new build questions

Cavi

New Member
Soo I am semi new to this. My son has a E-bike that I have done significant work on, and I fly RC Electric airplanes which use the same idea, electric brushless motor, speed controller and Lithium batteries. I am now going to convert a Specialized Pitch hardtail MTB. The idea is I want a bike with full tiwst throttle that I can either twist and cruise the trail or pedal and use the throttle when I hit a steeper hill to help me up it. I am leaning twords the BBSHD. I am also considering the
52V 750w Tongsheng TSDZ2

or even the BBS02 in the 750W version. Will I hate myself if I use anything other than the BBSHD for my build. The only reason for the other two considerations is they are a couple of hundred dollars less
 

harryS

Well-Known Member
BBS02 owner here. Get the BBSHD. Only a few hundred bucks. You may have a lot more than that in spare RC parts laying around.
 

indianajo

Well-Known Member
Pedaling a mid drive motor power off without a one-way clutch is dragging the motor with your feet. Few people do it. And I need the exercise of pedaling.
I ride unpowered 2/3 of my commute, using power only on a hilly extension of my route that keeps me off a 55 mph highway. My geared hub motor does not drag. Most of these have a one-way clutch. I got my 48 v power wheel kit from ebikeling.com but he only sells 36 v ones now. You can sometimes get a 48 v geared hub motor from lunabikes.com but is often out of stock. Mine is a front hub, which allows me to have a 11:32 8 speed rear sprocket. I tried a rear hub but only 7 speed sprockets would fit, and nobody stocked an 11:32, only 14:28. I can pedal up 15% grade in 32:32 ratio, if the battery failed. The btrbattery & sun-ebike batteries failed every trip until I bought a luna battery, so pedal power was important since cell phones don't work out there.
 

AHicks

Well-Known Member
Soo I am semi new to this. My son has a E-bike that I have done significant work on, and I fly RC Electric airplanes which use the same idea, electric brushless motor, speed controller and Lithium batteries. I am now going to convert a Specialized Pitch hardtail MTB. The idea is I want a bike with full tiwst throttle that I can either twist and cruise the trail or pedal and use the throttle when I hit a steeper hill to help me up it. I am leaning twords the BBSHD. I am also considering the
52V 750w Tongsheng TSDZ2

or even the BBS02 in the 750W version. Will I hate myself if I use anything other than the BBSHD for my build. The only reason for the other two considerations is they are a couple of hundred dollars less
Another (long time) RC'er here. My advice would be to get something you can get parts for without too much difficulty. I really have no knowledge regarding the Tongsheng motor to share. That, and I'm not real sure about being tied down to an internal controller. Truth be known, I'm not big on mid drives as I don't need the granny gear climbing abilities that they feature. I'm a MAC fan (geared hub), so I do believe gear reduction is important, and if I had it to do over again, I would go with a GMAC. Not because I like to see how much money I can spend, but more because I like getting it right the first time so I don't have to mess with it again. That, and I'm OK with the technolgy involved. Point being, like it or not, you might want to have a look. The concept is brand new, and I believe it's a game changer in the e-bike world. Thinking you might want to know about it prior to making your call.
 

harryS

Well-Known Member
Hi indianajo. The bafang BBS02 and BBSHD have very little drag. The crank will spin about 10 seconds on its own with a flip, if the chain is removed. A regular crank will spin for a minute, so there is drag,

That may not be true of the TSDZ2. I can feel more friction when I turn the crank, but I haven't mounted it yet with pedals. It may go a few seconds with the weight of the arms/pedals.

I also find turning the axle of a geared motor difficult with my fingers, but put a wheel on it and a forward flip will spin it for 10-15 seconds. On the other hand, it doesn't spin at all on a reverse flip, as you must now turn the motor thru the gear multiplication..

If I were used to the drag of a direct drive motor, I might want the GMAC concept for regen, but I will continue to be dubious of a motor that is always cogging.
 

AHicks

Well-Known Member
Re: GMAC "drag", yup no doubt it's in play. The difference here though is that it's been dealt with by supplying a very small amount of power to it, just enough voltage to effectively cancel out the drag. Upside is the fact you have gear driven performance, with huge amounts of regen available, right down to walking speeds.

Granted, with a dead battery (or no battery), there will be very noticeable drag.
 

Cavi

New Member
ok, so I am going to order the kit tomorrow. I am ordering from Luna cycle due to their customer service. I am ordering a BBSHD kit. Do I really need the brake levers with the cut offs? I would rather have less wires running down the tube. I am fine with letting off the throttle to hit the brakes. Also, I would like a smaller sproket, but Luna suggested to wait on ordering it until I have the kit installed due to the fact that the bfang one gives the most ofset. I has still wondering if I could get the luna one and a smaller sproket to try, or should I really wait?
 

harryS

Well-Known Member
Brake cutoffs are great insurance. I've had two incidences this year of runaway throttle. My wife rode thru deep water, which threw water into the throttle connector and locked her bike on throttle. On one of mine, the throttle ground wire came loose, and that also locked on full throttle. However these were little motors, so it sounds scarier than it was. Hitting the brakes was enough.

The BBSHD PAS is probably pretty high in level 1, too, so being able to keep the power off in low speed maneuvers is pretty handy.

I have a stock chain ring. The BBS02 kit was almost $600 in 2016 when I bought it.
 

Cavi

New Member
Well got a Specialized Pitch as the donor bike last week, cleaned it up however it needs a new derailleur in the back which I have ordered. Today I went ahead and ordered the kit from Lunacycles!!! BBSHD!!!!