AKM 100 250w vs 350w, how do they compare?

woody27

1 mW
Joined
Oct 10, 2021
Messages
13
Hi All,

Looking to get a rear hub for 10mi commute (5 mi each way) in London (down hill from Hampstead in the morning, back up in the evening). 26 in wheels, needs to be stealth and quiet and I will pedal along the motor, currently doing the commute on pedal only. I currently have a 9 speed cassette but could replace for a freewheel if required.

I'm looking at the AKM motors on topbike and see 3 versions:

- 250w "AD CST": http://www.topbikekit.com/21kg-tbk100ad-cst-cassette-36v250w-ebike-rear-driving-hub-motor-3236-holes-p-1037.html

- 250w version "CST" 201 or 328 rpm: http://www.topbikekit.com/akm100cst-cassette-36v250w-ebike-rear-driving-hub-motor-3236-holes-p-728.html

- 350w version 201, 260 or 328 rpm: http://www.topbikekit.com/akm100h-36v350w-ebike-rear-driving-hub-motor-p-679.html

Anybody knows what is the difference between these? I thought they were all similar in a 100mm diameter case and only the flywheel/cassette changed?

I'm tempted to get one that comes in 260 RPM (not 201 but not 328 due to mix of flat, hills and red lights in London)?

Any advice most welcome, thanks!
 
Over at BMS battery, they sell the Q100CST and Q100H (freewheel). They state the Q100H has 30% more torque than the Q100, but they don't sell a Q100, but I always thought the Q100CST had less torque.

Someone else said the Q100CST was a little thinner, to fit the cassette, so less metal means it will heat soak sooner if we were trying to cook bacon with it. I've never had my hub motors get hot. I also thought Aikema developed these motors initially, and whoever makes the Q models probably worked there, and started making copies across the street.

I have three Q100H (260 rpm) motors in use on 20" rims. I replaced one with a AKM100 (328 rpm). I think the AKM is stronger, or maybe I like its higher unloaded top speed. Anyway, I would suggest the 350W AKM motor.
 
I'm tempted to get one that comes in 260 RPM (not 201 but not 328 due to mix of flat, hills and red lights in London)?
How fast do you want to go in the flat?
In a 26" whl.:
A "260" speed-range Q100 on 36 Volts does about 19 to 20 MPH.
A "260" speed-range Q100 on 48 Volts does about 22 to 23 Mph.
A "260" speed range Q100 on 52 Volts does about 23 to 24 MPH.
One or two MPH doesn't sound like much, but it makes a big difference.
Under 20 is boring, above you feel like you are getting somewhere.
I have never found that the "201" climbs any better than the 260
A 260 in a 26"whl on 52 Volts w/ a 17 to 20 Amp controller is the best combo. for the Q100, but the 260 in not avail. in the CST.
The CST, while having a narrower stator, is actually slightly wider (a couple of milimeters). I've had three CST's and they deffinately produce less power. Given that one doesn't shift much w/ an ebike and the 260 is stronger and easier to mount I don't recommend it.
One of the nice things about the "Cute", is it so small and light, it makes for a good front whl. install. The system doesn't make enough power for it to ever Feel squirly and most of the time it is not noticeable in the frt. And all your shifting stuff stays intact.
I would order the motor/whl. assembly unless you are skilled at whl building. Yes, there is more frieght, but if you take it to a shop, the overall cost will end up higher.
If you have any other questions, ask or search my posts, I used Q100's (maybe a dozen) for almost 10 years.
Q-series motors don't have a tendency to get very hot, but their controllers do.
 
Thanks both!

I normally do my 5mi commute in 30 min with no motor. Pedalling at 12 - 15 mph and up to 19 mph in slight downhill. Now looking to cruise at 20 - 21 mph with the motor. Sometimes I will ride the bike without the battery so I'm trying to keep it light, no resistance is important and thinking about it, keeping the cassette also matters in this case. I'm 180 lbs. It's to commute so needs to be reliable.

If I get the CST in the 26 in wheel from what I read the 328 won't be good, especially with the city's red lights.

I could go for the H and replace the 9 speeds cassette with a 7 speeds freewheel and adjust the derailleur boundaries to prevent the chain to go in the spokes? Or will this be clunky and frustrating when riding with no battery? This seems to have a 11t gear: https://www.amazon.co.uk/DRIFT-MANIAC-Freewheel-11-28T-11-34T/dp/B07XYNSHZC?th=1

It seems that a standard, no trouble build is 201 rpm 36v with a 48v battery and 15a controller, but will this get 21 mph on flat? Should I go 17a instead or will I burn everything by cruising without pedalling?

Re battery I was thinking of getting this (10 Ah as my commute is 5mi, maybe even smaller battery, I can charge at work): http://www.topbikekit.com/48v10ah-samsung-inr2170050e-liion-battery-small-size-and-large-capacity-p-1064.html
You mention using 52v with 20amp, I wonder if 48v controller would cope and if the motor would cope ...

