hazben1

I have a FSA SL-K light triple crank with 30/39/52T chainrings. I just replaced the worn-out 52 due to it getting 80% of the miles. The other 2 chainrings looked great. Is there any larger chainrings I could use in place of the 30/39 chainrings. Maybe something like a 33/42. What I am trying to accomplish is get a larger middle and small chainring so perhaps I would even out the chainring wear. Are there some chainrings I could easily switch out? Would doing this create too much duplication of gears? The spacing is 130

ThermionicScott 

42T is a common size in 130BCD. I'd get that for the middle.

fietsbob

A 130 bolt circle is a common standard now.

RE duplication of the gears ? Do the math and answer your own question.

multiple people have done sophisticated ways to visualize the patterns,. computer programmer types.

Cheaper steel and more expensive 7075-T6 alloys are longer wearing,
Odd numbers are not done that much . particularly thec 3rd one.

TA machines odd tooth counts in France in 7075, they will be Expensive.

hazben1

I found a 42 middle chainring on Amazon which I think would work well. How about the smallest chainring any suggestions. What size is the largest small chainring do you think I could put on there?

Andrew R Stewart 

Since the inner ring doesn't need pins or shift ramps it can be subbed with any number of different ones without much if any shifting issues. It's bolt pattern is likely to be a 74mm diameter. A quick look at the selection from QBP shows a Sugino 32T #74J-32T SIL. This small a bolt pattern and it's inner location means that not much was ever offered by any one in anything like a medium or large tooth count. It's a granny after all Andy

desertdork

Triple front derailleurs can be fairly specific in regards to the tooth difference between large and middle rings, and your current FD may not get along with the small 10t difference.

I don't know about FSA, or for that matter whichever 42t middle ring you located, but some mfrs (e.g., Shimano) may recommend using "matching" large and middle rings so the ramps and pins are oriented for optimum (indexed) shifting.

zonatandem

54/42/32 on our tandem.

hazben1

Did some checking around this is what I found.

Middle: FSA 130bcd 42t s-10 $30. This shows to be Ultra Narrow? Found an identical FSA 130bcd 42T except it is n-10 and $147. My big ring (52T) is n-10. Would the s-10 work? Don't know if I am ready to pay $147 for the 42T.

Inner chainring I found a Stronglight Dural 5083 34T (265008) 74bcd for $22. Would this work OK. Is the 34T going to play nice with the 42T middle? I think they also had it in a 32T. Is Stronglight a decent brand?

ThermionicScott 

Stronglight is an excellent brand. Granny rings don't need to be anything special, though, and I subscribe to Grant Peterson's thinking that if you find yourself needing one, you might as well keep it small. Sugino 32T rings are cheap and easy to find.

I'd be surprised if the $30 42T ring didn't work well for the middle, too.