My current bicycle is a 2013 Specialized Allez C2. It has an 8 speed rear cassette. If I swap the current chainring (50/32) to a larger one (52/36 OR 54/39), other than the chain itself, what else would I need to change, if anything?


1 Answer 1


You need to first check that your front derailleur has enough capacity to handle the new chain rings and can clear it (i.e. you can re-position and adjust the front derailleur to handle these chainrings). You should refer to your front derailleur's data sheet to see if this is possible. In general, you also need to check the rear derailleur's capacity to see if the rear derailleur is long enough to take up the extra possible slack, but in this case, the capacity required will go down for a fixed rear cassette, so you don't need to worry about it. You also need to make sure the chain adequately clears the frame under the new chainring size (which may require changing the bottom bracket or other things, if possible).

Here are some directions on adjusting the front derailleur.

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    The capacity of the front derailleur shouldn't cause much trouble. A 50/32 has 18 teeth difference whereas the 54/39 only has a difference of 15 teeth, so the climb of the chain would be easier. As Batman points out the rear derailleur's capacity is the most important point together with the length of the chain.
    – Carel
    Commented Sep 9, 2014 at 17:44
  • The ability for the front derailleur to clear a 54t chainring is another matter to capacity - e.g. the Shimano 105 FD-5700 can but FD-5703 can't clear something more than 50t, so i think this is a more important point than rear derailleur capacity, since thats usually quite conservative.
    – Batman
    Commented Sep 9, 2014 at 18:03

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