its just a bit of a cheapo controller - try to find one with a KT controller - they have power based PAS levels rather than speed based PAS levelsMaybe this?
36V250W 26" Electric Bike Freewheel Conversion Kit Rear Hub Motor Wheel Black | eBay
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I'm a fan of front hubs albeit small light ones that don't affect steering via weight ot torque steering.
At 11st one is perfect for one and 1.75st lighter then me and I love my small front hub.
The only advice I can give with front hubs is to always fit them into steel forks , my fork of choice is a Surly disc trucker fork.
At 11st one is perfect for one and 1.75st lighter then me and I love my small front hub.
The only advice I can give with front hubs is to always fit them into steel forks , my fork of choice is a Surly disc trucker fork.
OK - fine and dandy.No the BBS-01 is fine, could be a long walk if the chain breaks though and I don’t really like the way the mounting plate cuts into the bottom bracket. And I like the look of a compact hub motor. The mid drive was just the first type I tried now I want to try a hub
I carry a small chain breaker and a quick link. If the chain breaks, I'd only need to remove one pin and fit the quick link to the two ends.
I think that given the small power of a 250 watt Bafang, the likelihood of a chain snapping is pretty small. In my whole cycling and motor cycling life, I have only once broken a chain and that was fifty years ago on a 650cc A10 side car outfit when I had put the back wheel on misaligned so the sprockets were sawing the inside of the chain plates. That chain was completely chewed all the way along and one plate broke and it snapped.
I was riding with very strong cyclist once, who snapped a bicycle chain. We were able to fix it so he could get back to base.
That's a freewheel motor, so OK for gears up to 7-speed. If you have 8 or more, you need a cassette motor.Maybe this?
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When you choose a hub-motor, you have to get one that meets your needs, not just any one that's cheap, though it can be that a cheap one meets your needs perfectly. How fast do you want to go? What sort of hills do you have?
Going up in voltage is no problem, although your low speed biking may be faster than you want. Usually happens with 3 speed controllers, which are set too high in PAS 1 at 36V.
I own bikes with motors front/rear and in the middle, I prefer the mid motors for a faster install. No PAS sensor and controller box, Less work for a flat tire too,
I don't care for the niggling concerns about a front fork failure with my front motor bikes. As an engineer, I should trust my work though.
In the end, it's the bike, not where the motor is located. Give me a light sporty bike that runs good w/o a motor, and it's better for this old man with any motor.
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I own bikes with motors front/rear and in the middle, I prefer the mid motors for a faster install. No PAS sensor and controller box, Less work for a flat tire too,
I don't care for the niggling concerns about a front fork failure with my front motor bikes. As an engineer, I should trust my work though.
In the end, it's the bike, not where the motor is located. Give me a light sporty bike that runs good w/o a motor, and it's better for this old man with any motor.
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Yes - I have a 1.6kg AKM-75 front motor in a folding bike and I am 16.5 stone ! It seems to do fine
Converting a little folder
That's with the cutoff set to 17mph (15.5 +10% leeway that is legal). With the @saneagle DNP Freewheel (11 teeth for the highest gear) I can go at a faster speed down the hills without any assistance. I think it should be OK reliability wise - it's just an Aikema hub motor, PAS sensor, KT...
www.pedelecs.co.uk
I recently snapped one on my hub-motor bike by starting off in a too high gear, then trying to shift while I was standing on the pedals. It made a complete mess of it. About 4 links were damaged.
Small hub motors work well in bikes with small wheels - not so well with big wheels. It's best to get the size of motor that can handle the torque that you expect to give it.Yes - I have a 1.6kg AKM-75 front motor in a folding bike and I am 16.5 stone ! It seems to do fine
Converting a little folder
That's with the cutoff set to 17mph (15.5 +10% leeway that is legal). With the @saneagle DNP Freewheel (11 teeth for the highest gear) I can go at a faster speed down the hills without any assistance. I think it should be OK reliability wise - it's just an Aikema hub motor, PAS sensor, KT...
S
Steelframe
Guest
8 speed freewheels are available. Never saw them a few years ago though so maybe more demand now. Not concerned about going fast and the hills are not that big or steep but I could maybe do with a wee bit of assistance.
Front wheel motor is good. Rear hub is better. 48V controller is the one you want and 48V battery with good cells.
Always have a quick link with you. Hub motor or mid drive. It is tiny and light and can save you a lot of trouble.
They're too wide for an ebike motor. You can use one, but you'll have to offset the rim, which gives uneven tension on the spokes, and it's quite difficult to get the wheel in unless you open the frame a bit. I've done that many times, but now I don't bother. It's easier to get the right motor.
S
Steelframe
Guest
How would I know what torque I would need for 26” wheels? The BBS-01 I used on my last build had 80nm which is probably too much. There was also a delay in the freehub and from the output of the BBS-01 which caused chain snatch. Another reason why I’m thinking hub motor would be better. The posts above have convinced me a rear hub motor is the way to go. No extra pressure on the drivetrain has to be a good idea along with improved traction and steering. Is torque adjustable with KT parts?
I might be over complicating things…
What's chain snatch?
If possible and if you haven't already, install a gear sensor? Works a treat preventing gear crunches on mine, hasn't worked out so well for others, but I have no idea why.
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Have you an example of the steepest hill you are going to cycle up ? I've gone with a 48v Bafang G020 (26" wheel rear hub cassette) with a KT max 22a 9 mosfet controller , but I am 16.5 stone and occasionally want to get up mile long hills that peak out at 30% incline
Something like the Bafang G020 or akm100 or 125 will have plenty of torque at slower speeds. Some of the lighter hubs are not as torquey at low speeds but the most important thing is the max power (volts*amps) of the controller.
