headloss: I hope this and the related pages at the CTC site will answer your questions. http://www.ctc.org.uk/desktopdefault.aspx?tabid=4068
Front Derailleur Max Capacity
OK, so I'm looking at touring cranksets and I find that the Sugino -600 is popular. The first one I see is a common gearing of 26-36-46t which would work with both a Shimano road triple with the (max capacity of 20) and it clearly falls into the allowable range for a mtb (max capacity of 22). Then I see one that is sort of a front gear mega range of 24-36-50t (it also has a ridiculously small crank arm length of 152mm). http://www.amazon.com/Sugino-XD600-152mm-24-36-50-8spd/dp/B001PRX9FU
*note that SRAM doesn't publish the max capacity on their webpage (not that I can find at least).
So in order to use the 24-36-50t chainrings, would I be required to use friction shifting? Are there front derailleurs that exist from any manufacturer that cover such a range? This is all hypothetical, as I wouldn't want such a wide range, but I'm trying to understand the chainring selection and I'm just completely baffled by this crankset.
The range between the front chainrings also influences the selection of *rear* derailleurs.