Table of Contents:
http://www.pedelecs.co.uk/forum/electric-bicycles/4682-diy-stage-1-received-bafang-tongxin-kits-photos.html#post59183
http://www.pedelecs.co.uk/forum/electric-bicycles/4734-diy-stage-2-received-li-ping-lifepo4-battery-photos.html#post59988
http://www.pedelecs.co.uk/forum/electric-bicycles/4737-diy-stage-3-motor-testing-fork-photos.html#post60039
http://www.pedelecs.co.uk/forum/electric-bicycles/4747-diy-stage-4-16-wheel-lacing-building-photos.html#post60153
http://www.pedelecs.co.uk/forum/electric-bicycles/4769-diy-stage-5-prepping-fitting-electricals-photos.html#post60345
http://www.pedelecs.co.uk/forum/electric-bicycles/4778-diy-stage-6-fork-hub-torque-protection-photos.html#post60504
http://www.pedelecs.co.uk/forum/electric-bicycles/4786-diy-stage-7-first-ride.html#post60641
http://www.pedelecs.co.uk/forum/electric-bicycles/4825-diy-stage-8-continuous-improvements.html#post60991
http://www.pedelecs.co.uk/forum/electric-bicycles/6956-diy-stage-9-a123-nano-battery-pack-photos.html#post88165
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I love it !!
I first used my Merc to test the wheel build on the road (the Merc is a cheap 1990's Brompton clone, with an alloy frame instead of steel). I "dumped" all the electrics into the front touring bag (clear sunny day). No pedelec, no brake cut-off, just the thumb throttle and the 3-"speed" selection (it's actually a power/current limiter).
The Merc only has 3 hub gears, yet I rode 5 miles on all the local hills where I normally struggle with my 6-speed Brompton, and I didn't break a sweat ! You still need to pedal of course, which is fine by me as I love cycling ! It's just like having bionic legs, or just like living in a flat country (Cambridge comes to mind). I use the motor only on the hills, as I ride faster on the flat than the max motor RPM anyway (let's not even talk about going downhill, where the motor is totally pointless).
The 3-speed switch and built-in electronic regulator in the controller is great !! I don't know if it helps saving battery life (although it probably does decrease the consumption indeed), but it's just a nice feature to have: the first level is only usable when walking next to the bike, or when maneuvering REALLY slow around car parks, etc. The second speed is usable whilst pedaling, and it's good enough for small slow hills or to help moving forward from a standstill (with human pedal assist of course, as always...I mean, it's not strictly necessary, but I make a point of not stressing the system...a behavior which will be needed with the slipping gears of the Tongxin). The third level is full power, and it really pulls the bike on the flat (I don't know the max speed, but it's not much), and it's necessary for any serious hill. That's why these levels are not "gears": they limit the power output, so there is no need to "switch down a gear" (e.g. level 2) hoping that it will help climbing a hill. The torque from the motor is constant, and the full power output is needed to climb anything serious.
The Bafang is noisy, and it has drag. Nothing new here. It's a compromise I can live with given how it "flattens" the landscape for me ! Now of course I must try the Tongxin before I make my mind up. That's probably for next month, as I won't have time to finish the Tongxin and I intend to ride the Bafang for some miles first.
So, do I want more power: well, actually I'm happy with this level of power, as I am a keen cyclist. I love to pedal, and I don't want an electric scooter. However if there was something to improve: yes, less noise and less drag please
Maybe the Tongxin will deliver this ! 
PS: following the test ride with the 3-speed Merc, I immediately moved to the 6-speed Brompton which is my main bicycle. Apart from the fact that the real B is a better bike (an updated, more modern version as well), the above remarks are all valid. Although I constantly pedal in the highest gear at low cadence, it is still nice to have 5 other gears to play with in situations where I don't want to or can't use the motor (low battery, etc.).
http://www.pedelecs.co.uk/forum/electric-bicycles/4682-diy-stage-1-received-bafang-tongxin-kits-photos.html#post59183
http://www.pedelecs.co.uk/forum/electric-bicycles/4734-diy-stage-2-received-li-ping-lifepo4-battery-photos.html#post59988
http://www.pedelecs.co.uk/forum/electric-bicycles/4737-diy-stage-3-motor-testing-fork-photos.html#post60039
http://www.pedelecs.co.uk/forum/electric-bicycles/4747-diy-stage-4-16-wheel-lacing-building-photos.html#post60153
http://www.pedelecs.co.uk/forum/electric-bicycles/4769-diy-stage-5-prepping-fitting-electricals-photos.html#post60345
http://www.pedelecs.co.uk/forum/electric-bicycles/4778-diy-stage-6-fork-hub-torque-protection-photos.html#post60504
http://www.pedelecs.co.uk/forum/electric-bicycles/4786-diy-stage-7-first-ride.html#post60641
http://www.pedelecs.co.uk/forum/electric-bicycles/4825-diy-stage-8-continuous-improvements.html#post60991
http://www.pedelecs.co.uk/forum/electric-bicycles/6956-diy-stage-9-a123-nano-battery-pack-photos.html#post88165
------------------------------------------
I love it !!
I first used my Merc to test the wheel build on the road (the Merc is a cheap 1990's Brompton clone, with an alloy frame instead of steel). I "dumped" all the electrics into the front touring bag (clear sunny day). No pedelec, no brake cut-off, just the thumb throttle and the 3-"speed" selection (it's actually a power/current limiter).
The Merc only has 3 hub gears, yet I rode 5 miles on all the local hills where I normally struggle with my 6-speed Brompton, and I didn't break a sweat ! You still need to pedal of course, which is fine by me as I love cycling ! It's just like having bionic legs, or just like living in a flat country (Cambridge comes to mind). I use the motor only on the hills, as I ride faster on the flat than the max motor RPM anyway (let's not even talk about going downhill, where the motor is totally pointless).
The 3-speed switch and built-in electronic regulator in the controller is great !! I don't know if it helps saving battery life (although it probably does decrease the consumption indeed), but it's just a nice feature to have: the first level is only usable when walking next to the bike, or when maneuvering REALLY slow around car parks, etc. The second speed is usable whilst pedaling, and it's good enough for small slow hills or to help moving forward from a standstill (with human pedal assist of course, as always...I mean, it's not strictly necessary, but I make a point of not stressing the system...a behavior which will be needed with the slipping gears of the Tongxin). The third level is full power, and it really pulls the bike on the flat (I don't know the max speed, but it's not much), and it's necessary for any serious hill. That's why these levels are not "gears": they limit the power output, so there is no need to "switch down a gear" (e.g. level 2) hoping that it will help climbing a hill. The torque from the motor is constant, and the full power output is needed to climb anything serious.
The Bafang is noisy, and it has drag. Nothing new here. It's a compromise I can live with given how it "flattens" the landscape for me ! Now of course I must try the Tongxin before I make my mind up. That's probably for next month, as I won't have time to finish the Tongxin and I intend to ride the Bafang for some miles first.
So, do I want more power: well, actually I'm happy with this level of power, as I am a keen cyclist. I love to pedal, and I don't want an electric scooter. However if there was something to improve: yes, less noise and less drag please
PS: following the test ride with the 3-speed Merc, I immediately moved to the 6-speed Brompton which is my main bicycle. Apart from the fact that the real B is a better bike (an updated, more modern version as well), the above remarks are all valid. Although I constantly pedal in the highest gear at low cadence, it is still nice to have 5 other gears to play with in situations where I don't want to or can't use the motor (low battery, etc.).
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