Chain rubbing and noise

Triathlon Forum
1

A friend of mine ( this is not one of those " i have a fiend but it is really me things" BTW) has a Trek 5900 (?) It has Full ultegra and a 9sp rear cassette. When he is on the front small ring, and uses any of the 4 smaller rear cogs, the chain catches on the larger ring and rubs and lcicks etc… I have said that it is because he shouldn’t be using that gearing! Any other reasons why this might happen. We have checked the bike over, and nothing seems amiss…

Thanks

Weeman

2

My bike is doing the same thing, though I have a triple chain ring. I am having a little trouble figuring out the gearing and such so that is probably it. The bike is a Cannondale R400 and is a 2003. NIce ride.

3

Thats called crossover if you are using these gears your doing it wrong use the BIG ring,You really should not use small front ring and small gears on the back,its a bad chain line and a lot of chain slack for the rear derailer to take up
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4

So if I’m in the big chainring, how far up the 9-speed cassette can I shift?

5

I do not use the two biggest gears when in the big ring,if i need that much of a lower gear i shift to the small chainring,in the old days your small ring was a 42 tooth so if you did go small ring small gear in back the chain would not touch to large ring,also years ago the large rings were 52 tooth,IMHO i think a 39 is to low unless you live in very hilly aera i use 42 as my small ring,aqnd live in a hilly aera,when i go to ride in the mountions then i use a 39 or 38
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6

I have a 52/39 chainring & 11 - ? (not sure at the moment) cassette on my Giant MCR2. When in 39-ring and 4 smallest cogs, no chain rub on the 52-ring. Instead, I notice cable rattle, probably due to extra slack hitting the inside wall of the chainstay (internally routed derailleur cable).

Conversely, in the 52-ring and 3 biggest gears, chain rubs on the front derailleur cage. As you mentioned in your earlier post, bad chain line is what it is.