Chris Taylor wrote:

I wish to go compact on my road bike but wish to spend as little as I can
Just a thought I have altegra 6500 on the bike now. would the HG93 9
speed chain work with the Shimano Ultegra 6650 Hollowtech II Compact
Chainset.

10-speed chain is narrower (slightly) than 9-speed chain, so there
should be no compatibility issues with a 10-speed crank.

how do I find out if I have English or Italian bottom bracket?

Check out what it eats. If it's nasty, then it's English. If tasty,
then Italian.

Chalo