Triple crank & BB, triple front der.... You will also need a new left
brifter to shift the triple.

If a wider cluster might fit your needs you can use a 12-27 with the stock
105, and maybe up to a 30. Or just switch the rear derailer to a MTBike (XT
or LX or ...) and use a 12-34. That's what I do with my Dura-Ace setup when
I want to tour with some extra baggage. I use a 12-34 w/ a 50-38, and only
switch the rear derailer. The 12-34 has very even ratios of 10 to 15%.
12-14-16-18-20-23-26-30-34

15.4% = ln(14/12)
13.4%
11.4%
10.5%
14.0%
12.3%
14.3%
12.5%

-Bruce



"Rick Onanian" wrote in message
news

I'm looking at Shimano's website, considering a triple
crankset for my 2001 Giant TCR2, stock all 105 double.

I'm trying to figure out how little I can get away with
changing to put a triple on here.

I can see that I'll need [obviously] a crankset and a
front derailleur, but I wonder if I can get away with
no new rear derailleur.

How about, instead of a triple, compatibility with a
mountain bike rear derailleur and then I use a really
wide ratio cassette? I'd rather have the triple, but
are Shimano road shifters compatible with Shimano
MTB rear derailleurs?

I think I don't understand a few terms. Here's what the
site says about 105 double and triple rear derailleurs:

Rear derailleur for double cranksets:
Total Capacity: 37t
Front Difference: 22t

Rear derailleur for triple cranksets:
Total Capacity: 29t
Front Difference: 14t

Maybe I don't understand the terminology, but I figured
that the capacity is the amount of chain slack that the
derailleur can take up, and the front difference is the
largest difference in chainring that the rear derailleur
can swallow suddenly (though I'm sure I'm wrong about
that, I think I'm right about capacity).

Everything else is the same (except the one for triples
weighs a few more grams).
Info from:
http://bike.shimano.com/Road/105/com...umber=RD-5501-
SS-S
http://bike.shimano.com/Road/105/com...umber=RD-5501-
GS-S

Or, in tiny URLs:
Double -- http://tinyurl.com/jilr
Triple -- http://tinyurl.com/jilp


--
Rick Onanian