Stinky Turnigy 80-100 -Nuvinci semi auto

[Burtie]

bURTIE,

How many watts are you putting into the Nuvinci? What kind of speeds are you hitting?

...Could you check the hub temp next time you ride for around 10 miles?

Thanks Drew

Hi drew,
I have temporarily dialed down the power to stop the chain slipping, so it is now only about 2.8kw, and gets to about 32mph max on the flat.
NV hub probably gets about 5 deg C above ambient after 3 or 4 miles.

[drewjet]

Thanks Burtie. I am currious to see how it goes once you get your chain sorted out and put some more power through it.

[lostrack]

Very cool - I'm going through this chain tension issue right now. Alignment and tension really helps.

How did you fix it in the end?

[Burtie]

I haven't fixed it,
I just turned the motor torque (phase current limit) down until it stopped slipping.

Still great fun, but it would be nicer to fix it somehow so I could use full power


Wierd thing is, that I managed to put more torque though my old 8 speed derailur setup than I can now with this bmx chain.

[lostrack]

Wow, a few months and still no fix?

I have been improving my setup and realised that the chain line has to be millimetre perfect, laterally, and then add as much tension as possible before drag becomes too much.

Secondly, the bike with no weight on worked fine, but due to the spring setup, the chain pulling tension reduced Much more when I sat on it, making the pull weak. Jumping off, it's fine. so, leaning forward when accelerating fine, leaning back, skippy chain.
Going to add more chain tension or try and change the design so it's an equal pull the whole of the spring travel.


Sorry if this doesn't make complete sense, half watching tv...

[rodgah]

are you sure its the rear slipping?

[Burtie]

are you sure its the rear slipping?

Yeah pretty sure.

I flipped the front 44t chainwheel over, so it is using the unworn side of the teeth on the pulling side, no change.

Beginning to think the only way to fix this will be to use substatialy larger diameter rear sprocket somehow.

I guess this chainslip may not be a problem in applications where you have no chain growth, and you can use a fixed tensioner.
But with this suspension bike, the need for a spring loaded tensioner is causing problems.

[rodgah]

i really dont understand how it could of changed from the derailleur.....sure if you were experiencing problems with the same tooth count on the cluster it would make sense. Have you tried putting the cluster back on and locking the derailleur on a similar T gear (like you have already done) and see if it slips? I am amazed that the short little funny shape teeth on gear clusters hold pedalling power let alone motoring power.

Rodger

[lostrack]

are you sure its the rear slipping?

Yeah pretty sure.

I flipped the front 44t chainwheel over, so it is using the unworn side of the teeth on the pulling side, no change.

Beginning to think the only way to fix this will be to use substatialy larger diameter rear sprocket somehow.

I guess this chainslip may not be a problem in applications where you have no chain growth, and you can use a fixed tensioner.
But with this suspension bike, the need for a spring loaded tensioner is causing problems.

Check with your weight on the bike it's still pulling as hard as you need.

[Burtie]

I did have an external coil spring on the derailleur, applying some serious chain tension, to the point where I thought the idler bearings would suffer badly. It helped a bit, but did not eliminate the skip.

I get the feeling that since I have done a few 10's of miles on this setup, the chain and sprockets are bedding in an the situation is improving slightly, but I am probably clutching at staws here.

I might try re-fitting the external spring to refresh my assessment.

[kfong]

How old is the chain Bertie? I used a chain tool to measure the streaching. I've had to replace my bike chain twice already on my cyclone setup. This could be the cause of your skipping. You will be surprised at how much a chain can streach from hard use.

[Burtie]

I used new chain(s) and several new sprockets.
I removed the Lipo to use on another bike, so haven't played with it for a while now.

The plan is, to re-engineer the gearing so I can use a much bigger rear sprocket. That should enable me to transmit a decent amount of power to the wheel before the chain acts up.

Burtie

[Kin]

Just wondering, did you have any shots of how you added the external bearing support on the other end of the shaft? I couldn't tell from the photos on the first page.

Also, what were those two notches on the non-power side of the 80-100 shaft?

Coolios build.

[Burtie]

Kin, sorry I missed that last question

Support bearings are sandwitched between the two plates at each end of the motor, see in this photo:
viewtopic.php?f=28&t=12768#p189713
Tho I have now removed the bearing from the back end, as it is not really needed.

The notches are for the grub screws on the bell to engage with. Standard feature on this motor (photo shows shaft inserted backwards in bell)


Fresh look at the slipping chain problem revealed a couple of stiff links in the primary , it was actually the primary chain that was slipping
Now cured.

[kfong]

Good to know it's fixed. Thudster is rewinding my burnt out motor so I can finally join in on the RC fun.