Overall, I think this is a great little kit for anyone who isn’t afraid of a bit of tinkering. If you’re comfortable with a bit of bike maintenance, you will be fine with this.
Relatively straightforward to fit
No need for separate controller box
Hard to make cables tidy
Display remote badly designed
Need crank arm and bottom bracket removal tools to fit
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The Tongsheng TSDZ2 Mid Drive e-bike conversion kit is a robustly built, attractively priced solution for anyone looking to give their existing push bike a bit of a zing in the pedal department. It’s not difficult to fit, but if you’re scared of a spanner it probably isn’t the solution for you.
The main component of this marvel is the motor unit which sits under your pedals and replaces your existing bottom bracket and crank arms. As well as being the source of the electrical torque, this neat little unit also houses all of the control technology, so all the other components connect to it. It also means, unlike some other e-bike conversion kits, there’s no need to house a separate controller box on your frame.
The kit comes with its own metal brake levers for cable operated brakes. These also contain switches that tell the controller not to power your chain when you’re braking. These, along with an optional throttle, connect to the display which then connects to the motor unit.
The display is one of the best laid out I’ve seen on a kit. It can be controlled via buttons on the display unit itself and also has a remote which you can mount closer to your hand-grips.
You have four levels of assistance ECO, TOUR, SPEED and TURBO. Each one providing more assistance than the last but obviously also consuming more battery as well. This assistance is supplied when the built-in pedal torque sensor determines it’s required.
There is, however another way to get an extra boost, which is to use the optional throttle. This will override the pedal sensor and supply the additional oomph as you require. It’s a proportional control, so you can be quite nuanced as to how much power you add.
It’s important to ensure your frame has the right sized bottom bracket for the kit you’re fitting. As long as that’s the case, and you know how to remove a bottom bracket, fitting is pretty straight forward. You remove your pedal arms, your bottom bracket and the new unit just slots in. In my case I had to re-route a gear shifter cable that ran under my pedals, but that really was the most challenging part of the conversion.
The display, throttle and brake levers just slide on your handlebars once you’ve removed your hand-grips and then the challenge is to route the cables as neatly as possible. I’ve been told if you’re not using the throttle, replacing your existing brake levers isn’t strictly necessary because of the way the pedal sensors work, but I personally would always rather be safe than sorry.
The kit doesn’t come with a battery so you will need to source one and then connect that up to the motor unit as well. I used a generic down tube battery, but there are plenty of designs out there that will work. The entire build took me a couple of days and amusingly the instructions only cover fitting the motor so I had to use my initiative to fit the display, brakes, throttle and battery.
Because this is a mid-drive unit, the assistance is much more subtle than rear or front wheel drive units. The power is blended in much more smoothly and I imagine would be much less disconcerting to a rider not used to an e-bike.
In ECO mode I was hardly aware the bike was assisting however it definitely was, as a journey I take home up a steep hill on my unpowered bike always results in me needing a shower when I get home! Using this kit in ECO mode meant I still felt the ride but didn’t need a shower.
As you work your way up the modes, the assistance becomes more pronounced and your battery range is reduced. I have a 10 Ah battery and I weigh about 100kg. In the TURBO mode you get a lot of assistance and I got about 18 miles range from the bike. This is dramatically increased the lower you go in the assistance modes.
Another advantage to a mid drive unit is, because the kit drives the chain rather than the wheels directly, it means your gears work with the motor. So, when you are in first gear, you get the most torque which is of course when you need it. As you move up the gears the assistance becomes less pronounced.
Also because the pedal sensing is built into the motor unit and it is sensing the torque you put in through the pedals, it is very good at identifying when you need that assistance and blending it in smoothly. Something you don’t get with a standard pedal sensor which generally is either off or on.
Value and Conclusions
I was pleasantly surprised at how solid this kit felt. The motor housing was well built, the brake levers are metal and felt robust. If you already have a bike you want to convert or are prepared to search around for a second hand donor bike, you could have a very nice e-bike for around the $800 / £600 mark, which I think is not a bad deal.
I did have a few minor gripes. The instructions could have covered the entire build, not just fitting the motor. The design of the display remote meant I found it difficult to select the information button without accidentally changing the assistance level and I noticed, if you accidentally have your foot on the pedal when you turn the unit on, it seems to mis-calibrate its torque sensitivity and you end up with little or no assistance.
But overall, it was well built and offered a refined ride. The Tongsheng TSDZ2 Mid Drive ebike conversion kit is a good upgrade for those comfortable using a spanner.
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Leigh Emmerson is an engineering graduate and self-confessed gadget addict. His love of technology and cycling intersected in 2015 when he bought his first e-bike. After a lot of miles and a lot of fun, he decided it was time to upgrade to a higher spec model.
It was then he came to the realization that the best way to get a better spec e-bike – without spending a fortune – was to build it himself!
This has since become a bit of an obsession, as he continues converting bikes to electric with various kits. Much to his partner’s annoyance, he rarely gets round to selling them afterwards – which is why his double garage has no space for a car. It’s full of bikes.
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