Choosing a Conversion Kit

Hello Guys,

I recently have been very interested in getting a kit for my 29er. I am looking for a rear geared motor (do climb some hills by my house) that has enough power to scoot me along. I was looking at a 720W (36Vx20A) or so motor that I will have a speed switch on to limit to 250~, 500~, max. This way I can easily stay street legal on my commute to work around traffic... also safer so I dont die.

My (hopefull) requirements are

1. Disk breaks, love them and want to be able to stop fast whenever I need to. Current bike has them.
2. Decent top speed, would like to go 40kmph on flats with pedal assist... or 32 without.
3. change on the fly top speed, a switch on handle bar would be awsome.
3. Not to die on hills. I live on a hill so to and from work is always at least 1 up and down.
4. Decent cassette size, currently have a 3x8 speed, would like to keep it to 3x6/7 wont need as many low gears wit this
5. cheap, all in excluding battery I would like to stay less than 300-400.

From the following forum I found some items that I really like. http://www.electricbike.com/12-kit-power-levels-360w-to-8000w/

I really like the two bafangs and think that is what I may lean towards. I really like the size and kit in regards to the Bafang-BPM. I think it would be the best idea for what I am looking for... Any other suggestions would be awsome as well. Also is the BPM II worth it

If I get this motor I will need the following, all of which I know minimal about. Any recomendations would be great, or a site where I can purchase these all at once. So I can KISS (keep it simple stupid) the whole build. I would liek a full kit but also if I place 2/3 orders that is ok and can solder it together. I do not mind putting in some time if I can save some $$$$.

Controller - know next to nothing about these
Throttle - would like a full twist
Display - basic is all I need would like to see kmph, battery level and temp
Speed Switch

How long would it take to hook all these up to get working

Thank you all for your information and knowledge. Have been reading this forum for a while and very interesting ideas and people
Regan

Welcome to the forum
Before we can recommend anything, we'll need to know what part of the world you're in. I'd guess Europe based on some things you said, but we're international, and different parts of the world have access to different things.

We'll also need to know more about how you'll ride. Knowing the minimum range you need to go will help, as well as how steep the hills really are.

It would also help to know what brand and model bike you have, as some bikes work better with some kits.

Hi Sorry didn't really think about that...

I live in Southern Ontario, Canada, I am not going up any super steep hills/mountians but still I live on the escarpment (big hill) so either way I go is up hill somewhere. I try for the longer more graduale route wich according to quick google is about 30m up over 900m distance. I have a 29er Marin Muirewood, there was a conversion done on this site to this but but that is more extreme than what I want. I want a smallish size hub so look stock, while having decent top speed and some hill climbing ability.

Welcome to ES****Do this before your first post or now (it's retroactive)*****
Please go to the User Control Panel, select Profile, and then enter your city, state/province, and country into the Location field (country minimum) and save it. Once done, your location will appear in every post so you won't have people asking where you are ever again. This will help people help you. Example: Wylie, TX, USA. or just USA, but country as a minimum, and country is the most important. There are many cities with the same name all over the world. Without knowing what country you are in it's hard to make any recommendations. Thank you.
In Canada and there's probably more.
http://www.ebikes.ca/
http://www.goldenmotor.ca/

wesnewell said:

Welcome to ES****Do this before your first post or now (it's retroactive)*****
Please go to the User Control Panel, select Profile, and then enter your city, state/province, and country into the Location field (country minimum) and save it. Once done, your location will appear in every post so you won't have people asking where you are ever again. This will help people help you. Example: Wylie, TX, USA. or just USA, but country as a minimum, and country is the most important. There are many cities with the same name all over the world. Without knowing what country you are in it's hard to make any recommendations. Thank you.
In Canada and there's probably more.
http://www.ebikes.ca/
http://www.goldenmotor.ca/

Click to expand...

