Cute Q100 lightweight builds slow mtb, fast road

[d8veh]

In the UK, Insat International will make you a custom pack with whatever cells you want.

http://www.ebay.co.uk/itm/Insat-Li-NMC-eBike-Battery-Electric-Bike-10-15Ah-24V-36V-48V-e-bike-battery-/331485310419?var=&hash=item4d2e106dd3:m:m8c7FUsp_phLtXj3YKUmfLQ

 

[chas58]

In the UK, Insat International will make you a custom pack with whatever cells you want.

http://www.ebay.co.uk/itm/Insat-Li-NMC-eBike-Battery-Electric-Bike-10-15Ah-24V-36V-48V-e-bike-battery-/331485310419?var=&hash=item4d2e106dd3:m:m8c7FUsp_phLtXj3YKUmfLQ

That is great. Sam in Australia would also build a pack. But neither of them can ship to the US, so I'm out of luck. Tom at Luna liked my idea, but didn't want to build a small light pack. Paul at em3 came through with the ability to build to my configuration requirements.

 

[cycleops612]

I have long fancied the idea of a light road ebike dropbar

yes i know, weight is of the essence, but a 24v 5 or 10 amp (1 or 2kgs of cells respectively) lifepo4 battery would tempt me.

they come in long thin pouch shapes and you only need 8x cells wide for 26.4v (a key metric, as its what has to fit between your knees often, for good balance), not 12 as in 36v

a simple pouch battery could hang from the crossbar as in the story pic.

a sub 13kg good roadbike is dirt cheap 2nd hand, add a simple 24v front hub kit. pretty good. & fast.

for some, a far faster commute that a more powerful, less slippery and light (more effective pedaling) bike.

the 10ah battery & 200-350w motor should be sub 5kg.

my guess is triathlon etc. bikes are rated for 100kg total load -220lbs, so maybe not for 80kg+ riders.

as i am sure others have said, it seems a great app for a 2 speed hub motor (heavier & dearer) -saves all that fuss about getting rpmS right, especially as its a "oddball" non 26" mtb wheel gearing for roadbike wheels.

i cant see much gain from a messy rear hub motor and a limited fixie.

 

[chas58]

Hey cycleops612,

If you are down under, you can get some good batteries from Samd! Certainly 24v would be a nice and light weigh boost. Still, you should target 1KG, not 5kg.
And yes, a 700c drop bar bike requires less power than a 26” mountain bike. It is a misunderstanding to think that 700c wheels are an odd size; a mountain bike and a drop bar bike have basically the same tires circumference.

I’m not sure what you mean by messy rear hub and limited fixie. The only production bike I have seen this clean is the Sondor’s bike. And, this not fixed, it is single speed. Obviously it works best for flat to rolling terrain. If you need to use gears, you should really use a mid drive. The mountain bike has plenty of gears, but I only use one of them.

 

[cycleops612]

Hey cycleops612,

If you are down under, you can get some good batteries from Samd! Certainly 24v would be a nice and light weigh boost. Still, you should target 1KG, not 5kg.
And yes, a 700c drop bar bike requires less power than a 26” mountain bike. It is a misunderstanding to think that 700c wheels are an odd size; a mountain bike and a drop bar bike have basically the same tires circumference.

I’m not sure what you mean by messy rear hub and limited fixie. The only production bike I have seen this clean is the Sondor’s bike. And, this not fixed, it is single speed. Obviously it works best for flat to rolling terrain. If you need to use gears, you should really use a mid drive. The mountain bike has plenty of gears, but I only use one of them.

Whatever. The "standard" issue is about gearing, not tyres.

i dunno the math (PixD=r i am ok on), but a 2" gap between 26" and 28" rim plus tyre depth is a fair whack of extra diameter/circumference it seems to me.

most wheels out there are 26"?, and even more so for ebikes - and even more so in china?, which is the mindset of chinese motor makers re gearing/power characteristics of their volume/mainstream ebike motors models.

mid drive with gears is wonderful but:

heavy, dear

AND

The roadbike drop bar ebike approach is more pedal centric (it has greater effect on the lighter, slipperier bike), AND unless i am missing something, the ideal gear for the motor seldom coincides with the ideal gearing for pedaling.

