350w Bafang CST kit from eMax on 90’s Mongoose MTB

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Scotty T
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350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Nov 16, 2015 9:48 pm

The Build

First up, you can see my first build here to compare notes when I refer to it in this post.

This is my second build, and being totally convinced by the first that this is the best way to get around especially here in Canberra, I put together a plan. At first the plan was for me and my son to ride e-bike #1 a couple of days a week each to our respective, opposite direction commutes. Second was a plan to make this bike the e-bike:

Image

This is a great bike, but forum member byebyepetrol said he’d go for suspension forks for a more comfortable ride and put up with the weight penalty. I had bought the bike above because I had sold this bike previously:

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Next thing I know the dude who bought that off me rang me and said he’d bought a new MTB and was happy to return mine. We negotiated a price, and the bike I’d spent well over 2 grand on was returned to me for $200. I think I sold it to him for $300 some 6 years earlier, it was pretty much how I handed it to the guy with very little use. You can tell when the guy leaves the useless hardened dirt tyres on with not much wear, it that it had an easy life for that time . I digress, but you may know what I mean when I say this bike is special to me, I owned it from 1996 to 2008.

But what to do? I was looking at the Bafang mid drive kits, but I decided that my rear wheel was less worthy than my cranks. I got in touch with eMax bikes and sorted out a spec, they had freewheel stock, but I am not a fan of freewheels especially when it is an 8 speed so I ordered in the Bafang CST 350w. It was laced up to an Alex DM18 with Sapim spokes, built in Sydney by one of eMax’ builders, as per the recommendation. It was ordered in the Chinese new year period which caused a massive delay but finally it arrived.

I went for the Bafang C961 display and compatible controller, all the bits arrived minus the battery and I started to plan the build. Unfortunately the battery was lost by Aus Post and it turned out that Ewan from eMax was coming down to Canberra and could bring a replacement, and claim the lost one through the post. We had a great pub lunch and chat, and the battery was in my hands, along with some Tektro V-Brake e-bike levers with cutoff switches, I was ready to go.

But first I had to turn the MTB into a commuter, I ordered some Rain Dog mudguards, moved the pannier from e-bke 1 as my son uses a back pack. I then moved the clipless pedals, Specialized Nimbus tyres and the saddle from the rigid bike shown above.

I started building. I actually had no idea that the controller would be a separate unit from the battery. But of course the basic kit and small battery I’d dealt with before is quite different from the larger battery and Bafang setup. I had to figure out where to put the controller and at first I was thinking of mounting it on the pannier rack. I would have needed a battery extension to do it so I looked at another solution. It turned out that I could fit a bottle cage cut down to the size of the controller to securely mount it to the frame. I covered the tips of the bottle cage in heatshrink. As with the other bike I used sections of inner tube to cover up all the connectors to keep dirt and water out.

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As usual everything just plugged in, I had to get some spiral binding from Jaycar to keep the cables tidy and used some inner tube as previously to cover the connectors.

As is typical on these kits I struggled to find room on the handlebars to set up the cockpit properly. The display allows you to offset it which is shown below, it would have made the light very difficult to mount if it was stuck in the middle. I also had to put the throttle on the left, which means pushing it up instead of down, and it can get stuck on because it’s not totally on a flat piece of handlebar. It would be great to see some left mounted, high quality thumb throttles on the market. The other bike has the grip twist throttle which is OK but gets uncomfortable on a long ride as the twist throttle part is a larger diameter than the grip and I typically only use the PAS anyway.

Image

The Tektro brake levers come without connectors, I could have soldered them but I wanted to be able to disconnect the controller without cutting or de-soldering cables. I found some crappy circuit board style connectors which were the smallest thing I could find at Jaycar, they worked but needed to be taped as they didn’t hold together well. I’ll see if I can find some better connectors for that.

The PAS was a massive drama to install due to my cranks being a very tight fit. It didn’t want to work on the left crank either, face the magnet either way and the wheel only turned pedalling backwards. On the drive side I couldn't get the bottom bracket lock ring undone, and aside it would not have had room with the tight fitting cranks, the bottom bracket shell overlapped the inner part of the crank arm. I removed the sensor from the metal ring, I used a piece of twisted thin galvanised wire to hold the pas, inserted into a block of foam I stuck on the back, with a few globs of silicone. I did the same thing as I’d done on the other bike, with a holesaw to make a larger hole in the middle of the PAS magnet ring to fit it on the crank where the granny chainring used to be.

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All good to go! Tested the bike and took these pics of the finished product on it's first commute to work.

