GNG 450w mid on a 75mm BB?

[t0me]

I really hope I can make it work.
Has anyone fitted one to a 75mm (might be 73mm?) wide BB?

Came across a sweet frame on Gumtree (I guess the Aussie equivalent of Craigs list?).

A Schwinn Straight 6. Never been built. Its a thing of beauty and my 48V 15AH battery will fit nicely in that frame triangle.

Has anyone modified the GNG brackets to work on a 75mm BB? Any tips?
I'm running the Cyclone 148mm ISIS 444432T chainwheel and crank set. I don't mind if I have to lose the 32. I don't use it anyway.

I'll probably start on it tomorrow afternoon (will be swapping the parts over from the current bike). I'll start on the BB first as I'm hoping that's the only real problem to solve.

 

[christerljung]

Thats what iv'e done on the Scott gambler. You can cut the bb-bracket in two halves.
The diffence is that im not using any pedals.

 

[christerljung]

If youre lucky you got 73mm. Then it's just to file it down to 68mm and Everything will fit.

 

[t0me]

Here's hoping

Did you have any problems with the chainring hitting the swingarm on your frame?

 

[Electric Junk]

I have a 100mm BB i want to fit the gng on. Cutting it in half looks pretty easy

 

[christerljung]

I have a 100mm BB i want to fit the gng on. Cutting it in half looks pretty easy

You will need to replace the BB-spindle with a wider one. Maybe a BMX-shaft or something from cyclone.tw could fit.
Also the jackshaft will need to be replaced. The setup in the pic above is pedal-free and without a jackshaft.

 

[t0me]

Well it definitely worked. Yes, needed to grind a few mm away from the BB. The Cyclone crankset etc was fine for up to 73mm if you didn't add in the motor brackets, so took some off the BB to give it a few teeth to bite on

Spent a good half an hour frustratedly trying to screw the crank shaft in the wrong way around thinking I'd stuffed the threads. Went on nice an easy once I had it the right way around (am I the only muppet who's done that?).

Had to space the chainrings out a little as they hit the rear swingarm.
The battery tray I'd made for a previous frame only needed a little modding to fit. The motor brackets, just split them down the centre, fitted them, and added some weld to join them back together (probably didn't need that but couldn't hurt).

Other than that, it all went together nicely. Just need to find some wide black tape to make the battery look a little better, and tidy up/hide the wiring a little and its done (for now no doubt).
Will probably get a little test ride in tomorrow.
Hoping the seat position is fine cos I'll never get that seat post back out after having to pound it in with a gimpie

 

[t0me]

Runs well. Very very plush rear suspension.

 

[mwkeefer]

That is actually quite nice, full sus - frame mounted battery (it looks) - proper alignment, chain primary reduction.

And on that bike, very sweet!

I may be interested in duplicating your setup with my GNGv1 drive spare (right now), I'd like something I can run off-road.

-Mike

 

[t0me]

With the battery there (yes in the frame - on a cradle that's attached via the 2 bottle holder captive nuts and a bolt around the upright on the frame) it becomes much harder to get the front end up. Worth considering.
I'll have to keep an eye out for a set of longer travel forks. With that plush rear end having 6" of travel it really show up the Suntour XCR's (the bike's a hodge podge of bits from all over the place). With longer forks it may make it a bit easier to wheelie again

The chain primary mod is one of the best mods I've done to it IMO.