I should probably know this. 😐

My 2013 Defy 3 has a OEM Square Taper BB and FSA cranks. Its Sora 3500 9sp.

Can I use a 105 5700 (10sp) crankset on it, and 105 Hollowtech BB? e.g. these:

http://www.merlincycles.com/shimano-105-5700-bottom-bracket-49200.html

http://www.merlincycles.com/shimano-105-5700-chainset-black-49195.html

Yeah she’ll be reet.

Yep. Just done a similar swap on my CX bike. Square taper with sora crankset to Uber ceramic BB and Tiagra chainset.

Pay close attention to the spacers for the BB.

Excellent thanks!

I’ve noted that Merlin don’t have the compact in stock though.

Kryton, Merlin have 5800 105 cranks in for £80. Pretty sure they’ve got most lengths in most sizes. Bonus is you can run compact/semi compact/standard on the same cranks.

Righto. I must admit I’ve no idea how two chain rings could be 9, 10 or 11 speed specific unless the ratio paired with the cassette was different.