Bafang G310 geared hub - 11:1 reduction ratio!!!

I've just purchased a 310 from Grin unlaced. I plan to build it into a Sun Rhynolite 26" rim I have, 2 cross with some 14G plain gauge spokes I am able to source very cheaply from SJS Cycles (I have a frame-builder friend who can include them in his next order so I can save on postage).

Has anyone built one of these into a wheel yet?

Justin/GRIN recommend 13/14G Sapim Strong spokes because the 13G threads provide a stronger nipple engagement. However these are quite an extra cost. Has anyone used 14G plain gauge spokes? What's the general feeling - will they be OK? Should I use brass washers under the heads?

ta,
Sam.
 
samsavvas said:
Justin/GRIN recommend 13/14G Sapim Strong spokes because the 13G threads provide a stronger nipple engagement.
Click to expand...
Hmm...maybe it's because mine are for a small 20" wheel, but the 13/14 butted spokes I have from Grin are just single-butted, only 13g at teh spoke head, not the nipple end (which is just 14g).
 
Are you running a disc brake? The butted option will provide a some margin but more important will be the quality of the actual build in terms of strength and durability. I built up a g311 with a Rynolite with 13/14/13 spokes and quite happy but I would have used 14s if a cheaper option. I recommend you not use washers.
 
G310 installed on my Surly Krampus, thanks Grin for the kit :)
Battery 52V/10.5+7Ah, rims Ryde Andra 40, tires Surly Extraterrestrial.
After a first 15kms ride, this new version of my e-Krampus is muuuch better for my use (mainly road) than the previous one with BBS01 and 29+ tires.

Before :
1557002269-20190503-151309.jpg


After :
1556999513-p1160398.jpg
 
Thanks ;)
I'm used to the basic PAS, that's why I choosed it, but I think my next try will be a torque sensor.
 
Nice sweet build! And stealthy too. Well done!
 
Thanks Tomjasz :)
Yes this motor is very stealthy (despite its 6-700W of max power), it's even more visible on the other side :
1557065831-p1160405.jpg
 
Watch out with the max power. 700W-1000W is entering the gear failure risk territory. Use slow up ramps and install a temperature sensor if you can. I'm yet to do the latter myself.
 
Indeed I'm using the 500-700W setup only at speed higher than 30 kph in order to limit the torque on the gears.
By the way, what is the maximum power that can be used safely on this motor during city commuting, with many
stop and go ?
 
I found my answer here: https://www.ebikes.ca/product-info/geared.html
"The nominal power rating of 250W from Bafang doesn't mean a whole lot. These motors can put out 30 Nm of torque continuously and upwards of 40-45 Nm for short times without overheating. At higher speeds (like 40 kph) this translates into a solid 600-700 watt continuous power levels, while the corresponding power at lower speeds is more like 200-300 watts. Usage beyond 50-60 Nm is not recommended as there is real risk of stripping the gears."
 
Jil said:
Indeed I'm using the 500-700W setup only at speed higher than 30 kph in order to limit the torque on the gears.
By the way, what is the maximum power that can be used safely on this motor during city commuting, with many
stop and go ?
Click to expand...

I can tell you that running it with a lot of stop and go at 1kW with sharp throttle ramps and no regards to temperature has resulted in melted gears in about 1000km. The same person who blew the gears is now running it limited at 700W with slower ramps and regreased very well hasn't had a problem again. I think he's well over the 1K km mark with the new gears. I'll be installing a temperature sensor on mine for monitoring and limiting. But it seems if you aren't going over 700W and your throttle ramps are low and you're doing leg work during starts, you should be fine.
 
Do you know if regen is possible with the G310 (and more genrally with reducted motors) ?
 
It's not, due to the freewheel/clutch. If you want to do regen in a geared motor, you can either buy a clutchless one (such as this) or weld the clutch fixed in your G310.
 
1N4001 said:
It's not, due to the freewheel/clutch. If you want to do regen in a geared motor, you can either buy a clutchless one (such as this) or weld the clutch fixed in your G310.
Click to expand...

Actually, while that advice holds with most geared hub motors, it wouldn't be advisable on the G310 because of the helical cut sun gear. That puts an axial thrust component on the planet gears and the motor rotor which is absorbed by thrust bearings, but those thrust bearings are only installed on one side.

ThrustBearings.jpg

If you run it with a locked clutch and did regen, then the planet gears and rotor would get pushed in the other direction and could scrape against a surface that wasn't meant for that.

I mean I haven't tried it yet, but first reflection is that this would be a real risk unless you went and modified the insides to have thrust bearings on both sides of the planet gears and rotor.
 
justin_le said:
ThrustBearings.jpg

I mean I haven't tried it yet, but first reflection is that this would be a real risk unless you went and modified the insides to have thrust bearings on both sides of the planet gears and rotor.
Click to expand...

That's an awesome picture - thanks. Always wondered how those cheap "thrust bearings" look like. I'm also interested in regen and quite crafty. Do you think the pinions offer enough space on the secondary reduction side for a second axial load bearing. Looks pretty tight to me.
 
qwerkus said:
That's an awesome picture - thanks. Always wondered how those cheap "thrust bearings" look like.
Click to expand...

Here's what they look like installed behind the planet gears, it's pretty slick since they fit inside a recess in the gear casting and don't add any width to to the gear assembly.
ThrustBearingInstalled.jpg

I'm also interested in regen and quite crafty. Do you think the pinions offer enough space on the secondary reduction side for a second axial load bearing. Looks pretty tight to me.
Click to expand...

