Converting fleet of citibike style share bikes- front hub vs bbs01

I had an owner of a local business that does app based bike sharing contact me- he was considering converting some to electric. Terrain is mainly flat, there are a couple areas nearby with mild hills that 350w should be plenty for and he was clear that he wants to limit the top speed assist to around 20 for liability purposes.

Going with something durable, as these are going to be pretty well thrashed. The first thing that came to mind was converting them with some of the surplus bafang jump front hub motors As the bikes have nexus three speed IGH So rear hub won't be an option. Another thought was a BBS01 As they seem to be pretty bulletproof and the overall cost probably wouldn't be much different once I factor in labor for wheel build, controller etc

Any thoughts on how each would fare over time or Which would be better for this application? Riders will run the gamut from drunk teenagers to overweight tourists and everything in between. Chances are we will run some type of shark pack style battery so its easy to swap out packs in between customers for quick turnaround.

TDCM has a rear direct drive hubmotor with a 5-speed IGH built-in to the center, as an option.

A typical system on flat terrain would be a front geared hubmotor. Overspec the motor and limit the amps with a small controller, to achieve durability.

If you get a system with a PAS sensor on the crank, you can eliminate the hand-throttle.

I like front disc brakes, but a rim brake on the rear should be more than adequate.

Personally, I would not recommend a BBS02 for a rental. A mid-drive allows the drunk rider to use the option of starting off in top gear, and even running top gear up a steep hill with an un-allowed passenger sitting on the handlebars...

Whatever you get, add a temp sensor to the stator and a high-temp alarm.

My vote would be for a hub drive as well.

I'm not sure how well the 3 speed would handle frequent shifts while under power. Even a BBS02 has a LOT of torque available when just speed restricted.

Hard to go wrong with the Jump bike motors. That's what they were for, after all. If you use 36V, the power will naturally peter out as you approach 20mph, and the speed limiter won't be too obtrusive when it cuts in.

Definitely do not max out the current capability of these motors-- the axle stubs are so short that it's difficult to fit in anything but the tabbed washers and an axle nut, no room for a real torque arm. 15 battery amps should do it.

They will sure like it. The "Lime" etc. rentals here started out with no motors. Once the motors started showing up, they all got motors pretty fast - I guess when you can get motorized, no one wants the ones without. They had a good deal of trouble with them, though - at one point, someone checked out a bunch and found about half of them broken, possibly in many cases just out of juice.

I think their gear must have been pretty rip-off-proof, I suppose the battery unit that you could get to fairly easily wasn't standard enough that you could open it up, discard the transmitter and use the battery for your own purposes.

donn said:

I think their gear must have been pretty rip-off-proof, I suppose the battery unit that you could get to fairly easily wasn't standard enough that you could open it up, discard the transmitter and use the battery for your own purposes.

Click to expand...

Not only do you need special tools to work the security fasteners on dockless rental bikes, but the difficulty doesn't stop there. I have repurposed a couple of salvaged Jump bike packs to make a bigger pack, and it was horrible.

The thing is so dead you can't even probe a pack voltage until it gets a secret handshake from the bike (which has long ago been scrapped). But to get the battery management PCB off, you have to dig out a bunch of sealant, nip off a lot of nickel interconnects, etc. Once you're down to just the cells, you can begin to build the pack back up into a functional system. It's not a crackhead level job.

If you pay yourself a prevailing hourly wage in the kind of city that has dockless e-bikes, you're probably not recouping that much value with your new used 36V 10Ah battery. The kind of folks who'd accept a lower return on their effort probably don't have the skills to make it into a working battery anyway.

Thank you for the input everybody. It seems like the overwhelming consensus here is front hub, I just looked at a photo of the bikes and realized that since they have chain guards that run the length of the chain stay adopting mid drive wouldn't be an ideal solution anyway. Not to mention the fact that I have already had a few customers of mine with long skirts get them stuck in the chainring even with the stock bafang and tongsheng Chain guards

The jump hubs are probably going to be the winner here, As we know they are capable of plenty of abuse and cheap enough to grab some extras for parts. As mentioned, 15A is probably about the max they will get, Should provide decent level of assist with a modest top speed.

This just leaves me to sort out batteries, the bikes have some sort of integrated rear rack but it has a basket on top. It remains to be seen if I can make a battery work with those, They are a step through design so another idea was to use the DNR hinged clamps on the seat tube And a shark style pack vertically. What makes it tough as I would like to be able to remove the batteries so they could just swap them out as soon as a customer returns it and put it in service, But I have no idea if it's possible to get hailong/reention Cylinders keyed alike. I know it will be a shit show if they all have different keys and there's a bunch of high school kids expected to swap out batteries in between riders and keep track of what takes what key without losing anything

I doubt there are more than ten different key profiles for the battery pack.

Even so, when ordering them, the retailer should be able to narrow the key profiles down to may three different keys?

If yes, they could be color coded with nail polish.

Rental bikes need to be simple and quick to service, hence the front hub recommendation. The service man can replace the front wheel in a minute and the bike is ready to go. The controllers and batteries need to be quick-swap too, all with unusual mounting fasteners for thief prevention. Front geared hubs are the norm on rental bikes, rear DD for the scooters.

Manbeer said:

The jump hubs are probably going to be the winner here, As we know they are capable of plenty of abuse and cheap enough to grab some extras for parts.

Click to expand...

You'll need extras because also because the wheels arrive in "as is" condition. Bent rotors are the norm, along with cosmetic damage from axles chewing on neighboring hubs. Some of the rims arrive bent. Most need nothing more than a little spoke tightening and minor truing.

Here's a picture one supplier sent me to help explain the condition of the wheels. It represents how they were delivered to the supplier.


If the rental bikes have rim brakes, well, sometimes the rims can't be coaxed to work well with rim brakes. It depends on the brake boss height and spacing. In the worst case, you have to relace the motors to better rims. I would kind of enjoy that job, but most probably wouldn't. If the bikes have front disc brakes, that's easiest, but you'll need to buy some rotors.

First manbeer where you located . As it could be cheaper to buy already made ebikes complete with a charger. On the West coast they would have bikes for a rental bike store and you can paste your name on them. How many bikes do you have in a fleet ?