Minuteman Road Club

Shimano and SRAM (as well as Campy) have 3 primary levels of component groups. For Shimano it's 105, Ultegra, and DuraAce. For SRAM it's Rival, Force, and Red (in order from lowest to highest). As you go up each level you go up in price and performance (smoothness, durability) and down in weight. The shifters between the two brands work pretty differently... I've used both and have developed a preference for the SRAM double-tap, but to each their own. One thing to point out is that there aren't direct parallels between the levels listed above. IMHO, Rival is a little better than 105, Ultegra may be a little better than Force (but I think Force is lighter), and I hear Red is better than DuraAce, but I haven't used either except for DuraAce chains. Certain parts of the two brands are compatible with each other, but I'd have to think about which parts. One thing I know from experience is that the chains and cassettes are 100% interchangeable.

If you have specific questions I might know more... your friendly Landry's employee could also answer questions (Try Jeff or Mark). Good luck.

Can you be most specific about what you find mysterious?

SRAM and Shimano use the same spacing so their components are interchangable and compatible.

Campy does NOT use the same spacing as either of the other two and is therefore not compatible with the other two manufacturers.

Campy has further confused things by going to an 11 speed cassette on their top end component group.

SRAM Red, although very new, has gotten a reputation as being better than Dura Ace and at least as good as Campy Record.
RED is lighter than D/A and about the same as Record. It's also a US company.

Bottom line: the top 2 or 3 groups from any of these 3 manufacturers are good quality, light and reliable.
All use a different shifting mechanism. You might have a preference there.

Lynn,
Rich and Colie have summed it up pretty well here. The key difference between SRAM, Shimano and Campy is the way their shifters work. Campy use a combo of a thumb lever on the inside of the hood and an inside lever for shifting up and down. You know how the Shimano shifters works (utilizing the brake lever to shift to larger cogs/rings). SRAM is unique in that it uses the same lever to upshift and down shift (a light inward click moves the chain to a smaller cog/ring, a hard inward click moves the chain to a larger cog/ring). I've made the switch to SRAM Red on my road bike and love it.

I'd suggest you take a SRAM equipped bike out for a quick test ride to get the feel of the shifting. The top end SRAM Red ain't cheap, but you can get the best of its features without all the cost by mixing and matching the components a bit. That is, you could splurge on Red shifters, but use a Shimano ultegra rear der, cog and whatever crankset you prefer. Some prefer the SRAM chain as it's easier to remove and replace (don't need a chain tool). I'd recommend the Red shifters, or Force at least. I tried and found the Rival shifters much less crisp and have heard others say the same. I've also heard the SRAM brakes are a bit spongy, so you might be better off with shimano there.

Are you guys sure that you can use SRAM shifters with Shimano rear derailleurs? Front yes (just installed Rival shifters on my 'cross bike with a Shimano front derailleur) but I've read in numerous places that the rear derailleur with each manufacturer is specific to their shifter.

Lynn, All this great advice on the merits of the various combi brake/gear shifting options may be a moot point if you are using bar end shifters on an aero base/tri bar setup. Not 100% sure but the interchangeability advice above between Shimano and SRAM probably hold true for the indexed bar end shifter for the rear gear. SRAM say their top end Red bar end shifters are "more aero dynamic" believe that if you will

i believe ian gave you the best advice - try before you buy. i went campy because i could not deal with the shimano shifting. once you commit to a brand, it is typically an expensive process to change brands (shifters, cassettes, derailerss are typically a set, and hubs often too)

the bit about bar-end vs bar-bend is quite interesting too. you mentioned you would be using this for triathalon, so testing may be a moot point if you are using separate brake and shift levers

--roger

The Red bar end shifter is supposed to be more aero because it springs back to center after you shift so the lever is always pointed forward.

If a 1 square inch shifter pointing up instead of forward is something that you're concerned about then you must really have the rest of the package dialed in.