compact triple or double

a triple is beneficial if you have a lot of hills or have troubles riding in harder gears. It gives you more gearing options on easier end.

If you did get a bike running a double it would most likely be in your best interest to run a compact double, so it'll be an easier transition from the triple.

The real difference is that triples don't shift as smoothly / crisply as a double. I own a Trek road bike with an Ultegra triple.  I like the granny gears on steep hills (and we have them aplenty), but I don't like the muddy shifting compared to my tri bike's double (admittedly, Dura Ace double). Oh, and people will tell you a triple has zero street cred, if that matters to you.  Compact doubles let you crank up the hills without looking like a newbie.

If I had to do over again, I'd buy a compact double with an appropriate cassette to get the same gear range.  I'd have the granny gears and the smooth shifting.

If you already have a Tiagra triple, it will cost a bundle to upgrade it and IMHO not really be worth it to just go to 105.  You'll take a bath on parts cost, even if you install yourself.You can get plenty of mileage out of your Tiagra setup.  I did my first few triathlons on a Tiagra triple.

see what I mean--new to this.  trying to figure out the differnce  between the 3 and 3 ring crank set overall.  given my still level and the terrain in these parts I think I'm better to stick with the tripple for now--I'm not worried about street cred.  thanks everyone for the input.  also good to know it may not be worth swapping out.  hadn't committed yet, and have had not problems with the tiagra stuff.  just considering the options.

You're right to not worry about the street cred. Just worry about what you need for your riding. (And really, the folks who look down their noses at triples needn't bother you.)

As already pointed out, the shifting does tend to work a bit better on a compact double, because the front derailleur does not have to move so far. Probably not a big deal for you right now. The more important question is whether you'll need the smallest gears that a triple offers. To compare the lowest gearing on a bike, take the ratio of the number of teeth on the smallest cog on the front and the largest cog on the rear cassette. For example, on my tri bike the ratio is 34/25, on my roadie with a compact double it's 34/27, and on my roadie with a triple it's 30/27. This means that on the easiest gear on each bike one turn of the crank gets 1.36 turns of the wheel on the tri bike, 1.26 on the compact double, and 1.11 on the triple. That makes the triple somewhat easier to take up the steepest climbs.

Do you need a triple? It depends on your strength, your weight, and where you plan to ride. If you're a well-built guy who is new to biking and wants to get up some of those NC hills, then a triple could be your friend. I'm relatively light, and climbing is my strength on the bike, but I'm still happy to have my triple when I ride hilly routes in England.

Keep in mind you can always get a compact 50/34 and then an 11-28 cassette.  That is a pretty big range but it all depends on where you are at an also your strength-to-weight ratio on the bike.

fwiw, I still tip the scales at 250 and live in the foothills of the blue ridge mountains with some significant climbs in the area.  haven't dared to ride with the climbers yet.

on the bright side, most of my training rides I rarely leave the center ring--although on the occasional enormous hill it's nice.  the only time I really spent any significant time in the easiest gears was in a race last year with a monster at the beginning and end of the race.

Stick with parts your bike has...no need to invest in improving parts. Save money for new bike in the future.

Triples like others have said tend to not shift as well. Compact doubles with 11-28 or the Sram Apex group up to 11-32 are similar gearing to a triple but can have bigger gaps in gear ratios. Go to Sheldon Brown's website and look up gear ratios and put different crank and cassette numbers in his calculator and see how the gear ratios change.

Your observation about what bikes have triples and which have doubles isn't what I see in market.  In 2006 I bought my first tri bike and back then compacts (which are doubles 50-34) were not very popular not speced (as bike came from mfg) on many bikes, Shimano had only one level compact (not dura ace, ultegra, 105) but I got a compact.

Since 2006 more and more bikes come with compacts as speced from Mfg.

I race cross and I don't think I've seen one cross bike with triple. Many cross racers use single chain ring up front or double with slightly different ratios then compact...I believe my crank is 47-34 or maybe 48, but it is specifically a cross crank.

I agree with this. It's much easier and tends to be more economical this way.

Agreed that most people should be riding compact cranks but most people I talk to either find it incredibly insulting or they don't know what I'm talking about.

I have a triple on my road bike.  I guess I'm a wimp when I ride that and one of the cool kids when I ride my tri bike (standard double).  I do most of my roadie riding on moderate hills and use the two larger rings then.  But when I ride mountains I'm occasionally thankful for the little ring.  I'd rather have it than have to change my cassette every time I go to the mountains.  BTW, I've not experienced any trouble shifting with the triple (Shimano 105).

I found keeping the triple on my cross (racer) has helped me tremendously, especially for steep muddy New England inclines. Most people laugh at me at cross races,  because I hardly ever  have to get off my bike and carry it.  Doubles are great but  triples are definitely ok on cross bikes, if you dont mind the quirky shifting.

Stick with the triple.  Use the small ring when you feel you need it.  As your bike fitness improves you should find that you need it less and less.  After a while, try harder NOT to use it.  I had a triple up until a few months ago and had Shimano Sora, which is one step below Tiagra.

In 3 years of doing Tri's not a single person said anything to me about my triple.  Especially in my last two OLY races

Just note to do this you will need a new front shifter, new front derailleur, and a new crankset.  It ends up being a good chunk of change to make the switchover.

At that kind of expense I'd buy a new bike and keep that one for cross, etc.

Agree most roadies are doubles, but ride what you got.  Been seriously humbled on many group rides by visiting Cat 2/3 road racers on rented entry-level bikes with triple cranksets.  It's the engine not the bike. 

BTW- nothing wrong with Tiagra FD's.  I have a triple Tiagra FD/compact FSA Gossamer crank on an old roadie & it works just fine.