( cadence, whole can of worms

eg.

"Cadence (cycling) - Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Cadence_(cycling)
Cyclists choose cadence to minimise muscular fatigue, and not metabolic demand, since oxygen consumption is lower at cadences 60-70 rpm. When cycling at 260 W, a pedal force was the lowest at 90 rpm, lower than at 60, 75, 105 or 120 rpm. It is primarily due to increase of inertia of the crank with increasing cadence.
")

my usual style on my 24 speed mid drive is; find a nice gear for the motor, and help out when it gets stressed a bit and its convenient. Except when the gear is so high, the 300w motor is straining normally, my pedaling cannot be fast enough to have much effect in many cases.

i dont mind kicking in the same effort as a stroll, steadily on the trip, and a quick trot effort briefly in spurts as a turbo mode now and then, but in my mild hills world, pedaling seems to get almost forgotten (bar for smooth gear changes) as an option

Hub motors separate the two gearings, simply by not providing any gears and bypassing the chain drive & .

A 2 speed hub motor would be ideal, tho heavier & dearer.

 

[Sunder]

i dunno the math (PixD=r i am ok on), but a 2" gap between 26" and 28" rim plus tyre depth is a fair whack of extra diameter/circumference it seems to me.

Lol. PixD=r looks like a user name.I think you were looking for C=2πr or C=πd

If you were talking about the circumference of the rim - You'd be right. Using ISO sizes:

26" = 1793mm
700c = 1953mm

Or roughly 9% bigger.

But that's not the end of the story. You don't ride your your rim, you ride on your tyres: 26" wheels usually use 2-3" tyres, where as 700c wheels typically use 19mm wide tires. Why does that matter? Because wider tyres are also taller to keep ratios correct.

Check out the table below - a 26 x 3.0 has exactly the same circumference as a 700c x 30mm:

 

[d8veh]

yes i know, weight is of the essence, but a 24v 5 or 10 amp (1 or 2kgs of cells respectively) lifepo4 battery would tempt me.

LiFePO4 has more or less had its day for electric bicycles. It's simply too heavy. Why would you want to use it?

 

[chas58]

yes i know, weight is of the essence, but a 24v 5 or 10 amp (1 or 2kgs of cells respectively) lifepo4 battery would tempt me.

LiFePO4 has more or less had its day for electric bicycles. It's simply too heavy. Why would you want to use it?

My thoughts exactly.

And Sunder knows his stuff too.

A typical mountain bike tire is 26x2.15, or 2070mm circumference
A typical 700 cc tire is 700 x 25, or 2105mm circumference.
i've gone up to 700x44 on these little motors and in practical terms there is no difference, other than that the 700c is lighter, rolls faster, and goes a lot farther per watt of power.

 

[cycleops612]

yes i know, weight is of the essence, but a 24v 5 or 10 amp (1 or 2kgs of cells respectively) lifepo4 battery would tempt me.

LiFePO4 has more or less had its day for electric bicycles. It's simply too heavy. Why would you want to use it?

i know thats the conventional wisdom, but am not so sure

an 18650 (LINm assumed here) is 50 gm, 10 amps life po4 is 250gm. 4.2v (yeah right, for the first 5% of discharge) vs 3.3v ~constant

mainstream: 18650 =2000na - same weight bar claimed voltage

20% of 18650 is pure dead weight - unusable

1 c discharge on 18650 (for 5 minutes & then dropping fast to uselessness for ebikes in many roles) vs 2c constant and i strongly suspect 3c doesnt hurt much.

2 things recently

1/ killed a $350 retail replacement bottle 18650 10ah 36v (rated but total BS) simply cos i for got to fuss over charge level while unused

2/ i left lights on on a new $200 retail lead acid car battery. i am told i have halved its life and next flat, may as well toss it

Further, what are the odds many of us have time or talent to diagnose

15 amps of 2000ma 36v i make is 8.5x7.5=64~ cells, arranged in parallel, poorly bmsED groups. any failed cell affects the whole, and must be located and solder replaced - 4 connectors.

its not gonna happen for most.

