damn freewheel broke!

[dirty_d]

i probaly havent even gotten a mile on my ebike and the freewheel mechanism already broke, i didnt care how or why it broke so i just took the wheel off and tried to weld it into a fixed sprocket. after that the welds broke since i just welded the inner and outer pieces to that thin metal cover thing that holds all the parts on the inside, then i tried to take the whole thing off so i can weld it on the thick metal on the back, no luck, i got a good grip on it with some channel locks and it wouldnt budge at all. i suppose ill have to weld something long to it to get some leverage. i just keep having problem after problem dont i.

 

[Lowell]

What kind of freewheel is it?

 

[dirty_d]

http://tncscooters.com/product.php?sku=103210, this is what i bought but its not the same one as in the picture i cant remember the name stamped on it.

 

[safe]

At the beginning of my project after about 100 miles I also lost a freewheel. After upgrading to a Shimano component it's been trouble free ever since. Sometimes the quality of the products we use is not that good. For example, I bought these really cheap bikes as source material to build my projects from a Toys R Us store. (seriously) My rear brake lever has been used for the 1800 miles or so I've been riding and it just decided to not completely fail, but to develop enough slop in it to need to be swapped out. (I bought three identical bikes, so I've got parts to spare)

Things break...

Your 1200 Watt motor running at it's full 48 volts is a lot of power. Normal humans can only produce a constant power of 400 watts continuously. So think of it this way... you are placing the power of three people on all your drivetrain components.

Maybe now you can buy that 114 tooth go cart sprocket and attach it to a disc brake mount on a front or rear hub. Then make the whole thing direct drive. For the sake of reliability you need to build things stronger and use less complexity.

 

[dirty_d]

well i welded the freewheel to the other side of the hub and everything is working fine now, i cant really tell a difference with or without the freewheel the motor doesnt really slow the bike down hardly at all while coasting, i put the old bike chain multispeed freewheel back on so now ill have pedal power too, i just need a masterlink for the chain that came with the bike. also ive fixed the chain slippage problem, i just didnt torque down the bolts enough on my motor mount bar things that go to the frame and the motor was pulling it forward and allowing the chain to get lose. i rode it around for a couple hours, i was surprised how long the batteries lasted although i wasnt full power all the time and towards the end i did notice a drop in power, im not sure if im running the batteries too low or not i want them to last a while. as for the direct drive deal, this setup is working fine for now and im not going to spend more money until something breaks, also those 114 tooth racing sprockets are aluminum, i think those will wear out extremely fast. heres the bike as it is now, its a little fuzzy because its dark out.

 

[safe]

i was surprised how long the batteries lasted although i wasnt full power all the time and towards the end i did notice a drop in power, im not sure if im running the batteries too low or not i want them to last a while. as for the direct drive deal, this setup is working fine for now and im not going to spend more money until something breaks, also those 114 tooth racing sprockets are aluminum, i think those will wear out extremely fast.

SLA (Sealed Lead Acid) batteries begin to sag the moment you start riding. So they sort of slowly lose power as you go. That's normal. That's why the other battery chemistries are more attractive since they tend to remain flat (same power) from beginning to end. On my bike I just don't even want to ride the bike after the batteries are half empty because the power loss makes it kind of boring. It's kind of like a built in gas guage... you know exactly how low the battery is by how much sag you are getting.

Aluminum has been used for sprockets forever. They should last longer than the chain which tends to wear out the fastest. Plus, the #35 chain is larger than the #25 chains that scooters use and so you get much more mileage out of them.

But I understand money... I'm cheap too and won't buy anything until I'm convinced that what I'm doing is hopeless. Your system will work, but we'll see how things are working after about 1000 miles which is where the long term durability of an idea really begins to get tested. Of course by then you'll probably have a new bike project in the works. (I'm onto project #2 myself... once you get hooked on this stuff it's hard to quit)

 

[Lowell]

Your project looks good so far. Batteries are pretty much ideally located on the frame which is nice to see.

How stiff is the rear motor mount bracket? It looks like it could use a triangulation rode between opposite corners?

 

[dirty_d]

i was surprised to find how stiff it actually is, i figured there would be a lot of flex but there isnt any at all its very rigid. youre right i could use another support, if the bolts arent torqued down tight the motor will pull the whole thing forward a little and i lose chain tension.

 

[Beagle123]

i was surprised to find how stiff it actually is, i figured there would be a lot of flex but there isnt any at all its very rigid. youre right i could use another support, if the bolts arent torqued down tight the motor will pull the whole thing forward a little and i lose chain tension.

I had a situation with my bike where the chain was loosening, and derailing sometimes. I finally figured out that the motor mounts had too much flex in them. The motor I bought came with rubber mounts that I guess were used to dampen the vibration. However, the power of the chain pulling on the motor was smashing the rubber, thus changing the angle of the motor.

When I took off the rubber mounts, everything was locked into place perfectly.

I think its best to have no flex in the motor or sprocket.

 

[TylerDurden]

i was surprised to find how stiff it actually is, i figured there would be a lot of flex but there isnt any at all its very rigid. youre right i could use another support, if the bolts arent torqued down tight the motor will pull the whole thing forward a little and i lose chain tension.

I agree with Lowell. If the frame can move fore/aft or left/right, your chain tension may vary.

You might add a threaded brace connecting the motor frame to the seatpost or brake-mount, so you can adjust the fore/aft motor position.

Likewise, the legs of the mount might be stabilized by adding diagonal bracing or blocking, to minimize side-to-side movement.