Gearing 20" wheel bike Bafang BBS02 750w

[simon_lipari]

Hi all. I'm not sure about gearing for the bbs02 750w 48v / 20" wheel bike I have in the works, not sure if this is gonna work out practically. I thought I'd ask around. Had another similar thread back in october. Anyone got experience with steep hills and maybe a 20" wheeled bike with a mid drive? The ones I found has a screw-on freewheel and the widest range one can find are 14-28 6 speed or 14-34 7 speed, together with the 48T chainring on the bbs02. Would the bbs02 have problems with this gearing? I'm 60 kilos, bike's gonna be probably 25 with motor and battery, plus dog, 20 kilos, on a frame welded front rack So 105 in total.
This obviously isn't built for speed, if possible I'd wished for a 11-34 range for a little bit more speed on the flats.

Start the think tank!

 

[trex]

I can't see a problem with this other than the power is a bit insane for your weight.

 

[flecc]

This obviously isn't built for speed, if possible I'd wished for a 11-34 range for a little bit more speed on the flats.

.
Cyclezee offers an 11 to 32 freewheel, see this link
.

 

[Kinninvie]

With 46 on the front and 30 on the rear mine pulls me up a 14% hill at 11Mph using assist 5 out of 9 .
Then you have to consider that I weigh 108 Kg,the bike weighs 24Kg AND thats on a 26 inch wheel with knobbly tyres!
On a 20 inch wheel I would be going up on the back wheel alone.
An 11/30 freewheel will be plenty for you.

 

[simon_lipari]

I can't see a problem with this other than the power is a bit insane for your weight.

Yeah I was trying to find the 500w version in the UK but couldn't, and many people said on different forums that the 250w 36v is a bit weak. Maybe those were americans tho, lol. But power is a good thing here because I need to haul stuff, unless it torques the bike to pieces..

With 46 on the front and 30 on the rear mine pulls me up a 14% hill at 11Mph using assist 5 out of 9 .
Then you have to consider that I weigh 108 Kg,the bike weighs 24Kg AND thats on a 26 inch wheel with knobbly tyres!
On a 20 inch wheel I would be going up on the back wheel alone.
An 11/30 freewheel will be plenty for you.

Damn, then I'll fly. Hm, well like I wrote to trex, can't find a motor in between the 250/350 and the 750, and these hills are steep.

.
John at Cyclezee offers an 11 to 32 freewheel, see this link
.

Thanks!

 

[trex]

woosh do BBSxx in 15A 250W, 18A 350W and 25A 500W in 36V, Eclipse do all 36V and 48V versions. I reckon 25A 500W 36V or 18A 500W 48V would be plenty.

http://wooshbikes.co.uk/?cdkit
http://eclipsebikes.com/bafang-8fun-bbs02-drive-750w-motor-p-1100.html

 

[simon_lipari]

woosh do BBSxx in 15A 250W, 18A 350W and 25A 500W in 36V, Eclipse do all 36V and 48V versions. I reckon 25A 500W 36V or 18A 500W 48V would be plenty.

http://wooshbikes.co.uk/?cdkit
http://eclipsebikes.com/bafang-8fun-bbs02-drive-750w-motor-p-1100.html

Is there any notable differences/benefits choosing one over the other of the 500 versions below?
18A * 48v =864 watts?
25A * 36v =900 watt?

Thanks

 

[mfj197]

Yeah I was trying to find the 500w version in the UK but couldn't, and many people said on different forums that the 250w 36v is a bit weak. Maybe those were americans tho, lol. But power is a good thing here because I need to haul stuff, unless it torques the bike to pieces..

Damn, then I'll fly. Hm, well like I wrote to trex, can't find a motor in between the 250/350 and the 750, and these hills are steep.

Thanks!

I don't think you'd find the 250/350 weak. Have you seen Electric Bike Review's look at the 350W version on YouTube, on a big Surly cargo bike? Takes off pretty smartish and gets up to 20mph quickly. If you get the 250W one it has the advantage of being legal here in the UK too (although you can programme it to the same 350W if you like).

I bought the 250W from Eclipse before Christmas - good service.

Michael

 

[Geebee]

I have a 20" wheel wirtth a BBS01, The rear cassette is 11 - 32 standard 46 tooth front ring, it will climb a 15% hill with out pedal assist and without using the lowest gear!
If I could pedal to assist I don't think there is a hill that it would not climb with ease, I would probably go for the 52 tooth front ring once you have it all tested.
You can buy free-wheels with a wider range, http://www.pedelecs.co.uk/forum/threads/dnp-epoch-freewheels-and-gearing-question.13139/page-3#post-217697

 

[simon_lipari]

I have a 20" wheel wirtth a BBS01, The rear cassette is 11 - 32 standard 46 tooth front ring, it will climb a 15% hill with out pedal assist and without using the lowest gear!
If I could pedal to assist I don't think there is a hill that it would not climb with ease, I would probably go for the 52 tooth front ring once you have it all tested.
You can buy free-wheels with a wider range, http://www.pedelecs.co.uk/forum/threads/dnp-epoch-freewheels-and-gearing-question.13139/page-3#post-217697

I'm starting to think I've underestimated this whole mid drive e-bike thing! So that was a BBS01 250 watt 36v you had?