Woops, sorry about that. There was an automatic field that we completed to show the country, figured that would show up.
I have looked at golden motor, but the price is just too high... I think the price limit I want is the 300-400 without battery.

For the $300-400 range, you can get a MAC. It has parts interchangeable with the BMC, but it's a better motor. A display for it will run you another $130, and then there is shipping costs. http://em3ev.com/store/index.php?route=product/product&path=36&product_id=138

If you want to go cheaper, there are other options from places like BMSbattery, although they aren't vendor I'd recommend normaly. They do carry the Bafang 500w motors, which would shave a few hundred off your costs, at the cost of some performance and reliability.

For climbing hills you're going to want a 500w nominal motor. While you may not want or need the added power, the added size allows them to climb without struggling, so they aren't as likely to burn out while trying.

A switch to change power levels is easy enough. the Infineon based controllers that EM3ev.com uses have an option for a 3 speed switch. with a programming cable, you can set those switch positions to be anything you want, as a percentage of the max power. For example, I have mine set to 0%, basically an off position without having to power down the bike, 10%, which for my bike lets me hit 19.5mph, just under the legal limit in Texas, and 100%, for riding like I really want.

Does this fit a 29er.
http://www.goldenmotor.ca/products/700c-Rear-Black-Magic-Conversion-Kit.html

Before you buy from anyone in China, be sure and check shipping cost.
You might also want to check ebay for a kit that will ship to Canada from the US.

Drunkskunk said:

For climbing hills you're going to want a 500w nominal motor. While you may not want or need the added power, the added size allows them to climb without struggling, so they aren't as likely to burn out while trying.

Click to expand...

What do you mean 500w nominal motor?

Also I have looked at golden motor, and it just is outside of my price range. I have looked on Ebay for some, but never really knew what I was looking for ie brand of motor... or off branded etc. I also wanted to check for power levels and switches, might buy motor etc from a site but a EM3EV conroller, seems like it will fit what I am looking for.

The MAC or BMC are both nice... from what I hear and are simular to what I want. For the MAC, motor kit, how do I know the Watts it will put out, just simple Amps X Volts, so the 6fet 25Amp at 36v would be equivilant to a marketed 900w motor? This motor would also not have any issues with heat? Then in regards to the T for the speed, is that just max RPM? I am a bit confused in regards to that section. I know approx 11.6rpm on a 29er is 1mph... found from another post. If that is the case I would get the 320RPM.

from EM3ev they are just a tiny bit out side my price but might get the few extra bucks just for the reviews and better communication than chinese companys. Also simple as I can purchase everything from one place...

Higher wattage motors are physically bigger and are able to more easily cope with heat generated in use. Actual motor power ratings are almost irrelevant. All they do is state a continuous amount of power that the motor is guaranteed to run at without issue by the manufacturer. Often motors are hugely underated for either legal or warranty reasons and can be ran at multiples of the rating. Voltage and controller current limit is what determines the operating wattage, not the sticker on the motor.

Check my Sig for my 29er build. I spent a bit more for a full MAC 10T kit at 14S but it does 50km/h on throttle and I have 9 speed rear and disc brakes.

morinr said:

Drunkskunk said:

For climbing hills you're going to want a 500w nominal motor. While you may not want or need the added power, the added size allows them to climb without struggling, so they aren't as likely to burn out while trying.

Click to expand...

What do you mean 500w nominal motor?

Also I have looked at golden motor, and it just is outside of my price range. I have looked on Ebay for some, but never really knew what I was looking for ie brand of motor... or off branded etc. I also wanted to check for power levels and switches, might buy motor etc from a site but a EM3EV conroller, seems like it will fit what I am looking for.

The MAC or BMC are both nice... from what I hear and are simular to what I want. For the MAC, motor kit, how do I know the Watts it will put out, just simple Amps X Volts, so the 6fet 25Amp at 36v would be equivilant to a marketed 900w motor? This motor would also not have any issues with heat? Then in regards to the T for the speed, is that just max RPM? I am a bit confused in regards to that section. I know approx 11.6rpm on a 29er is 1mph... found from another post. If that is the case I would get the 320RPM.

from EM3ev they are just a tiny bit out side my price but might get the few extra bucks just for the reviews and better communication than chinese companys. Also simple as I can purchase everything from one place...

