mk2 kollmorgan build

hello all
mk1 was a school project, it was a sort of benchmark to test motor and gearing, it didn't have any working pedals but performed quite well (in my opinion) 30-35km/h on flat.
now mk2 is the final design, it changes a lot from mk1 but all i learned from the project is adapted to this bike. It has freewheeling crank and motor, and it's a parallel 2 chain system. the motor is feed with 6s2p4000 of cheap lipos, range seems ok, around 15km with pedaling. the whole bike is fairly ligth, around 16-17kg, thanks to lipo's and light motor mount (compared to mk1's, 1.5kg hugth )
fun bike, need to test it off road

Nice work!

Looks very clean and simple.

Could you please post some details on how you attached your sprockets and freewheels etc. Was there any machining or fabrication involved, or was it mostly off-the-shelf stuff?

One of the things I really like is that with only small changes I could use 2 or all 3 of my Kollmorgan's on the same drive. What are the ratios in the 2 stage gearing, and how does it do on hills?

John

That's very sharp! I like drive side it looks very tidy. Yes, please more details on the rear sprocketing, ratios and battery choice. 8)

Nicely done! I like how the aluminum mounting plate is setup to provide massive cooling for the motor.

I bet she howls with those straight cut gears screaming!

this setup perform quite well on massive hills, climb a 20km/h with ligth to heavy pedaling.

there is absolutely no machining involved in this setup, jigsaw and dremmel are the most sophisticated things I used to get it done.

the motor has a geardown of 1/5.5 on first stage and 1/2 on second stage
motor chain that need a tensioner, it get off on each jump :lol:

I had some god present finding a rear wheel with the fw machined to fit a bmx freewheel,
just before that I was with my dremmel in one hand and the fw in the other one, "I gonna do something wrong" :wink:

need to do a proper battery box, and I will cover some parts of the motor mount with nice brown leather I have in my workshop, word be nice with the brown frame.

the motor mount is made of 2mm aluminum, really strong when bended like I did. it is fitted on the frame using the 4 bottle mounting points, I think it's the weak point in my system.

I'm using stock controller and cheap ebay lipo's, giving me 25km/h at 2/3 power, (I have to sort some potentiometer range problems) witch is about the max speed i feel ok to pedal with my gearing.
I need to find a 3speed hub at a good price

I dont plan using this bike for commuting, maybe go to scool when the weather will be better, we had cold rain this morning and hot sun this afternoon, almost no season here.

get fun

had some test ride today, 10km mostly downhill and flat to meet a friend,
then poping wheelies all around the near-sea bike path's , then 10km way back home.
so total trip length of about 25km with hard pedaling (too short potentiometer wires broke 2km before arriving home, grrr I had some battery left !)
I don't feel comfortable driving my bike at 38kmh (measured top speed of flat) without pedaling, and the bike is noisy and absolutely non legal here (France : 250w, pedaling sensor and no throttle allowed ) max speed so far 49.7 km/h on large downhill (30km/h on the other side!)

I am pretty happy with my lipo's so far, 5 cycles or so on them

next stage will be external controller, more batt's and single stage motor gearing, for simplicity and reliability (extremely fast gear wear, I don't exactly know why, these are massive industrial gears!)

get fun

is the pinion gear hardened steel? i think that will help with the pinion wear.

what pitch are the gears?

gears are 1mm pitch, I think it's called module 1.
on mk1, as you see on the image, only half of the gear was really used, and gears were not lubed...
I corrected these problems an now almost 100% of the gear surface is used to transmit power,
look way better, but won't last more than 500km I think...
I'm really happy with my setup ! there is some things to adapt, to correct, but I have a good basis

have fun (and wear a helmet)

How was the noise with the gears? I tried a ICE engine that used gearing like yours and it was very noisy.

Bubba

bah... yes the setup is very noisy, less than a ice moped, but noisy, I'll do a video to show the noise the setup produce. but gears where the only way to change motor rotation when I'll switch to external controler (next winter) I'll change the gearing to single stage chain

You can open them up and swap 2 of the phase wires and 2 of the hall sensor wires to reverse the rotation. There are threads in the forum on exactly how to do that. Some guys also run them with exterior controllers successfully at up to 48V for a lot more power than stock.

John

Hi,

bzhwindtalker said:

bah... yes the setup is very noisy, less than a ice moped, but noisy, I'll do a video to show the noise the setup produce. but gears where the only way to change motor rotation when I'll switch to external controler (next winter) I'll change the gearing to single stage chain

Click to expand...

A high speed chain (particularly with a small drive sprocket) will tend to be noisy also.

Can you change the rotation electronically?

If so you might want to consider replacing your primary reduction gears with a belt.

