What Is Shimano Shadow RD? Features and Benefits
What is Shimano’s Shadow RD used in their latest rear derailleurs? This article explains its features and the benefits of choosing Shadow RD.
Modified at: Mar 8, 2024
Posted at: Jan 5, 2022
Crank length is a small difference, but it makes a big difference in riding style. In this article, we summarize Shimano's crank length lineup for road cranks and how to find the best crank length.
Table of contents
Sponsored Link
While most complete road bikes come equipped with crank arms that are either 170mm or 172.5mm in length, Shimano actually offers a broader range of crank lengths to suit different rider physiques and preferences.
Shimano’s available crank arm lengths include:
That’s a total of 8 different crank lengths.
The current lineup of Shimano road cranksets offers the following crank length options:
Crankset | Series | 160mm | 165mm | 167.5mm | 170mm | 172.5mm | 175mm | 177.5mm | 180mm |
---|---|---|---|---|---|---|---|---|---|
FC-R9200 | DURA-ACE | ○ | ○ | ○ | ○ | ○ | ○ | ○ | - |
FC-R9100 | DURA-ACE | - | ○ | ○ | ○ | ○ | ○ | ○ | ○ |
FC-R8100 | ULTEGRA | ○ | ○ | - | ○ | ○ | ○ | - | - |
FC-R8000 | ULTEGRA | - | ○ | - | ○ | ○ | ○ | - | - |
FC-R7100 | 105 | ○ | ○ | - | ○ | ○ | ○ | - | - |
FC-R7000 | 105 | ○ | ○ | - | ○ | ○ | ○ | - | - |
FC-4700 | TIAGRA | - | ○ | - | ○ | ○ | ○ | - | - |
FC-R3000 | SORA | - | ○ | - | ○ | - | ○ | - | - |
FC-R2000 | CLARIS | - | ○ | - | ○ | - | ○ | - | - |
DURA-ACE offers the widest range, with seven crank length options—fitting for a top-tier race component designed for professional athletes of all body types.
The older FC-R9100 model included an 180mm option, but this was replaced by a shorter 160mm option in the newer FC-R9200 generation.
For ULTEGRA and lower series, the crank length options are typically limited to 4–5 sizes. This means that riders who need more precise adjustments may need to choose across series.
For example, shorter riders—especially women—seeking the shortest crank length of 160mm should consider DURA-ACE, ULTEGRA, or 105, as these are the only series that offer it.
Meanwhile, entry-level groups like CLARIS and SORA offer fewer length variations. Riders requiring finer adjustments should consider upgrading to at least the 105 series.
Sponsored Link
Since crank length essentially determines the radius of your pedal stroke, a longer crank means a larger pedaling circle, while a shorter one creates a smaller circle.
At first glance, you might think, “It just slightly changes the way you pedal, right?” — but in fact, crank length can significantly affect your overall bike fit.
For example, switching from a 170mm to a 175mm crank adds 5mm to the crank length. That means:
As a result, you may need to adjust your saddle height and fore-aft position.
If you’ve ever had a professional bike fitting, you’ll know that even a 1cm difference in saddle height can noticeably affect your ride. So a change of 5mm or even 2.5mm can make a subtle but real impact.
In general:
That said, these are only general guidelines. Your leg length and riding style also play a big role.
Traditionally, people used the formula:
Crank length = Your height ÷ 10
But in the last few years, the trend has shifted to:
(Your height ÷ 10) − (2.5 to 5mm)
Examples:
That’s why complete road bikes generally come with 170mm cranks — designed to suit the average male rider around 170–175cm tall.
In the past year or two, shorter crank arms have become increasingly popular, even among pro cyclists.
A notable example is Tadej Pogačar, who won the Tour de France twice. At 176cm tall, he was seen using 165mm cranks on his bike during the 2023 Saitama Criterium — something that caught a lot of attention.
