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FSA TH-7420ST BB upgrade or not....

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Hi All you super guru's!


I need to pick your collective please :)


My wife has a Merida Big Nine 300 with a 2 x 10 xt and FSA TH-7420ST Cartridge Bearing BB.


We would like to upgrade to 1x12 NX and here comes the question....


Do we:


  1. Change the bottom bracket and replace the entire group set with cranks (not sure if its 170mm or 175mm as its a small)

  2. Keep the BB and just upgrade the front chainring with an upgrade kit (Not sure about chain line etc)
  3. Any other suggestions?


This is all foreign to me but with the cost of the upgrade i would like to make sure we get it right first time. Im sure this will help a few other people out there in the same boat :)


Thank you in advance!



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First of all:

The BB ( bottom bracket) is the bearings of the crank set. The crank arms is where the pedals attach to.


I assume that you want to know if you need a new single blade crank, or can just change the 2 blade crank to a 1 blade.


I would change the crank set, although I am sure one can successfully change the 2 blade to a 1 blade.

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