shop guy questions . . . 105 levers

[ninjabirdman]

so i'm upgrading my drivetrain this spring from the crappy sora groupo that came w/ my bike. so far i have an ultegra casette ( el chup) and 105 rear derailleur.

So, I've been checking out 105 levers on ebay, and they seem to say that they support both 2 and 3 gear cranks. how does this work?

Once i have 9-speed levers, i should be able to continue to use the sora front der and 3-speed crank until i find good deals on those parts, right?

pardon my JONG

[Spats]

So, I've been checking out 105 levers on ebay, and they seem to say that they support both 2 and 3 gear cranks. how does this work?

You can't push the FD past the limit screws, so the third click never gets used.

You can do the same thing with trigger shifters on a MTB: lots of people run 2 rings + bashguard, but there aren't any 2-ring shifters anymore.

[1wsguy]

Rear deraileurs are either long cage (triple) or short cage (double). If your new deraileur is a short cage, then it might have trouble taking up the chain slack.

Also if you are considering switching to a double, you should also replace the bb and front deraileur, since theese are also double or triple specific.

[ninjabirdman]

wow, the RD is really different depending on front crankset? i thought shimano derailleur sets usually had 3 part nos . . . RD, 2FD and 3FD?

in any case, I like the flexibility of a 3-gear front crank and the extra weight builds character anyway. i was mostly trying to figure out if I was going to have to adjust the left lever into 3-gear mode

[Spats]

wow, the RD is really different depending on front crankset? i thought shimano derailleur sets usually had 3 part nos . . . RD, 2FD and 3FD?

The issue is how much cable the derailleur can pull -- which must be at least the difference between the small-small and large-large gear combinations. That's why you have short-cage and long-cage derailleurs.

The reason everyone doesn't just run long-cage is that the short-cage versions shift more quickly, don't bend as easily, and weigh less. A lot of DH mountain bikers actually use short-cage road derailleurs since they've only got 1x9.

[ninjabirdman]

how can i tell the difference?

if it looks "long"?