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Riding

I expected about a 30% better speed than the 250w and basically that’s what I got. About 32km/h @100% charge compared to the limited 250w 25km/h unit. The first thing I noticed though was how much grunt it had going up hills, it really pulls very hard. It translated immediately to about 4km/h higher average speed over the 18km commute. As I’ve become fitter this has crept up to 5km/h The battery life is great, the 11.6Ah unit will get me 2 round trips easily, and it charges in about 4 hours from dead (battery cut out, which I measured at 43.4 volts) to full charge (54.6 volts). I generally only have to put about an hour and a half charge in after an hour and a half riding to keep it topped up but not 100% full.

I’m in the process of fitting a Cycle Analyst and Grinfineon controller to the unit now, I was hoping to get a higher speed out of this but as far as I can tell it won’t change the top speed, it will just improve the speeds going up hills which generally are under 27 km/h compared to the . I will be able to run more watts to the motor, so it will give it more pulling power, but the top speed would only be affected by having more voltage in the battery pack. Being a bit of a n00b I wasn’t aware of that when I started the project, but now I know that a motors top RPM limit is governed by voltage and not watts. I will look in the future at putting a higher voltage pack in, because it would be nice for the motor to keep pulling up to ~36km/h on the flat, and this could easily be achieved with a 54 volt pack. Theoretically a 60 volt pack would pull 41km/h which I think would be a bit fast for the v-brakes, and possibly a problem for the phase wires and motor itself. If I did get a higher voltage pack I’d get LiFePO4 as the voltage drop on the LiMn pack is noticeable, and by around 60km on a single charge it will only pull 27km/h top speed.

Overall it’s a fantastic kit, It hasn’t missed a beat with 1900km on the clock. I had the wheel trued and tensioned after the initial break in period of about 100km and otherwise have just kept charging and riding it. I also upgraded the V-brakes to Shimano XT, as the cruddy Truvativ ones from the 90’s were not performing well at all and downright scary in the wet. The old forks were a tad sticky so I had them serviced too, and they are running smoothly, and I’m really glad I went with front suspension for the build, it makes the 36km round trip nice and comfy on the hands.

There was also a problem with the chain coming off because I was running only the one chainring now, I picked up a Paul Components Chain Keeper for that and it has worked very well. The chain is also a tiny bit short but it is still working well for now so I haven’t changed it.

I will update the thread once I have the CA3 and Grinfineon up and running and have done some miles to report back on.

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motomech
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by motomech » Nov 17, 2015 1:19 am

As is typical on these kits I struggled to find room on the handlebars to set up the cockpit properly. The display allows you to offset it which is shown below, it would have made the light very difficult to mount if it was stuck in the middle. I also had to put the throttle on the left, which means pushing it up instead of down, and it can get stuck on because it’s not totally on a flat piece of handlebar. It would be great to see some left mounted, high quality thumb throttles on the market. The other bike has the grip twist throttle which is OK but gets uncomfortable on a long ride as the twist throttle part is a larger diameter than the grip and I typically only use the PAS anyway.
Turn the thumb throttle upside down and place the h.bar lever bracket inside of the throttle.
I much prefer a left-hand, half twist throttle to a thumb.
Motomech

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, 2.4 Holly Rollers run ghetto tubeless. 25 mph. Mean Well HLG-320H-48A
https://endless-sphere.com/forums/viewt ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 12S LiPoly elifebike 9-FET 17A controller. 20 MPH.
https://endless-sphere.com/forums/viewt ... 8#p1237928

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motomech
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by motomech » Nov 17, 2015 1:32 am

[quote]
I expected about a 30% better speed than the 250w and basically that’s what I got. About 32km/h @100% charge compared to the limited 250w 25km/h unit. The first thing I noticed though was how much grunt it had going up hills [quote]

I plugged your data into the Ebike CA simulator and the results show that you have a 201 rpm @ 36 V motor. Much too slow a motor for the open country shown in your pic.s.
The 270 rpm @ 36 V motor speed(actual-285) would have been the right motor for your needs and would have a top speed of 44.4 Kmh on 48 V in a 26" wheel.
Motomech

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, 2.4 Holly Rollers run ghetto tubeless. 25 mph. Mean Well HLG-320H-48A
https://endless-sphere.com/forums/viewt ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 12S LiPoly elifebike 9-FET 17A controller. 20 MPH.
https://endless-sphere.com/forums/viewt ... 8#p1237928

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motomech
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by motomech » Nov 17, 2015 1:53 am



I’m in the process of fitting a Cycle Analyst and Grinfineon controller to the unit now, I was hoping to get a higher speed out of this but as far as I can tell it won’t change the top speed, it will just improve the speeds going up hills which generally are under 27 km/h compared to the . I will be able to run more watts to the motor, so it will give it more pulling power, but the top speed would only be affected by having more voltage in the battery pack.
That's right, the Infineon controller will not add to the top speed. It will hit harder, be slightly louder and you will loose the nice display.
I would talk/complain to the Vendor that sold you the wrong motor. All you need is the 270 rpm bare motor and you can swap it into your wheel/hub housing.
Motomech

