Rear Hub Drive -TO- Mid-Drive

[creativepart]

In Dec 2020, I converted an acoustic hybrid Specialized Crosstrail with a Rear Hub Kit from Dillenger. The project was fun and easy and I have over 450 miles on the build bike now. I love it. BUT! I want to remove the Hub drive and get a BFang BBS02 Mid-Drive motor. It would be ideal if I could reuse the battery, battery cradle with integral controller, the C965 display, thumb throttle and the handlebar selector switch. OK, it doesn't have to be all of that stuff. But the majority of expensive stuff would be good.

Dillenger says they make most all of the parts themselves and that if I want to change to a Mid-Drive I should buy a complete kit and remove the original complete kit.

I'm trying to figure out how I can make this change without buying a whole new kit including battery. It seems connectors and the controller will be the major issues but I'm unsure how to plan and begin this project.

Any help or advice for starting this project will be greatly appreciated.

 

[AHicks]

The BBS02 contains it's own controller, but it should have no trouble use any 48v battery. No clue on your components, but if the system you have now is 48v, I see no reason why you couldn't re-use most of it and go with a conventional rear hub/tire.

 

[creativepart]

The BBS02 contains it's own controller, but it should have no trouble use any 48v battery. No clue on your components, but if the system you have now is 48v, I see no reason why you couldn't re-use most of it and go with a conventional rear hub/tire.

Thanks for that info. Yes, my battery is 48v. The controller is built into the bottom of the battery cradle. I guess a new cradle without a controller would remedy that issue.

Here's a photo of my battery cradle with the built in controller AND the connector from the motor to the controller. I don't know if this kind of motor connector is standard or not.

 

[EMGX]

I'm curious why you want to go from your rear hub motor to a mid drive? I prefer mid drive but the 500w geared rear hub that I put on an old mountain bike works well. It has a KT controller/display and doesn't have abrupt power/speed cut in that are reported with some others.
The battery cradle should work if you can open up the box containing the controller, remove the controller and put connectors on the leads that come from the battery contacts.
I don't see how the standard 9 pin connector cable in the top image would work to power your mid drive because that comes from the controller that you won't be using.

 

[creativepart]

Thanks @EMGX, The reason is not based in solid facts, but I like the idea of a mid-drive working WITH the gears in the drivetrain. Rather than the rear drive motor going X speed and me finding gears to match or exceed that speed.

I was set on doing a mid-drive DIY project from the start and chickened out because I already had a rear hub drive and knew how they worked. So, I went with what was familiar.

Thing is, my rear hub drive bike is great fun. It works very well but the whole concept of the mid-drive seems more correct. There is no "real" reason to switch. I'm retired and I like to work on the bike. I have enough money to play around with things. I don't want to spend $4,000 on a pre-built mid-drive bike so I plan on selling my Blix Vika+ folding eBike and that should more than pay for a new mid-drive motor and associated parts. Then I can sell the rear hub drive wheel and move on to something new.

About the connector - I still had it in my head that the motor needed to plug into the cradle/controller from the hub drive bike. Obviously, that's wrong thinking and I was being slow to understand the implications.

 

[AHicks]

Seeing what you have, I would be considering the resale value of your existing components as part of your project. Makes it more interesting...
Selling the Bafang motor/wheel should be pretty easy and help pay for the new project.

Regarding the battery/controller combo, the controller is worthless on your new project. I don't know anything about the battery. Is the battery going to be up for something like this? Maybe you want to sell the whole thing with the rear wheel/motor as a "kit"? If the battery is over about 16ah, I'd be tempted to keep it.

If I were buying a BBSxx, and the BBSHD were not too much more than the BBS02, I think that would be money well spent. My understanding is they are pretty much bullet proof.

I would plan on reusing everything forward over again (brake cut off, throttle, and display). That should all plug right in to the BBSxx. -Al

 

[creativepart]

The battery is a 52v/48v 14 amp hour battery so it will be fine for this. All of this talk is building my confidence that I can figure this out.

I ride every day - I'm 71 it's good for me - and I want to get everything purchased and figured out ahead of time so that there is not more than a couple of days of downtime for the bike.

We leave for a 6-week RV trip on the 28th and I want everything done and ready to go by then.

 

[EMGX]

I like to mess around with projects also. Just finished, finally, installing a 36v MXUS geared front hub motor on my wife's new Biria Easy Boarding bike that won't work with a mid motor. I made the job harder by having laced that motor into a 16" rim for another whimsical project (was going to put it in a single wheel trailer that I have but decided not to) then had to re-lace into the 26" rim for her bike, also had to splice WP connectors onto the stock non-WP motor cable.

I can't speak for Bafang mid drives but I can say that the three bikes that I installed TSDZ2 mid drives was overall easier and neater than the hubs including dealing with the crank sensor (I had to get three to finally find one that worked with the Biria) and maze of wires with the hub drives. I have to say though, with a KT controller the front hub motor works really well on her Biria as does the 48v 500w rear geared hub motor on my old mountain bike.

IMO a big downside of mid drive is chainline issues. I might buy a 10mm offset (stock is 5mm offset) chainring for my most recent install because the chainline is marginal in first gear. Dual chainring is theoretically possible but on my bikes isn't feasible also due to the chainline.

Good luck with your project if you decide to proceed. If you want torque sensing and if you're open to considering a TSDZ2 you can get 48v or 52v 750w and depending on the display chosen there is a throttle option - if that is important to you. I got my most recent one with a new C3 display that has 5 levels of assist and is very easy to program (VLCD-5 was a bother), no throttle though (not something I want). Eco-cycles has been good to deal with, they answer questions same day, often within minutes of sending an email.

