Chain slipping on cassette under load

davidphilips

Über Member
Location
Onabike
Well the good news is that halfords have sram pg830 cassettes for £13.28 and sram chains pc830 for £5 (all 8 speed). Chainrings can be bought on ebay or even a used chainset, Some times i am surprised how fast chains/cassettes and chainrings can wear out in bad weather.
 
This reminds me my Triban needs a new chain/cassette :okay: The inclement last month on the busway has speeded up the wear nearly 2,000miles probably didn't help either :laugh:
 

Ajax Bay

Veteran
Location
East Devon
Last time I had this problem after replacing both the chain and cassette, it was a worn chainring causing the problem. Is it happening on every chainring?
I'll try it on those and see what happens.
You don't seem to have answered @Threevok 's question.
But, together with the image of the large chainring, your assertion that "rarely use the inner and middle rings" and the fact that the cassette and chain are both new, these symptoms are consistent with a worn chainring - I agree with @Threevok 's implied cause. I had exactly this earlier this year: replaced chain and knew the cassette had less than 1700km on it, so expected it to be excellent, and it carried on slipping - on the middle ring only though. Replaced middle ring and rode on - happy days.
 
OP
Dec66

Dec66

A gentlemanly pootler, these days
Location
West Wickham
OK, up and down the road in the wrong gear, and I can't replicate the issue on the middle or inner rings.

So, a new big ring it is, then.

Cheers all :okay:
 

keithmac

Veteran
View attachment 441806
Outer chainring, looking more "peaky" than "shark finny"

View attachment 441807
Cassette
If your local bike shop has deemed that outer chainring ok you need to be finding a new shop!.
 

Ajax Bay

Veteran
Location
East Devon
As @davidphilips says, it can be done. But frankly it's much easier to fit a new large ring (on a triple) if you take off the crank (which takes 30 seconds. Otherwise it can be a faff to get assured access to the slotted nut on the middle ring side to secure that and get the bolt suitably tight. Depending on your chainring sizes the teeth of the middle ring obstruct the access you need, for some of the bolts [Edit: especially if the larger BCD is only 110mm (as opposed to 130mm)].
Also this is an excellent opportunity to clean the chainrings and all the crevices of the cranks thoroughly. When assembling use threadlock on the chainring bolts.
 
Last edited:

NorthernSky

Veteran
@Dec66 did you get the issue sorted?

my chain is slipping EVERY time load is applied from a stop (at a junction or on steep hills)
bought new chain and still happening so next step is a replacement cassette me thinks

Q. can i replace a 12-27t cassette with a 12-28t? i've just fitted the chain for the current 12-27t so may have snookered myself?
 
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