Freeride Hardtail 3speed cassette GNG

[k1kk0_1t4]

Hello, that's my second ebike build, my first ebike is 1500w MXUS rear hub crusier used mostly for commuting, now i'm ready to the next step, a mid drive bike to be used exclusively for fun.
Actually i'm building 2 bikes: an hardtail for me and an old downhill bike for a friend that is a welder. The plan is to build the bikes, test them and let the natural selection do the hard job of destroing components... until we design and made a frame built on measure on our desires.
View attachment 3

The bike is an overbuilt crmo frame, similar to the old evil empire or the nicolai 2mxtb, the frame is handbuilt by a small company in eastern europe and totally overkill: 3,5kg, dual top tube, modern gravity geometry, capable of dual crown forks, bombproof, bulletproof, idiotproof and unbreakable even by Hulk.


200mm dual crown Rockshox Domain,
200 mm clarks hydrobrakes with inverted levers (left-rear, right-front),
26 inches rims, heavy downhill tubes and maxxis holy roller tires,

The intresting part is the drivetrain:
9 speed alivio 36-12 cassette,
heavy duty 9 speed KMC ebike chain (yeah, i'm spending money for science... finally we will know if ebike chain is really better built than normal mtb chain)
36t capacity shimano zee derailleur,
3 speed shimano front shifter

The cassette has been opened and the sprockets moved so i will use only 3 speeds: 36, 24 and 18, the derailleur has new and longer limit screws so i can mount the speeds i will use on the centre of the cassette.
I choose a 3 speed front shifter so i can mount it on the left and i don't have to worry about cable pull: the only speed indexed is the middle one, torque mode and speed mode are regulated by the derailleur limit screws (i found a similar idea in the mega-long gng topics but i'm unsure if someone has done something similar, if you have a similar setup, please join this thread to exchange ideas/implementations)

Motor is a chain drive gng 60v (on the way from china), modifications will be made after some tests, the controller is (for now) the stock one (i'll shunt mod it until i burn it), then i'll upgrade to something better and i'll hook-up my CA.
Battery will be spot welded and probably made by 15(or 16) panasonic NCR18650PF in 5 or 6 parallels groups (depends on frame space) from nklon.nl . The battery pack will be capable of 50A continuos and be around 16Ah so i can have some fun...

To do:
Choose a BMS
Search for a good quality thumb or ATV style throttle
Weld the battery (and build a spotwelder)
Build a battery enclosure (in frame or backpack battery, depends on dimensions)

Thanks for reading.

 

[cheekybloke]

Hi mate,
I am doing a similar 3 speed set up
Same rear mech short cage long throw zee
Thumb shifter on friction shift as gears are no longer indexed
18 23 and 28 cogs on rear
The chain line is run a straight as possible and then you can use a single speed chain as it has just enough side flex for a gear up and a gear down.
Also the rear mech will need a washer in it to widen the cage slightly for the wider chain.
The only other thing i may need to do is move the rear mech outboard slightly with a custom dropout if i cant get the gears i require.
Good luck with your build
Darren

 

[k1kk0_1t4]

Thank you Darren, i have seen your aft bike thread and your bike is amazing (and super fast!).
I'll try singlespeed chain when i'll break the 9speed chain i have bought.
When i get the motor i'll try to get the straightest chainline that i can, actually i've mounted the cassette with that scheme:
NOT used gear
NOT used gear
36,
NOT used gear(should help derailling the cahin)
24
NOT used gear
18
NOT used gear
NOT used gear.
I ll'test the bike that way and then i'll try to have the 3 gears i plan to use without a spacer gear in between, i doubt the chain will deraill easily with the huge gaps i plan to use but i'll try and reports the results here.

 

[cheekybloke]

You may have a little trouble getting the 36t to run at position 3 on your freehub as 36 is the max the rear mech will do.
If this is a problem either use a slightly smaller cog or move mech away from the frame by about 10mm with a spacer on the dropout.
Hope this helps
Darren

 

[sascha2770]

How's it going on?

Had some problems on my gng kit with lower than 13t.
Went back to single speed with 16t in the rear, not a bit of chainslipping...

