best rear wheel rear-hub conversion kit?

stw

Member
Region
USA
What rear wheel, rear-hub, conversion kits should I be looking at for quality and performance?
Lots of eBike conversions (hub or mid-drive) emphasize low cost in order to just get started ebiking and try it out.
I've been using a Bosch mid-drive eBike, and now I want to try a rear-wheel conversion.

I need a 26"/559 rear wheel which I am guessing is a common option(?), but I'm only starting to search this out. A 650B/584/27.5 rear wheel would work fine too.
I'm good at building spoked wheels--is it better for me to get the hub and build it myself?

I prefer pedal assist / pedal-throttle, but maybe that's not as common for rear-hub conversions, or doesn't work as smoothly as for mid-drive?

I prefer not to have brake levers included in the kit, or will need to bypass and not use them if included. I think they're sometimes included because they have sensors in them that might be necessary for motor cut-off during braking.

I want to mount the battery on the frame (down tube probably using bottle mounts on top of downtube (and bottom mount too if possible)
Hoping for a 500 watt hour battery (or better) if I can find it in a usable size for mounting on bike frame.
thanks for any ideas or instruction for this newbie, -STW
 

mclewis1

Member
Region
Canada
City
Fredericton, NB
What rear wheel, rear-hub, conversion kits should I be looking at for quality and performance?
...
How much power do you want/need? (Peak watts - what you can get on a moment's notice for squirting through traffic or climbing that short steep really nasty hill. Sustained watts - continuous power output available without overheating the motor. You could also think of these in Nm of torque/force if you like). No points here for saying "the most I can get" ... lol.

Are you constrained by the size of the location where you want to mount the battery? Is it particularly tight to mount a 500w battery or can you get away with the more common cases that house 600-750w batteries?

How heavy are you?
What kind of riding do you mostly do? (urban, some trails, trekking, serious off road, etc.)
Do you value before and after sales/service?
Do you value being able to tailor/customize your setup (tuning various settings)?
Do you prefer information (knowing what's going on) vs. simplicity and brevity?
 

Deacon Blues

Well-Known Member
As RunForTheHills mentioned, Grin makes excellent products, but they are on the pricy side. Then-again, you usually get what you pay for. They are also very knowledgeable.
 

harryS

Well-Known Member
Ebikeling has one of the better customer service responses, sells on amazon, also being based in Chicago, but his controllers/displays suck, in my opinion. Grin customers must be no-compromise physicists or bike purists seeking torque sensor nirvana. I'm an engineer, looking for the lower cost solution. By the way, I ruled out direct drive motors a long time ago. If you want to Go-Fast, and don't mind a heavy motor, a $200 1000-1500W kit will get you to 30 mph easily, proving you spend proportionally more on a battery to support it.

After doing about a half dozen or more rear wheel kits. I've settled on buying the components ala carte. It's not the cheapest, but I get the parts I like.

I buy a bare motor, and get a good rim plus Sapim spokes separately. It's no cheaper than buying the complete wheel, but I have better components. Motors I use are the Q100 and Q128, 350W and 500W, and with approcimate motor diameters of 100mm and 128mm respectively. Also available as the AKM100 and AKM128. Freewheel and cassette versions available. Bafang motors are also good.

I use KT (Kunteng) controllers and their displays. I like the feel of their pedal assist implementation. Bought my last parts from topbikekit.com. I used to buy from pswpower.com, but they sent my last order 1000 miles away and told me to go there and get it.

As far as batteries, I have bought ebike packs from US vendors and also CHinese vendors. Also bought firebombs out of hoverboards, and surplus/recycled packs that came out of Segway scooters and Uber Jumpbikes. The latter two were very high quality builds. I just had to replace their proprietary BMS wih a generic model and I had a very reliable pack.

For a make-buy decision, it's less money to buy an inexpensive import. You can be riding a hubmotor bike for under $700. Converting a bike is more of a hobby, but it does allow me to have a lighter ebike.
 

