More gear slipping problems

[bushbiker]

Hi
I recently changed both back cassette and the chain on my mountain bike. Since doing this I have been plagued by gear slippage problems whenever I apply a lot of pressure (e.g. steep hills) - in fact the gears slip quite violently when I do this. I have followed all of the instructions found on these pages and others but the problem remains.
To summarize:
- the cassette and chain were bought at the same time in the same shop so I am sure they are compatible.<br />
- I have tweaked the cable tension to perfection (I swear the alignment is perfect on all cogs) but it still slips. I have even tried different tensions on the same back cog to see if it makes a difference - and it doesn't.<br />
- I have set the rear derailer so it is sitting in the preferred position in relation to the cassette<br />
- I have checked for stiff links and cannot find any
I have come across some posting that suggest that wear on the chainring could cause this? Is that correct? But to be honest the wear does not look too bad.
This did get me looking at the chainring and I noticed a red sticker on the chainring which reads thus:
"Shimano IG chain only"
The new chain I bought is a SRAM PC-951 - "compatible with 9 speed systems'
Any comment?
Thanks
PS I live and ride in West Africa, so popping down to my local bike shop to get it sorted is not an option! You guys are my local bike shop techies!

[DaveM]

If this began suddenly after changing the cassette and chain, it would seem like it would have to be your front chainrings. Does it only happen in the small chainring in front or on both equally. A chainring has to be pretty worn for this to happen and usually the small one is more worn since people generally spend more time in it.
It's possible the 9 speed chain is designed for narrower chainrings than what you've got. But if the chain looks to drop down into the teeth fully, I don't know that that would be it.
Other possibility is that it is the ratchet in the cassette body slipping. But it would be a pretty bizarre coincidence to have that happen right after you change the chain.
If you can get this to happen at fairly slow speeds (up a steep hill?) see if you can get someone to run next to you and watch. Sometimes they'll be able to see where it's slipping much better than the person on the bike.

[bushbiker]

Thanks for this - this proved to be the case although it is a problem with the middle chain ring not the smallest one. I am now going to change all three chain rings and will endeavour to spread my work out across them in the future!
Cheers

[DaveM]

Glad you found the problem. Check your chain for wear and replace it more often and you should avoid wearing out the chainrings in the future. They wear much quicker on an old chain because the teeth wear to match the "stretched" old chain.