Accessories Bicycles Parts Specials Tools View Cart

In West Newton Since 1952 - On The Web Since 1995

NEW! harriscyclery.net Catalog for a more Contemporary Shopping Experience.

Rear Derailleurs from Harris Cyclery

Shimano

Simplex

divider

Adaptor Claws | Cables | Chain Deflectors | Derailers (Front) | Derailers (Rear) | Shifters | Hangers

divider

A note about range:

Rear derailers are often differentiated into "road" and "mountain" models. This is actually a false distinction based on marketing hype. A more meaningful distinction would be:

RangeCage
Code
Cage
Length
Note
Wide
Range
SGS86 mm center-to-centerIf you want to use a rear sprocket bigger than 30 teeth, this is the type you must have.
The marketeers call this a "mountain" size, but that's a bogus designation. This is what you want for most touring applications.
Medium
Range
GS74 mm center-to-centerErroneously called "long cage" in "road" contexts, this is actually the medium length cage.
It is, however the longest that has the marketing designation "road."
Narrow
Range
SS50 mm center-to-centerRoad racing. SS cage derailers are not recommended for wide-range cassettes or triple cranks.

Generally, in the Shimano line, the wide-range models will handle up to a 34 tooth sprocket; medium-range models will handle up to 30 tooth sprockets, and narrow-range models will handle up to 28-30 tooth sprockets. Wider range models also have more chain takeup capacity, which makes them more compatible with wide range (triple) chainwheel sets.

A note about capacity:

Manufacturers have to assume that their customers are clueless, and will expect the chain to have some tension on it even in the bad gears where the chain is using small chainrings with small rear sprockets. Thus, the rated chain-wrap capacity is very conservative. A competent cyclist who uses the gears properly can generally exceed this by several teeth with no problem.

Most derailleurs also specify a maximum size rear sprocket. This is often a pessimistic value, based on the largest sprocket that is normally provided as part of that group.

How Many Speeds?

Rear derailleurs often are referred to as "7-speed", "8-speed" or "9-speed." This is not as important a distinction as it might appear. Current model derailers are pretty much interchangeable within brands. A "7-speed" or "8-speed" designation generall just indicates that the derailer is an older design, or a cheaper model. They'll all work with all 3 systems, though the models marked "9-speed" will generally be slightly better (whatever cluster you use.)
 
Shimano Rear Derailleurs
(Work with most shifters. Check with us if you're not sure.)
ModelRangePriceLargest
Sprocket
Chain Wrap
Capacity
WeightShimano
Series #
Note
XT Shadow
Top Normal
WideRD0776 $129.95
buy button
3645 235 gRD-M772 DESCRIPTION
SLX SGS
Top Normal
Shadow
WideRD6030 $89.95
buy button
3445 260 gRD-M662 DESCRIPTION
Deore SGS
Top Normal

(Silver)

WideRD7592 $62.95

buy button
3443 300 gRD-M591 DESCRIPTION
Deore SGS
Top Normal

(Black)

WideRD7590 $62.95

buy button
3443 300 gRD-M591 DESCRIPTION
Acera SGSWideRD8789 $27.95
buy button
3238 DESCRIPTION
Tourney MegaRangeWideRD8154 $19.95
buy button
3440 DESCRIPTION
Tourney MegaRangeWideRD8153 $18.95
buy button
3440 With
adapter claw
DESCRIPTION
Tiagra SS "Double"NarrowRD4600 $59.95
buy button
30N/A N/ARD4600 SS DESCRIPTION
Tiagra GS "Triple"Medium *RD4404 $56.95
buy button
2737 280 gRD4500 GSDESCRIPTION
RD-2300 SS "Double"NarrowRD2300 $29.95
buy button
26
(Conservative spec
from Shimano.
Will accept 28t.)
N/A N/ARD2300 SS DESCRIPTION
For More Rear Derailers, Check the QBP Catalog Here

Low-normal vs High(Top)-normal

Most rear derailleurs are pushed by a spring toward the highest (smallest) sprocket, and the shift cable pulls them toward the lowest sprocket. Shimano "Rapid Rise" rear derailleurs ( XTR Rapid Rise, Nexave T400, MegaRange Rapid Rise and Tourney Rapid Rise )work the opposite way, springing toward the lowest (largest) sprocket. This system provides slightly better downshifting, but can be confusing to a rider who is accustomed to high-normal derailleurs. Either type may be used with any contemporary Shimano shifter, but if you use a low-normal derailleur on a shifter made for high-normal, the indicator numbers will read backwards, and you will have to shift in the opposite direction. However, if you use a Rapid Rise derailleur with bar end shifters, both shifters will shift in the same direction ( up will be higher ).

Hanger vs Frame Mount

Some derailleurs include a built-in hanger, an adaptor claw that permits them to be attached to a frame that does not have a built-in derailer mount on the right dropout.

The adaptor claw's bolt and its special shoulder nut fit in the back of the axle slot. When normally installed, the left end of the wheel's axle will wind up near the middle of its axle slot.

This is normal. There are millions of bikes on the road using this system.

Adaptor claw
This dropout fits a standard derailleur This dropout requiers a derailleur
with a hanger,
or a separate adaptor claw
Adaptor claw $3.95
buy button
Many newer bicycles have built-in but replaceable hangers. There is a bewildering variety of types of these, with limited interchangeability. See our:

Replaceable Derailleur Hanger Page

divider

Front Derailers

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

Articles by Sheldon Brown and others
Harris
Home
Beginners Brakes Commuting
Lights
Cycle-
Computers
Do-It-
Yourself
Essays
Family
Cycling
Fixed Gear
Singlespeed
Frames Gears &
Drivetrain
Bicycle
Humor
Bicycle
Glossary
Bicycle
Links
Old
Bikes
Repair
Tips
Tandems Touring What's
New
Wheels Sheldon
Brown
divider

Web site by Sheldon Brown

URL: http://harriscyclery.com/derailers-rear.html

Copyright © 2005, 2008, 2010, 2012, 2013 Harris Cyclery