 

[Kinninvie]

You can get the 750 and program it to 18A which makes it a 500.
If you later need more power just reprogram it.

 

[Geebee]

I'm starting to think I've underestimated this whole mid drive e-bike thing! So that was a BBS01 250 watt 36v you had?

Well that's up for debate
The seller in Oz sells the BBS01 350w 36v stamped one only, but reprograms to 250w spec. the power to me feels more than my Tonaro so I would assume 350w, one day I will stick my watt meter on it and find out

My top speed, if you set speed limit to 50 kph is 40 kph on the flat, but my trike is aerodynamically about the same as a road bike wiith the rider on the drops, in a full tuck.

And yes a CD is a whole different animal to a hub in hilly terrain.

 

[simon_lipari]

Well that's up for debate
The seller in Oz sells the BBS01 350w 36v stamped one only, but reprograms to 250w spec. the power to me feels more than my Tonaro so I would assume 350w, one day I will stick my watt meter on it and find out

My top speed, if you set speed limit to 50 kph is 40 kph on the flat, but my trike is aerodynamically about the same as a road bike wiith the rider on the drops, in a full tuck.

And yes a CD is a whole different animal to a hub in hilly terrain.

It's hard deciding between legal 250 or going for one higher, eliminating the risk of bike feeling sluggish on the climbs with heavy load on the bike(will post a picture of the hills later for fun). So your unit is engraved 350? If so, how would that work if you had the coppers stop you?

 

[mfj197]

The 250 and the 350 are the same unit, just the 250 is set to 15 amps and the 350 to 18A. You can change that setting yourself if you buy a programming cable. I've gone for the 250 so it is marked as such.

 

[Geebee]

It's hard deciding between legal 250 or going for one higher, eliminating the risk of bike feeling sluggish on the climbs with heavy load on the bike(will post a picture of the hills later for fun). So your unit is engraved 350? If so, how would that work if you had the coppers stop you?

It would not but it was ~$200 aud cheaper than any others and with local support, the rating would require some destructive searching to find and I can refer to the site where they state they are 250w.
So I will cross my fingers if I am ever pulled over, but its unlikely as I always ride with the PAS, so constantly pedaling, I can't add any human power but it is some exercise at least and it feels like riding a bike

I would be much more comfortable with the 250w stamped casing as it does worry me at times as I like to be legal even if it is just the casing stamp.

 

[trex]

Is there any notable differences/benefits choosing one over the other of the 500 versions below?
18A * 48v =864 watts?
25A * 36v =900 watt?

Thanks

it depends on what you want. The 48V has higher maximum crank speed, about 110 RPM, the 36V version has bigger torque but lower RPM, about 86 RPM.
There is little price difference between all the BBSes. Woosh sell the 250W for £330, 350W for £349, 500W for £365. The 48V are more expensive, my guess it's because of the smaller market size.
I have the 250W, but like the 350W more.

 

[Deleted member 4366]

If your motor is stamped anything other than 250w, you'll have a very hard time convincing anyone that it's rated at 250w. The EN15195 requirement is that the motor must be rated at 250w. If you take a 350w motor or higher and run it with a reduced current, it doesn't change the rating, so that doesn't make it compliant.

On the other hand, if the manufacturer stamps or labels it 250w, there's very little anyone can do to argue. There's so many factors that affect the rating that it's virtually impossible to prove that a motor is underrated. The EN test methods can only prove whether one is overrated.

 

[Geebee]

Maybe I should just paint over the 350w and let them work it out
They reprocessed a stack of them when they did the upgrade so they got over stamped.

 

[shemozzle999]

Hi all. I'm not sure about gearing for the bbs02 750w 48v / 20" wheel bike I have in the works, not sure if this is gonna work out practically. I thought I'd ask around. Had another similar thread back in october. Anyone got experience with steep hills and maybe a 20" wheeled bike with a mid drive? The ones I found has a screw-on freewheel and the widest range one can find are 14-28 6 speed or 14-34 7 speed, together with the 48T chainring on the bbs02. Would the bbs02 have problems with this gearing? I'm 60 kilos, bike's gonna be probably 25 with motor and battery, plus dog, 20 kilos, on a frame welded front rack So 105 in total.
This obviously isn't built for speed, if possible I'd wished for a 11-34 range for a little bit more speed on the flats.

Start the think tank!

You would need a minimum of a 52 chainring driving an 11 tooth rear @ a max efficiency 60 rpm cadence to give you a flat speed of 16mph from a 250W BBS01.

 

[Geebee]

You would need a minimum of a 52 chainring driving an 11 tooth rear @ a max efficiency 60 rpm cadence to give you a flat speed of 16mph from a 250W BBS01.

Except in reality the low gearing allows the motor to spin higher and thus the below statement, surprised me as well, GPS and speedo matched.
I am getting less than 8 Wh/k with no rider input and a few steeper hills so efficiency is pretty good at the higher rpm's

"My top speed, if you set speed limit to 50 kph is 40 kph on the flat, but my trike is aerodynamically about the same as a road bike wiith the rider on the drops, in a full tuck."