12 x 15 amp pouches in series tho, is diagnoseable and fixable, even for me.

THIS IS A VERY REAL RISK, AND THEREFORE COST, TO FACTOR IN

LIFEPO4 IS RELATIVELY BULLETPROOF it seems, literally - still sorta works after being shot, even with a garlic coated bullet.

2000 charges means it never wears out (or even 1500 is forever if you aggressively fast charge it), vs a few years for 18650 if you have a perfect run and endure reduced storage and performance
on paper, 18650 yes, real world, i am far from convinced. 2000 charges is a full cycle every day for ~6 years

on balance, i would perhaps take a 10 amp lifepo4 over a 15 amp 18650 rig. lets see how weights compare then?

I love that there is no need for messy parallel cells, just choose the pouch size you want and wire in series to get volts you want. baba bim...

very simple and consistent quality pouches and simple construction where each individual cell has its own bms channell.

lifepo4 would be a far more robust battery for heavy users like forklifts, taxis, pedi-ecabs, delivery trucks...

charge speed can be a killer factor for power users, and not just full charges over night. Its interim top ups too. How fast can i pump it up to 80% during breaks & therefore work it all the shift.

we can all only speak from our frame of reference, and i am 75kg and from a sort of centralish burb in EU rules Sydney with trains and mild hills. 7km is a big trip for me but i use it almost exclusively over my car.

Americans e.g seem very much larger mostly, 700watts~ is ok and more spread out (car centric), so i respect their different needs.

battery weight has to be viewed in the context of GVM. for me its 100kg~ ex battery. for a 150kg rider, it would be 175kg (more really due to needing a heavier bike). There is a big difference in the relative effect of an extra few kg of battery. Best to focus on whats the best battery, then consider weight as a percentage increment of the total.

briefly, as may be repetition, my 12ah kosher panasonic bottle battery is 12x36v=432 watts right? BS. It only shows 4 bars on my meter after mere minutes of full use of my 350watt motor. Then its a wimp and no fun.

 

[Neskie]

Hi Chas58,

Thanks for putting together this thread and maintaining it. I am an ebike newb looking to get started, and this project seems to be about as close to what I want to do as I can find on ES so far.

I am also an avid cyclist who commutes on almost entirely flat terrain (good old Minnesota prairie). While it doesn't sound like I can put down as much power as you, I do maintain the 15-17mph range comfortably on my single-speed, cyclocross frame commuter. However, I recently changed jobs that upped my one-way commute to 20mi. I don't mind the extra distance too much, but I'm not to fond of the extra time day-in-day-out for the forseeable future. I've been researching the hell out of ES forums to try to put together a minimalist kit to attach to my existing commuter to try to bring my travel time to around 1hr (so, 20mph avg). Here's some specs:

Rider Weight: ~160lbs
Bike : ~21-30lbs depending on load in rear panniers, steel-frame, cyclocross geometry, 700c wheel with 25mm gatorskins, Spot-Brand Sprawl
Desired Distance: 20mi (one-way if I take charger with me), 40mi (round trip)
Desired Nominal Speed: 20-25mph
Economy (hopeful): ~10 kwh/mi
Minimum kwh needed (calculated from above): ~200kwh (~300 kwh, more realistically)

Like yourself, I'm planning on using this purely as a pedal assist and hope to contribute at least 50% of the power. I'm just looking for something to bring my speed up by ~5mph without "crushing it" everyday. Especially on those windy/rainy days when it will be a challange to convince myself not to drive ... Given that I'm not climbing hills and I'm willing to do all the pedaling (unassisted) below 10mph, I'm thinking the 328rpm Q100cst with a 48V battery is the way to go. I'm saying the cassette version because I'm also running a gates belt drive, so I don't have a freewheel/threaded sprocket. I'm limited to the 9-spline cassette.