RunForTheHills

Well-Known Member
Region
USA
My response last night was a little terse as I was going to bed. As @harryS said, you can also buy the components separately, but it will take a lot more work and knowledge to put it together and and make everything work together. The MAC geared hub motors are very popular and Grin sells a version of it, but the Grin MAC motor does not have a clutch so that you can use regen with it. However, the GMAC motor has a built in torque arm and uses a 10mm axle so you don't have to file your dropouts to make it fit. Grin sells another brand of clutched geared motor called EZEE instead. Grin makes a few unique things that you can't find anywhere else, such as the Cycle Analyst (CA v3) and the Cycle Satiator. Their kits are more complete than others including torque sensors, torque arms, and brake switches (to attach to your own lever) that other kits leave out. You can buy the kits with or without a battery. Grin makes quality batteries, but I ended up buying a battery from EM3EV instead as I felt I got a little more bang for the buck and they also make a high quality battery.
 

stw

Member
Region
USA
How much power do you want/need? (Peak watts - what you can get on a moment's notice for squirting through traffic or climbing that short steep really nasty hill. Sustained watts - continuous power output available without overheating the motor. You could also think of these in Nm of torque/force if you like). No points here for saying "the most I can get" ... lol.

Are you constrained by the size of the location where you want to mount the battery? Is it particularly tight to mount a 500w battery or can you get away with the more common cases that house 600-750w batteries?

How heavy are you?
What kind of riding do you mostly do? (urban, some trails, trekking, serious off road, etc.)
Do you value before and after sales/service?
Do you value being able to tailor/customize your setup (tuning various settings)?
Do you prefer information (knowing what's going on) vs. simplicity and brevity?

Very helpful replies so far. This is fun bike stuff to learn. thanks.

This conversion would be for road use, but it includes some hill climbing on roads. So something that can do sustained hill climbing without overheating is important, which I've read is an issue for hub-motors. I'm about 90kg (200 lbs) with my cycle bag total, a long-time experienced road cyclist, new to eBikes. This would be on a strong stable road bike with hydraulic disk brakes.

Torque would help for the climbing but I don't want or need the kind of torque-biased motor they're putting on e-mountain bikes now. I'd rather have a speed-performance-biased motor for efficient cruising at 28mph. Wouldn't mind having that 28mph de-limited too, but not the main goal of this conversion.

Power needed would be about the same as what I have now on a different bike: Bosch Active Line Plus, 50nm. 500Wh Bosch battery pack. Simplest display (Purion I think). It's an iZip Sumo fat bike ebike with huge 26x4" tires, so the same 50nm torque and 500Wh would, or might, feel like more on a road bike. (Using smooth road bike tires in 26"/559 or 650B/584/27.5") I guess I should say this would be the minimum power I'd want.

I value being able to customize it a bit, since I use drop bar levers and don't want switches or sensors in the brake levers for example. I'm an experienced cycle mechanic and can manage cycle customization, build wheels, etc., but not at all experienced with building electronics components. I enjoy learning but might be best off with a good electronic set-up in place. For information delivery, I like data a lot but perhaps I like small displays more. The simple Purion is giving me plenty of info currently.

I'm not constrained by the frame shape or size battery mounting on the down tube or seat tube. I ride a large-sized steel road frame with an open diamond frame, level top tube, with down-tube bottle mounts top and bottom. Main goal is not to put the battery on a rack over the rear wheel. I do not need to remove the battery frequently so quick on/off is not a requirement.

I'm judicious and can cope with limitations so whatever gets me a quality powerful set up on this conversion bike will be great. --STW
 
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tomjasz

Well-Known Member
No other kits have the Grin features. Grin controllers function over a range of batteries. I can use my 36v, 48v, and 52v with their controllers. All that data that some of us care about is only real-time available with the CA2 and CA3.

HarryS is the best builder here. However, I've had too many nightmares sorting budget kit gremlins for local riders. Weird crap like blue and brown power wires instead of red and black.
 

Timpo

Well-Known Member
What rear wheel, rear-hub, conversion kits should I be looking at for quality and performance?
Lots of eBike conversions (hub or mid-drive) emphasize low cost in order to just get started ebiking and try it out.
I've been using a Bosch mid-drive eBike, and now I want to try a rear-wheel conversion.

I need a 26"/559 rear wheel which I am guessing is a common option(?), but I'm only starting to search this out. A 650B/584/27.5 rear wheel would work fine too.
I'm good at building spoked wheels--is it better for me to get the hub and build it myself?

