is the motor I have comon in other kits?

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Jun 22, 2020
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Hi ,

I have a mid drive Kit installed, on a bike with an xtracycle free radical extension. 36 volts 350w. It works very well for my needs, until it doesn't. Today I rode 15 miles into the city with no issues, but on the way back the short chain came off about 20 times before i gave up and simply pedaled home without it.

I sometimes am able to fix it by bending and aligning the tension bar, but sometimes not. I work in film production and carry allot of equipment on it, so I need something more reliable as I cannot arrive late.

My question is, is there a better designed kit, that I could use with the motor I have?
https://www.gngebike.com/48v500w-2015-belt

thanks
 
I work in television, never close enough to carry equipment on a bike. But equipment for me might mean a RED Scarlett W, lights, etc. 350W????

Might the strain of some serious weight have been too much for the chain? Have you pulled it off separate to see if it is still straight, flat, etc.? Might the idler gear be wobbly?

From the pics I see I don't know what the tension bar is, I don't think I see anything that should be bending. I think if you can bend something it's already too late for that part.
 
Kein Kochendes said:
I have a mid drive Kit installed, on a bike with an xtracycle free radical extension. 36 volts 350w. It works very well for my needs, until it doesn't. Today I rode 15 miles into the city with no issues, but on the way back the short chain came off about 20 times before i gave up and simply pedaled home without it.
Is the short chain between motor and cranks, or is it between motor and wheel?

If any of the chainrings have any lateral play in them, or they are worn (or the chain is), derailment is easier, and takes less lateral twist/bounce/etc to cause it.


Is it possible the bike frame itself is twisting under the torque of the motor and causing the chain derailment? (it's not uncommon with various types of middrives). Especially if the chainline crosses the "border" between main bike frame and extension--there could be twist (even just a tiny bit!) between them.

That particular problem is why I started using hubmotors on my long cargo bike CrazyBike2, because I got tired of frame twist causing derailment and destruction of parts, and leaving me unable to pedal because it would take out the whole drivetrain sometimes. (but it takes a lot bigger battery, controller, and motor to do the same thing in a hubmotor as with a middrive thru the pedal drivetrain).


Also, if you can bend a bracket by hand that is needed to resist motor torque...you need a better bracket. ;)
 
If the sprockets don't lie in the same plane, the chain will tend to come off. The best thing you can do is to adjust everything so the sprockets are parallel and in line with each other.
 
And that the brackets are designed in a way (and are strong enough) to prevent the pulling of the "top" of the chain to allow twisting of things relative to each other that then un-lines-up the sprockets.
 
Thanks for the replies.

I work in television, never close enough to carry equipment on a bike. But equipment for me might mean a RED Scarlett W, lights, etc. 350W????

I get away with it because I do sound and can pack 3 cases on the xtracycle. 15 miles into DC, its a nice ride, and 350W allows me to do some of the work. The DPs I work with certainly could not get there gear on a bike.

From the pics I see I don't know what the tension bar is,
What I meant was the spring loaded lever with the red sprocket that puts tension on the chain that keeps coming off. I bend it to try to align the red sprocket with the chain ring.

Is the short chain between motor and cranks, or is it between motor and wheel?
The shorter chain between the motor and the crank.

Is it possible the bike frame itself is twisting under the torque of the motor and causing the chain derailment?
I would suspect the mounting system would give in before the frame. Ive sometimes had to tighten the motor on the frame as it has come loose, causing misalignment. The motor is secured to the down tube by a simple bracket.

If the sprockets don't lie in the same plane, the chain will tend to come off. The best thing you can do is to adjust everything so the sprockets are parallel and in line with each other.

Thats why Id like to look into better quality mounting parts, like the ones I see in photos of the stokemonkey for example. My original question was if anyone is aware of a mounting system compatible with the motor I already have, which works well.




Thanks
 
I don't know of one that's directly compatible. It's very likely that you'd have to make some parts of your own to do it. Or at least draw them up in a CAD program (relatively simple, once past the learning curve) and have them cut or cnc'd for you (there's lots of places around the intarwebs that do this with a file you send them, or evne just upload directly to their site for a quote).

I know there are some threads around the forum for GNG that include various custom solutions people have made over the years; I don't know if any are useful. This is a list of just threads with GNG in the title; I have not read them (at least, not in years) so I don't know which, if any, would help; there are mulitple versions of the GNG kits.... :oops: There are also other posts in other places about the GNG.
https://endless-sphere.com/forums/search.php?keywords=gng&terms=all&author=&sc=1&sf=titleonly&sr=topics&sk=t&sd=d&st=0&ch=300&t=0&submit=Search

At one time, Lightning Rod here on ES made brackets for at least one version of GNG, but that was a long time ago. If you can find one used that fits yours...or find some of the build pics using them around here and make your own version (or see if LR will make one for you)
 
I was able to fix the previous issue by changing out the the chainrings and freewheel crank with much nicer ones from Sick bike parts when they were open.

My issue now is that the 20mm reduction belts keep snapping. I tried using a higher quality Gates belts, but they come only in 25mm, so I had to trim it, and it didnt last long.
Changing belts is easy, but I hate generating even more waste.

Any tips on how to change the reduction side of this kit to either a chain or 25mm belt, I would be very grateful.
By looking at the kit I have, I cant yet decipher how to remove the belt sprockets to see what parts I could replace with. There is a bolt on the big one. The small one I haven't a clue where to start.

I could just sell this kit and get a better one, but honestly I wouldn't feel right selling something that is continuously failing.

Thanks
 

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Kein Kochendes said:
My issue now is that the 20mm reduction belts keep snapping. I tried using a higher quality Gates belts, but they come only in 25mm, so I had to trim it, and it didnt last long.
Changing belts is easy, but I hate generating even more waste.
Hmmm, they shouldn't be snapping so often like that. Aren't those belts basically similar to timing belts used in many cars? Changeout schedule varies, but figure 65,000 miles average?

Unless you are tensioning it too tight, or foreign objects (gravel?) are getting pulled into between the cog and the belt. That'll snap it for sure!

Try tensioning it only tight enough so you can easily twist the belt (at the slack area between the two cogs) 45deg, using your fingers and thumb.
 
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