Click to expand...

The nominal rating is what the motor can run continuously without overheating in normal conditions. Most motors are rated this way, However, some vendors quote the maximum power of the motor kit, and that can get confusing.

You have the right idea, the max a motor kit will put out is simply the Volts X Amp limit of the controller. A 36v 20A controller can put out 720 watts. A 48v 30A controller can put out 1440 watts. Some vendors may sell those as 750w kits, and 1500watt kits, others will sell them listed by the nominal rating of the motor.

The limit of the motor is something you can really only find through testing or research here. The MAC and BMC are known to handle 1500 watts of output for short periods of time, and 1000 watts for quite a while. Small 250 watt motors generally can't handle more than 750 watts max for short periods of time, and will overheat if run at 500w for very long.

As for the speed, you're on the right track, but there is more to it. the T is the number of "Turns" of copper around the stator. More turns means less speed, but also more efficient production of torque. a lower T, or lower turns of copper means more speed, but it will get hot much faster while lugging up a hill.
The common compromise is to use a slower motor with more voltage. More volts = more speed, and you can get both the speed and efficiency you want this way. in your case, it's probably not advisable to use 36 volts for an off road hill climbing bike. a motor that gets the speed you want won't be a good hill climber at that voltage. A higher T motor with more volts would be better, and can achieve around the same top speed.

Thanks for the great info Drunkskunk really appreciate it. I won't be using it for much of off-roading just some rail trails and such, no crazy mountain biking etc.

In regards to volts, I want to get something simple ie 48v or 36v. just because the batteries are easy to find and decently priced... So the 48v will give me a bit more speed top end and whatnot, so not sure if I want the 48 or 36 or if there is much difference... Might lean towards the 36 just to max out at the 720W. I think 720 is more than enough.... but not too sure what the max speed I could get using this would be.

my MAC 10T at 48V (14S lipo does 50km/h)... B grade roads sorta stop me from going much faster without full suspension...

[youtube]RO-nubyUX64[/youtube]

You said you want a full-width throttle, which IMHO is not a good idea. You can't pedal so easily because you don't have a solid grib on the bars, plus, it's too easy to inadvertently open the throttle when moving your bike around. Thumb-throttles are much better and safer. You soon get used to them. Ebikes are not like motorbikes unless you build an electric moped type. A half-width throttle is also better than a full-width one.

If you fit a rear hub-motor, you'll have to make some changes to your gearing. Most motors, including the BPM and MAC can't use cassette (free-hub) gears. Instead, they use the screw-on freewheel gears. This means that you lose the 11T top gear, and have to go right down to 14T, which makes pedalling uncomfortable above 25 km/h. Also, 8 spd makes the hub wider and off-sets the rim, so you have to put a substantial dish in the wheel, which can increase the incidence of broken spokes. Therefore, you have to go down to 7 spd, which can give indexing problems, although you can probably live with that. You can get a DNP freewheel gearset with 11T top gear (if you can find one), but you have to add the additional cost to your project.

If you don't want to pedal, none of these things are a problem, but then you need more power, which means more expensive kit.

I, m assuming that you want to pedal along with your bike, but without having to put in too much effort. 29er bikes are normally a step up in quality from your average wally bike, so I'm making some assumptions about that.

If you want to keep your gearing the same,or even make it better, you can do that with a cassette motor. The Bafang 500W CST has the same power as the BPM, and it fits right in the speed range that you specified. I calculate a maximum speed of 42 km/h, and it'll make good power at your cruising speed or max legal speed of 32 km/h.