I prefer pedal assist / pedal-throttle, but maybe that's not as common for rear-hub conversions, or doesn't work as smoothly as for mid-drive?

I prefer not to have brake levers included in the kit, or will need to bypass and not use them if included. I think they're sometimes included because they have sensors in them that might be necessary for motor cut-off during braking.

I want to mount the battery on the frame (down tube probably using bottle mounts on top of downtube (and bottom mount too if possible)
Hoping for a 500 watt hour battery (or better) if I can find it in a usable size for mounting on bike frame.
thanks for any ideas or instruction for this newbie, -STW
What's your budget?

Grin is the best option if you have the money.
 

stw

Member
Region
USA
My response last night was a little terse as I was going to bed. As @harryS said, you can also buy the components separately, but it will take a lot more work and knowledge to put it together and and make everything work together. The MAC geared hub motors are very popular and Grin sells a version of it, but the Grin MAC motor does not have a clutch so that you can use regen with it. However, the GMAC motor has a built in torque arm and uses a 10mm axle so you don't have to file your dropouts to make it fit. Grin sells another brand of clutched geared motor called EZEE instead. Grin makes a few unique things that you can't find anywhere else, such as the Cycle Analyst (CA v3) and the Cycle Satiator. Their kits are more complete than others including torque sensors, torque arms, and brake switches (to attach to your own lever) that other kits leave out. You can buy the kits with or without a battery. Grin makes quality batteries, but I ended up buying a battery from EM3EV instead as I felt I got a little more bang for the buck and they also make a high quality battery.

The Grin MAC motor and GMAC motor you mention are the same motor right?

HarryS mentioned he gave up on direct drive motors, so I've been looking it up to compare the geared hub motors to the direct-drive. I'm guessing there is a FAQ section or similar here on EBR where I can go learn more about why/why not a direct drive.

Sounds like I could get a limited kit from Grin with hub complete with torque sensors, torque arm, and sensors I can attach to my own brake levers, plus choose a controller. Then shop for a battery separately. --STW
 

Timpo

Well-Known Member
The Grin MAC motor and GMAC motor you mention are the same motor right?

HarryS mentioned he gave up on direct drive motors, so I've been looking it up to compare the geared hub motors to the direct-drive. I'm guessing there is a FAQ section or similar here on EBR where I can go learn more about why/why not a direct drive.

Sounds like I could get a limited kit from Grin with hub complete with torque sensors, torque arm, and sensors I can attach to my own brake levers, plus choose a controller. Then shop for a battery separately. --STW
Grin does have batteries.

Here are some examples:

72V 9.5Ah

52V 20Ah
 

RunForTheHills

Well-Known Member
Region
USA
The Grin MAC motor and GMAC motor you mention are the same motor right?

HarryS mentioned he gave up on direct drive motors, so I've been looking it up to compare the geared hub motors to the direct-drive. I'm guessing there is a FAQ section or similar here on EBR where I can go learn more about why/why not a direct drive.

Sounds like I could get a limited kit from Grin with hub complete with torque sensors, torque arm, and sensors I can attach to my own brake levers, plus choose a controller. Then shop for a battery separately. --STW
Yes, the GMAC is the Grin version of the MAC motor. They customized it by removing the clutch to allow regen braking and adding an integrated torque arm. I bought the GMAC kit, but I bought a prototype from them that had a clutch. The clutch allows coasting and easier peddling without motor assistance, but I liked the idea of the integrated torque arm and 10mm axle. Grin does make the most flexible kits and you can pretty much do anything you want with them. Since I bought mine, they added virtual clutch programming to the CA v3 to feed a little bit of power to the motor while you are coasting. The CA v3 allows a lot of the flexibility, but is also a larger retro non-color display. If you are mounting switches to drop handlebars, Grin also has this overpriced mount for attaching switches to drop bars, although you may be able to fabricate something yourself.

https://ebikes.ca/handle-bob.html
 

RunForTheHills

Well-Known Member
Region
USA
Geared hub motors are lighter than DD motors and because of the gears can be designed to operate more efficiently for a specific speed range (also research motor turns - 8t vs 10t vs 12t). However, DD motors have less moving parts and can handle more abuse such as long hills and more power. People building very high powered hub motor bikes use DD motors like those from Leafbike. DD motors do not have a clutch and so you get the cogging effect that adds drag when you are not under motor power. DD motors are usually large and heavy.

