Crank chain ring compatibility question

Just bought a Marin bear valley se for the princely sum of £25.

The large and middle chain rings have teeth missing! (Shimano stx RC) 42 and 32/33? Teeth

Can anybody advise me as to what I should be looking for in replacement rings? I have no clue as to what will fit on the existing crank. Does it have to be shimano etc? Is there a measurement I need such as distance between bolt centres for each ring or are they all (shimano) similar?

Thanks in anticipation THM

58mm: inner
94mm: mid and outer

I got the info from this thread:

http://www.cyclingforums.com/t/231307/h ... s-chainset

SP

If the missing teeth are all in the same place relative to the chainrings, that is deliberate and aimed to make the chain derail better. I think it's the 6 and 12 o'clock positions, but stand to be corrected!

Missing behind pedal arm. One tooth each ring? Would that be normal?

I asked a similar question on wear

viewtopic.php?f=1&t=244500

may be deliberate, rather than wear

Looked bollyhoxed to me! Having read other thread now, should I just leave it and rebuild the bike and see how it goes?

No, they are exactly the same teeth in the same position on both rings. Bet you that the ones diametrically opposite will be stubby too. Shimano do it to improve shifting.

Well you live and learn. Thanks for the clarification. Happy now.

Indeed. I got massive aggro for selling a chainset on ebay last year that arrived "wiv missing teef"

Checked and surprise surprise, matching missing!