is fairly easy to maintain, if you consider dropping the motor and splitting it apart to replace grease, bearings, and clutch parts your ideal way to spend a weekend once a year (or twice a year, if you ride it constantly four seasons, like I have). The parts are no longer expensive, or difficult to get, and the grease is easy to buy (Mobilith SHC 100 optimal)

- At high power levels, the Ultra will consume approximately two cassettes and chainrings per 5000km, in addition to many meters of your finest chain. You could try to use only super tough parts, but they will severely inhibit the options and gearing range of the system (a wide gearing range really benefits the Ultras power delivery over a wide speed range, and it's sporty as hell with lots of gear shifting so long as you cut power during the shifts).


Notes: it's a great motor if you don't mind the increased cost per km for drive train parts+labor, it's one of the sportiest (PEDAL BICYCLE) ebike motors I've ever ridden and I ride it often. Actually, I'd even say it's the gold standard today for ebike mid-drives in North America, good in basically every performance and feature metric, reliable, mostly waterproof, and good value all around. Weight and displacement of the drive unit are on the heavier side, but at least it isn't a noisy little bitch without common crank spline format like the Bafang M600 :lol:

Deafcat said:

- Q-factor is approx 200mm with standard offset crank arms (16mm), can be reduced to about 185mm with aftermarket options (+8,0 offset combo)

- The Excess/Archon controllers claim the highest efficiency values, but they are gutless programming, turning your Mustang into a Prius, basically. Their peak wattage claims are optimistic at best. not very sporty

Click to expand...

Deafcat thanks for sharing. Could you elaborate more on crankset options to lower the q factor - other than Miranda?

Why would you consider X1 controller gutless programming? Also maybe you have real life experience on efficiency/range gains with X1 vs stock controller? This is a real puzzle to me as I didnt notice power delivery issues whith stock controller, nor any overheating issues even under thogh conditions. Also 35% gains seem technically impossible, but standard 15% when switching from block to FOC is still tempting. I seriously considered this upgrade as FOC is state of the art control mode across virtually all EV applications.

Finally did anyone come across info - whether stock controller is block or sinwave?

Great read thanks for sharing .

Absolutely love my Ultra it's insane!!.. eats anything you throw at it.

I'm sure I read somewhere Bafang should be releasing an update shortly how true is this?.

I have a programming cable and have adjusted a few settings but would look forward to see what a 2021 software update would bring.

Thanks again..

I find the Ultra annoyingly loud on the Frey 1000HT. Google says that is normal on the Ultra. I have no comparison to brand new condition as the bike was bought used but fairly new. It can be properly be heard from 10m away. Way louder than my other M600 and TSDZ.

Is there a way to reduce the noise? Will grease repacking help?

xp67 said:

I find the Ultra annoyingly loud on the Frey 1000HT. Google says that is normal on the Ultra. I have no comparison to brand new condition as the bike was bought used but fairly new. It can be properly be heard from 10m away. Way louder than my other M600 and TSDZ.

Is there a way to reduce the noise? Will grease repacking help?

Click to expand...

Somebody, I forget who, is working on a composite gear that was supposed to be released this fall. That's kinda what I'm waiting for.

That in mind, it helps to know that the early/original Ultra (G510) was introduced with a composite gear that ran quietly. Problem was, some who were pushing the Ultra motors WAY higher than their rated power, were having some trouble with the gear, so Bafang installed a metal one that wouldn't melt, eventually changing the model number to M620.

Actually, those early Ultras with a plastic gear failed within normal operation (30A) pretty easily. They gave up on plastic gears in these stronger offerings, as well as improving the one-way clutch component over the years for better reliability. People still break those occasionally, but only by misusing the power in wrong gear. Bafang also "nerfed" power from a standstill for many motors to protect against that, but it can be fixed in programming.

Sadly, 2021 has brought us more and more nerfs from Bafang for these motors. The new canbus controllers really suck, impossible to get full performance. I still really dig the Ultras, and I don't recommend modifying the stock non-CAN controllers, keep em alive, don't frock with the shunts. 1700W with 52V is plenty, don't get greedy!

Hi guys,

I touched a throttle wire (don't know which one) on the frame, spark and controller error... Do you guys think I can fix the controller by replacing some components?

jeron said:

Hi guys,

I touched a throttle wire (don't know which one) on the frame, spark and controller error... Do you guys think I can fix the controller by replacing some components?

Click to expand...

Maybe a little more info to give us something to go on would be helpful?

Does the display come on?
Does walk mode work?
Does the pedal assist (PAS) work?

In other words, what works, and what doesn't?

G510 controllers seem to have issues. By far the most frequent requests for replacements. Adding to the confusion there are two different versions. California eBike has pulled them from their website. Only available now from the Benicia repair shop.

late reply sorry. I replaced the controller with a innotrace X1 controller.

