Yes, I know this is a popular one and most people do it by changing to an mtb crankset. Well, I don't want to do that. I'm riding a 2007 Trek520 and am very happy with the two larger chainrings (52/40 they suit most of my riding perfectly) but as I'm running out of puff on some of the nastier hills around here, a smaller granny gear (from the current 30) would be appreciated. If I'm going to change the small chainring, I'd might as well change it for something suitable for heavy touring (not that I'm planning it but while I'm doing the change ...).
Any suggestions on what sized chainring to go for?
As I said, I'm keeping the Ultegra crankset and 105 derailleur, so the new ring has to be compatible with that. A mate has suggested going to a 24 (which looks good on the gear chart - nice overlap, a few more ratios) but the lbs reckons the 105 shifter won't handle the 52-24 range. Any thoughts?
Better still, has anyone done it?