So I have a few questions:

1) It's been a few years since the original project date. Would you still recommend the Cute Q100 as one of the best options for a minimalist, pedal-assist hub motor? Or have there been any major competitors that now outshine the Q100 that you know of? (I know this is a big question, perhaps there's a better thread that someone could refer me to?)

2) Do you think there's any chance a Q75 or Q85 could get that 5mph bump with a little weight savings.

3) Towards cycleops612's recent comments, I'm very conflicted over battery chemistry. I've been researching the heck out of it for the past couple weeks, but the technology seems to have shifted dramatically in the last couple years, so my brains is a little overloaded (especially since I'm simultaneously getting caught up on motors and controllers). As a newb, I really like the idea of a 18560-Li-Ion-based pack with built in BMS for the sake of stability/safety. But I'm not really seeing any very attractive options for a low kWh (low amph), minimalist pack. The smallest I tend to see is ~48V, 9ah which all seem a little bulky to me. Perhaps this is simply because my expectations are too high for the low weight-to-range ratio I would like to see. Do you think that EM3ev might be willing to put together a smaller 18560 pack? I'm also hoping to save a few $$ here.

4) I think I read earlier in this thread that it is not recommended to use this hub motor with PAS only? I'm not a big fan of the idea of having a throttle since I have traditional drop bars. I would much rather use some sort of controller (maybe CAv3?) to turn on the motor with PAS only after reaching a certain minimum speed (say 10mph). Or maybe easier would be to use a simple 1-position switch to manually turn on the PAS activation after I hit a certain speed. I know I need to do more research here, but maybe you can just let me know why I can't use PAS only with a basic motor controller?

My apologies for blowing up your thread with my "20 questions". Feel free to ignore or re-direct my newbery as appropriate

 

[leo99]

Hi neskie,
You should start your own thread. So we can all help us without spamming this thread. :wink:
I am sure we will all be happy to help

 

[d8veh]

i know thats the conventional wisdom, but am not so sure

an 18650 (LINm assumed here) is 50 gm, 10 amps life po4 is 250gm. 4.2v (yeah right, for the first 5% of discharge) vs 3.3v ~constant

mainstream: 18650 =2000na - same weight bar claimed voltage

20% of 18650 is pure dead weight - unusable

1 c discharge on 18650 (for 5 minutes & then dropping fast to uselessness for ebikes in many roles) vs 2c constant and i strongly suspect 3c doesnt hurt much.

2 things recently

1/ killed a $350 retail replacement bottle 18650 10ah 36v (rated but total BS) simply cos i for got to fuss over charge level while unused

2/ i left lights on on a new $200 retail lead acid car battery. i am told i have halved its life and next flat, may as well toss it

Further, what are the odds many of us have time or talent to diagnose

15 amps of 2000ma 36v i make is 8.5x7.5=64~ cells, arranged in parallel, poorly bmsED groups. any failed cell affects the whole, and must be located and solder replaced - 4 connectors.

its not gonna happen for most.

12 x 15 amp pouches in series tho, is diagnoseable and fixable, even for me.

THIS IS A VERY REAL RISK, AND THEREFORE COST, TO FACTOR IN

LIFEPO4 IS RELATIVELY BULLETPROOF it seems, literally - still sorta works after being shot, even with a garlic coated bullet.

2000 charges means it never wears out (or even 1500 is forever if you aggressively fast charge it), vs a few years for 18650 if you have a perfect run and endure reduced storage and performance
on paper, 18650 yes, real world, i am far from convinced. 2000 charges is a full cycle every day for ~6 years

on balance, i would perhaps take a 10 amp lifepo4 over a 15 amp 18650 rig. lets see how weights compare then?

