Newbie's project idea: 2 motors on my commuter MTB.
- Thread starter erik_m
- Start date
wesnewell
100 GW
A. Terrible idea.
B.No.
C. You can do whatever you want to.
I think you're going about this all wrong. A single 48V 1000W rear DD motor kit is all you need. I've got over 11,000 miles on mine now. Total cost of bike, add ons, motor kit, and battery pack was under $1000. But what's the point? You've already bought the kits from what I read. I'm 67, but only 270 lbs.
B.No.
C. You can do whatever you want to.
I think you're going about this all wrong. A single 48V 1000W rear DD motor kit is all you need. I've got over 11,000 miles on mine now. Total cost of bike, add ons, motor kit, and battery pack was under $1000. But what's the point? You've already bought the kits from what I read. I'm 67, but only 270 lbs.
It'll work, but the Hilltopper kit is relatively low power and low-speed. I don't think that it'll make much difference. The only time you'll notice it is during hill-climbing. It would be better to use two hub-motors of equal speed and power.
If the mid-drive were pedelec and the hub motor on a manual throttle then the systems would be completely independent and ought to (based on speculation) work together. You, as the rider, would balance the load. Failure of either one would leave the remainder working, it might just be a bit slower and/or you need to pedal a bit more.
The system will be a bit of a miss-mash, but you already own some parts, which constrains available options, and the redundancy of two systems is hard to beat when considering reliability.
Whether the specific motors/batteries/kits you have selected are right for the job, I'll leave for those with direct experience to address
The system will be a bit of a miss-mash, but you already own some parts, which constrains available options, and the redundancy of two systems is hard to beat when considering reliability.
Whether the specific motors/batteries/kits you have selected are right for the job, I'll leave for those with direct experience to address
spinningmagnets
100 TW
How bad are the hills on your commute?
If you want two motors to have redundancy (one motor/controller stops working, other motor still provides some assist while pedaling), it is still useful to consider two identical motors. For a two-hub commuter, I recommend two identical geared hubs. Geared hubs freewheel, unlike the direct drive, which have some cogging when unpowered (also, DD's are heavier). When considering geared hubs, I feel the Bafang-BPM has a lot to offer. The MAC/eZee/BMC's are larger and more powerful than the BPM, but if there are two of them, you might be shocked at how much power they can put out.
The most popular commuter around here seems to be the MAC 10T at 48V. A lot of happy customers using that. The bigger MAC is a great choice for a single hub bike, but when using two hubs, the slightly smaller BPM will cost a lot less and still perform fantastic.
The combination of a small front geared hub and a mid drive will have some benefits and drawbacks (as every choice does). If you are using one throttle, it will be hard to balance the inputs of both motors (and using two throttles has its own issues). In that instance I would use the mid-drive most of the time, and only use the small front geared hub if the mid-drive stopped working.
Teklektiks Mundo and the Mental Manno both have identical twin geared hubs, twin controllers, and one throttle/one battery. The "Duty Cycle AWD" is the same. If you don't want to waste the investlent of the motor you already have, consider getting an identical motor that is configured for the rear, and then run them both at 48V. these smaller motors are limited on the amps they can survive, so start with higher volts, while limiting the amps. adding temp sensors will allow you to drive more amps without exceeding 93C/200F internally, so they survive. Getting a Cycle Analyst will help a lot as soon as you can squeeze it eventually into your budget.
http://www.electricbike.com/custom-build-gallery-teklektiks-dual-motor-yuba-mundo/
http://www.electricbike.com/custom-build-gallery-zlatkos-mental-manno/
http://endless-sphere.com/forums/viewtopic.php?f=3&t=51612
If you want two motors to have redundancy (one motor/controller stops working, other motor still provides some assist while pedaling), it is still useful to consider two identical motors. For a two-hub commuter, I recommend two identical geared hubs. Geared hubs freewheel, unlike the direct drive, which have some cogging when unpowered (also, DD's are heavier). When considering geared hubs, I feel the Bafang-BPM has a lot to offer. The MAC/eZee/BMC's are larger and more powerful than the BPM, but if there are two of them, you might be shocked at how much power they can put out.
The most popular commuter around here seems to be the MAC 10T at 48V. A lot of happy customers using that. The bigger MAC is a great choice for a single hub bike, but when using two hubs, the slightly smaller BPM will cost a lot less and still perform fantastic.
The combination of a small front geared hub and a mid drive will have some benefits and drawbacks (as every choice does). If you are using one throttle, it will be hard to balance the inputs of both motors (and using two throttles has its own issues). In that instance I would use the mid-drive most of the time, and only use the small front geared hub if the mid-drive stopped working.
Teklektiks Mundo and the Mental Manno both have identical twin geared hubs, twin controllers, and one throttle/one battery. The "Duty Cycle AWD" is the same. If you don't want to waste the investlent of the motor you already have, consider getting an identical motor that is configured for the rear, and then run them both at 48V. these smaller motors are limited on the amps they can survive, so start with higher volts, while limiting the amps. adding temp sensors will allow you to drive more amps without exceeding 93C/200F internally, so they survive. Getting a Cycle Analyst will help a lot as soon as you can squeeze it eventually into your budget.
http://www.electricbike.com/custom-build-gallery-teklektiks-dual-motor-yuba-mundo/
http://www.electricbike.com/custom-build-gallery-zlatkos-mental-manno/
http://endless-sphere.com/forums/viewtopic.php?f=3&t=51612
mrzed
100 W
if your commute is flat, a single rear direct drive motor is easily the top option. rear geared would also work, and be stealthier but ultimate reliability goes to direct drive as noted above.