Your guidance is gratefully received before I order!
 
Sometimes I will ride the bike without the battery so I'm trying to keep it light, no resistance is important and thinking about it, keeping the cassette also matters in this case.
You might do this,....once. Although road bike/lycra types claim to do this, more mortal ebike riders quickly tire of this notion. Although the added weight doesn't seem like much, the motor resistance (clogging which all hub motors have to some degree) and extra weight add up to a sum more than the parts would indicate. Remember, the motor is IN the whl. If you want a workout, the way to do it is to keep the power low and pedal on top of it. For example, say you want to go 20 mph, set the set limiter to 18 and pedal to add to get to 20. You can can get all the exercise you want, but traveling faster than a pedal only bike. That's the beauty of a good assist ebike.
I could go for the H and replace the 9 speeds cassette with a 7 speeds freewheel and adjust the derailleur boundaries to prevent the chain to go in the spokes?
I used to do this all the time, Enoch 7 sp in a 9 sp system. No changes or special adjustments necessary, although sometimes w/ the DNP free whl., the derailuer needs to be moved slightly more "under" the free whl. to better grab the DNP's shark-fin teeth.
It seems that a standard, no trouble build is 201 rpm 36v with a 48v battery and 15a controller, but will this get 21 mph on flat?
Not quite, more like 18 to 20 MPH.
A 260 will get you to 22 MPH, much more fun. As I have already mentioned the 201 doesn't climb any better than the 260, the only disadvantage to the 260 is it won't take a cassette. Having used both systems, I prefer the 260/Enoch set-up. The 201 on 48 Volts is too slow. If you think of yourself as a "roadie type", go w/ the 201, if you think of yourself as more of an "urban warrior", get the 260 on 48 Volts, or better yet 52 Volts for some real fun.
After years of using the Cute (Dual Cutes for a couple of years), I decided to build the ebike I always wanted. I stepped up to a bigger Bafang (2.5 Kg. vs 2.0 kg.) cassette mount on 52 Volts and a 18 Amp controller, 24 to 25 MPH and quieter than even the Q100, which is fairly quiet. Perfect, but the Bafang is more than twice the cost of the Q100.
It's getting late for me, tell me which way you want to go and we will talk about the big subject of controllers, and batteries and how to build for stealth.
(Hint-Black or dark donor bikes are best)
Also, you will need some things that perhaps you haven't considered like torque arms (pretty cheap), frt big chain ring as large as can be fitted(I usually end w/ 48 to 50T units) and after a flat or two, most folks go w/ flat resistant tires and extra thick tubes.
 
Thank you Motomech, I've been reading your messages a lot this week and I've learnt a lot.

Your point on the difficulty to pedal with the motor and no battery is taken. Maybe then I'll just swap wheels as I will want to pedal without sometimes and I don't have room for two bikes in the flat.

Regarding Q100CST vs Q100H, you say in your messages that with a 7 speed freewheel it ends up being ~134mm, BMS says the same. But TopBikeKit says its 138m (!). See their diagram here: http://www.topbikekit.com/AKM-100H Rear motor.png

I sent an email and they confirmed its 138mm at their end for the AKM ... 138 mm it's definitely too large for me and my 130 mm alu frame. Especially that I'll need steel washer to prevent marks in the aluminium dropouts. Could it be that this Q100H is not the same Q100H sold by BMS :confused: ?

My second questions is regarding reducing the length of the spline. Is the cassette hub of the Q100-CST made for 7 speed cassettes or 9 speed cassettes?. You say in one of your message that it is possible to remove a cog of the cassette and trim the spline to save space. But if you trim the spline, will you still have thread to screw the lockring of the cassette?

Re controller I am thinking of a simple KT15A, placed under the rear panier rack, protected by the mudgard and maybe some other cover, and will stay on the bike at all time. The smaller the easier to hide. The small battery (likely 7Ah, maybe even less if I find it as my commute is 5mi each way and I do pedal!) will be hidden in a topeak case or in a bag under the saddle.
 
