Originally Posted by
hybridbkrdr
I was told on a triple crankset you should avoid "big-big" & "small-small". If I'm on the lower chainring on the crankset, can I use any gear in the back? (Like on a 11-32T cassette.)
In general, chains last longer if they are in the ring/cog combination which uses the largest ring/cog combo available to get that same gear. So for example, say you're in the middle ring, smallest cog. You can approximately duplicate that gearing in the big ring and a cog somewhere in the middle of the cassette. The larger the rings/cogs in use, the lower the chain tension. Thus small-small is the worst possible combination.
That said, of course in trying for a certain cadence at a certain speed, there may only be one ring/cog combo which yields that cadence, so fine, use that.
And that said, In general when in the big ring, don't use the 2 largest cogs in back. In the middle ring, you can use all the cogs, In the granny ring, only use the 4 largest cogs. That totally avoids the small-small business. There's never a reason to use it. Honest. Been riding triples for 25 years in the mountains and on the flats. Still use triples on all my bikes.
Modern chains are narrower and built differently than trad chains. Thus the old advice about not cross chaining to avoid chain wear no longer really applies. Thus it's OK to run the whole cassette from the middle ring if your FD cage and FD trim allows it without rubbing. I will occasionally find myself in the 2nd largest cog in the big ring, though I'll quickly change out of that, and I never use big-big, well because that is cross chaining and I just don't feel right about it.
The trick with triples is to use the smallest cog you can get away with for the granny, and thus the closest ratio cassette that gives you the low gear you need. I have one bike with 53-39-26 in front and 12-25 in back. Very nice as long as I'm not doing a lot of climbing.
Since you're new to triples, I might mention that over time, you'll wear out chainrings. Either the chain jumps on the ring when you're out of the saddle, or it won't shift to the next larger ring, or you get chain suck when shifting to the middle ring. So, new rings: an ordinary double big ring will work with a 39T middle, but not with a 42 middle and vice versa. You have to have a special triple ring for the middle, and any ring will work for the granny. If your current rings are 30-42-52, know those 42-52 rings are the only combination that'll work together. Thus if you can't find a 42, you'll need to go 39-53.
You might want to print this and save it somewhere, just in case.