I love that there is no need for messy parallel cells, just choose the pouch size you want and wire in series to get volts you want. baba bim...

very simple and consistent quality pouches and simple construction where each individual cell has its own bms channell.

lifepo4 would be a far more robust battery for heavy users like forklifts, taxis, pedi-ecabs, delivery trucks...

charge speed can be a killer factor for power users, and not just full charges over night. Its interim top ups too. How fast can i pump it up to 80% during breaks & therefore work it all the shift.

we can all only speak from our frame of reference, and i am 75kg and from a sort of centralish burb in EU rules Sydney with trains and mild hills. 7km is a big trip for me but i use it almost exclusively over my car.

Americans e.g seem very much larger mostly, 700watts~ is ok and more spread out (car centric), so i respect their different needs.

battery weight has to be viewed in the context of GVM. for me its 100kg~ ex battery. for a 150kg rider, it would be 175kg (more really due to needing a heavier bike). There is a big difference in the relative effect of an extra few kg of battery. Best to focus on whats the best battery, then consider weight as a percentage increment of the total.

briefly, as may be repetition, my 12ah kosher panasonic bottle battery is 12x36v=432 watts right? BS. It only shows 4 bars on my meter after mere minutes of full use of my 350watt motor. Then its a wimp and no fun.

Well, you baffled me with all that. There's a reason that OEMs don't use LiFePO4 anymore! Perhaps you could send your theories to them to see if they'll change.

 

[d8veh]

H
1) It's been a few years since the original project date. Would you still recommend the Cute Q100 as one of the best options for a minimalist, pedal-assist hub motor? Or have there been any major competitors that now outshine the Q100 that you know of? (I know this is a big question, perhaps there's a better thread that someone could refer me to?)

2) Do you think there's any chance a Q75 or Q85 could get that 5mph bump with a little weight savings.

3) Towards cycleops612's recent comments, I'm very conflicted over battery chemistry. I've been researching the heck out of it for the past couple weeks, but the technology seems to have shifted dramatically in the last couple years, so my brains is a little overloaded (especially since I'm simultaneously getting caught up on motors and controllers). As a newb, I really like the idea of a 18560-Li-Ion-based pack with built in BMS for the sake of stability/safety. But I'm not really seeing any very attractive options for a low kWh (low amph), minimalist pack. The smallest I tend to see is ~48V, 9ah which all seem a little bulky to me. Perhaps this is simply because my expectations are too high for the low weight-to-range ratio I would like to see. Do you think that EM3ev might be willing to put together a smaller 18560 pack? I'm also hoping to save a few $$ here.

4) I think I read earlier in this thread that it is not recommended to use this hub motor with PAS only? I'm not a big fan of the idea of having a throttle since I have traditional drop bars. I would much rather use some sort of controller (maybe CAv3?) to turn on the motor with PAS only after reaching a certain minimum speed (say 10mph). Or maybe easier would be to use a simple 1-position switch to manually turn on the PAS activation after I hit a certain speed. I know I need to do more research here, but maybe you can just let me know why I can't use PAS only with a basic motor controller?

My apologies for blowing up your thread with my "20 questions". Feel free to ignore or re-direct my newbery as appropriate

Q100 is an old motor. We now have Q100C and Q100H, which are better.
Q75 is sensorless, so not very smooth. It also lacks power. Q85 is for frony wheel and is best for bikes with small wheels.
You can't run a 328 rpm Q100 at 48v. That would go to 437 rpm, so it would overheat at any speed below 17 mph and be very inefficient.
If you want to maintain 20 mph, the 201 rpm 36v Q128C with a 48v downtube battery would be a good solution. The batteries with included sinewave controllers and LCDs give excellent PAS function. You don't need a throttle with them.

 

[chas58]

Hello Neskie, and welcome to ES. It sounds like you have some interesting ideas brewing. I think a cyclocross bike is an ideal platform for an e-bike road build. 32mm gatorskins are great on an ebike.
I do hope you have been playing with this to design your build: http://www.ebikes.ca/tools/simulator.html

Your situation seems a lot like mine.

I was commuting about 9 miles, and on a traditional road bike that took me about 30 minutes. I now am commuting 20 miles, and on the same bike it takes me about 75 minutes pedaling. I’m going slower over the longer distance because 20mph, 40 miles a day, every day is just too exhausting.