Hello. Are the bolt mount patterns the same for the m600 and m620 utra? I'm trying to find a carbon full suspension frame.

Deafcat said:

I feel like a dozen threads must already exist summarizing this motor, it's very mature tech by now... Did you give the search function a try?

Glad to add info to the thread if not


Some quick tidbits:

- Q-factor is approx 200mm with standard offset crank arms (16mm), can be reduced to about 185mm with aftermarket options (+8,0 offset combo)

- Actual torque output can be in excess of 200 Nm with 52V+ packs and full designed amps (30A). This high torque invalidates most IGH solutions except the heavy, clunky shifting Rohloff. Sturmey Archers will literally self destruct before your eyes, It isn't pretty.

- Aftermarket ESCs can bump the max power beyond 2300W, but results may vary integrating the Torque PAS

- The Excess/Archon controllers claim the highest efficiency values, but they are gutless programming, turning your Mustang into a Prius, basically. Their peak wattage claims are optimistic at best. not very sporty

- Ultra motor is fairly easy to maintain, if you consider dropping the motor and splitting it apart to replace grease, bearings, and clutch parts your ideal way to spend a weekend once a year (or twice a year, if you ride it constantly four seasons, like I have). The parts are no longer expensive, or difficult to get, and the grease is easy to buy (Mobilith SHC 100 optimal)

- At high power levels, the Ultra will consume approximately two cassettes and chainrings per 5000km, in addition to many meters of your finest chain. You could try to use only super tough parts, but they will severely inhibit the options and gearing range of the system (a wide gearing range really benefits the Ultras power delivery over a wide speed range, and it's sporty as hell with lots of gear shifting so long as you cut power during the shifts).


Notes: it's a great motor if you don't mind the increased cost per km for drive train parts+labor, it's one of the sportiest (PEDAL BICYCLE) ebike motors I've ever ridden and I ride it often. Actually, I'd even say it's the gold standard today for ebike mid-drives in North America, good in basically every performance and feature metric, reliable, mostly waterproof, and good value all around. Weight and displacement of the drive unit are on the heavier side, but at least it isn't a noisy little bitch without common crank spline format like the Bafang M600 :lol:

Click to expand...

WTF ??? This may be an old post, but clarification is in order.
You say: "The ... Archon controllers claim the highest efficiency values, but they are gutless programming, turning your Mustang into a Prius, basically. Their peak wattage claims are optimistic at best. not very sporty" leads me to question your experience" ???
Perhaps you can qualify that statement?

I beg to differ.
The 2300watt Archon is far from "gutless" and programming is up to the user.
My 100NM 52lb bike - in it's highest settings - won't touch my 63lb WW w/ Archon - in it's lowest level setting -'Economy Level 1'.
For perspective: The Archon has 5 Econo settings and 5 Sports Mode settings.
In every mode setting from Eco 3 up, the front wheel will come up off the ground on take-off.
The extent of the rise gets pretty damn serious around SP 2.
I've been 34mph, up a slight grade, in 10th of 11 gears - running in Sp 2.
EFFICENCY ???
Without even trying, I get right about 40miles, recharging the 52v 16Ah battery at 46.5 - 47v (w/ 25% left).
I've was (finally) able to reduce it to 39miles by constantly running in Eco L 4 and burning up the tarmac.
The EFFICENCY is OUTSTANDING.
I don't know about what someone told you they heard was on utube, but speaking as an owner I say I love my Archon controller.
I also note that nobody (on any forums) that own these controllers co-sign your statements.
The code is outed and they are now open source. One can program and Archon to 3000 real Watts.
It's on the WW Programming thread at EBR.
Owning this controller is like owning a '67 427 SCI Cobra Crate Motor.
You think not? Try and buy one.
So much of what you say strikes me as 100% accurate, I really had to call you on this crazy stuff.

Deafcat said:

I feel like a dozen threads must already exist summarizing this motor, it's very mature tech by now... Did you give the search function a try?

Glad to add info to the thread if not


Some quick tidbits:

- Q-factor is approx 200mm with standard offset crank arms (16mm), can be reduced to about 185mm with aftermarket options (+8,0 offset combo)

- Actual torque output can be in excess of 200 Nm with 52V+ packs and full designed amps (30A). This high torque invalidates most IGH solutions except the heavy, clunky shifting Rohloff. Sturmey Archers will literally self destruct before your eyes, It isn't pretty.

