Bicycle Mechanics - Newb question about derailluers and STI shifters

I've got a bike with Sora components and mostly to improve my bike mech. skills, I'd like to upgrade most of the drive train components.

What determines whether a derailluer and/or shifter is for a triple/double (front) or a 8/9 speed (rear)? To make things simpler, Shimano components only please.

As far as the rear, it's the same. The only difference for the rear is the chain, where the links are skinnier and can handle an extra gear. You will also need matching shifters for the swap from 8 to 9 speed.

As far as the front, I'm thinking it's the shifter and adjustments on the stops, but I'm not totally sure.

Originally posted by purple hayes
I've got a bike with Sora components and mostly to improve my bike mech. skills, I'd like to upgrade most of the drive train components.

You know, you could accomplish that goal by just removing, cleaning and lubing, and reinstalling the same parts. Sometimes it's a lot more cost effective to just sell a low-end road bike and buy a new one with the drivetrain you want. Drivetrain parts are far more expensive as aftermarket upgrades than they are as part of a new bike. Just a thought.


Originally posted by purple hayes
What determines whether a derailluer and/or shifter is for a triple/double (front) or a 8/9 speed (rear)? To make things simpler, Shimano components only please.

FD's for triple usually have a deeper inside plade to assist the jump from the inside ring. "Double" FD's will usually still work. RD's will work with either 8 or 9 speed -- it's the shifters that determine which you have. You'll have to replace the Sora levers if you want 9-speed, and that's the most expensive drivetrain part. Thus what I said above.

With a Sora drivetrain, you can upgrade either derailleur (but you'll still have an 8-speed drivetrain), the cranks, the cassette (but only with another 8-speed cassette).

RichC

The nine speed front der. is very slightly narrower than the eight or seven. If you swap to nine but leave the old front der., shifts will be sluggish, you can tweak the thing skinny with a pair of channel locks however.
If you want to learn use what you have. Adjust things one adjustment at a time, watch what change it makes, if you don't get an improvement with that adj. go back to the start point.

Triple front derailleurs are different from doubles in a couple of ways:

The inner cage plate is deeper to minimize throwing the chain over the grannie ring and to lift it up to the middle ring better. The cage is also longer in back to prevent chain rubbing if you use the grannie with a small cog combination.

Most, but not all, of the Shimano STI shifters are rated to operate either a triple or a double front crankset. Unfortunately for you, Sora is one of the nots.

9-speed cassettes cram 9 cogs in the same amount of space that 8-speed cassettes have 8. Consequently, if you try to use a 8-speed shifter with a 9-speed cassette, it will be noisy in most gears and will skip one gear as you shift up the cassette.