11-40 cassette 46-30 chainset working with tiagra 4700

If your gravel bike came with the usual compact set up and you need more gear range...here is a quick write up about my new set up.

I swapped the tiagra 50/ 34 for absolute black 46/30 chainrings. Bit of fiddling to get them to fit the cranks. Had to file to fit. Absolute back say it's not much but in my experience it's quite a bit. In retrospect I would either get 105 cranks that fit as is. Or ditch the absolute black for the FSA tempo 46-30 chainset. That said I like the look of the absolute black.

For the cassette I swapped the 11-34 to a sunrace 10speed 11-40. Easy swap

Used a sunrace extender to shift the derailleur down in order to accommodate the 40 tooth gear

Quick re alignment of the derailleur and it all seems to run fine. No chain sag in any combination at all. I didn't put a new chain in as the original had done so few miles I don't think it's worth it.

On the road it all works well. The front derailleur is a little stiff to shift but not so much that it bothers me. Fully loaded on hills the extra range is fantastic. That said if I didn't travel much in the mountains I think a 11-36 cassette would probably be ample.


  • While it's good that it working you have confused working with compatible. As your chain wears shifting will degrade more quickly and you may get a slack chain in small small. That what shimano means but not compatible. Compatibility has to be function as the manufacturer intends throughout the proper service life of the chain.

    Of course the fuctuon may be acceptable to you but not to shimano.

    Sorry for being picky but the term compatible is misunderstood.
  • Thanks for the linguistics lesson...I think you'll find I haven't used the word 'compatible' in the post above. I have said that it 'works'. For how long and how well remains to be seen, to be thorough I will give an update after a few hundred miles.
  • call back when have put in 200miles on 40/30
  • Might be a while...