MTA: If you want regen braking then, except for the GMAC, DD motors are your only choice.
 
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mclewis1

Member
Region
Canada
City
Fredericton, NB
What rear wheel, rear-hub, conversion kits should I be looking at for quality and performance?
Lots of eBike conversions (hub or mid-drive) emphasize low cost in order to just get started ebiking and try it out.
I've been using a Bosch mid-drive eBike, and now I want to try a rear-wheel conversion.

I need a 26"/559 rear wheel which I am guessing is a common option(?), but I'm only starting to search this out. A 650B/584/27.5 rear wheel would work fine too.
I'm good at building spoked wheels--is it better for me to get the hub and build it myself?

I prefer pedal assist / pedal-throttle, but maybe that's not as common for rear-hub conversions, or doesn't work as smoothly as for mid-drive?

I prefer not to have brake levers included in the kit, or will need to bypass and not use them if included. I think they're sometimes included because they have sensors in them that might be necessary for motor cut-off during braking.

I want to mount the battery on the frame (down tube probably using bottle mounts on top of downtube (and bottom mount too if possible)
Hoping for a 500 watt hour battery (or better) if I can find it in a usable size for mounting on bike frame.
thanks for any ideas or instruction for this newbie, -STW
Ok, so with those questions answered let me take a crack at your requirements from your original post. First off though I have no affiliation with Grin other than having just put over 1000 miles on one of their kits I installed last October.

Either a 26 or 27.5 rear is fine, but I think you'll find more road oriented tires and rims in the 27.5" size. This will create a "mullet" style bike (bigger in the back ... lol). You should be able to handle the wheel building just fine (there's a couple of good videos about building wheels with hub motors on Grin's website), but remember that you'll be working with a 36 hole rim (often harder to find these days, especially in the narrower sizes) and big 12-13 gauge spokes. A wheel like this becomes a strong and seriously stiff/noncompliant wheel, so tire choice and pressure will be important. If you don't want to bother, Grin builds some really nice wheels for not much money.

Pedal assist from Grin is IMHO about the best around. It's the way the Cycle Analyst handles the sensor and ramps up the power as you spin. The physical parts (sensor and it's mounting) are dead simple. The alternative is to delve into a torque monitoring BB (the torque sensor options). The upside is an even more natural feel to adding power, the downside is that these specialized BBs can require drilling the BB mounting on the bike and/or require unique crank arms. If you're like me and picky about your crank arm length and such you may be better off staying away from the torque sensor and using only the PAS as this will give you more options in your choice of crankset and crankarms.

No problem not having brake sensors. Some folks prefer them, some don't (I don't ride with them). I think they become more important from a safety point of view if you are running higher power (kw class and up) motors. With the Grin kits there's usually a small multifunction switch setup that has a nice simple red power on/off switch on top. So if you ever did experience a sticky throttle (didn't shut off) then just pressing the little red button beside your thumb removes any problems. The real "need" for brake cut out sensors is on mid drive bikes that may not have a shift sensor installed. This way the motor's power can be briefly cut off while you shift (unloading the gears). With a hub motor this isn't a concern at all since the human is the only one putting pressure on the gears.

Your battery choice will be a balance between what you want for distance vs. weight, and there are a lot of variables that will affect the choice. As mentioned already you'll find it helpful to go down the rabbit hole of running Grin's motor simulator and trying out various battery capacities and voltages against various motors. This will show you what kind of range you can expect. You likely won't want to be carrying a lot of excess battery capacity. Also as mentioned above the Grin controllers (BaseRunner or PhaseRunner) can run any of the popular voltages so you have lots of choices.

