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Rear Derailers from Harris Cyclery

Shimano	Simplex

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

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:

Range	Cage Code	Cage Length	Note
Wide Range	SGS	86 mm center-to-center	If 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	GS	74 mm center-to-center	Erroneously 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	SS	50 mm center-to-center	Road racing. Not recommended for general use. SS cage derailers don't work any better than GS models, just a couple of grams lighter.

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 derailers 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 derailers 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 Derailers (Work with most shifters. Check with us if you're not sure.)
Model	Range	Price	Largest Sprocket	Chain Wrap Capacity	Weight	Shimano Series #	Note
XT Shadow Top Normal	Wide	RD0776 $99.95	34	45	235 g	RD-M772
LX SGS	Wide	RD5626 $64.95	34	45	288 g
Deore SGS (Silver)	Wide	RD7518 $49.95	34	43	300 g	RD-M531
Deore SGS (Black)	Wide	RD7517 $49.95	34	43	300 g	RD-M531
Acera SGS	Wide	RD8789 $27.95	32	38
Tourney MegaRange	Wide	RD8154 $19.95	34	40
Tourney MegaRange	Wide	RD8153 $18.95	34	40		With adapter claw
Tiagra SS "Double"	Narrow	$47.95	27	29	265 g	RD4500 SS
Tiagra GS "Triple"	Medium *	$49.95	27	37	280 g	RD4500 GS
Ultegra 10 Speed SS "Double"	Narrow	$93.95	27	29	209 g	RD6600 SS
Ultegra 10 Speed GS "Triple"	Medium *	Special Price!$79.95	27	37	219 g	RD6600 GS
For More Rear Derailers, Check the QBP Catalog Here Low-normal vs High-normal Most rear derailers are pushed by a spring toward the highest (smallest) sprocket, and the shift cable pulls them toward the lowest sprocket. Shimano "Rapid Rise" rear derailers ( 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 derailers. Either type may be used with any contemporary Shimano shifter, but if you use a low-normal derailer 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 derailler with bar end shifters, both shifters will shift in the same direction ( up will be higher ). Hanger vs Frame Mount Some derailers 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. This dropout fits a standard derailer This dropout requiers a derailer with a hanger, or a separate adaptor claw Adaptor claw $3.95 Many newer bicycles have built-in but replaceable hangers. There is a bewildering variety of types of these, with limited interchangeability. We carry some of these, and can order some others for brands that we are a dealer for. See our: Replaceable Derailer Hanger Page http://harriscyclery.com/hangers/index.html The 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. Front Derailers Adaptor Claws | Cables | Cassettes | Chains | Chainrings | Cranks Derailers (Front) | Derailers (Rear) | Freewheels | Shifters 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 Feedback? Questions? Web site by Sheldon Brown Ordering Feedback? Questions? URL: http://harriscyclery.com/derailers-rear.html Copyright © 2005, 2008 Harris Cyclery