THe 11 tooth gear was crunching under pressure

[stevebills]

I took my bike to Andy at the bike shop near me because the high gear was crunching under electric power and he set the derailleur up and it was indexing great and I tested it and it still crunched so we changed the cable which looked slightly worn and tested again and same thing it crunched and then Lenny came out of the shop and had a look and put the bike in top gear and started to pedal it down the path and I spotted the chain jumping off the teeth on the high gear.
He had a 12 tooth he had ordered for a customer and I borrowed it and swopped it with the 11 tooth and I tested the bike it was fine so now we have ordered a replacement Shimano HG40 11-34 speed cassette at a bargain price only £19.99 delivered

 

[stevebills]

I am guessing (Flecc may put me right) that the high gear will always be first to break as its used the most and being small has more chance of slipping the chain

 

[HarryB]

Did you change the chain and not the rear cassette? Sometimes you get that happening if you allow a worn (stretched) chain to wear out the sprockets. You can get away with just a new chain if you change it regularily and use a chain stretch indicator tool. Yes it is always the smaller sprockets that wear first.

 

[stevebills]

Did you change the chain and not the rear cassette? Sometimes you get that happening if you allow a worn (stretched) chain to wear out the sprockets. You can get away with just a new chain if you change it regularily and use a chain stretch indicator tool. Yes it is always the smaller sprockets that wear first.

Chain is fine it was checked with calipers and chain works on new 12 tooth gear and all the other gears

 

[HarryB]

OK - very odd that it would not wear and the sprocket would. At least you have a cheapish fix.

 

[stevebills]

OK - very odd that it would not wear and the sprocket would. At least you have a cheapish fix.

I thnk the chain must be stronger than the gear

 

[HarryB]

It is just that it is usually the chain stretching that wrecks the sprocket or they both wear together beautifully until the floppy chain breaks or becomes a nuisance!

 

[flecc]

I think 11 tooth and smaller rear sprockets are always questionable, but especially so when the motor drive goes through the transmission as well.
.

 

[stevebills]

I think 11 tooth and smaller rear sprockets are always questionable, but especially so when the motor drive goes through the transmission as well.
.

I was thinking the same and the power of the motor must wear the gear down
quicker

 

[stevebills]

It is just that it is usually the chain stretching that wrecks the sprocket or they both wear together beautifully until the floppy chain breaks or becomes a nuisance!

I think the SRAM PC971 chain must be strong