You can get it from BMSbattery as just a motor wheel, then add one of their battery kits for a plug-and-play solution. All you need extra is a pair of their torque arms and a spoke key. The frame-mounted battery looks very neat. The controller is a sine-wave one for smooth quiet operation, and you get a LCD control panel where you can set the amount of assistance. Many of the alternative systems suggested above are not very good in that respect.

http://www.bmsbattery.com/ebike-kits/589-q11-48v1kw-front-driving-hub-motor-e-bike-conversion-kit.html
http://www.bmsbattery.com/36v/678-bottle-ebike-battery.html

Thanks for that info,

the only reason I was thinking full throttle is because I used to have a half grip gear changer on my older bike... was completely rubish and not sure about having thumb trottle as i have thumb gear shifter... But won't be using at the same time. I might go for the thumb, great point about pedaling and putting force on the handlebars never even occurered to me.

In regards to gearing I would like the 11t gear for the long flat stretches, won't be using it everyday on the way home but if I have a rear wind and want to get home in a hurry can go into 48tx11t and crank away.

You are corect about that, the bike was a gift and its a mid range price commuter. BMS battery with controller is pretty great solution, sleek and simple. Those two items look like a great solution and may fit exactly what I am looking for. The onlything I would want to do is get it to have a speed switch, I see only certain controlers they have will fit the speed switch they sell. So may have to asemble the kit if I do it that way.

What exactly is a cassette motor? Vs the Hub motor?


Thanks,

Regan

Update:

I have been doing a lot more reading and think I may actually change from a rear drive to a Bafang BBS02 mid drive motor. I think the price will be a bit higher, however I will get more out of it, from reading it seems thats the issue with lots of first builds... not getting enough bang and wanting more out of it. This way it will be able to easliy conqure the hills I have avereage grades of 4% but that includes some flat areas. With the BBS02 I will be able to drop it into a low gear and just chug along up the hill without generating a ton of excess heat that may cut the motor when I want the assist mostly. This will also alow me to go into a high gear and get a top speed to what I am looking for. I also think the programming availible is fantastic if I can make/get my hands on a programming cable. So I can customize the assist levels for various options. Will work like the switch I was hoping to get to be able to change on the fly max speed and level of assist etc. If I require more top end speed or low end torque it is as easy as chagning gears or swapping out rear cassette or front chain ring for larger/smaller depending on my needs.

From reading the thread relating to programming it, I was wondering if anybody ever thought of mailing a cable around, I know I can buy the bafang extension and TTL converter and get it to work, but with shipping etc, this will end up being $40+. For an item I will hopefully only need to use 2/3 times within a week of commuting to set what I need and then will sit in a box and never be used again. Anybody have or know someone who may have on in the GTA area in Ontario? Could buy used or just borrow and pay for shipping, I am sure some people have them and havn't used for a while...

Let me know what you think

Hey mate,

BBS02 750w is a good choice and is what I would have gone for if I was to do it again for more stealth. Make sure you do all the reading on the chainline issues (non centered bottom bracket) and that the widths are correct. Also try to buy from someone who can remove the 50km/h speed limit.

I think Bafang released a new revision recently that fixes those issues, so double check you're not getting older stock.

Thanks for the info. I think the bbs02 is probably more costly than I want... but will fuful my needs and won't need to buy a second kit in a year or so. I think because of that it is the best decision to fit what I need. Will not over heat on some of the longer hills I climb, can drop it down a few gears and make my way up.

I am unsure about the chainline issue, read abit about it but with a standard size bottom bracket should it fit? I have a 8 speed rear and a 3 speed front. I figured the new front crank would fall within the 3 gear area. Not need any adjustments to make it fit... I could be totally wrong though. I beleive that my bike has a centered bottom bracket.

I am looking to buy a cable to program it. I ordered the usb to ttl, however still need the bafang connector... Trying to find best place to purchase it by.

In regards to the version, I was wondering if anybody knows the date that it was changed to the v2. I read it somewhere before but cant seem to find it.