Are you going to use a freewheel or cassette ?
S
Steelframe
Guest
Yeah I fitted a gear sensor. And that helped but the motor would turn from standstill then the chain wheel turns then the play in the cassette takes up and when there is no more play the chain would snatch. Hope that explains it
S
Steelframe
Guest
Probably a freewheel because 7 gears would be enough but not set in stone.
I take it the Bafang GO20 or AKM100/125 are not the lightest hubs?
Is the controller something like this one:
And what is KT?
The hills that get me are long inclines not sure what percentage they are though.
It doesn't have 80Nm. That's just an arbitrary number for advertising. The actual torque depends on your gearing. You can get 1000Nm if you want - just lower the gearing.
When you've ridden a load of different bikes with different motors at different currents and at different voltages, you get an idea of how much torque they give, and you can choose whatever you need.
I'm 71 years old, normally not that fit, but I've been riding bikes for a long time, so I can pedal OK. I live in a very hilly area (Ironbridge Gorge, where there are many 20% hills and a few up to 30%. I'm 100kg.
A normal sized hub-motor at 36v and 15 amps isn't enough for me to not have to kill myself on 20% hills. 22amps can manage that with moderately hard pedalling. 36v 22 amps is not far off 48v and 15A with the same motor, which is what I've been using for the last 8 years. I can just manage the fairly short 30% hills with pedalling hard.
I've now increased the current to 22 amps because I'm a bit unfit and have had a few illnesses to deal with. It's no effort to pedal up any normal hills, I reckon I can do about 20% without pedalling as it could do 14% without pedalling before (measured and tested). I wouldn't be put off attempting any hill now.
Most people that slag off hub motors have never tried the geared ones at 48v. It makes a 30% difference compared with 36v at the same current. That 30% difference is massive, and most not too heavy people (<100kg) shouldn't have any trouble with normal hills, even in a hilly area. If they're a bit unfit, 20A or 22A makes the bike almost into a moped. When you have that much torque, a crank motor has no advantage, only disadvantages.
If you want to do some towing of moderate weights, a crank motor comes back into its own again or if you're exceptionally heavy and live in a hilly area.
There are several different sized geared up-motors. Obviously, the bigger they are, the more torque they can handle. I wouldn't put numbers of Nm on them because it's pretty meaningless when everybody else is making up numbers, and people want to compare.
This guy does some interesting work. he built a dynamometer to test bikes. It's a shame he never mentions the current and voltage some of these bikes are running at. This video shows a Bafang M560 that produced about 58NM at the back wheel and at a power of around 1500w, so input power must be about 2kw, which would be somewhere around 35 - 40 amps at 48v. If he ran at our typical 15amps, that motor would produce about 25Nm at the back wheel, since torque is proportional to current in a DC motor.
That's what "Chain snatch" sounded like to me, but I didn't want to presume. If you still have this build, have you fiddled about with the controller's firmware? You can slow the rate of throttle starts to reduce that, by reducing "Start current" in the throttle section of whatever configurator you are using. It's 20% by default, maybe try lowering to 10%, see how that goes? Also use current control for throttle, rather than speed. Start current at 10% for PAS too, makes for a more controllable motor. Less jerky, U-turns are easier. But there's no reverse for parallel parking.Yeah I fitted a gear sensor. And that helped but the motor would turn from standstill then the chain wheel turns then the play in the cassette takes up and when there is no more play the chain would snatch. Hope that explains it
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S
Steelframe
Guest
No reverse? Serious omission!
It’s all in bits now the motor is back in the box and probably heading to Gumtree very soon. I’ll be keeping the 36v battery for now as I can’t afford a new one yet. Maybe next year for a 48v upgrade.
This is the controller I bought, KT is the brand
T09S 36V/48V500W 22A KT Sine Wave Controller For ebike [T09S KT 9Mosfers Controller] - $25.48 : Zen Cart!, The Art of E-commerce
Zen Cart! T09S 36V/48V500W 22A KT Sine Wave Controller For ebike [T09S KT 9Mosfers Controller] - ★★★★★ T09S 36V/48V450W-500W Torque Simulation Sine Wave Controller For ebike 1--Rate Voltage: 36V/48V Compatible 2--Maximum Current:22±1A 3--Low Voltage Protection:DC30±0.5V 4--Speed Set: 1-4.2V...
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The same site has akm128 hub motors (2.8kg) although they are rated 800w so not UK legal. There are 250w rated hub motors on that site
AKM-128H 36V/48V 800W Rear Driving Hub Motor with 20/26/28inch wheel rim [AKM-128H 36V800W] - $123.76 : Zen Cart!, The Art of E-commerce
Zen Cart! AKM-128H 36V/48V 800W Rear Driving Hub Motor with 20/26/28inch wheel rim [AKM-128H 36V800W] - ★★★★★ AKM-128H 36V/48V 800W Rear Driving Hub Motor with 26inch or 28inch wheel rim Specification: 1. Voltage: 36V/48V. 2. Brake type: V-brake, rim brake and disc brake are compatible 3...
topbikekit.com
I know some people learn by experience but as @saneagle said, if you fit this kit to a bike with rim brakes you'll be constantly adjusting and maintaining the brakes because of the extra weight , power and speed (and it's so much fun you'll be using it all the time) and it will wear the wheel rims. You can get perfectly good old bikes off Facebook with manual disc brakes for £50 and then upgrade them to hydraulic brakes (I got a pair of Shimano mt200s for £35 from Ali express) - takes 20 mins max to fit them. They will last thousands of miles of maintenance free and worry free braking
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