Slippage, so frustrating, please help!

[CharlieBravo]

I have an MTB, it's not new but I've looked after the bike well.<br />
Last week I broke my chain, purposefully, to clean it as it needed a clean.<br />
Got it beautifully clean and all links were nice and flexible as they should be. Popped the chain back on and my problems began.<br />
First of all my 8spd trigger shifter broke and I had to replace that, so I've now a new one on the bike and as far as I can tell I've got it sweetly adjusted.<br />
I went for a ride and found that when I put pressure on certain gears (my favourite included) it slips with a loud KLANG and I almost break my leg.<br />
I thought I may have done my chain in so I ordered a new one.<br />
I first measured the new chain with the old, shortened it to the old chain length and then put it on the bike using the joiner that came with the chain.<br />
Bike rides much smoother but still that annoying slippage when applying pressure to the pedals, particularly when going uphill.<br />
Please help!<br />
Thank you.

[Jordan300]

it sounds like you might have some wear on the cassette. Take a look at the teeth on the cassette a worn tooth will start to look more like a "shark fin shape" rather than a tooth that it used to look like. This can cause chain slippage. Another cause could be chain wear as well.

[CharlieBravo]

Looking at my rear cassette I find it's in good order, however, looking at my big chainring I can notice some shark fins in there and a couple of broken teeth too, both alongside each other.<br />
The chain is brand new.

[cyclerUK]

Unfortunately it sounds like your cassette is worn, especially if it's a Shimano.<br />
There is a fine line between good and worn and can not be judged by just looking at the teeth.<br />
The only way to tell is by fitting a new one really.<br />
If the chain still slips on the other chainring as well then I would think this proves it.<br />
By the way some Shimano chainrings have low teeth in a couple of places to help shifting. Are these your "broken" ones?<br />
Also if you have worn chainrings then these will wear out chains quicker.

[CharlieBravo]

Problem solved. Replaced the rear cassette. Bike now runs sweet as a nut. Stunning.<br />
Thank you for all your feedback!

[swift1ne]

wow i had the same problem ...but to make sure did this happen to you when shifting or just when pedaling? For me it happens at certain parts in peddling and when i examined my bike while flipped i noticed it "slipped" where the chain was kinked... i'm looking into buying a new chain but sadly it sounds like i need to spend more money... how much aprox did the repairs cost you?

[DaveM]

swift1ne - It sounds like you might have a stiff link in the chain. Try flexing the "kinked" link side to side a little (90 degrees to the way it is supposed to bend) to free it up.

[swift1ne]

Davem- i did this and even used degreaser and am now soaking my old chain in chainsaw oil i figured chainsaw chains are under way more stress , not sure if it will work but i'm looking for a new chain as well