On the ebike here, what took me 75 minutes pedaling, now takes 50 minutes with my custom
Specialized Turbo (the silver bike). Average cruising speed without the motor is 17-18mph, or about 25mph with the motor.

Battery: my 1.6kg 36v9.5Ah battery is about as light as you can go for 20+ miles.
Do not use the 328rpm version at 48volts. I’m happy with the 328rpm at 36volts (and lots of pedaling), but you could also do the 260rpm version at 48 volts for a little more power (and less pedal effort, and a slightly bigger battery). Either way will get you about 25mph.

1) Yes, batteries have changed but not so much motors. The Q100 is pretty proven and well used here, while other similar motors have fallen away. The two speed hub motor is an interesting option if you have hills, and Bafang has some newer motors out. As d8veh said, the Q100 has been upgraded to stay up to date. (Q100C and Q100H).
2) No, not if you are going to push it past its design specifications as we are discussing. Yes, if you don’t want to go over mph.
3) Yep, Paul (EM3EV can build you any (reasonable) configuration you want with 18650 batteries.
4) Yes, you can use PAS only. I do a lot of riding unassisted – basically anything below 17-20mph I am not using the motor. But for most people, PAS is the best choice for a drop bar. You can use both PAS and Throttle at the same time, or put a simple switch in to turn the PAS on/off.

We are looking forward to seeing your build report!

Hi Chas58,

Thanks for putting together this thread and maintaining it. I am an ebike newb looking to get started, and this project seems to be about as close to what I want to do as I can find on ES so far.

I am also an avid cyclist who commutes on almost entirely flat terrain (good old Minnesota prairie). While it doesn't sound like I can put down as much power as you, I do maintain the 15-17mph range comfortably on my single-speed, cyclocross frame commuter. However, I recently changed jobs that upped my one-way commute to 20mi. I don't mind the extra distance too much, but I'm not to fond of the extra time day-in-day-out for the forseeable future. I've been researching the hell out of ES forums to try to put together a minimalist kit to attach to my existing commuter to try to bring my travel time to around 1hr (so, 20mph avg). Here's some specs:

Rider Weight: ~160lbs
Bike : ~21-30lbs depending on load in rear panniers, steel-frame, cyclocross geometry, 700c wheel with 25mm gatorskins, Spot-Brand Sprawl
Desired Distance: 20mi (one-way if I take charger with me), 40mi (round trip)
Desired Nominal Speed: 20-25mph
Economy (hopeful): ~10 kwh/mi
Minimum kwh needed (calculated from above): ~200kwh (~300 kwh, more realistically)

Like yourself, I'm planning on using this purely as a pedal assist and hope to contribute at least 50% of the power. I'm just looking for something to bring my speed up by ~5mph without "crushing it" everyday. Especially on those windy/rainy days when it will be a challange to convince myself not to drive ... Given that I'm not climbing hills and I'm willing to do all the pedaling (unassisted) below 10mph, I'm thinking the 328rpm Q100cst with a 48V battery is the way to go. I'm saying the cassette version because I'm also running a gates belt drive, so I don't have a freewheel/threaded sprocket. I'm limited to the 9-spline cassette.

So I have a few questions:

1) It's been a few years since the original project date. Would you still recommend the Cute Q100 as one of the best options for a minimalist, pedal-assist hub motor? Or have there been any major competitors that now outshine the Q100 that you know of? (I know this is a big question, perhaps there's a better thread that someone could refer me to?)

2) Do you think there's any chance a Q75 or Q85 could get that 5mph bump with a little weight savings.

3) Towards cycleops612's recent comments, I'm very conflicted over battery chemistry. I've been researching the heck out of it for the past couple weeks, but the technology seems to have shifted dramatically in the last couple years, so my brains is a little overloaded (especially since I'm simultaneously getting caught up on motors and controllers). As a newb, I really like the idea of a 18560-Li-Ion-based pack with built in BMS for the sake of stability/safety. But I'm not really seeing any very attractive options for a low kWh (low amph), minimalist pack. The smallest I tend to see is ~48V, 9ah which all seem a little bulky to me. Perhaps this is simply because my expectations are too high for the low weight-to-range ratio I would like to see. Do you think that EM3ev might be willing to put together a smaller 18560 pack? I'm also hoping to save a few $$ here.