Looking at his Strava data, Pogačar’s:
It’s likely that the shorter cranks help him maintain high cadence efficiently.
Crank length can pose a challenge — especially for women riding road bikes.
Take a woman who is 159cm tall, for example. Using the same formula, the ideal crank length would be between 155mm and 157.5mm. However, Shimano’s shortest available crank is 160mm. So in this case, either:
Women often have to pedal in a larger arc compared to men of the same height, which can place more stress on the knees and feet.
To offset this, it’s a good idea to:
These tweaks can help make riding more comfortable and efficient.
That said, there’s no one-size-fits-all rule when it comes to crank length. Even among professional cyclists:
The best way to find what works is by comparing how different lengths feel during actual rides or using ride data.
Since most people can’t easily test multiple crank lengths, your best bet is to visit a bike shop that offers test rides or fittings for different crank setups.
Sponsored Link
Understanding bicycle crank sets
The crankset is an important part of a bicycle. The crankset itself is expensive and cannot be removed without special tools, so it is not an easily accessible customization, but it is also a part that has a large impact on your riding.
PCD compatibility chart for cranks and chainrings
We have compiled a PCD compatibility chart to use as a guide when replacing the chainring on your crank.
Essential Special Tools for Installing and Servicing Shimano Hollowtech 2
Hollowtech 2" is the standard adopted by the latest Shimano front cranks. We have compiled a list of special tools required for installation and maintenance of "Hollowtech 2", which is unavoidable when upgrading to higher grade front cranks.
Shimano Crank Length Lineup and How to Find the Best Crank Length
Crank length is a small difference, but it makes a big difference in riding style. In this article, we summarize Shimano's crank length lineup for road cranks and how to find the best crank length.
Summary of FSA cranks, grades and ratings
FSA cranks are often chosen as standard equipment for complete bikes. Here is a summary of their grades and why they are often rated low.
Q Factor: Measurement, Determination, and Adjustment
Q-factor is an important factor for improving pedaling efficiency. we summarize what Q-factor is, how to measure it, how to determine the proper value, and how to adjust it.
How to Choose a Road Bike for Women - Check Before You Buy
We have compiled a list of how to choose a road bike and parts for women to suit their specific pains and concerns. Please read this before purchasing a road bike.
How to prevent crotch gap in women on road bikes
One of the major concerns of women who ride road bikes is crotch sores. Women's delicate zones are sensitive and can cause more pain and discomfort than men. In this article, we have compiled a list of ways to prevent crotch sores in women.
Shimano Crank Length Lineup and How to Find the Best Crank Length
Crank length is a small difference, but it makes a big difference in riding style. In this article, we summarize Shimano's crank length lineup for road cranks and how to find the best crank length.
Road Bikes for Short Girls: How to Choose the Right Manufacturer
In road bikes that are mainly sized for men, there are few road bikes that can be ridden by women of short stature in the first place. In this article, we'll show you how to choose a road bike that can be ridden by women of short stature, and list the manufacturers that produce road bikes specifically for women.
Choosing the Right Saddle for Your Road Bike, MTB, and Hybrid Bike
The comfort and running performance of road bikes and hybrid bikes depend on the type of saddle. I have compiled a list of how to choose a saddle that suits you.
Advantages and disadvantages of an anagaki saddle
Holey saddles reduce crotch chafing and buttock pain on road bikes. We summarize its advantages and disadvantages.
Customizing a road bike seat post and its effects
Seat post customization has become a standard because it is easy and simple to do, even for beginners of road biking.
Q Factor: Measurement, Determination, and Adjustment
Q-factor is an important factor for improving pedaling efficiency. we summarize what Q-factor is, how to measure it, how to determine the proper value, and how to adjust it.
5 important factors in choosing a road bike frame size
When buying a road bike, frame size is one of the most difficult issues. We have picked up five essential points for choosing the frame size to help you figure out how to select the right frame for your body.
