Firstly, you can swap a Shimano 5760 cranks for 5700 cranks.
Shifters and front derailleur are standard for both the compact or standard cranks. Just remember to lower the derailleur to clear the top of the large chain ring by a couple of millimeters.
Secondly, both the Shimano 5700 and 5750 cranks use the same bottom bracket, namely the SM-BB5700. Therefore no need to install a new bottom bracket (although I believe the new 5750 cranks will come with a new bottom bracket) which you can keep as a spare if you do not sell the 5700 cranks,
As Donald said, with the addition of: You will have to shorten your chain as well, as fewer teeth means your chain will now be too long.
and if you have a set of cranks spare.....I'm looking for some....and I can do the conversion for you if you arent mechanically minded (or equipped) ;)
From my experience Trent I'd go Compacts over the 28 (I've got both but I'm a girl) although changing the cassette is cheaper if that is an issue.
I think you can get smaller custom chain rings, but 38 is the smallest you can go on a 130BCD, any smaller and the chain will interfere with the bolts
Sorry, 34T chainrings wont fit a standard crank. I should have consulted this first
Makes a good read for anyone thinking about compacts.
great article DD but now i am more confused! lol not really but i do like the sound of an 11-25 on the back with compacts
My searching when building up my bike found that Shimano Chainsets are not good value for money.
1: New ones dont come with a Bottom Bracket - So you'll need to use your old one, or buy a new one seperately.
2: FSA or SRAM Chainsets are much cheaper
There is no compatibility using SRAM / FSA chainsets with a Shimano groupset, many bikes will be built up with a FSA chainset in the middle of an Ultegra groupset.
The benefit with SRAM/FSA is that they usually come with a BB as well.
I'd search around on evil bay for a SRAM Apex or Force compact chainset.