too much torque

[flux]

I don't think my smallest sprocket is surviving the torque of my motor very well. Is this common on e-bikes?

 

[Wisper Bikes]

Hi Flux, I have only seen this on mid motor bikes. What model do you have?

 

[flux]

Hi,

Its a Liberty Stealth, which i believe is a U.S version of the ProRider e-voyager with some minor tweaks like disc brakes.

 

[Wisper Bikes]

Is that mid motor?

 

[flux]

No, its a rear hub motor. I'm the mid motor part

 

[Wisper Bikes]

I though so much from the image. I have never seen this on a hub drive bike, there isn't any power going through the chain drive apart from the rider's. It's probably down to poor adjustment.

 

[flux]

Everything seems pretty well aligned and there are no odd noises or rubbing. I thought that too. its got a lot of torque, but the stress on the sprocket is due to me pedalling not the motor.

 

[flux]

5th gear is looking a little bit twisted too, but nowhere near as bad as 6th. The rest are fine, but its fairly rare i'll ever drop into 4th.

 

[Wisper Bikes]

It looks well used, so maybe time to change the freewheel or cassette. Sorry I cant be more helpful but I am sure it has nothing to do with the bike being electric.

 

[KTM Bike Industries UK]

decent cycle components are designed to take more power than eBikes put out. What cassette is that?

 

[flux]

other than it being a shimano set i don't know much more. Its likely one of the budget end ones

 

[Artstu]

Just buy a new one, and a new chain.
http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2060353.m570.l2632.R2.TR3.TRC1.A0.H0.X6-speed+cassette.TRS0&_nkw=6+speed+cassette&_sacat=7294

Like this one?

 

[flux]

Just buy a new one, and a new chain.
http://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2060353.m570.l2632.R2.TR3.TRC1.A0.H0.X6-speed+cassette.TRS0&_nkw=6+speed+cassette&_sacat=7294

Like this one?

thats the one.

 

[flux]

Will probably have to replace it at some point. Its not slipping or anything. do you think it will snap the chain?
They only have 6mths of use on them so not a great lifespan.

 

[Artstu]

I don't think my smallest sprocket is surviving the torque of my motor very well. Is this common on e-bikes?

thats the one.

In that case the only torque load on the cassette is from you.
I guess Ian Stannard could produce too much torque, you're not Ian are you?

https://www.strava.com/activities/597034291#14541649296

I'd put a decent chain on at the same time, because the bike is so long a bike shop will cut one off the roll for you, most boxed ones could be too short.

 

[flux]

haha no, not quite. It does require a lot of effort and perseverance keeping it anywhere near 20mph though.
If i'm going to change the sprockets/chain i'd ideally like to increase the gearing at the same time. gears 1-4 are never used and 6 spins out too early.

 

[flecc]

Your chainwheel is quite small, very small by my standards, forcing you to the smaller freewheel socket to get high enough gearing. Hence the spinning out too early you report.

If you change the chainwheel to one with many more teeth you'll be able to use the larger rear sprockets much more and spend far less time on the smallest one which wears the fastest.
.

 

[Artstu]

Yes Freewheel, getting my cassettes and feewheels mixed up.

http://www.ebay.co.uk/sch/i.html?_odkw=6+speed+cassette&_osacat=7294&_from=R40&_trksid=p2045573.m570.l1313.TR3.TRC1.A0.H0.X6+speed+freewheel.TRS0&_nkw=6+speed+freewheel&_sacat=7294

 

[RobF]

Looks like 26" wheels which will give lower gearing than 27.5 or 29er.

The OP is probably spinning a fairly high cadence at 20mph.

As flecc says, a bigger ring on the front would be a sensible mod.

 

[flux]

Better a few more teeth on the front then than a few less on the back?