It is tight, and there isn't the same amount of space for a thrust beraing washer like there is on the other half of the gear. Assuming though that the ball bearings inside the gears bottom out against a lip, then you could in principle replace the 3 bearings here with angular contact bearings that have the same geometry but are designed to take a thrust load as well.

G311 Planet Bearings.jpg

That would be the neatest solution. Then you should just need to add a small thrust bearing on the end of the helical sun gear to take the thrust loading on the rotor. I've taken apart another small geared motor with helical gears which had one of these on it:

ThrustBearings on Rotor.jpg

So that's definitely doable too. Unfortunately Bafang isn't a company that is game for upgrade requests or small mods like this unless you are talking orders in the 5K-10K volumes at least, so until then any regen ona G310/G311 motor would have to be a DIY affair.

I do have lots of random miscellaneous G310/311 motor parts around if someone wanted to carry the torch and try this out!
 
justin_le said:
So that's definitely doable too. Unfortunately Bafang isn't a company that is game for upgrade requests or small mods like this unless you are talking orders in the 5K-10K volumes at least, so until then any regen ona G310/G311 motor would have to be a DIY affair.

I do have lots of random miscellaneous G310/311 motor parts around if someone wanted to carry the torch and try this out!
Click to expand...

Awesome reply. Thanks a lot for the details. I'm in - though I doubt the small g311 can handle a lot of regen heat, even with ATF cooling, so I'm going for the larger brother g360.500... as soon as I find a seller for it! Will keep you updated. The only question remaining is how to lock the one way bearing which acts as a clutch, but I'm confident a simple solution will come up.
 
qwerkus said:
Awesome reply. Thanks a lot for the details. I'm in - though I doubt the small g311 can handle a lot of regen heat, even with ATF cooling, so I'm going for the larger brother g360.500... as soon as I find a seller for it!
Click to expand...

I'll be posting my disassembly analysis and test results on the G360 on this thread here later today
https://endless-sphere.com/forums/viewtopic.php?f=2&t=100461
In the end we'll probably not be carrying and offering this hub motor for reasons that I'll be outlining there. It took us about 6 months to get a sample from Bafang so I gather there could have been supply or mfg. issues that they needed to sort out.

The only question remaining is how to lock the one way bearing which acts as a clutch, but I'm confident a simple solution will come up.
Click to expand...

Most people just degrease and give it a few zaps with an arc welder, but if you don't have access to welding gear then drilling and inserting screws or dowel pins does the trick too. Just beware that it's usually hardened steel and the domain for cobalt bits and not your typical cheapo TiN coated hardware store stuff.
 
justin_le said:
I'll be posting my disassembly analysis and test results on the G360 on this thread here later today
https://endless-sphere.com/forums/viewtopic.php?f=2&t=100461
In the end we'll probably not be carrying and offering this hub motor for reasons that I'll be outlining there. It took us about 6 months to get a sample from Bafang so I gather there could have been supply or mfg. issues that they needed to sort out.
Click to expand...

Yes, saw your other thread. Fascinating work - thank you. I also kindof figured out what you take on the g360 will be :)
I've been trying to get another sample of a high power dual geared hub from quarks: https://www.alibaba.com/product-detail/24v-36v-48v-The-lightest-Rear_60641812323.html?spm=a2700.8443308.0.0.56f23e5fIb7dUj

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HTB1zk3EQFXXXXX4XXXXq6xXFXXXl.jpg_.webp


If the picture is an accurate description of the motor, it should be pretty torquy, or so I gather from the number of poles and the rotor/stator width. They told me 800W is the max. power the nylon pinion would handle. Unfortunately, they also don't seem to be open to deal with small timers like myself,so getting a sample will be tricky.
 
Quick update, I have made more than 2000 kms with my G310 in 2.5 months, it works flawlessly.
I use it at 450 W in town (or when I restart after a stop), 675W on roads (only above 20 kph), with 14S battery, up to now it handles well these settings.
 
Jil said:
Quick update, I have made more than 2000 kms with my G310 in 2.5 months, it works flawlessly.
Click to expand...

Thanks for the long-ish term report!
I have a G310 but i still haven't fired it up :oops:

qwerkus said:
If the picture is an accurate description of the motor, it should be pretty torquy, or so I gather from the number of poles and the rotor/stator width. They told me 800W is the max. power the nylon pinion would handle. Unfortunately, they also don't seem to be open to deal with small timers like myself,so getting a sample will be tricky.
Click to expand...

From the motor spec sheet, it doesn't look like you're missing much. That's a lower continuous power rating than the MAC, and if we think of motors in terms of 'power per pound', it's right on par with the MAC.. and this makes me wonder exactly what went wrong with the design, or if we're looking at heating being a limiting factor..

I like geared motors a lot and wouldn't touch it.
 
Hi,
Do you know if it's possible to replace the standard freewheel hub of the G310 by a Sram XD ?
Indeed I would like to mount a 10/42 or 9/46 (11 speeds) cassette, and it seems to be impossible with the current freewheel.
The resason for my question is that I have mounted the largest chainring possible (36 teeth) on my Surly Krampus frame, and my top speed is limited by my 11/46 Shimano cassette.

EDIT : it's impossible to install a SRAM XD hub on the G310.
I managed instead to install a 38T chainring with a boost Sram GX crankset, and it is perfect with my 29x2.5" tires : at 45 kph - my max speed on flat terrain - with 38x11ratio I pedal at 95 rpm.
 
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