 

[AHicks]

The battery is a 52v/48v 14 amp hour battery so it will be fine for this. All of this talk is building my confidence that I can figure this out.

I ride every day - I'm 71 it's good for me - and I want to get everything purchased and figured out ahead of time so that there is not more than a couple of days of downtime for the bike.

We leave for a 6-week RV trip on the 28th and I want everything done and ready to go by then.

That's a pretty aggressive target date in my experience. Best of luck!

 

[EMGX]

That's a pretty aggressive target date in my experience. Best of luck!

Due to shipping times or is the bafang glitchy or difficult to install for some reason? If he gets his battery figured out in advance (remove old controller, put connector on the wires feeding from the battery contacts to the old controller - if possible) and replace the hub motor wheel with the stock wheel then all that remains (assuming Bafang install is similar to TSDZ2) is pull the old crank assembly (which can be done in advance also), slide motor in bottom bracket, tighten it down (the TS has an additional collar over the crank that attaches simply with two screws and two spacer washers), attach torque mechanism (if any), crank arms/pedals, rear wheel speed sensor (optional), put display/control on handlebar and hook up the battery.

 

[AHicks]

I agree assembly will be no big deal. I'm thinking sourcing the motor and anything else necessary, then shipping delays - including the time it takes the vendor(s) to actually ship. Then assemble, and a day or 2 to troubleshoot (which may or may not involve sourcing more parts - e.g to correct the chain line for instance), which might require the internal controller config be changed, more testing, etc.

And I'm figuring MY work ethic, which is mostly puttering mode, involving much "thinking about it" and of course the required afternoon nap! -Al

 

[creativepart]

I took two half-days to install my rear hub drive and found it an easy process. I have a good bike stand and plenty of bike tools.

I don't know if shipping will be much an issue. But I'll remain flexible and we'll just have to wait and see. If it doesn't work out, that's OK I can finish it whenever. Retirement is pretty sweet.

 

[EMGX]

Here is an interesting comparison hub vs mid drive, doesn't appear biased.

 

[EMGX]

I agree assembly will be no big deal. I'm thinking sourcing the motor and anything else necessary, then shipping delays - including the time it takes the vendor(s) to actually ship. Then assemble, and a day or 2 to troubleshoot (which may or may not involve sourcing more parts - e.g to correct the chain line for instance), which might require the internal controller config be changed, more testing, etc.

And I'm figuring MY work ethic, which is mostly puttering mode, involving much "thinking about it" and of course the required afternoon nap! -Al

That was exactly my experience with hub motor installations. It took considerable time for me looking at where I wanted to mount the controller, then changing location a couple times. Trying to figure out where to route the rat's nest of wires and changing the routing once or twice, or more. The cadence sensor that came with a kit didn't fit at all for bottom bracket cartridge on my wife's Biria, the two piece sensor fit on the axle but the Biria frame didn't work to mount the pickup - then I ordered a third one piece sensor that did work with cogs that fit into the cartridge retainer - all in all I probably spent a couple hours, just on this, plus ordering and waiting a few days for the final workable crank cadence sensor to be delivered.

The TS mid drive was a simpler and cleaner installation without those complications.

Function wise my mid with torque sensing vs hub drives without are different but I like them both and both versions are very good pulling long and steep hills where I ride - but I like the torque sensing power delivery better overall. I don't see that (for me) there would be much of an advantage of a Bafang without torque sensing vs a hub without it. Wheel removal for things like flat repair (I've had a couple flats on my Yamaha mid drive gravel bike) is not a problem with the mid drive, would be much more of a hassle with the hub motors.

 

[AHicks]

Re: flats w/hub drive, they get easier each time for me. Sure, the mid drive is easier, but the hub drive just isn't that big a deal. Not any more anyway....

 

[creativepart]

I thought I'd better circle back to finalize this thread at this point. After reading these comments, talking to suppliers, and doing a lot of soul searching I have decided that this is folly to undertake another change to a rear hub drive bike that works great and meets all my needs just because I like the idea of a mid-drive ebike at the moment.

If I build another bike, or if I have a serious problem with my current DIY eBike then, sure, why not. But change for change sake isn't very prudent.

I must admit that I am prone to get mono-maniacal about things and sometimes want to keep pouring money and effort into things.

Thanks everyone for their advice and opinions.

 

[tomjasz]

Run both with a selector switch from the battery to one or the other motor. tons of fun.

 

[kmccune]

I thought I'd better circle back to finalize this thread at this point. After reading these comments, talking to suppliers, and doing a lot of soul searching I have decided that this is folly to undertake another change to a rear hub drive bike that works great and meets all my needs just because I like the idea of a mid-drive ebike at the moment.

If I build another bike, or if I have a serious problem with my current DIY eBike then, sure, why not. But change for change sake isn't very prudent.

I must admit that I am prone to get mono-maniacal about things and sometimes want to keep pouring money and effort into things.

Thanks everyone for their advice and opinions.

I think it is a disease called"Tinkeritis", finally I am getting better(I hope)

 

[AHicks]

I think it is a disease called"Tinkeritis", finally I am getting better(I hope)

I refer to it as something along the lines of e-bikeitis....
Once hooked, you could be at this a very long time.....

 

[creativepart]

It’s certainly not limited to bikes, not inthe least. All hobbies and pastimes are plagued with this “gearitius.”

Cars, boats, fishing, guitars, audio, photography, the list goes on and on. I don’t know if it’s limited to males, but it seems likely to be. We become fixated on the things, the gear, we read about it, talk about it and we keep spending, tinkering and modifying.