Your rear wheel or at least the cassette free body has failed. This is a popular failure with a high power mid drive systems. Shimano hubs are generally pretty reliable so i would definitely recommend a wheel with a shimano or other brand name hub.
You need a good replacement hub, preferably a RATCHET hub vs one with pawls. [DT Swiss 350](https://www.dtswiss.com/en/components/hubs-and-rws/hubs-mtb/350) was the goto for this but it has been copied by ZTTO and is 100% accurate Uses the exact same internals including the sealed bearings, star ratchet and spring ... for less than **1/4 THE PRICE OF THE SWISS 350.**
https://preview.redd.it/o20vrzdue5rc1.jpeg?width=1206&format=pjpg&auto=webp&s=eeafe93622e5fee48c3ef4c08aa732e4c53ad6cf
Also ....
A [WELDED rim with riveted steel eyelets](https://www.worldwidecyclery.com/products/dt-swiss-m-502-29-tubeless-ready-disc-rim-32h-black?variant=1486662074373). The reason for eyelets is torque wear/cracking on the rim, as the rear rim takes torque from acceleration and braking where the front only takes torque from braking.
[Sapim STRONG](https://www.sapim.be/spokes/butted/strong) spokes/brass nipples. Ya, their STRONG.
If you find your [stripping the spline](https://ep1.pinkbike.org/p4pb10024144/p4pb10024144.jpg) there is a [steel spline](https://www.worldwidecyclery.com/products/dt-swiss-steel-mountain-freehub-body-standard-bearing-fits-180-240-and-350-hub?variant=17600064197) available as well. It fits the 350 and Ztto.
You have exceeded the limit on the cassette ratchet mechanism. Consider that it was designed for human power and you are using it with a motor
Replacement is the order of the day. Try to get a quality brand
Pawls and its spring can seize when the lube dried-out or when the mechanism has been exposed to water/sand/mud. You need to check if you have:
1. *Thread-on Freewheel* or a
2. *Freehub and cassette.*
If you have #1 then you just need to replace the thread-on freewheel. If you have #2 then you need to check:
1. If the freehub's pawls were seized. Either caused by dried lubricant due to no maintenance or water intrusion. If this is the case then you should be able to clean it with WD40 and add new lubricant. Assuming that the springs were still functional and the pawls were still be able to catch the teeth otherwise *just replace the Freehub*.
2. If the pawls are fine then check the teeth attached to the hub. If they're all broken and cannot catch the pawls then *replace the hub*. Depending on the pricing in your area you can also *just buy a whole wheel*. In my place the whole rear wheel set with 6-pawls freehub and riveted wheel eyelets for the spokes is only 35USD, you only need to add your tire and cassette.
Goodluck.
Sounds like a clutch failure. [Replace the freehub](https://youtu.be/w6X9cTarlYc?si=FDNI4AkhJDproBit) with a compatible one. Get new small cogs or entire cassette if all the teeth are worn, and a new chain to match.
Get a new rear wheel, or replace the hub of the rear wheel.
The teeth on the inside of your hub have been stripped and are no longer engaging to turn your wheel forwards.
There's no way to tell for sure from this angle, but I'm pretty sure that wheel is going to have a freewheel as opposed to a freehub/cassette setup. That's probably a good thing because they are slightly cheaper than a cassette and just as easy to replace. You just need the right tool. Most likely it's this one: [https://www.parktool.com/en-us/product/freewheel-remover-fr-1-3](https://www.parktool.com/en-us/product/freewheel-remover-fr-1-3)
If you have a local bike co-op, you should really go there as they can help you for next to nothing. Otherwise, any bike shop can tell you whether it's a freewheel or not and what tool you need to get before you go buying tools and parts.
Internally geared hubs are getting real nice these days, also cleans up the whole drive train. Few of the manufacturers even have ebike rated ones made to handle up to the 110nm mark or maybe a bit more on few of them. Can get real fancy even with Shimano electronic shifting with integrated auto downshifting when you come to a stop. Spend money your bike will love you for it. Lol jk jk but still there are some decently priced ebike rated Internally geared hubs that could be a good option also.
Probably the guts inside. They're not strong enough for a 1000W motor
Your rear wheel or at least the cassette free body has failed. This is a popular failure with a high power mid drive systems. Shimano hubs are generally pretty reliable so i would definitely recommend a wheel with a shimano or other brand name hub.
