TSDZ2b kit on a gravel bike

baisikol

100 µW
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This is a unstructured review of a tsdz2b motor I used to convert a gravel bike into an ebike.

The base bike is an aluminium 1x12 gravel bike with through axles and 68mm bottom bracket.

The conversion kit was purchased from pswpower who ships from inside EU. Actual purchase portal is on aliexpress and there are few customization choices.
Engine I selected is 48v/500W, display is 850c and battery of 17.5aH (HL-plus). The cost of the kit was 570€ shipped.

The kit arrived in a bit over week, few days longer than shipping promise was. Everything one could assume is included, is.
The motor, rpm-sensor for rear wheel, y-split to the rear fork to attach lights, battery holder, battery, 2A charger, various fixing screws, cranks, pedals, throttle, display, tool to tighten bottom bracket.
I did not plan to have the throttle attached so I am not interested in brake sensors nor gear-shift sensors.

The installation manual is rather short, but it actually is pretty much as simple as that. I did watch the manufacturer installation video on youtube which was helpful.

What you extra I needed: various length zip ties, 5mm and 8mm hex socket tools, torque wrench, front and rear lights, xt60 connectors to replace the bullet connectors, soldering iron, a broken fatbike inner tube, original bottom bracket removal tool

To start, I cut the bullet connectors from the battery holder and the motor off and soldered xt60 connectors in.
Installation begins with removal of old bottom bracket. After that is done, the fitting of the engine can begin. With the bike I had, this was very simple, I could just push the brake/shifter cables aside, push the engine in and place the cables in appropriate places where they're not in the way and can still work. Fixing the motor in place is done using a tightening plate in the rear fork and this was a tight spot but eventually it worked out just fine.
Battery holder comes next. Since the bottleholder screws are so close to each other, I drilled space to the top of the holder to allow a thick ziptie to fasten the top part to the frame. Thus, the holder is held in place by 2 bottleholder screws and a ziptie.
Lastly it's the fun part, which is cable management. A lot of zipties and happythoughts later, it will not look like a bike from a factory but hopefully something you won't feel ashamed riding on.

The installation took a day for me with long pauses between. This was the first ebike I've built with a little experience in electrics and bikes.

So far I've ridden about 100km with it. The first ride was 2x27km at max assist level on a -4C weather with variable road-profile and a mass of around 100kg on the bike (+10kg bike, +10kg motor/battery). The battery was almost empty after the ride. Second rides were 1x27 with battery at around 49v at the end.

The assist feel very much the same as it does on my factory built fatbike with a M400 bafang motor. It does have a sharp kick-in/out, and riding at the threshhold (the maximum speed I've set it to assist at) can feel bouncy. I knew before I bought the kit that the 42T chainring will not work and it doesn't, I only use the 5 lowest cogs on the cassette and they'll likely wear out very quickly. A 52T chainring is a must for this bike.
The tool for tightening the engine (the included BB tool) is bad, you're supposed to tighten the BB to 40Nm but the tool cannot be attached to a wrench. I've already once had to undo the pedal to tighten the BB and it's loose again.
 

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FME with a BBS02, if a lock ring secures the system, a Hozan tool is very effective; I beat on it with a hammer and it hasn't loosened in eight years.
 
The BB coming loose is apparently a fitting error on my side. Either the plate used to secure the motor to the BB on the other side was too far away (I used two washers between) leaving the tightening piece loose or the motor collided with the frame on the other side disallowing the BB to be tightened.
I put a washer on the fixed side and left one washer off on the other and the BB seems secure now after two commute rides (totaling around 120km).
To clarify, see the attached picture > Washer added to where the green is, one washer removed from where the red is.

I also have had one problem with the motor, during my third commute the engine stopped assisting. I stopped and it seemed like walk mode was enabled (the motor pushed forward at a slow pace). I turned it off and back on and got error 04h. It's throttle stuck error which seemed odd because I don't have throttle. It must've been moisture getting into the throttle connector as it was raining and I had not properly clogged it. It's clogged now and the problem hasn't returned.
 

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The mainstream thoughts for mid drives are that they should be spun fast to be efficient. That imolies 52T will be too high, unless you're really flying. Maybe you are, as you're burning 15AH (700+ watts) to cover 54 km,
 
I ordered a 50t chainring. Cadence calculator suggests I can use 15t rear sprocket to maintain a speed of 30,2kph at 70rpm with 50t instead of 29,2kph with 13t rear sprocket with 42t chainring. This is the reason for bigger chainring - I dare not forcefeed the 11/12/13t sprockets because of bad (excessively worn chain, worn chainring) experiences with my other middrive.

However, now that I've driven about 500km with the bike, it looks like assist level 3 is perfect for riding. The bike feels very natural at this level and the threshold is not noticeable.
 
Great to read this post as it’s exactly what I’m looking to do with my Trek cyclecross.

I’ve currently got a 2x9 setup with a 50T and 36T front chainring set.

So with converting would o be correct in thinking I will be going down to a single chainring on the crank? Should o look at a 52T?

I’m only wanting pedal assist like you, don’t want throttle as I simply want assist in the hips as they are plentiful where I stay.

Can you send a link to the video that was mentioned so I can get a look at it?

Thanks
Mark
 
The front chainring size you pick will usually be whatever gives you the pedal gearing you use the most in the worst conditions you have. You'll want to pick one that lets you still ride even if the assist fails, in whatever conditions you must still ride in if that happens. (or else walk the bike).

You can be limited by the specific middrive and the specific bike frame because of chain alignments, sprocket sizes taht will fit on the drive, etc. Sometimes you can change the rear cassette and derailer to compensate for this, to give you a bigger or smaller rear cog to fix having to use a smaller or bigger front ring than you want.
 
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