OUTCH
I been lightly hit by a car today... I was just turning left, yes a bit fast and I didn't rise my arm to show my way and the car was passing on my left?.. had some chance and I just fallen on the ground without any damage, and none to the bike, ok I've some chance after all... I had a helmet but I had music to a bit high volume, when I go riding I wear my kitesurf helmet with self-implemented waterproof mp3... It's a thing to forget... maybe I'd heard the car without the music!

Do you have turn lights and do you rise your arms when turning?

get fun (and beware of unwatchfull car drivers...)

offroad fun this morning, I will post the vid later
the bike as is now

I was going to by some steel mod 1 gears for a similar project but was told by a shop worker that they should be submersed in oil, it may be similar for yours.

it may be worth finding out.

human

Hi,

MitchJi said:

Hi,

bzhwindtalker said:

bah... yes the setup is very noisy, less than a ice moped, but noisy, I'll do a video to show the noise the setup produce. but gears where the only way to change motor rotation when I'll switch to external controler (next winter) I'll change the gearing to single stage chain

Click to expand...

A high speed chain (particularly with a small drive sprocket) will tend to be noisy also.

Can you change the rotation electronically?

If so you might want to consider replacing your primary reduction gears with a belt.

Click to expand...

You could swap the motor 180 degrees, make the first stage belt on the left side, then use a jackshaft for a chain driven second stage.

when I'll go back to school ( next week ) i'll ask my professors if I can get a big alloy belt pulley machined by the mecanical section ... free! If it's ok I'll use a single stage belt geardown and just put a second bmx fw on the rear, then change motor rotation electronicaly ( and maybe try a a delta/wye switching for better top speed )
I dont need a big pulley, as my total reduction of 1/10 give me 35kmh top speed and good low end torque
so a 20mm puley driving a 200mm rear will be nice

[youtube]SMxX8Lgx-r8[/youtube]

hie all
I had a bit of testing with a belt system, actually a wash-machine belt^^
like mitch said, left side drive is really simple, using existing disc brake mounts.
no motor fw, but it's ok, I rode the bike in this setup (unusable motor due of belt slippage and too low geardown, 1/4) the motor does not produce high cogging torque or electrical breaking, and no motor fw simplifies a lot the system

I draw my pulley and will ask my mechanical teacher if It's ok to do this at school.
It's 150mm and 20mm wide, but maybe I draw it a bit thick and heavy...no tooths, but with proper belt tension I found them unnecessary (?)
with a small scooter pulley, I'll get 1/10-1/15 geardown, 30 to 35km/h's full speed, an SILENT ride trough the woods


yes i just forgot, were is the cheaper place to buy long htd belt's and scooter pulleys?




get fun

bzhwindtalker said:

OUTCH
I been lightly hit by a car today... I was just turning left, yes a bit fast and I didn't rise my arm to show my way and the car was passing on my left?.. had some chance and I just fallen on the ground without any damage, and none to the bike, ok I've some chance after all... I had a helmet but I had music to a bit high volume, when I go riding I wear my kitesurf helmet with self-implemented waterproof mp3... It's a thing to forget... maybe I'd heard the car without the music!

Do you have turn lights and do you rise your arms when turning?

get fun (and beware of unwatchfull car drivers...)

Click to expand...

There's a reason why I don't listen to music while commuting and why my bike has satisfyingly humongous mirrors. I also tend to use turn signals as I think it's pretty critical to be used. Considering how pissy I am when car drivers do not use turn signals when their turning would intersect with my path, I'd be a hypocrite if I didn't. And, no, I don't have turn signals(As in lights) as I have a feeling people on the trails might get suspicious if they saw a bike with a huge hub and turn lights in the back(The trails around here don't allow motorized transportation, though I periodically use my scooter on them.).

Hi,

Glad you are not hurt. Please be careful!

Mitch said:

You could swap the motor 180 degrees, make the first stage belt on the left side, then use a jackshaft for a chain driven second stage.

Click to expand...

bzhwindtalker said:

hie all
I had a bit of testing with a belt system, actually a wash-machine belt^^

like mitch said, left side drive is really simple, using existing disc brake mounts.
no motor fw, but it's ok

Click to expand...

I meant :lol: that you can:
1. Flip the motor so that the drive is on the left
2. First Stage Belt Reduction to a jackshaft (input is belt on the left)
3. Use the output of the Jackshaft on the right side to drive through the right side (I'd choose the Crank to use the gears).

bzhwindtalker said:

yes i just forgot, were is the cheaper place to buy long htd belt's and scooter pulleys?

Click to expand...

I think a lot of people use sdp-si:
http://sdp-si.com/