What Is Shimano Shadow RD? Features and Benefits
What is Shimano’s Shadow RD used in their latest rear derailleurs? This article explains its features and the benefits of choosing Shadow RD.
Shimano Chain Compatibility for Road, MTB, and Hybrid Bikes
An overview of Shimano chain compatibility across road bikes, mountain bikes, and hybrid bikes. Includes guidance on how to choose the right chain for your drivetrain.
Shimano ESSA Lineup and Compatibility with Existing 8-Speed Parts
An overview of Shimano's newly released 8-speed component group "ESSA" and its compatibility with existing 8-speed parts.
SRAM Cassette Compatibility Guide
Compatibility guide for SRAM cassettes used in road and MTB bikes. Find matching drivetrains and wheels easily.
Compatibility Guide for SRAM MTB Components
A detailed explanation of compatibility between SRAM MTB components. This guide outlines which parts can be used together and which combinations are not compatible.
Road and MTB Sprockets Compatibility Overview
A guide to the compatibility between road and MTB sprockets, explaining whether they can be used together with different components.
Shimano CUES Cassette Compatibility Guide
A detailed guide to the compatibility of Shimano CUES series cassettes. Includes an overview of compatible rear derailleurs, chains, and wheels.
Shimano Hydraulic Brake Hose and Connector Standards Guide
An explanation of the differences between Shimano’s hydraulic brake hoses BH90 and BH59, the types of connecting bolts, and how to choose the right hose for your brake system—including key points to watch out for.
Types and Compatibility of Shimano Di2 Batteries
The Di2 battery is the core of the Shimano Di2 system, influencing the overall system layout. This article explains the different types and their compatibility.
Shimano Di2 Wire Types and Compatibility
Overview of Shimano Di2 electric wire types and their compatibility with Di2 components.
How to Identify Shimano Di2 Generations
Explains the generational differences in Shimano Di2 components and their compatibility. Includes a list of component series and their corresponding generations.
In-Depth Guide to Shimano 12-Speed Cassette Compatibility
A detailed explanation of the key compatibility factors when using Shimano's 12-speed cassettes—specifically the required wheel (freehub) and drivetrain, which differ significantly from previous 11-speed systems.
Perfect Guide to Shimano 11-Speed Cassette Compatibility
A detailed explanation of two key compatibility factors when using Shimano 11-speed cassettes: the required wheel (freehub) and drivetrain.
Perfect Guide to Shimano 10-Speed Cassette Compatibility
A detailed explanation of two key compatibility factors when using Shimano 10-speed cassettes: the required wheel (freehub) and drivetrain.
In-Depth Guide to Shimano 9-Speed Cassette Compatibility
A comprehensive explanation of two key compatibility factors when using Shimano 9-speed cassettes: the required wheel (freehub) and drivetrain.
Shimano I-SPEC Shift Lever Mount Standards Explained
A complete guide to Shimano's I-SPEC shift lever mount standards, covering features, differences between models, and compatibility.
Shimano Hydraulic Disc Brake Standards and Selection Guide
Unlike mechanical brakes that only pull a cable, hydraulic disc brakes come with various standards and technologies depending on the manufacturer. This article highlights Shimano’s hydraulic disc brake technologies and standards, along with key points to consider when selecting one.
Shimano CUES Components Lineup and Compatibility Guide
A comprehensive guide to Shimano's new CUES component group for MTB and lifestyle categories, including gear ratios, part lineup, and compatibility with traditional components.
TPU Inner Tube: Features, Pros, and Cons for Road Bikes and MTB
TPU inner tubes are gaining attention as the third force in bicycle tires. We summarize its features, advantages and disadvantages of using it on Road bikes and MTBs, and major manufacturers.
Shimano Mechanical Brake Levers for MTB and Hybrid Bike
Shimano mechanical brake levers are now few and far between. The following is a summary of the current model lineup, specifications, and compatible components.