Good Morning to Everyone on the Board –

I have a technical question that I hope someone can shed some light on…

Recently, I cleaned the chainrings, cassette and chain on my touring bike. The large and medium chainrings were unbolted, removed and cleaned; as I left the crank arms attached, the small chainring was cleaned on the bike. The cassette was removed and cleaned as well. The chain was not removed from the bike and cleaned using the Park Tool chain cleaner device and oiled afterward.

Now that everything is back together, the chain skips on the center ring, specifically when I apply power to the cranks when taking off from a light. Sometimes, it’s so bad, the chain comes completely off of the chainring on to the bottom bracket. When this happens, I’m usually the middle gear of the cassette (gear 4 of 7). A check of the front derailleur showed that it had not drifted inwards towards the small ring. The FD is also appears to be in good alignment.

A visual check of the chainrings showed that they are not out of alignment (no lateral movement when I spin the cranks). When I reassembled the crank, I tightened the bolts in a star pattern (like one would tighten lug nuts on a car wheel). The chain ring tooth counts are facing outwards (I was told that was important, not exactly sure why). I’ve checked the chain, and there are no stiff links (all the same – the chain was not removed).

The only thing that was odd during reassembly is that four of the five stack bolts tightened without the need of a screwdriver to hold the back in place; one, however, did. That said, I was able to tighten it.

The problem is intermittent, but it only seems to occur when I’m on the center chainring. Further, if I start off in a lower gear, there’s no problem.

Thoughts on this?

Thanks.