- Aftermarket ESCs can bump the max power beyond 2300W, but results may vary integrating the Torque PAS

- The Excess/Archon controllers claim the highest efficiency values, but they are gutless programming, turning your Mustang into a Prius, basically. Their peak wattage claims are optimistic at best. not very sporty

- Ultra motor is fairly easy to maintain, if you consider dropping the motor and splitting it apart to replace grease, bearings, and clutch parts your ideal way to spend a weekend once a year (or twice a year, if you ride it constantly four seasons, like I have). The parts are no longer expensive, or difficult to get, and the grease is easy to buy (Mobilith SHC 100 optimal)

- At high power levels, the Ultra will consume approximately two cassettes and chainrings per 5000km, in addition to many meters of your finest chain. You could try to use only super tough parts, but they will severely inhibit the options and gearing range of the system (a wide gearing range really benefits the Ultras power delivery over a wide speed range, and it's sporty as hell with lots of gear shifting so long as you cut power during the shifts).


Notes: it's a great motor if you don't mind the increased cost per km for drive train parts+labor, it's one of the sportiest (PEDAL BICYCLE) ebike motors I've ever ridden and I ride it often. Actually, I'd even say it's the gold standard today for ebike mid-drives in North America, good in basically every performance and feature metric, reliable, mostly waterproof, and good value all around. Weight and displacement of the drive unit are on the heavier side, but at least it isn't a noisy little bitch without common crank spline format like the Bafang M600 :lol:

Click to expand...

WOW !!! Lol. Which Archon X1 have you ridden? They're so powerful, the rep is they eat drivetrains. I can vouch for that.
Owners are consistently getting 100 miles from 16amp batteries.

I don't feel gutless ???

whats up with the UART ultra? some people were saying the early ultras were no good. can the canbus bafang be reprogrammed somehow, do you even need to, are either sold engraved at 750w, can the canbus ultra use any battery. does anyone sell complete ultra UART bikes. i found one retailer with 750w UART ultra motor but it was fat mount . is the ultra louder with steel gears . does the ULTRA actually have more torque or just torque sensing

uhmwpolyethylene said:

whats up with the UART ultra? some people were saying the early ultras were no good. can the canbus bafang be reprogrammed somehow, do you even need to, are either sold engraved at 750w, can the canbus ultra use any battery. does anyone sell complete ultra UART bikes. i found one retailer with 750w UART ultra motor but it was fat mount . is the ultra louder with steel gears . does the ULTRA actually have more torque or just torque sensing

Click to expand...

UART ultra is fine, I think most will highly prefer it over the canbus, which can be reprogrammed but requires a expensive bafang tool vs a cheap connector and free pc software. You might not need to reprogram but it highly depends on what you want from the motor, programming can change the torque sensors feel, the power you get in each pas mode, change the throttle power, the top speed limiter etc. Also worth mentioning the commonly considered best display for bafang bikes the eggrider doesn't work with canbus motors on uart. You can purchase a 750w ultra if you would like, although I've heard it's not just firmware so I don't believe you can up the power back to stock after if you wanted too. I'm not 100% sure but I believe the canbus can still use a diy battery? Emtbforums probably has more information on that. Lunacycle, Biktric, freybike, "wince" / dengfu, wattwagons. All Ultras come with steel gears which can be somewhat loud, people online do regrease the inside to help lower the noise but bafang actually very recently updated the internal gears and from the few people I've seen talk about it online it does help but it's still very new so not a lot online about this yet. I'm not sure exactly what you mean with the last comment, the Ultra / m620 definitely has a lot more torque than say a m600 if that's what you mean, it's not just marketing you can tell the difference immediately.

Not sure about any UART full bikes, but i was able to get a current m620 UART motor kit from greenbikekit's website. Included the new rotor design, 1000W, and i was able to use one of my already owned eggriders with it to program most settings. Only issue i've been having is a power save mode thats forced on you at ~30% battery voltage. The reseller told me nothing can be done about it, but im sure theres a firmware out there that turns this off. I was hitting this wall that limited me to 350W suddenly on my rides up the mountain and wondering why no one has complained more about it, especially people with large packs. I was losing access to 6AH of battery because of this. I figured it must not be this bad for most people, and there must be a variable its based off. So a few days of testing and horrible rides up the mountain:

Power Save mode is 43% of your programmed current limit.
Default is 30A, so you will get maximum 13A when you hit it. Unfortunately, i had mine set to 18A and so it was rough endings to my commutes, being limited to 7.7A while on 11% grade. I haven't finished testing, i still need to find out if theres different tiers of power save as the battery drains further, and if Offroad mode uses a different threshold. You cant go higher than 13A unfortunately due to firmware restrictions on the current limit.

So if you want to still limit your current, i will recommend leaving the Limited Current: 30 Amps. Instead change your Assist levels to compensate. Ive set my Assist 9: Limited Current 60% which equals 18 Amps

Noise wise, itsmuch quieter than a cyc stealth. My bbshd had a chain guard to correct the chain line when climbing, its quieter than that, but not quieter than a bbshd with a good chainline. Only time its get a bit louder is when you are maxing out the motors RPMs by being in too low of a gear.