The Big Wheel

So I have been thinking about turning my bike into an ebike for quite some time now (as in years). I finally narrowed it down to either the Bafang BBS02B 48V 750W or the BBSO3 48V 1000W mid drive kit.

See the problem is that my bike is the Mongoose Blackcomb, so it's very difficult to find a good mounting position for the battery. I would prefer not to mount the battery on the rear rack because I always use that for transporting things.

https://www.rcgrabbag.com/wp-content/..._1980-edit.jpg

(Insert image button above is broken, won't let me insert image)


So I suppose my question is, what is the smallest battery I need? I don't plan on going more than 10 miles each way and I plan on peddling a lot and not using the bike as a scooter. All the batteries I found so far are the "dolphin" style which are HUGE.

Doc_Wui

I have the Luna Mini battery (although the seller doesn't have any at the moment.)
https://lunacycle.com/batteries/pack...-6ah-3-pounds/

It wasn't sold with the bag when I bought mine, so I cannot tell you if their bag is strong enough to be suspended under the seat. For myself, I have not found a bag that I trust and that is also big enough to hold it. On most f my bikes, I have a rear rack and put my batteries there.

It's only 28 cells and about 300 watt-hr. That should cover at least 15 miles at 16 mph. I only used it with my BBS02 a few times.

The Big Wheel

Hi Doc, thanks for the link! That's exactly the type/size battery I'd like to get. Can you or someone else chime in and tell me more information on it? As in, would that battery be better suited for the 750w vs 1000w motor kit? Also, 16 mph doesn't seem that fast. When I was in France last year I rented an ebike with a middrive kit which had a 250w motor (the legal limit in Europe) and it topped out at 15mph. At first I really liked it but over a couple of days (I went on a 50 mile trip over three days) I got used to it really quickly and wished it went faster, 25mph fast.

Also, is it OK to use a 52V battery on a 48V kit?

2old

I'm using the "mini" with a Bushwacker Tacoma bag on my BBS02. Cut a couple of holes for the wires and it performs perfectly for pretty rigorous off road venturing. I put some foam inserts in the bag to insulate the battery from shock. Also, 52V battery works fine with 48V kit, but display isn't accurate for battery usage. Range is at least 20 miles at my speeds. For me the BBS02 is already too powerful with a top speed of 30+mph if geared accordingly.

The Big Wheel

Nice, this is the bag, yes? https://www.amazon.com/Bushwhacker-T.../dp/B00B5199PU

The Mini seems to be popular with the BBSO2. 2old, what kind of mph you can go with that setup?

Nightdiver

Just FYI, the 250W motor isn't the reason the bikes you rode in France topped at 25kph (15mph). The reason is because that is the legal limit so manufacturers program the motors to stop providing assistance at that speed. The exact same motors configured for the US will top at 32kph (20mph). Some folks like to "de-limit" these same motors and 250W can easily push you up to the 25mph speed, provided your setup isn't creating too much drag.

Also, lower power motors will usually provide better range for the same size battery. So if you wanted to purchase a Bafang motor, you might consider the 350w option with a smaller battery size. This will lower cost, weight, etc, only at the cost of pure power for hills, high loads, throttle-only use, etc.

2old

I don't worry too much about top speed since the riding is off road, and usually the terrain is a limiting factor (except downhill). With the stock 46t chainring the bike has exceeded 30 mph on the street. I've geared it down with a 42t Lekkie ring lately. My wife's bike is even "slower" with a 36t ring. We seldom use higher than level "1" (of 5) off road.

The Big Wheel

I'm thinking of getting the BBS02B and Lunacycle mini battery. The reasoning behind this is that I could mount the battery in a bag under the seat post to make it look really stealthy and I could always buy a second mini battery later and just switch them out. And as you can see from the first post my bike doesn't really have a good place to mount a battery. I also have read that most people actually buy a battery that is 2 or 3 times the size (distance wise) they really need.



Only question now is which sprocket should I go with? Choices are:

1. 44T
2. 46T
3. 48T
4. 52T

Can someone explain the differences? Would a 52T give me more acceleration/torque but reduced top end? And a 44T would give me the slowest acceleration and highest top end speed? If I plan on using my bike as a bicycle and not a moped, meaning I want to paddle 100% of the time should I go with the 52? When going as fast as the motor/battery will allow I would still like to paddle and feel like I am making the bike go faster.

Also, the mini is 52V while the BBSO2B kit is a 48V. From my understanding is that the battery meter won't work on the display. Anyone know how to fix this? Seems like it would be a really simple fix. Otherwise, how would you know when to charge the battery?

How much does lunacycle charge for shipping? The mini is sold out right now so I can't add it to my cart and see what the shipping is. If it's like $40 maybe it would be worth it to buy two at the same time, to save on shipping, no? What do you guys think.

Doc_Wui

You have it backwards. The smaller gear (T means teeth) accelerates better because the gearing is lower. On a pedal bike though, your legs can only spin so fast, so smaller T also means lower top speed. This is less true with a strong motor.

Your mountain bike probably has a 42T/33T/22T crank gear, but you can count the teeth on the biggest gear. If you plan to pedal, and the Mongoose goes fast enough, then you might get a similar gear on the the BBS02.

However, most mountain bikes are geared for under 20 mph, so you might want the higher T gears to accomodate your pedaling. The tradeoff here is if you don't know how to ride a geared bike, you might climb a hill in the highest gears, load the motor down, heat it up, and melt the internal nylon gears in the motor's transmission. The vendors encourage buyers to go with 42T (or less) for this reason.

The BBS02 has enough rpm to maintain a good speed with a 42T, more than your legs anyway. I think you only want the higher T, so your pedal cadence matches the expected speeds.

I think I bought either the 46T or the 48T. I also bought the standard bafang gear. No lekkie. I wanted to keep my spending down. No gear sensor either. I don't shift bikes or cars with power on.