Regarding Q100CST vs Q100H, you say in your messages that with a 7 speed freewheel it ends up being ~134mm, BMS says the same. But TopBikeKit says its 138m (!). See their diagram here: http://www.topbikekit.com/AKM-100H%20Rear%20motor.png

I sent an email and they confirmed its 138mm at their end for the AKM ... 138 mm it's definitely too large for me and my 130 mm alu frame.
Are you sure your drop-out width is 130 mm, all the ones I have used were 135 MM. Anyhow it doesn't matter.
First of all, all chain stays are different, they are built on jigs and they vary to a degree.
The H with the 7 sp DNP drops right in, the DNP 9 sp usually requires pulling the chain stay apart slightly by hand and the CST w/ the 9 sp needs some gentle prying w/ a screwdriver. You will be suprised at how easily the ends of the chain stay can be spread apart.
The problem with the CST fitment of the wide-bodied Q100's is not getting them between the drop-outs, it's getting the rim centered. The spline to fit the cassette is longer than the free whl.s and this moves the hub center-line to the left (when viewed from the rear). What then is required is "dishing", adjusting the spokes to pull the rim into an off-set to get back on the center-line and it varies from bike to bike how much.
All my bikes have been quality alum framed mountain bikes, Idrive, Rocky Mountain and my current Motobecane. For the CST, the Idive and the Motobecane required little dishing while the Rocky Mountain required extreem dishing, to the point I gave up and used an H. How the CST/cassette would fit on your bike I can't say. The free whl units, even with a 9 sp all dropped in.
Especially that I'll need steel washer to prevent marks in the aluminium dropouts
.
You do understand that you will likely have to enlarge the drop-outs w/ a round file to accept the motor axle? We all strive to prevent scratching our beautiful bikes, but it does happen. You can use rubber strips for mounting things like the torque arm clamps, but you need to accept that converting your bike runs a risk of it getting scratched somewhere..
You will need one sm. flat washer supplied w/ the motor kit, it goes between the cassette spline/free whl. and the inside of the drop-out to prevent rubbing. Actually, I keep a selection of flat washers that I stack to get perfect alignment of the torque arms (yes, two).
Use the C-washers that come w/ the TA's first, it goes in the recess formed by the Lawyer's lips and provides a flat surface to stack on, then some variation of washers to get the TA aligned to a flat surface of the chain stay to clamp it to. Then the nuts w/ thread locker.
Re controller I am thinking of a simple KT15A,
This where things always get complicated.
That tiny KT only comes in 24V/36V and that's problem. If you use a 36V batt., with the 260, that's about 18 MPH. The 328 is not relevant. Actually, I don't care for any of TOP Kit's controllers (or batt.s for that matter).
The next step up is the 22 Amp 9-FET square wave (What they call Torque Simulation), which would be ok with the 260H. I've run them up to 25 Amps before they start to hammer the motor w/ shock waves, great fun! But another thing I don't like about TK's off'ings is the displays they offer are only LCD, there goes the stealth, they are dead give-a-ways.
I always try to get everything from one vendor to save on shipping, both my builds and the ones I've try to help with here, but have never succeded. The combo seems to want something from at least two vendors.
An example, here's the controller I prefer;
https://www.pswpower.com/products/36v-48v-350w-brushless-dc-square-wave-controller-ebike-electric-bicycle-hub-motor-controller-with-right-output-31
w/ a simple LED display, 17 Amps is perfect for the Q100.
A comment on stealth;
When I started, I was crazy about it, dark bike, all blk. wires, homemade water bottle style batteries (the round brushed alum. kind), I even put blk. tape over over the sm. LED lites on the display. Eventually, I moved away from it because where I live and ride, nobody cares about ebikes. But if you are serious about it, you need to think about how to hide the batt.
Anyhow, back to reality. You could get the KT sine wave that goes into the battery case, they work with 48 Volts. That's probably your best bet if you want to get everything from TK.
Final question, what's your bafang model? Is it a SWX02 rated for 36v 250w? I thought it was more than 2.5kg.
You are right! It's 3.3 Kg. This is the exact one I got;
https://hilleater.ca/bafang-swx02-rear-cassette-motor-fast-11-turn-winding-fits-juiced-ccs/
Notice that is an 11 turn, most SWXO2's would be 13 turn 270 or so speed range. I had one and it did 27 mph, faster than I nedd or want to go. The 11T is around a 250 sp.-range. And as I said, it accepts the cassette and it's blk. ticked all the boxes for me. I'm using the 17 Amp controller from the Q100 system and it could easily take a controller in the 20 to 25 Amp range, but it's ok. Forces me to pedal a little more.
 
Are you sure your drop-out width is 130 mm, all the ones I have used were 135 MM.

Yes I confirm it is 130mm, see photo:
https://ibb.co/VJL08nz

It came with a 7 speed Freewheel (in the 90s) and I replaced it with a modern wheel with OLD 135mm and 9 speed cassette hub. It's actually marked the frame a bit, I suspect from riding with the quick release not properly tighten once, see photo:
https://ibb.co/FDD3tQH

So I'm really not willing to stretch much more than than total 135mm. If I cannot make it work it'll be a front hub or another bike, but I am still trying to find a combo that will work with this bike + rear hub. I'm going to start looking at the slimmest freewheels I can find, even if its 5 or 6 speed, or better maybe a 9 speeds trimmed down, if that's possible at all. I don't need 11t, large chain ring and 20 mph will be sufficient, it's only city riding and I'm happy with 18mph at present pedalling, don't need much more.

