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Front Derailleurs from Harris Cyclery

Double
Full Sized
Double
Compact
Triple
Full Sized
Triple
Mid Sized
Triple
Compact

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There are more complications involved in choosing a front derailer than with a rear:

Mounting

There are 5 different mounting types for front derailleurs, depending on the seat tube diameter of your frame, among other things:

Cable Pull

Large Chain Ring Size

Front derailleurs shift best when they are mounted as low down as is possible without having the cage foul the teeth of the chainrings. In particular, the bottom edge of the outer cage plate should be closely matched to the curvature of the largest chainring.

If you use a front derailleur with a larger ring than it is meant for, the rear of the cage will get too close to the chainring before the front of the cage is close enough to provide crisp shifting.

If you use a front derailleurs with a smaller ring than it is meant for, the front of the cage will get close to the chainring while the rear of the cage is still far away from it. This won't hurt shifting, but will require excessive "trimming" of the front derailer as you change gears at the back.

Mis-matched derailleurs/chainrings may be satisfactory with friction shifting, but will likely cause problems when used with indexed shifters, such as Shimano STI units.

If you have unusual gearing requirements, and are handy, you can re-shape the outer cage plate with a grinding wheel to match a non-standard large chainring.

Double/Triple

Modern derailleurs are optimized for either double or triple chainwheels. The shape of the shifting cage is tailored for the application intended.

"Double" front derailleurs will work with triples, but if the middle ring is much smaller than the big ring, they will be balky shifting up from the small to the middle chainring. They do, however, work well with "half-step-plus-granny" setups, where the middle ring is only 3-5 teeth smaller than the outer ring.

"Triple" front derailleurs may have interference problems between the extended inner plate and the inner chainring.

Indexing Road/MTB

The ratio of cable movement to derailleur movement differs with Shimano's "road" vs. "MTB" front derailleurs. This can cause indexing problems if you use a "road" front derailleurs with upright handlebars or a "MTB" front derailleurs with drop handlebars.
For more on front derailleurs, adjustment and troubleshooting, see my Derailleur Adjustment Article.
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Front Derailleurs:

For Full-Sized Triple Chainrings (Big Ring 52 Teeth or Larger)

See Quality Special Order Catalogue

 

For Mid-Sized Triple Chainrings (Big Ring 46-48 Teeth)

BrandModelRingsBig RingClampPullPriceNote
I.R.D.Alpina-dTriple481 1/8"
(28.6 mm)

1 1/4"
(31.8 mm)

1 3/8"
(34.9 mm)

Braze-on

Bottom
$45.95 buy button
IRD Alpina-d Front Derailleur
The only currently available front derailer that is designed for mid-range ("compact road") triple chainwheels
and compatible with Shimano "road" (drop handlebar) STI shifter indexing.
 

For Compact Triple Chainrings (Big Ring 42-44 Teeth)

(Typical contemporary mountain bikes.)

See Quality Special Order Catalogue

 

For Full-Sized Double Chainrings (Big Ring 52 Teeth or Larger)

(Typical "road" bikes with double chainrings)

See Quality Special Order Catalogue

 

Multi-Purpose (Big Ring 50 Teeth or Smaller)

BrandModelRingsBig RingClampPullPriceNote
ShimanoFD-CX70Double/Triple46-501 1/8" or 1 1/4"
(28.6 mm or 31.8mm)
Bottom
$50.95 buy button
IRD Alpina-d Front Derailleur
Designed for cyclocross but works great for double & triple cranks with smaller chainrings. Works with Shimano STI.

This site also features many
useful articles by Sheldon Brown
and others
.

Articles by Sheldon Brown and others
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