Help needed: Converting Lashout/Rayos to Left-hand mid drive

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DrInnovation   100 W

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Location: Colorado Springs, CO

Help needed: Converting Lashout/Rayos to Left-hand mid drive

Post by DrInnovation » Mar 23 2016 9:14pm

I've decided I'm tired of trying to keep the Lashout Planetary gear from being destroyed. I'm guessing its the torque from my hills, maybe combined with all all the bumps/potholes (I do ride it off road and over lots of stuff).

So my idea (based on lots of reading here) is to reduce torque convert it to a mid-drive using a tandem crank (similar to https://endless-sphere.com/forums/viewt ... =28&t=8665) except that I'll keep my motor mounted in the back on the left (where it already is mounted). I'll have to match my existing crank arm.. but do I need a longer bottom spindle or bracket?

Also I need to make it free wheeling. for which I see 3 choices..
1) Find a way to mount a sufficiently large #25 chain sprocket on the left hand crank and keeping the existing planetary/sprocket set.

2) replacing the older lashout plenary motor final gear (#25 chain) head with something that uses a standard chain. So I'd need something that fits on the 12mm roller bearing(or 18mm roller not sure which I have).

3) Find a way to directly attach to the Mac motor (3/8 D-spindle) with some type of free wheeling sprocket that can be used with a standard chaing and crank arm. This will need to be a small sprocket so I can keep the gear ratio reasonable. This is removing the plenary gear (a 4.8:1 reduction).. but since its going mid drive I think the gear ratio will work. Any ideas where I might find that type of freewheeling sprocket?

My real preference is #3.. and be done with the washout custom planetary gear. Any help appreciated.

Finally advice on gear ratios would be appreciated.
Owner of a Crystalyte 4012/409 with 10aH 16s Headway on a old huffy frame. Its not fast but it climbs my daily commute up 8% and 10% grades nicely. Washout frame with a "e-bike" front-drive hub with a home-built 18650-based 20ah-36v. My bigger "E-ride" is a chevy volt.

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DrInnovation   100 W

100 W
Posts: 110
Joined: Jul 28 2014 7:27pm
Location: Colorado Springs, CO

Re: Help needed: Converting Lashout/Rayos to Left-hand mid d

Post by DrInnovation » Mar 26 2016 5:42pm

Following up on my own post. No I now I'm not sure I can do any of these (definitely not #1 or #2), as I did the math for the ratio'sI cannot get it to work out because the lashout 7speed has a larger sprocket on the crank (42) than any of the rear sprockets (largest is 27), so the end-to-end ratio will be decreased, not increased, by going through the mid drive approach. Thus I expect it would put more torque on the motor not less. Is my analysis correct?

By maybe I'm asking the wrong question.. could the MAC motor provide enough torque even at a lower gear ratio, which might work for #3 My problem is that it is destroying the planetary gear, not that the MAC is overheating and cutting out. Any easy way to tell what torque it can handle?

If I put an 11tooth sprocket directly on the motor and a 80 on the wheel, it would drop from 13:1 to 7.2 to 1.. but would git rid of the planetary gearing that is give me the problem. But could motor provide enough torque or would I fry it? Could the #25 chain handle that torque?
Owner of a Crystalyte 4012/409 with 10aH 16s Headway on a old huffy frame. Its not fast but it climbs my daily commute up 8% and 10% grades nicely. Washout frame with a "e-bike" front-drive hub with a home-built 18650-based 20ah-36v. My bigger "E-ride" is a chevy volt.

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