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, 2.4 Holly Rollers run ghetto tubeless. 25 mph. Mean Well HLG-320H-48A
https://endless-sphere.com/forums/viewt ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 12S LiPoly elifebike 9-FET 17A controller. 20 MPH.
https://endless-sphere.com/forums/viewt ... 8#p1237928

Scotty T
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Nov 17, 2015 4:20 am

Thanks for the info motomech, I have to say if I was told you can have a motor that does ~32km top speed, or one that does ~40km top speed I definitely would have chosen the faster one. As you say it kind of makes the Cycle Analyst a bit worthless, and I can pedal under my own steam at over 32km on the flat on a normal bike that is 7 kilos lighter :? I will have a chat to Ewan/Emax and see if we can work something out.

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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Nov 17, 2015 9:24 pm

I plugged your data into the Ebike CA simulator and the results show that you have a 201 rpm @ 36 V motor.
I looked up the codes for the motors and it seems a code 10 would have been the faster one and I have got a code 15.

I have 180m altitude gain over 18km with 5 short climbs and I pedal fairly hard, so I don't think efficiency or overheating would be an issue.

I can't find anywhere on the web that specifies the code 10, even after reading up on it in other threads, it's still quite confusing.

This supplier for example is offering a 48v 500w specifying 255RPM:

http://www.aliexpress.com/item/new-whol ... 50256.html

And a 36 volt specifying 255RPM:

http://www.aliexpress.com/item/new-whol ... 51217.html

You could assume that the latter will get 340RPM at 48v. But from what I've read I don't know if I'd be happy to make that assumption.

I wish I'd read this too before deciding that 350w was good because it's not much over the legal limit and could become legal here like in other parts of the world.

http://www.ebikeschool.com/myth-ebike-wattage/

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motomech
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by motomech » Nov 17, 2015 11:59 pm

This the one you want;
https://bmsbattery.com/ebike-kit/492-ba ... e-kit.html
Both D8veh and friendlyuk have used it and have confirmed it goes 22 to 23 @ 36V and 24 to 26 @ 48V.
That has it falling between Bafang's rather cryptic codes # 12 and #11.
They discribe it as a "nice balance of speed and power".
It is also on the Ebike CA motor simulator and it shows it as doing; 22mph @ 36V and 28 mph @ 48 V, a strangely wide spread.

http://www.ebikes.ca/tools/simulator.html

It looks like it climbs well enough, you can calculate your grades and plug them in. Time to Over-Heat is the critical item.

Bms Battery also sells gear sets, which they list as "for CST", but do not specify which speed motor. One would assume it would be for "260", but assumpsions on these Chinese web sites are dangerous. The other thing, I am not that knowledagble about BPMs and cannot say how much of the speed differences come from the winding and how much is mechanical ratios. They are not expensive and if I were you, I would buy a set to play around with the motor you have now. You could count the # of teeth on your motor and the # in the pic and maybe know befor ordering. At any rate, It never hurts to have an extra set of gears.
https://bmsbattery.com/ebike-kit/634-ge ... e-kit.html
BMS Battery has lot's of neat do-dads, that are cheap(It's the shipping that hurts), so I would suggest you look over their product line.
I strongly recommend the $4 half-twist, left-hand throttle.
https://bmsbattery.com/ebike-parts/611- ... parts.html
Also, order the Hidden Brake Sensor, so you can ditch the clunky Tekno levers and put the originals back on.
While I am spending your $$, D8veh is a big fan of the S12S sine wave controller and SLCD_3 on the %00W BPM.
https://bmsbattery.com/ebike-kit/552-s1 ... e-kit.html
These are budget high-tech stuff with remarkable features. Things like 5-speed limiting AND current (torque)limiting on PAS! It is described as a great PAS experience. The display show more stuff than you can imagine. If you are a techy sort and have the time to play around with the sensor installations, they are great fun.
Sounds like you will be building another bike with left-overs :roll:
As always, commucation is the key to not getting your order screwed up with the big vendors in China. I usually talk with Jack Xie a couple of times to prevent a foul-up.
No returns with these out-fits.
Motomech

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, 2.4 Holly Rollers run ghetto tubeless. 25 mph. Mean Well HLG-320H-48A
https://endless-sphere.com/forums/viewt ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 12S LiPoly elifebike 9-FET 17A controller. 20 MPH.
https://endless-sphere.com/forums/viewt ... 8#p1237928

Scotty T
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Nov 18, 2015 10:56 pm

It does seem from other posts online that the RPM is coming from the motor wind but it would be nice to go faster for 20 bucks.