I was wrong earlier when I said that the CST is the "no trouble" solution, actually there would be a lot of dish and you seem to say the total length with motor + nut + washers is about 137mm in another post, a bit too much for me. If only I could modify the spline to change it to a 30mm (to slide 7 speed cassettes on) instead of 35mm (to slide modern 9 speed cassettes on) that would save me 5mm and close the point...

You do understand that you will likely have to enlarge the drop-outs w/ a round file to accept the motor axle?

I don't quite understand this point yet. My dropouts are quite big and it seems that the axle of the motor is filed down around the M12 thread to make two flat sides to slide onto normal dropouts. photo of my dropouts, they are about ~9.7mm:
https://ibb.co/prHdG0g

Do you think I need to file? If yes how much and will I still be able to use a normal quick release 9 mm axle later on the bike?
 
So I'm really not willing to stretch much more than than total 135mm. If I cannot make it work it'll be a front hub.....
A frt mount would be the obvious and easiest solution, especially since you are still harbouring the notion that you will want to go back and forth between powered/unpowered.
I'm going to start looking at the slimmest freewheels I can find, even if its 5 or 6 speed....
You will have to change at least the chain, or likely the whole shifting system.
I don't need 11t, large chain ring and 20 mph will be sufficient, it's only city riding and I'm happy with 18mph at present pedalling, don't need much more.
Yes you do, the 11T sm. gear is key to lowering the cadence, even for a 18 to 20 mph cruise.
I was wrong earlier when I said that the CST is the "no trouble" solution, actually there would be a lot of dish and you seem to say the total length with motor + nut + washers is about 137mm in another post, a bit too much for me.
Then use this motor;
https://www.pswpower.com/products/bafang-swx02-48v-500w-rm-g020500dc%E2%80%8B-rear-freewheel-rear-cassette-wheel-gear-motor-for-electric-bicycle-conversion-kit-118
Mine dropped right in the 135 mm drop-outs of my Motobecane (w/ 9-sp cassette) and this is a great price. The fact is, this is a better motor than the Q100 in every way and the 10T (as shown in the pic) would be a "240", perfect for what you want to do.
I don't quite understand this point yet. My dropouts are quite big and it seems that the axle of the motor is filed down around the M12 thread to make two flat sides to slide onto normal dropouts. photo of my dropouts, they are about ~9.7mm:
https://ibb.co/prHdG0g

Do you think I need to file? If yes how much and will I still be able to use a normal quick release 9 mm axle later on the bike?
All hub motor installs require "contouring" the drop-outs to some degree. The motor axle must go all the way in so that the semi-half round axle sits flush to the top portion of the drop-out. It's no big deal.
 
One thing about the Q100H is that it uses two bushings and a nut. under the freewheel to set the O.L.D. I did a bike that also had a 130mm dropout. It was an alloy frame with a integrated luggage rack,which gave it an extra pair of stout chainstays that I was not going to force.

In this picture, both bushings were originally the same length. I cut one with my trusty sawzall, and went from a 7 speed freewheel to a 6 speed. I got the O.L.D down to 130. Not many other motors allow that. You can change the freewheel, but the axle is machined with a shoulder.

By the way, this is a Q100H from BMSBattery, not the Aikema from Top Ebike Kit. I don't recall if my AIkema is the same.

drive_side-1.jpg
 
The AKM100 and AKM100cst are the same electric motors, only difference is the freewheel/cassette housing.
It is stated as 250W continuous.
It is 135mm wide.
It ways about 2kg (cassette version).

The AKM100H and AKM100Hcst are the same electric motors, only difference is the freewheel/cassette housing.
It is stated as a 350W motor.
The freewheel version is 135mm wide and the cassette version is 142mm wide.
It ways about 2,2kg

Pay attention, the Q100 motors at BMS battery are not always the same as the AKM at topbikekit.
Sometimes I received clearly rebadged AKM motors from them and sometimes they seemed slightly different.
As someone states above the Q100C doesn't seem to come from AKM, or at least it isn't in their catalogue.
The Q100C from BMS battery is 350w with cassette body and 135mm wide.

We use the non-H versions on light race bikes, for sportive riders that don't do big climbs.
It is lighter and thus more suitable to be used in cases where riders only activate the assistance once in a while but also ride non assisted.
It is perfect for a subtle assistance.
As the non-H CST version is 135mm wide, it can often be used in 130mm race frames.

We use the H versions for users that need more assistance and that keep the system active permanently.
This motor has more torque, it's presence is felt more compared to the non H version (at the same controller settings).
The H version can handle a lot more "misuse", it's electric motor really can handle a lot more power than the non H version, it resist way better to long or steep climbs (still not for real mountain though).
The 142mm wide cassette version is hard to put into 130mm frames, we don't do that because of the risk of overstretched frames.
 
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