*Updated* Converting Merida Crossways to ebike, some adviced needed

[piotr]

Hi,

I'm new to the ebike-world. I have a Merida Crossway bike that I want to convert to an ebike. I have already done a lot of reading and research and have decided to go with the Bafang mid-motor but I'm not sure what version is right for me: 250, 500 or 750 watts.

I will use the bike to commute to work, 22km on flat bikelane. I want to maintain a speed of 30kmh (about 19mph) with moderate pedaling. In the "Read this first" section of the forum I found that I need about 21wh at the desired speed of 20mph.

When I get the Bafang BBS02b/750w/48v with a 48v/14.5ah battery (SAMSUNG INR18650-29E cells) can I expect to make the roundtrip on a single charge ?

There's only a small difference in price between the bsb01b/250/350 and the bsb02b/750 motors and I understand that I can tune a lot in the settings, so is it wise to stay with 250w (legal in my country) or there a huge difference with the 750w (not legal in my country)



Thanks for your tips and advice !

Best regards,

Peter

Update: installed the Bafang. A perfect fit, did'nt need any spacers. Waiting for the battery now.

 

[markz]

Buy the BBSO2 750W for sure!

48V x 14.5Ah is 700Wh divided by 21Wh/km is 33km total.
You say 22km but is that one way or round trip?
If that 22km is round trip, then you are fine, however if that 22km is one way then you require a larger battery, or charge the battery at your destination.

If there is wind, stop and go, hills, you go faster, carrying more weight (like groceries) then that will affect total distance.

Are you in Australia?
Seems like AUS is 250W.
https://youtu.be/IxB2j-egWcQ?t=672
Pay close attention to 12:05

to interrupt a continuous wattage you need to specify an rpm.

there is no single definition of a wattage rating of a motor, its a dynamic variable which depends on how fast you are moving and the rpm of the motor..... no where in that benchmark that says ah thats the continuous power point.....

Those are great points to ponder. But also, how is the street beat copper going to know what power rating anything is, they wont, and they cant. They only know how to write up traffic tickets, harass bums and eat donuts. Lets say someone ebiking is a complete assshole, doing wheelies, going fast and scaring people, they will get a ticket. Now a responsible ebiker riding respectfully and no one will even know you are riding an ebike. Park your bike at the local 7-Eleven convience store, and you might get someone asking you "How far can you go on that thing" or "How much did that cost you" but if you do it right, especially with a hub motor, you can hide all the components. Rear hub motor behind some saddle pannier bags, battery inside bags, controller camouflaged or hidden well. With a mid drive setup it is a bit harder to do, but there are ways to do it. One that comes to mind is having a completely black motor, and a black and very large ring gear or ring protector to help hide the motor. I have seen some very nice setups.


You can look at and buy from http://dillengerelectricbikes.com.au
The bbs02 kit - http://dillengerelectricbikes.com.au/electric-bike-kits/mid-drive/8fun-mid-drive-kit-bbs02.html

Various random pictures of bbs02 on bikes, confirming that even using a regular crank, 44T large crank gear and a much larger "crank protector" to hide the motor will work. In the picture below, the battery would stick out, so saddle pannier bags would work great in hiding the battery but that also disrupts the weight distribution. A triangle bag would work well.
https://i.redditmedia.com/Shj15JbaKHJJSI8s3a1lOk2qMowLvRBWXNNv6zQUmDc.jpg?w=1024&s=1f33ff60eada5ef95df05f7514faa5ad

https://www.electricbike.com/wp-content/uploads/2016/03/bbshd-diy.jpg

 

[wturber]

Frankly, for flat road commuting on a road/hybrid/cross type bike, I'd use a small, rear, geared hub motor. It will virtually disappear behind your large, dark, rear gear cluster and the small ones don't add a lot of weight to the bike. If you had hills to climb, I'd be much more enthusiastic about opting for a mid drive.

As to the power of the motor and controller, I think that depends a lot on how strictly the laws are enforced and how you'd like to ride. As I said above, I favor the hub motor for a commuter bike. They are simple, durable and they don't put any strain on your bike's regular drive train. And the low power units can be very hard to spot. That's an advantage if you are running at illegal speeds or power levels. It also makes your bike a bit less of a target for theives.

In my experience, on flat land and without wind being a major factor, 250 watts of power will be quite sufficient to let you average 20 mph - especially if you are going to be putting in a fair bit of pedal effort yourself. Of course, it is nice to have more to help you accelerate from a stop, climb a hill when you aren't commuting, or deal with a head wind.

If your country's laws regarding power are ambiguous, I favor the constant power rating of the controller approach. Many controllers have maximum power outputs of about twice their continuous rating. So if you had a controller that was nominally 250 watts with a max output of 500 watts, you'll have a fair bit of reserve power and still have a strong argument to make in case you are questioned about the legality of your gear.

If you are dead set on the mid-drive, that's fine by me. Make yourself happy. It's your bike after all. Adapt what I had to say about power etc. accordingly. Keep in mind that relatively low powered mid-drives will put less strain on the bike's drive system that more powerful ones - assuming that you actually use the power that the higher powered system can deliver.

 

[piotr]

Thanks for the input so far ! I have decided on the Bafang bbs02b/750. Now for the battery, bigger is better I asume. I know it's a bit tricky to get a battery from China but there are sellers with good reviews and they use brand-cells for their battery-packs.

Found this on Aliexpress: 52v 20ah is this ok for the Bafang (which is a 48v motor). This would give me a range of appox 49km and that should be enough for a rondtrip (44km).

Ps: I'm in the Netherlands, so flat terrain.

 

[MadRhino]

Yes it is a match, charging 58.8v
14s lico cells is the best match for 48v lifepo4

 

[markz]

Netherlands, so flat terrain.

https://nl.aliexpress.com/item/US-EU-No-Tax-Electric-Bicycle-52V-20Ah-Lithium-ion-Battery-1000W-E-BIKE-Triangle-Battery/32846211354.html

Unit Pack Power is a great choice for a battery purchase.
Remember to buy the charger as well, preferably from the same place.
Be sure the connectors match.

https://unitpackpower.aliexpress.com/store/1178407?spm=2114.10010108.100005.2.25bf2fd3cvmhSd
Looking at their website, doesnt look like they sell chargers.

Next quality purchase "go-to" is either www.ebikes.ca in Vancouver, www.em3ev.com in China, www.lunacycle.com in California

Cheaper units from www.bmsbattery.com in China, could pose an issue, do a search here on ES, www.batterysupports.com is another in China but it looks like batterysupports is no longer.

 

[piotr]

The triangle battery-pack weighs 6.6kg, isn't that a lot of weight to put relatively high in the frame (see first post for a picture of my bike).

 

[piotr]

First post updated with Bafang installed. A perfect fit to this frame.

 

[half_brick]

NIce! Do you know which model of Merida Crossway that is? I'm looking at buying the same.