I would recommend a standard wind motor and a 52v battery. This will give you a higher top speed vs. the often seen fast wind motors combined with cheap 36v batteries. If you choose a downtube style battery with a nice road frame you'll want to have a mounting plate under the battery base. This will do two things, first it gives you more flexibility in the position of the battery with respect to where your water bottle mounting bolts are (so you can alter the position of the battery up and down the downtube a bit), and second it offers a flat base to attach the battery base to. This prevents rocking which can destroy the water bottle nuts in the frame when a big heavy battery starts torquing on them sideways. These mounting plates are just the same as (and in many cases are the original) the water bottle mount extension products. I know this will sound like a broken record but Grin makes (IMHO) the best version of these mounting plates, the BOB.

Now I haven't mentioned a particular motor. This is going to be quite a personal choice that will depend on a bunch of options but primarily just how much power you want. Given what I assume is pretty reasonable power output on your part I think you'd be fine with a motor in the 500w class but I'll leave that conversation to the smarter folks around here. As always there is the inevitable trade off, in this case it's weight vs. power. All things being equal a bigger geared hub motor obviously gives you more torque (the voltage and wind speed will with the wheel diameter determine top speed) and the additional weight from the mass of the motor assembly dissipates more heat so they would take longer to overheat, if at all. Many motors now come with a temperature sensor so if things are all wired up correctly you can monitor the temp of the motor. The idea is to prevent it from overheating on long climbs and such. Grin's Cycle Analyst does this and will automatically start to roll back the power if the motor starts to overheat. This has an interesting effect of allowing you to run a slightly smaller (and lighter) motor that performs well and won't destroy itself if you push it too hard.

OK, that's probably TMI in one post, but you did ask ... lol.
 

tomjasz

Well-Known Member
Yes, the GMAC is the Grin version of the MAC motor. They customized it by removing the clutch to allow regen braking and adding an integrated torque arm. I bought the GMAC kit, but I bought a prototype from them that had a clutch. The clutch allows coasting and easier peddling without motor assistance, but I liked the idea of the integrated torque arm and 10mm axle. Grin does make the most flexible kits and you can pretty much do anything you want with them. Since I bought mine, they added virtual clutch programming to the CA v3 to feed a little bit of power to the motor while you are coasting. The CA v3 allows a lot of the flexibility, but is also a larger retro non-color display. If you are mounting switches to drop handlebars, Grin also has this overpriced mount for attaching switches to drop bars, although you may be able to fabricate something yourself.

https://ebikes.ca/handle-bob.html
Bob is Member here!
 

creativepart

Active Member
Region
USA
I know everyone likes Grin and have done a good job selling you on them. But I wanted to add that Dillenger Bikes makes excellent Rear Hub Drive kits. I used the Premium Off-Road kit, which just means it's a 750/1000 w motor and has a top speed of 28 mph.

Their kit cost $750 or so and included everything I needed., including 52v battery with 14aH. They are located in Australia but keep product stocked at a fulfillment warehouse in Southern California. It took 4-days from the day I ordered to receive the kit.

I used to kit to convert my Specialized Crosstrail and have put 700 trouble free miles on it since January.


IMG_3660.jpgSpCT-eBike-Rockport.jpeg
 

tomjasz

Well-Known Member
Their kit cost $750 or so and included everything I needed., including 52v battery with 14aH
Be suspicious. My cost for a well-made battery is 3/4 of the price you quoted. That's Yugo pricing as opposed to Toyota pricing. If you're interested in becoming your own support and make building a hobby...
I get it, but if you don't want to struggle with unsupported issues buy a budget kit.

The good news here is fellas like HarryS are really helpful in sorting issues. I do get that some DIY fellas just don't have a Grin budget. Just be sure to follow leads from posters like HarryS.

I'm somewhat financial strapped but I know longer am interested in strugling with budget kits. I'd save my $$ and step up to a better kit.

I don't know how many miles you intend to ride a year, or how many miles Harry puts on.
 
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creativepart

Active Member
Region
USA
Nothing to be suspicious about in my book. They've been around for years. Are successful internationally. Have good reviews and attentive customer service. EBR has posted a couple of reviews of customer builds and there are no bad reviews out there that I've found. I know I only built my kit the last week of Dec 2020 - but my 700 miles completely trouble free sure doesn't make me suspicious.

Are there more expensive kits and/or batteries with pricier cells? No doubt. If and when my battery misbehaves I may look at them. But for now, I just ride the bike.