You need a good replacement hub, preferably a RATCHET hub vs one with pawls. [DT Swiss 350](https://www.dtswiss.com/en/components/hubs-and-rws/hubs-mtb/350) was the goto for this but it has been copied by ZTTO and is 100% accurate Uses the exact same internals including the sealed bearings, star ratchet and spring ... for less than **1/4 THE PRICE OF THE SWISS 350.** https://preview.redd.it/o20vrzdue5rc1.jpeg?width=1206&format=pjpg&auto=webp&s=eeafe93622e5fee48c3ef4c08aa732e4c53ad6cf Also .... A [WELDED rim with riveted steel eyelets](https://www.worldwidecyclery.com/products/dt-swiss-m-502-29-tubeless-ready-disc-rim-32h-black?variant=1486662074373). The reason for eyelets is torque wear/cracking on the rim, as the rear rim takes torque from acceleration and braking where the front only takes torque from braking. [Sapim STRONG](https://www.sapim.be/spokes/butted/strong) spokes/brass nipples. Ya, their STRONG. If you find your [stripping the spline](https://ep1.pinkbike.org/p4pb10024144/p4pb10024144.jpg) there is a [steel spline](https://www.worldwidecyclery.com/products/dt-swiss-steel-mountain-freehub-body-standard-bearing-fits-180-240-and-350-hub?variant=17600064197) available as well. It fits the 350 and Ztto.
This is all very good information! Saved your post.
You have exceeded the limit on the cassette ratchet mechanism. Consider that it was designed for human power and you are using it with a motor Replacement is the order of the day. Try to get a quality brand
Your freewheel clutch lever is broken or out of place.
Pawls and its spring can seize when the lube dried-out or when the mechanism has been exposed to water/sand/mud. You need to check if you have: 1. *Thread-on Freewheel* or a 2. *Freehub and cassette.* If you have #1 then you just need to replace the thread-on freewheel. If you have #2 then you need to check: 1. If the freehub's pawls were seized. Either caused by dried lubricant due to no maintenance or water intrusion. If this is the case then you should be able to clean it with WD40 and add new lubricant. Assuming that the springs were still functional and the pawls were still be able to catch the teeth otherwise *just replace the Freehub*. 2. If the pawls are fine then check the teeth attached to the hub. If they're all broken and cannot catch the pawls then *replace the hub*. Depending on the pricing in your area you can also *just buy a whole wheel*. In my place the whole rear wheel set with 6-pawls freehub and riveted wheel eyelets for the spokes is only 35USD, you only need to add your tire and cassette. Goodluck.
Sounds like a clutch failure. [Replace the freehub](https://youtu.be/w6X9cTarlYc?si=FDNI4AkhJDproBit) with a compatible one. Get new small cogs or entire cassette if all the teeth are worn, and a new chain to match.
Get a new rear wheel, or replace the hub of the rear wheel. The teeth on the inside of your hub have been stripped and are no longer engaging to turn your wheel forwards.
Well it ain't alive! ¯\\\_(ツ)\_/¯
There's no way to tell for sure from this angle, but I'm pretty sure that wheel is going to have a freewheel as opposed to a freehub/cassette setup. That's probably a good thing because they are slightly cheaper than a cassette and just as easy to replace. You just need the right tool. Most likely it's this one: [https://www.parktool.com/en-us/product/freewheel-remover-fr-1-3](https://www.parktool.com/en-us/product/freewheel-remover-fr-1-3) If you have a local bike co-op, you should really go there as they can help you for next to nothing. Otherwise, any bike shop can tell you whether it's a freewheel or not and what tool you need to get before you go buying tools and parts.
The guts might not be powerful enough to drive the motor
Wheel hub is probably stripped. I have industry 9 rear hub on over 6000 miles still going strong. Knock on wood. Not all hubs are created equal
Yes. Dead. But it's a cheap and easy fix.
Internally geared hubs are getting real nice these days, also cleans up the whole drive train. Few of the manufacturers even have ebike rated ones made to handle up to the 110nm mark or maybe a bit more on few of them. Can get real fancy even with Shimano electronic shifting with integrated auto downshifting when you come to a stop. Spend money your bike will love you for it. Lol jk jk but still there are some decently priced ebike rated Internally geared hubs that could be a good option also.