4) I think I read earlier in this thread that it is not recommended to use this hub motor with PAS only? I'm not a big fan of the idea of having a throttle since I have traditional drop bars. I would much rather use some sort of controller (maybe CAv3?) to turn on the motor with PAS only after reaching a certain minimum speed (say 10mph). Or maybe easier would be to use a simple 1-position switch to manually turn on the PAS activation after I hit a certain speed. I know I need to do more research here, but maybe you can just let me know why I can't use PAS only with a basic motor controller?

My apologies for blowing up your thread with my "20 questions". Feel free to ignore or re-direct my newbery as appropriate

 

[Khumarahn]

Hi, I tried to look up differences between Q100 and Q100C, and did not find anything informative. Why is Q100C better?

 

[d8veh]

Hi, I tried to look up differences between Q100 and Q100C, and did not find anything informative. Why is Q100C better?

It has the spline for cassette gears, the same as the Q128C, Bafang SWX02C and Bafang CST, i.e. it's a free-hub rather than a free-wheel motor.

 

[Khumarahn]

ah, ok. thank you!

 

[1KW]

Where to buy these motors other than bms? Rather pay 10-20 more and have cheap shipping... Are these motors even the q128h too weak for anything over 25mph? They accelerate same as a direct drive hub on 1200w? There are also the bafang Bpm versions that are more like a Mac, but they are heavy.

Thinking either a cyclocross bike with the fattest tires the frame will fit, or a full rigid 29 with skinny tires(essentially similar but I can swap wheels on the 29er and go down mountain roads better than cx bike.)


Opinions? I want to keep the weight down. I would go bafang mid drive however they seem complex and cause too many maintence variables, trying to keep my bike a single speed as I can actually go faster than geared riders on rides.

 

[chas58]

Well, I got mine from greenbikekit.com. They seemed to do better at answering my questions, and put a spare motor in the box for no extra shipping charge (several years ago). Try doing that with BMS.

Yeah, over 25mph would be pushing it too far. Try a MAC or Bafang. With power/speed comes weight.

Yep, good cyclocross or 29er is great. 42mm tires should be big enough (I use 28-32mm (road) or 54mm (mountain)).

Nashville huh? I go down there every once and a while…

 

[Khumarahn]

By the way, what controllers are people using? I'd be interested in a smallest controller which can do 36v 250w. I really like controllers built into batteries from bmsbattery, but I had some negative experience with them. Also would prefer a controller which is independent from battery, so it is easy to replace. Also I am trying to minimize the amount of wire clutter and additional bags on the bicycle.

 

[motomech]

I like the controllers from Elifebike.
This is their Ebay store which saves on the shipping;
http://www.ebay.com/itm/24V-36V-350W-6Mosfets-E-Bike-Scooter-Brushless-Hub-Motor-Controller-throttle-/22207716873

 

[Khumarahn]

Hi motomech, your ebay link does not seem to work.

 

[motomech]

works for me.
The Ebay vendor is diyebike, which is really elifebike;
http://www.elifebike.com/peng/pic.asp

 

[chas58]

works for me.
The Ebay vendor is diyebike, which is really elifebike;
http://www.elifebike.com/peng/pic.asp

The link doesn't work for me either, do you mean that QQ 250 controller?

 

[cycleops612]

You have the right idea as u know

see wind resistance charts here

https://tunedintocycling.com/2014/06/28/aerodynamics-part-1-air-resistance/

after 25kph (sustained using 100watts), you need another 100 watts per extra 5kph. Suitable battery weight gets out of hand fast if u wanna push this wind envelope sitting upright. If you must, then 25kph still sounds a good speed to do it at. 5kph more, halves your range.