GNG Crank-drive kit

[amigafan2003]

Yup okay, we may be departing from conventional norms of the pedelec comfort zone but this isn't a moped

According to some on here if you have 251watts or more and the bike assists above 17.05mph then it's a moped!

Common sense has no place in those debates!

 

[mike killay]

I don't know if I am looking at it correctly, but it seems that the chain barely contacts the chain ring?
Also, does the engine heat up under full power?
Mike.

 

[eddieo]

Are there any cyclists left on this forum......

 

[Deleted member 4366]

Hmm, thinking 44.4v 12s lipo and programmable controller to bring the amps back down.

What's the top speed like? Anything more than about 24mph on my mtb and I could keep up pedaling.

Top speed is a bit difficult to assess because it uses the gears. Going downhill at 30 mph, there was significant acceleration when opening the throttle. 40 mph or more should be possible on a long dwn-hill Don't forget, whatever power it has will be added to whatever you already have, because it's not limited on speed like a hub-motor. I would estimate top speed on the flat with my bulk on it not pedalling at about 25 mph.

 

[Old_Dave]

I don't know if I am looking at it correctly, but it seems that the chain barely contacts the chain ring?

Its two chains onto 2 separate 'rings'

 

[Deleted member 4366]

I don't know if I am looking at it correctly, but it seems that the chain barely contacts the chain ring?
Also, does the engine heat up under full power?
Mike.

Not sure what youmean. All chains/belts are properly engaged with their sprockets.

After about 15 minutes of mainly full power, the motor was hardly warm. You could just about feel that it had been used. Don't forget, I was running it at 48v and it's designed for 54v.

 

[KirstinS]

Wow this is really interesting stuff. And sounds like a 36v battery would provide a fair bit of oomph

Meaning most wbikers folk already have a 36v battery so if they wanted an off road , south/north downs eating beast of a hardtail it'll only cost 270 quid

What a total bargain !

 

[Deleted member 4366]

36v is more than enough for it, but your average 10aH won't be able to give enough current. You need 22 amps continuous, which means 20aH, A123, Headway, or Lipos. I think Lipos are probably best. I tried a 10aH headway battery, but the BMS kept cutting off. It must have been set to 15amps because there was no sag showing on the throttle LEDs.- never went below amber. The current requirements are different to a hub-motor because you can use the gears to get the motor into a higher torque (current) zone and so it'll always be drawing a lot from the battery unlike a hub motor whos current decreases with speed. Therefore a strong battery is a prerequisite.

 

[catsnapper]

Hi Dave,

The kit specifies it's only for bikes with 68mm BBs. Does it look as if it's possible to do any mods to make it useable with a 73mm BB? Apart from reducing the BB shell to 68mm and recutting the threads in it...

Alan

 

[Deleted member 4366]

Hi Dave,

The kit specifies its only for bikes with 68mm BBs, does it look as if it's possible to do any mods to make it useable with a 73mm BB? Apart from reducing the BB shell to 68mm and recutting the threads in it...

Alan

No chance I'm afraid Alan. The main bracket is fairly rigid nld fits exactly over the BB. I screwed in the free end of the BB first so that I could unscrew it into position because it's not easy to hold it all up and start the BB threads without cross-threading. When fully in, the BB was still sticking out about .5mm and it was a struggle to get the main bracket over it. You could of couse get your angle grinder out and thin down your frame 2.5mm each side.

 

[catsnapper]

Hi Dave,

Thanks for letting me know. I'll stick to using another frame with a 68mm BB, makes life simpler.

Alan

 

[vhfman]

I have just uploaded 4 YT videos all in 720p HD. The first one is a quick look round the test set up for my GNG Mid Drive. It still needs the controller and wiring repositioning and boxing up.

[video=youtube;vdHFhpNv5mU]http://www.youtube.com/watch?v=vdHFhpNv5mU&feature=player_detailpage[/video]

The controller I am using is not the 48V supplied with the kit, but a 36V CON91 from GreenBikeKit, I modified it with a direct connection for the Cycle Analyst. The battery is 12s A123 7Ah.

I have replaced the 38T chainring that came on the kit with a 44T, and have an 18T sprocket on the Nuvinc N360 Hub. But I think I may try a 16T as I feel that with the motor and pedal power the gearing is too low even on steep uphill climbs. The Nuvinci hub is smooth but not easy to vary up under high load. It certainly is easy to use and less chance of braking chains compared with clunky derailleurs.
The bike is a much modified Python Venom 180 DD complete with new forks, rear shock, wheels, Avid BB7 brakes and a KS adjustable seatpost. In fact it’s almost just the frame that is original.
The bike is a bit weighty with the motor, N360 and all the other accessories, at 25Kg. It does give a smooth ride even on the muddy bumpy tracks. I will however have to put some better tyres on as the back wheel has skidded sideways under hard braking on more than one occasion.

In the second video I have made a comparison with one of my other bikes, a light weight Full Suspension setup at 20Kg, powered by the BPM Hub.

I had to put the url link here as only 1 embeded video per post

Comparison rides - YouTube

I used the same camera, a Veho muvi HD10 at 720p the camera is in the waterproof case attached to the frames of each bike which seems to amplify the sound of the motors.
This 3rd video is an attempt to show the noise level of the motor with the camera off the bike. Unfortunately I picked a spot next to a streamlet which I barely noticed when I set up the camera. Also I think I moved the camera after I framed the shot so the track is a bit off to the side. But it still demonstrates, that what on the bike, appears to be a swarm of angry bees is almost inaudible with the camera a few feet away.

GNG ride past cut - YouTube

This last video was taken after riding a mile or so, and shows the reason for the siren I referred to in the previous video.

crash - YouTube

Chris

 

[amigafan2003]

Thanks VHF man - I think you've made my mind up - deffinately going to get a CNG kit for my full sus - seems to be ticking all the boxes. Thanks for the upload!