You could use even the 13t, it gives you about 40-45 km/h topspeed.

 

[k1kk0_1t4]

Sorry but no upgrades... the motors will probably be delivered on monday, fun fact:
Yesterday they went from china to india to abu dhabi to malpensa airport (100km from me)

today they made 60km...

Italian efficiency!

In the meantime i'm rebuilding a Prusa i3 3d printing i had in the basement, so i can make some plastic parts i will need:
- a thumb throttle matching my left shifter,
- spacers for my cassette, so i can experiment
- mounting points for the controller
- mounting points for the battery

 

[k1kk0_1t4]

Hello, i'm back.. today the motors arived but i noticed some differences between my motors and the classic gng 650w kit seen elsewere.

I'll send some photos after work but here are the anticipations:

-new upgraded freewheling crankset... and in my opinion is not really an upgrade... images after i disassemble the unit, the right crank is no more a threaded one where you can screw a bicycle freewheel on.
the parts is not using bicycle freewheel but still has a bearing for support the load (the bearing seems to be bigger than the one you can see in the gng thread.

-different motor/jackshaft assembly (the assembly is not metal sheets but a different one -> that part seem beefy, but less moddable than the stock part)

-new controller (or new sticker): "700w bicycle moto controller" (but on the side i can see only for screws so i think is a 4 mosfet one (4 mosfet??? isn't that on the low side?) -> i bet that will be the first part to find the way for the recycle bin

-no primary chain tensioner, the chain is really sloppy, i'll need to hack something on because actually is probably usable at really small power at best.

-all black: almost all parts are black, the motor is black too... cool look

I have to say that i haven't bought the units from gng but on aliexpress, so i can't say if that is a knock off of the classic gng or is the "new year model".
More images after work

EDIT: it seems that the "upgrades" on my unit are the same that the ones on the gng website: http://www.gngebike.com/60v650w-brushless

 

[k1kk0_1t4]

Here are the images of the modifications made by gng from the previous genereation, the last two images are the new freewheeling block.

I mounted the drive on the bike yestarday but i haven't take pics yet, i had to mod the mounting and i need to do some minor modification on the drive: add a chain tensioner, add a small spacer between the crankarm and the freewheeling part because there is about 1mm of space and the freewheeling part moves a bit to much laterally.

I tested the motor for some minutes using my 53,3 battery charger, the motor seems ok but is really noisy, hope the tensioner could tame some of the noise.

 

[sascha2770]

Looks like an improvement over the former freewheeling kits...

Are you able to tension the chain or is just an optic update on that jackshaft on the motor?

Looks like they don't use freewheels like dicta or acs anymore, are those one way bearings?

Could you please post a link to the seller?

Can't find it on aliexpress...

Greets from germany

Edit: 25H Chain mod reduces the noise by an adequate level.

 

[k1kk0_1t4]

http://m.aliexpress.com/item/2027903619.html?productId=2027903619&productSubject=48V500W-BRUSHLESS-Gear-MID-DRIVE-ELECTRIC-MOTORIZED-E-BIKE-CONVERSION-KIT&tracelog=wwwdetail2mobilesitedetail

That's the aliexpress link, the photos on aliexpress are mixed some are the old model some are the new. When I ordered the new photoes weren't online so when I received the new model i was surprised, the price is also a bit more than the listed priced at the time i bought it.

The freewheeling crank is not made with a bicycle freewheel but I'm sure it doesn't contain a one way bearing, it's definitely a freewheel because it clicks.

The chain is tensioned with a derailleur jockey like the old model on the image the chain seem tensioned but it's only an optic effect.

I taped my old 48v 25a in fine on controller and my konion battery on the bike to try that and I must say the power is brutal.
The bike tries to wheelie even on the hardest gear from a dead stop.
I'm having some isuess with the chain tensioner (is really bad) but I hope to solve them tomorrow if i have the time to go shopping at the hardware store.

The three speed shifter works really well even if is not super fast shifting, I didn't need to add a spacer between the derailleur and the hanger as suggested because my hanger is befieer and larger than a standard one.

