Triple vs Double chainring? I'm bike shopping for my first road bike, and I've asked for a lot of advice from my father who was a serious cyclist once upon a time.  After showing him one prospective bike, he dismissed it with a simple "you don't want a triple" with zero explanation on why.

What are the pros and cons in having a Triple, vs having a Double crankset?  Does it differ from road bikes, to mountain bikes?
The idea used to be that a triple was just a double with an extra small, 'granny' ring (i.e. only grandmothers would need to use that one) so there was definitely some snobbery in a triple; that it was designed for those who needed a little more help. So on the club training run, you might be teased for it. (Google for 'triple granny ring' for various forum discussions and banter; don't worry, most of the responses are SFW.) 

Practically, what it tends to mean is not necessarily a bigger gear at the top (i.e. big front ring &amp; small back ring) but a much lower gear at the bottom, for the hills. So with the same rear cassette you might compare a 50/34 double for a 50/39/30 triple (although a 50/34 is probably more what is called these days a 'compact'). That range of triple combined with a typical rear cassette of 12-28 would work for most hills. 

You also get a lot more options; so you'll get the similar effective ratios in several ways, because the ranges on the big ring overlap more with the middle, and the middle with the little one. Also, the gears are closer together - so you're more likely to find something that works well at the right time. 

It is also easier to change on the front ring of a triple, on a compact you'll often need to change down a gear or two on the back when you move on to the bigger front ring, which means the chain is being yanked both ways and strained that bit more. But on the triple, you're not as far away, so you'll often not need to change the back at the same time as shifting the front.