Looking for recommendations for E-bike conversion kit


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2:29 PM
Jul 31, 2020
Our city recently approved E-bikes on our local bike paths. My commuter/grocery getter/beer runner/spousal unit hauler is a Surly Big Dummy. I was thinking a little help now and again, when I'm pushing 400 lbs operating weight, might be nice.

I've been doing some online research for conversion kits. The company that's popping up most often is Bionx, but putting a $2000 kit on a $1100 bike seems silly.

So, I'm looking for recommendations on conversion kits. What to look for. What to avoid.

My rig uses a 26" wheel, 9 speed Shimano with rim brakes.

I don't want regenerative braking/pedaling. Most of my riding is 20 miles round trip. Because of the heavy loads, a solid, well built wheel is very important.

Any recommendations appreciated.
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While BionX was one of the first companies to really push e bike kits in to the mainstream they are pretty weak in comparison to a mid drive for your application. Not to mention all proprietary and $$ to begin with.

I would suggest a Tongsheng TSDZ2 @ 52v. A good price on them here: 52v TSDZ2 - VLDC 5 w/ Throttle, E-brakes, Light Cables - Re-Cycles E-bikes They also have a 13.6Ah battery for $360 that would mate well with it.

It is a torquey unit @ 52v. I have one on an old mtb and it climbs everything I point it at as long as I can hold my line. Would be perfect on a cargo bike.

It is DIY but a pretty straight forward installation that requires removal of the old crank and bb as it replaces them.
It sounds like you are going in the direction of a hub motor; for DIY I'd consider a mid-drive like what Bigwheel is suggesting. You'll be able to use your stock wheel and rear cassette gearing; but be wary of the mid-drive front chainring tooth # choices.

Also check out Luna Cycle; they have both hub and mid DIW kits plus all the usual e-bike paraphernalia.

Do you want to emulate Class 1 (motor activated by pedaling) or Class 2 (hand throttle)?

(Many DIY do both)
If your application is strictly road or very smooth trail and you don't have any steep hills, IMO a hub system is more than adequate (I have a couple that function very well). Front hubs have the advantage of easier installation and better weight distribution, but rear hubs do the job too and are preferred by many DIY types (look at endless sphere). A mid-drive seems to do everything well, but wears out drivetrain parts more rapidly. Best to try out a few different bikes if possible before deciding which is preferable.
I am a die-hard mid-driver, but in your case a hub motor seems to be better suited. Look at a Magic Pie from Luna or others and pair it with either a mini battery or a Sharkpack.
I was leaning towards a rear hub motor but after reading all the recommendations, it sounds like a mid-drive would be better. I didn't even consider a mid-drive because I assumed it wouldn't work with my bike. But after looking at the link you provided, it definitely will.

Not sure whether I want Class 1 or 2. If I go class 2, how does it work? Can I pedal along with the motor to conserve battery power? I've only ridden one E-bike and it was a class 1 pedal assist, no throttle.

One other thing I just thought of if I go with a mid-drive, I won't be able to run gears as low as i have right now which is 22 and 32 teeth chainrings. I know that seems ridiculously low but when you're weighed down with 100 lbs of cargo, it's necessary. This wouldn't be a problem with a hub motor.

I'm kind of shying away from a front hub based on advice from others. I was told it's an odd and unsafe feeling having the front wheel powered.
The best use for a throttle on a mid drive is to aid in starting out, especially if you are loaded. Just apply it until you can get your pedals going enough to kick in the torque sensing PAS, well in my case anyway because the TS is torque sensing instead of the Bafang cadence sensing. Big difference in how natural the bike will feel pedaling between the two. Key is to have stopped in a low gear so you don't have to lug off the line.

While you won't be able to run as low a gearing with any of the available kit mid drives that is mainly because the drive side gear reduction casing sits out further than normal from the bb and so if you want any sort of decent chainline, especially if you are going to be using your lower gears, the chain ring has to be big enough to fit over it to get the teeth further toward the chain stay. I use a 42/42 on my TS and find it to be more than adequate while the power is on, even eco the lowest setting which I ride in 99% of the time. You would need to get a bigger range cassette and a Wolf Tooth derailleur dropper though.

Front hub motors have their place in the e bike world no matter what "others" give out their keyboard advice on. Real world mileage has proven to me that with the correct installation they are perfectly safe and super reliable. Biggest benefit is they leave the bikes drivetrain to be whatever you want it to be and better allow for cadence variation while maintaining the same speed over ground. I find this feature more desirable on my road bike and have the TS on my mtb as the lower speeds I go on it generally don't require as high a cadence and I am more in to the amount of torque it puts out.