Bafang BBSHD, 1000W, 68mm-120mm BB

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anttipaa   10 W

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by anttipaa » Nov 29 2017 9:11am

Could someone help me to find right size chainring for bbshd. I have Canyon Dude fat bike with 11-42t cassette and Im going to use it for commuting, slow trails, snow etc. I need 25mph top speed. What size would be best 28t, 32t, 36t or 42t? I dont like to buy many because of the price..

Im going with 15s li ion battery and charge only to 4.09 so it works without modding.

Chainline looks like this with mighty mini:
https://lh4.googleusercontent.com/jMjH1 ... 7exzlE0_Au

Not bad? I dont need to use all 11 gears. I can re arrange my cassette.
Canyon Torque + ?

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fechter   100 GW

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by fechter » Nov 29 2017 9:25am

I have a 30T mighty mini on my fat bike and I can reach 28mph in the top 3 gears. My speed is limited by power, not the gearing. I do a lot of steep hills, so I like the low gearing, but it makes human assist pretty impossible under most conditions. I re-arranged my cassette to get the chain line better.
"One test is worth a thousand opinions"

Bullfrog   10 W

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by Bullfrog » May 19 2018 9:04am

Yes, I know this is an old thread but wanted to throw out a little helpful advice. Probably going to start a new one with a title like "Gearing a Bafang BBSHD Top Speed and Off Road"...just so it shows up when somebody is searching for gearing info.

When people are talking about gearing they need to at least specify what size wheels they are running and the actual tire diameter would be even better. Just specifying the front and rear sprocket size is only part of the equation.

I am running a BBSHD on a 14s6p battery with a Maxxis FBR rear tire that is 26x4.0 and OD = 725mm (28.5 inches). I have a 28 tooth front chainring and three cogs in the back (took my freewheel apart and rearranged things to get my chainline nice and straight). When riding off road, I use either the 23 or 26 tooth rear cog and if I want to get somewhere quicker I use the 17 tooth rear cog.

Did a lot of experimenting with small cogs in the rear to see how fast I could go on flat ground without drawing more than 1,000 watts steady state at full speed. The 28 front and 17 rear with the 725mm diameter tire was the fastest set up I could get and my top speed was about 25 mph...a lot had to do with whether I sat straight up or leaned over because even at 25 mph, aerodynamic drag is a big factor when you are only working with 1,000 watts or 1.3 horsepower.

Yes I could go a little faster with different gearing but the more wattage (actually amperage) you push thru the motor, the more it will overheat and potentially damage something. I felt very comfortable running my BBSHD at 1,000 watts continuously so for me, the top speed of my BBSHD is 25 mph.

Not what the BBSHD fans want to hear but my recommendation for a drive when you are going to be putting in miles on pavement is a Geared Hub Motor like the MAC or just a Hub Motor like the Crystalyte (many good choices for hub motors since they are very simple). Why...because you don't transmit any power thru your gears or chain (assuming you don't pedal). It is a simpler set up and will have much less wear and tear on your Bike's drivetrain. If you ever intend to leave the pavement...the BBSHD is my choice.

endrew   100 mW

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by endrew » May 20 2018 2:45am

Bullfrog wrote:
May 19 2018 9:04am

Did a lot of experimenting with small cogs in the rear to see how fast I could go on flat ground without drawing more than 1,000 watts steady state at full speed. The 28 front and 17 rear with the 725mm diameter tire was the fastest set up I could get and my top speed was about 25 mph...a lot had to do with whether I sat straight up or leaned over because even at 25 mph, aerodynamic drag is a big factor when you are only working with 1,000 watts or 1.3 horsepower.
How can you tell the power consumption while you ride?

Bullfrog   10 W

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by Bullfrog » May 20 2018 7:41pm

endrew...excellent question. I forget everybody doesn't have the exact same set up as me.

You need a display that shows the wattage or amperage...with the DCP14 color display that EM3ev sells you can select wattage or amperage.

I believe most of the black and white displays just have a bar graph with no numbers for power...if you buy a new display, make sure it shows what you want before purchasing.

I have had several and looked at several other people have had and my favorite is the DCP14.

tomjasz   1.21 GW

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by tomjasz » May 21 2018 12:55am

endrew wrote:
May 20 2018 2:45am
Bullfrog wrote:
May 19 2018 9:04am

Did a lot of experimenting with small cogs in the rear to see how fast I could go on flat ground without drawing more than 1,000 watts steady state at full speed. The 28 front and 17 rear with the 725mm diameter tire was the fastest set up I could get and my top speed was about 25 mph...a lot had to do with whether I sat straight up or leaned over because even at 25 mph, aerodynamic drag is a big factor when you are only working with 1,000 watts or 1.3 horsepower.
How can you tell the power consumption while you ride?

If you want useful information add a wattmeter to your kit for occasional plug in a system check. The display is data poor.


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Thanks Justin_le we're here thanks to you. All the best to the mods for their tireless work keeping it on an even keel.

endrew   100 mW

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by endrew » May 21 2018 6:44am

Bullfrog wrote:
May 20 2018 7:41pm
endrew...excellent question. I forget everybody doesn't have the exact same set up as me.

You need a display that shows the wattage or amperage...with the DCP14 color display that EM3ev sells you can select wattage or amperage.

I believe most of the black and white displays just have a bar graph with no numbers for power...if you buy a new display, make sure it shows what you want before purchasing.

I have had several and looked at several other people have had and my favorite is the DCP14.
I wish I new this a few weeks ago!!!!
Thanks a lot!

mick2d2   100 µW

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Re: Bafang BBSHD, 1000W, 68mm-120mm BB

Post by mick2d2 » Jun 11 2018 6:22am

Cycle Analyst gives very useful accurate info too.

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