I'll probably swap the smallest cog with a 13t or 14t because the brief test i had demonstrated that that this kit as enought torque and a higher top speed is never a bad idea..

I'll upload some photos tomorrow (i hope).

 

[sascha2770]

Got a question on your 7-speed cassette.
You are using those 3-speed triggers to move you derailleur, but you can't control which sprocket it will choose, right?
I mean, when you push the trigger the derailleur wents by an amount, you can't really control. So you hav to put the sprockets on the right places?
You push, derailleur moves 2 sprockets to the right, again and 2 sprockets to the right, a third time and you are again 2 sprockets to the right.
Do I understand that correctly?

Hope you understand me

Would like to do the same but I am worrying about those 3 speed shifters. I mean if they would take the biggest, a middle one and the smallest it'll be perfect, but what if not?

 

[k1kk0_1t4]

Sorry for the late answer, not exactly: i can choose what cog the derailleur will go.

I'll try to explain: 1 decided the 3 speed i wanted, i dismantled the cassette so i positioned the cog i need int he central position of the cassete to have a nice chainline.

I regulated the shifter to be on position 2 with the middle gear i have choosen.
When i shift to 1 (or 3) the derailleur cage moves more than i need to the gears i wanted to use, so i changed the limit screws in the derailleur with longer ones, and i regulated them on the position of the gears i wanted to use.

The limits screws controls gear 1 and 3, the cable/shifter controls the 2(or middle) one.


If i wasn't clear, please tell me so i can upload photoes or try to find a better explanation.


Sorry but this weekend i hadn't time to work on the bike, hope to do something this week.

 

[k1kk0_1t4]

Sorry for the necro posting but I finished the bike.
Really happy!
Final specs are:
45a controller (some minor mods: changed some cable routing, added CA plug, cutted all the extra cable, high quality thermal paste)
5p16 panasonic pf custom battery (with 50a max BMS)
3 speed cassette (that works well) two real use speeds while the lower one is only for wheelies and for fun
Custom battery bag made of waterproof material
Front and back led light for night riding
Cyclone Isis bb, custom spider.

And most important upgrade... A riding buddy. In two the fun is much much more.

 

[crossbreak]

nice built! But i dont get why u use a 7 speed cassette but only 3 speeds? why not use 7 speed shifter? shifts as desired and has more gears? I used Shimano CS-HG50-7 with 14-32T which really worked well with a similar 74V/30A setup (20s5p Sony 18650 pack). I used the SRAM 7.0 and later the SRAM X4 derailleur with the 7-SRAM 3.0 Comp 7-Speed ESP Twist Shifter (on the left and have the throttle on the right side of the handle bar). The 14-32 cassette shifts really well and fast with the CN-HG70 chain.

BTW the shimano zee DH M640 10speed derailleur with short cage and shadow+ technology is said to work also very well with this SRAM ESP shifter (it has the same 2:1 cable lever). shadow+ (=active chain slack damping) helps a lot if you drive the chain so fast

in my experience, more than 32T does not shift well and less then 13T leads to chain skipping

 

[k1kk0_1t4]

Thank you!

I choose to use 3 speed because I think 7/8/9/10 are more than the speed I need for the power I am pumping in the motor.
My friend is using the stock controller and he need all the speeds off road.
With the 3 speed setup and the 45a i am more then happy with the speed.
Thinking about changing them a bit (to 28 20 15) I tried the 13 and chain skipping is present every acceleration and 14 the chain skipping is still present but a bit less.

By the way I destroyed a 9speed ebike specific chain last week.
Using a 7 speed cheap one now and no problem so far.

 

[crossbreak]

3 speeds is definitely enough if you use that 15-28 spread. u will change chains frequently no matter if you do 15-28 or 14-32. that come with midrive use. 1-2tkm is what most chains take, and this is why i have so much experience

still you can keep it somewhat reliable using a good spread and large gears. using more different gears will make it even more reliable as you wear those less as you use more different ones

keep your good work up! nice to see people do things different with reason

BTW dont use 9 speed chains as they are weaker