eZips - 15T drive sprocket

Oh Crap!

Just gittin' my 12T mod ready and I found a 15T version of the 12T motor sprocket.
From 24V, if the 12T motor - 16T freewheel allows some assist to 30mph, the 15T motor sprocket will provide assist to near 40 mph!

Possibly wasted potential, since pedal speed limits assist to ~30mph (w/DNP 11-32T 7spd freewheel).

However ... I am rebuilding my 2008 Li-ion packs. Careful measurements will allow me to shoehorn 8 x 12 18650 2600mah cells into an oem eZip pack. I can build 2 6s8P banks or 6s16p = 22.2V 41.6Ah = 932.52Wh.
With the reduced voltage I might need the 16T x 15T gearing to maintain 30 mph.

Cheap enough that I purchased 2, with no positive assurance that it is a proper fit.

Improperly listed as 16T, but is 15T.

I will confirm adaptability as soon as it arrives.

If this mod proves doable, it will be the new budget mod.
$12 includes shipping.

Received sprocket.
Not a 16T, but a 15T ... as pictured.

Large enough in diameter that alignment with freewheel must be fairly precise.

The good news ...
Fits snugly on eZip GR shaft.

Of course, you will also have to lengthen the chain.
click on picture

This mod by itself will increase (some) assist, from 18 to 30+mph - actual speed from 16mph to mid twenties?

As a solitary mod, might require no re-alignment.
Now that I consider it, might be able to do the mod without any disassembly of the rear.
Loosen motor bracket,
"Break" chain,
Mod "key" (see 12T upgrade),
Install 15T,
Replace chain with longer, and repair link,
retighten motor bracket, done.

Interested in seeing the results of this. Is this easier to perform than the 16t mod?

matt912836 said:

Interested in seeing the results of this. Is this easier to perform than the 16t mod?

Click to expand...

Easier? ... cheaper!
Mod the "key" and lengthen the chain.
Downside is alignment must be more precise.

Gotta try the 12T first, can't do that till good weather ... maybe another month or 2?
But will have a chain assortment ready. Can probably swap 12T to 15T in 15 minutes.

Problem is got 2 eTrike projects and eZip drivetrain to 700C Haro Express Deluxe in the works too.
In the middle of rebuilding 5 18650 Li-ion packs and additional 26Ah Lipo builds.

So ... jumping around between too many projects, trying to stay enthusiastic and entertained while pulling them all together for Spring.
Oh ... supposed to be working ... also.

Curious did this sprocket worked? I have ezip trailz woman step through and I want too add more power without building a nuclear reactor. So if this is as simple as changing the Sprocket I want to do it...

happycow said:

Curious did this sprocket worked? I have ezip trailz woman step through and I want too add more power without building a nuclear reactor. So if this is as simple as changing the Sprocket I want to do it...

Click to expand...

The 15T mod will increase speed but at a sacrifice to acceleration and hill climbing power.
25mph might be possible, but might require reasonable pedal assist.

The 12T might be better, a 20mph speed, on motor alone.

Drkangel, I think this 13T sprocket will fit without any mods at all. Check it out. It's only $18 shipped.

http://www.gngebike.com/parts

elpq35 said:

Drkangel, I think this 13T sprocket will fit without any mods at all. Check it out. It's only $18 shipped.

http://www.gngebike.com/parts

Click to expand...

Thanks,
looks like good possibility ... ordered one up.
Hate $10 shipping on $8 item, actually no shipping discount on 2, is the annoying part.
Will post review same day received.

Also ordered up 4mm carbide rotary bits & 4mm oval Carbide bitfor sizing out the key slot on the 12 & 15T sprockets.

Progress! Received an email with a series of pictures, showing item being packaged and placed in a postaged, addressed, Honk Kong air mail envelope.

elpq35 said:

Drkangel, I think this 13T sprocket will fit without any mods at all. Check it out. It's only $18 shipped.

http://www.gngebike.com/parts

Click to expand...

Got 1!
10 days shipping.

Good fit, good alignment, just lengthen chain and all set to go!
I just emailed "Jon", requesting a quantity purchase with shipping discount.
Waiting on reply