Jonathan in Hiram
1 kW
- Joined
- Oct 6, 2009
- Messages
- 446
Headwinds aside you should be able to maintain 10 mph average on the flat even without a motor at all if you have high quality low rolling resistance tires on your bike. I'm sixtymumble and I can maintain 15 mph for a half hour without motor on a flat road but the only flat paved riding areas here are the rails to trails which never go where you need to go so they are strictly for recreation at least for me.
Ten mph would give you a half hour commute in either direction, if your current kit has 250 watts you should be able to manage 15 mph or so with a little added pedaling. My system is a real shade tree setup with repurposed salvaged laptop cells and a motor not that much stronger than yours and I can go 18 mph average for 10 miles non stop fairly easily through hilly but not mountainous terrain with what I consider moderate pedaling.
Bear in mind that your Trek is a mountain bike and that 300 lb limit is for use offroad, if you are riding strictly on paved surfaces and not jumping curbs and things like that it should have a substantial safety margin even at say 350 lbs.
IMHO you are more likely to have a problem related to tires than the electric drive system, I'd use what you have and concentrate on making the tires as puncture resistant as possible, good tires and tubes, anti puncture tire liner, slime in the tubes. The electric breaking down just means you have to pedal, if a tire goes flat you *will* be pushing your bike and that will make you much later to work than having to pedal with dead electrics.
Pedaling a bike is deceptive, it seems really slow until you have to get off and push and then you realize that you were going three or four times as fast on the bike as your walking speed (3 mph is a brisk walk).
Once you get some experience with the electric drive you'll have a lot better idea what more (if any) you need.
Ten mph would give you a half hour commute in either direction, if your current kit has 250 watts you should be able to manage 15 mph or so with a little added pedaling. My system is a real shade tree setup with repurposed salvaged laptop cells and a motor not that much stronger than yours and I can go 18 mph average for 10 miles non stop fairly easily through hilly but not mountainous terrain with what I consider moderate pedaling.
Bear in mind that your Trek is a mountain bike and that 300 lb limit is for use offroad, if you are riding strictly on paved surfaces and not jumping curbs and things like that it should have a substantial safety margin even at say 350 lbs.
IMHO you are more likely to have a problem related to tires than the electric drive system, I'd use what you have and concentrate on making the tires as puncture resistant as possible, good tires and tubes, anti puncture tire liner, slime in the tubes. The electric breaking down just means you have to pedal, if a tire goes flat you *will* be pushing your bike and that will make you much later to work than having to pedal with dead electrics.
Pedaling a bike is deceptive, it seems really slow until you have to get off and push and then you realize that you were going three or four times as fast on the bike as your walking speed (3 mph is a brisk walk).
Once you get some experience with the electric drive you'll have a lot better idea what more (if any) you need.
You're making it much more complicated than it is, although it would have been a lot simpler if you'd asked before you bought that under-powered Hilltopper kit with non-standard connectors.
Electric bike systems are modular. Any 24v battery will work with any 24v controller and motor. It's not 100% clear from your description, but it appears that you have a sensorless motor, so if you want absolute compatibility, you need a sensorless controller and motor for the rear. Many controllers can run with and without hall sensors (dual mode). Most motors with hall sensors can run sensorless, the exception being the Q100 series.
So, you can use any 24v rear motor except Q100 series; any 24v sensorless or dual-mode brushless controller; any 24v battery. The problem will be the connectors. Most kits except the Hilltopper use standard interchangeable connectors.
In practice, won't need to swap things around because you have two independent drive systems, so If one fails, you still have one working. I think you're making it unnecessarily complicated. If I were you, I'd buy a 36v 250v rear motor kit.
You'll need to think about the brake switches. It might be best to use the back brake switch for the back motor and the front one for the front motor otherwise it gets very complicated.
Electric bike systems are modular. Any 24v battery will work with any 24v controller and motor. It's not 100% clear from your description, but it appears that you have a sensorless motor, so if you want absolute compatibility, you need a sensorless controller and motor for the rear. Many controllers can run with and without hall sensors (dual mode). Most motors with hall sensors can run sensorless, the exception being the Q100 series.
So, you can use any 24v rear motor except Q100 series; any 24v sensorless or dual-mode brushless controller; any 24v battery. The problem will be the connectors. Most kits except the Hilltopper use standard interchangeable connectors.
In practice, won't need to swap things around because you have two independent drive systems, so If one fails, you still have one working. I think you're making it unnecessarily complicated. If I were you, I'd buy a 36v 250v rear motor kit.
You'll need to think about the brake switches. It might be best to use the back brake switch for the back motor and the front one for the front motor otherwise it gets very complicated.
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