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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by motomech » Nov 19, 2015 12:47 am

Take the cover off yours and count the teeth.
Motomech

'03 Rocky Mountain Edge 2WD 260 Q100H frt and Ezee V1 rear 2 Elifebike 20A & 25A 9-FET controllers 12S/20Ah Multistar Lipo rear 5Ah Turnigy frt Luna Cyclops Extra lite Alex 24DM rims, 2.4 Holly Rollers run ghetto tubeless. 25 mph. Mean Well HLG-320H-48A
https://endless-sphere.com/forums/viewt ... =3&t=83430
'07 GT Idive 4 4.0, Q100C 201 12S LiPoly elifebike 9-FET 17A controller. 20 MPH.
https://endless-sphere.com/forums/viewt ... 8#p1237928

Scotty T
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Nov 19, 2015 12:54 am

motomech wrote:Take the cover off yours and count the teeth.
I'll take a look this weekend :)

Scotty T
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Nov 19, 2015 1:02 am

Scotty T wrote:
motomech wrote:Take the cover off yours and count the teeth.
I'll take a look this weekend :)
Actually I won't bother because a quick search reveals that they are all 42 teeth for CST and BPM.

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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by zan5hin » Dec 09, 2015 2:50 pm

Nice review. I just am jealous because my BBS01 from Emax has only ever gone 38-40km range on a single charge. I have a "15 watt" battery back but my Grin cycle satiator battery charger says it only charges up to about 13.5, but still I wish I could get 72km like you report. Just last week I ran out of juice about 4km from home and it was torture. I am going to take my Grin charger with me more often.

I have butterfly bars on my bike, and I put the throttle on the left side and have it set up to push down with no issues. So that is something to consider, you can get a BBB bar from online for like $15. It also gives you more space to put the display, light and a phone mount.

Scotty T
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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Dec 09, 2015 6:12 pm

zan5hin wrote:Nice review. I just am jealous because my BBS01 from Emax has only ever gone 38-40km range on a single charge. I have a "15 watt" battery back but my Grin cycle satiator battery charger says it only charges up to about 13.5, but still I wish I could get 72km like you report. Just last week I ran out of juice about 4km from home and it was torture. I am going to take my Grin charger with me more often.

I have butterfly bars on my bike, and I put the throttle on the left side and have it set up to push down with no issues. So that is something to consider, you can get a BBB bar from online for like $15. It also gives you more space to put the display, light and a phone mount.
Cheers mate. I'm guessing you get lower range because the BBS01 (on the top PAS setting) will keep assisting you until you get up into the 40km/h plus speed, member byebyepetrol gets 45km/h top speed. Or you have more hilly terrain than I do.

I notice with the the CA3 now fitted that it pulls 50w or less power on the flats when I am pedalling along at the top of the motor speed (~32km/h) which would be a fair bit of my commute so I am not pulling much out of the battery for large chunks of the ride. I would still like to get higher speed and lower range but it's not going to happen with the current setup.

I've mounted the throttle quite a way in towards the stem now right on the bit that has no curve, between where the light and bell are in the pic above, as I never use it anyway. With the previous position one day I had gotten off the bike, and I bumped it, and it stuck on for a second causing the bike to ram into a fence post and buckle the front wheel slightly!

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Re: 350w Bafang CST kit from eMax on 90’s Mongoose MTB

Post by Scotty T » Sep 17, 2017 5:07 am

Coming up on 2 years soon. First up sorry about the images, I changed hosting for my personal site and lost a few bits and pieces which I am yet to re upload. I forgot about my posts here so will upload again and fix the missing images.

The motor has not skipped a beat and has about 4200km on it. I pedal fairly solid and my commute has very few steep bits, so the motor barely even gets warm. The battery has barely lost any power and still seems to have plenty of capacity, running the bike at 500w limit on the Cycle Analyst has helped I think, it used to fly off the line and pull about around 900w if I put no effort in so I set that limit a while ago and I still reckon I'd get the original range out of it of around 80km.

I hadn't ridden it in quite a while because I broke a spoke and then circumstance prevented me riding more, and I'm riding the non e-bikes a fair bit, but I took it for its first decent run in a while tonight which is 8.6km each way. I started out with about 51v on the battery and have 49.4 left. The same run on my MTB with very small slicks which is almost like a road bike I get average of 27km/h on the way there and 21km/h on the way back, it is 90% down hill on the way there, that is riding hard. On the e-bike I get 30km/h on the way there and 28km/h on the way back with about 3/4 the effort overall I reckon because I still have to pedal on my own above 31-32km/h.

I rode back in the dark tonight and while I'd like more top speed for my mostly daytime commute on really big open bike paths, riding this route which is smaller windy bike paths in the dark with a 350 lumen bar mount light, the 28km/h average was scary enough. The battery doesn't look like it will fade anytime soon so it will be a while before I over volt by getting a new battery to get some more top end speed.

Most of all this got me riding again and I ride my human powered mountain bike and commuter lots, have done a couple of races even. Now that the weather is getting better I hope I can get back on it more because it's just so nice to ride.

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