I have a Norco Monterey SL, 10 speed. This bike was given to me and needed work. I put a new chain and tires on it. The derailler is a Shimano SIS. Here is the problem, whenever I am on the two smallest sprockets, the chain slips. The chain is tight, and the teeth are 3.5mm wide. I am pretty new to this so any advice would be greatly appreciated.
Explain what you mean by “the chain slips.”
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the chain turns without problem, however when you apply more aggressive force to the pedals the chain will slip(or jump). It’s hard to tell because it only does it when you ride it, not when you manually turn the pedals. I have tried to watch it but as you can imagine this isn’t easy. My guess is that the sprockets are worn and since there is less contact with the smaller sprockets, the chain slips.
If it stays in the same gear when it slips, then it sounds like you have worn sprokets, which need replacement. Also you may have worn chainring.
Take bike to a shop, or if you want to DIY, then read up here:
http://sheldonbrown.com/chains.html
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Try adjusting the black barrell where the cable comes into the derailler. You may just need to adjust it a bit. Otherwise as said, worn sprockets
Here is a video on You Tube which will help adjust the rear derailer: