Posted at: Jul. 19, 2022
With the popularity of gravel road bikes and the spread of disc brakes, the choice of road bike wheel size has become not only the standard 700C, but also 650B. In this issue, we will look at the differences between 700C and 650B, and the advantages and disadvantages of each.
Table of contents
Sponsored Link
650B wheels have been gaining attention along with the popularity of gravel road bikes in the past few years.
The difference between the standard road bike 700C wheels and 650B wheels is the diameter of the wheel rim: 700C is 622 mm and 650B is 584 mm, with 650B having a smaller wheel rim diameter.
Although 650B wheels are smaller when compared only in terms of wheel rim circumference, there is no significant difference in tire circumference because gravel roads are equipped with thicker tires such as 44C.
The advantage of 650B is the smaller diameter of the wheel rim. One advantage of the smaller diameter is that larger tires, such as 43C, can be installed.
Installing a larger tire increases the air volume inside the tire, which increases the cushioning of the tire and improves vibration absorption performance, resulting in a more comfortable ride.
Another advantage of the 650B is that the same frame can be fitted with larger tires.
For example, since 700-25C and 650-45C are said to have roughly the same tire circumference, a frame with no clearance of about 700-28C maximum can be fitted with a larger 43C tire on a 650B wheel (if tire width is not a problem).
Although described as 650B in road circles, it is actually the same size as a 27.5” MTB. Therefore, 650B wheels can be used on 27.5-inch MTBs.
MTBs use thicker tires, so 700C (29er) wheels are taller and require more maneuverability, so the 27.5 size has become the standard for MTBs for city riding and entry-level models.
The conventional wisdom is that 650B wheels cannot be installed on a 700C bike. This was because the conventional brake was a type of brake that sandwiches the rim, and “smaller rim = brake arm cannot reach = another size cannot be installed”.
However, with the spread of disc brakes that sandwich the rotor, the distance from the frame to the rim is no longer relevant to braking, and 650B wheels can now be installed on a 700C bike.
Conversely, 650B wheels cannot be installed on 700C wheel models on rim-brake or V-brake sport bikes.
The advantage of a 700C wheel would be the higher turning performance due to the larger circumference; there is little weight difference between a 700C and a 650B wheel, so for the same weight, the larger circumference will go better. Also, for the same tire circumference, the 700C tire is narrower, so the tire itself is lighter.
The disadvantage of 700C is that the larger wheel rim circumference requires more clearance on the frame side to accommodate a larger tire.
Road bikes that are designed to accommodate large tires, such as gravel road bikes, have a wide clearance geometry, but normal racer-type road bikes are designed to have as little clearance between the tire and frame as possible, taking aerodynamic effects into consideration.
Therefore, a road bike designed for 700-28C or so will not fit a larger tire such as 700-44C in terms of clearance.
Let’s compare the circumference of 700C and 650B tires to see how much difference there is between them.
| Size | 700C | 650B |
|---|---|---|
| 25 | 2111mm | 1991mm |
| 28 | 2130mm | 2010mm |
| 30 | 2142mm | 2023mm |
| 32 | 2173mm | 2035mm |
| 35 | 2168mm | 2054mm |
| 37 | 2186mm | 2067mm |
| 38 | 2192mm | 2073mm |
| 40 | 2205mm | 2086mm |
| 42 | 2217mm | 2098mm |
| 44 | 2230mm | 2111mm |
※May differ from ETRTO’s specified circumference size
Reference: A Chart of Wheel Sizes with an explanation of BikeCalc’s math
So, which is better, 700C or 650B? It depends on “how fat tires you want to run”.
If you are fine with “a moderately fat tire” of about 30C, the latest disc brake road bikes have clearance up to about 28-30C, so you will have a lighter ride if you choose a 700C, which has higher running performance. However, at around 30C, stability when riding on gravel or dirt is not very high.
If you want MTB level stability on gravel and dirt, you can choose 650B because 700-25C and 650-45C have the same tire circumference, which solves the clearance problem, and 650-42C is almost the same size as 27.5 x 1.75, which is considered a little narrow for MTB. The 650-42C is almost the same as the 27.5 x 1.75 size, which is a bit narrower than the 27.5 x 1.75 size for MTB.
What you should pay attention to is “where you want to ride mainly.” A tire as large as 43C will give you stability on unpaved mountain roads, but the feeling of riding on paved roads will be lower than a 28C or 30C narrow tire.
If you mainly ride in town or on mountain roads, you can choose a 650B for a relaxed ride, or a 700C if you want to ride at a certain speed on main roads or bike paths.
Sponsored Link
What to do when you get a flat tire with a tubeless or tubeless ready tire
Tubeless tires have seen a dramatic increase in the number of users over the past few years. Even with tubeless and tubeless ready tires, punctures cannot be reduced to zero. The following is a summary of the causes of punctures and how to deal with them.
How to check compatible tires from wheel specs
When trying to change tire thickness on a road bike or other sport bicycle, it is important to know what tire size the wheel will allow. In this article, we will show you how to find out which tires are compatible with your wheel based on its specifications.
What is a tubeless valve? Types and How to Choose
The tubeless valve is an essential item for tubeless use. What is a tubeless valve, tubeless valve types, and how to select one are summarized below.
What is SRAM's XDR and XD? What is the difference from Shimano?
The following is a summary of SRAM's proprietary XD and XDR standards, what makes them different from Shimano's, and what to look for when purchasing.
Summary of Shimano wide ratio sprockets for road bikes
Shimano wide-ratio sprockets for road bikes are listed here, including compatibility by step number.
Summary of 12-speed chains for use with Shimano road bike and MTB components
We have compiled a list of 12-speed chains that can be used with Shimano road bike and MTB components. Also about chain compatibility with chains from manufacturers other than Shimano.
Types of bicycle disc brake mounts, how to recognize them, and how to choose an adapter.
Mounting adapters for bicycle disc brakes are essential when changing calipers with different standards or rotor sizes. This section explains the types of mount adapters, how to recognize them, and the model numbers of Shimano's mount adapters.
Inside, outside serrations? Types of center lock locking rings
There are two types of lock rings for center locking disc brakes, inner serration and outer serration. The following is a summary of the differences and how to select the right one.
Summary of mechanical disc brake calipers for road use
Mechanical (mechanical) disc brake calipers are ideal for ease of maintenance and as an upgrade from rim brake components. Models from major manufacturers are listed below.
What is a Through Axle? Types and How to Choose
Through-axle is becoming a major fixation method for disc brake wheels. What is a through-axle? Here is a summary of what types are available.
Types of disc brake rotors and how to select them
Disc brake rotors are an unassuming part, but they have a significant impact on the effectiveness of disc brakes. We have compiled a list of the different types of rotors, how to select one, and the lineup of rotors from major manufacturers.
Disc brake pad types and selection
Brake pads are installed on the calipers of disc brakes. In fact, there are multiple types in terms of material and shape. The following is a summary of disc brake pad types and how to select the right one.
Summary of hex wrench sizes to prepare for road bike maintenance.
For those who will be servicing their road bikes, we have compiled a list of hex wrench sizes that are commonly used for road bike maintenance and that you should have available.
Latex Butyl? Different tire tube materials and how to choose the right one.
There are two types of bicycle tire tubes, latex tubing and butyl tubing. The following is a summary of the differences between the two and which one you should choose.
Guide to Choosing Binding Pedals for Road Bikes
Binding pedals allow you to ride faster and more efficiently on your road bike. In this article, we will thoroughly explain what to look for when choosing binding pedals.
Summary of binding pedal cleat types and their respective characteristics
Cleats are the parts that connect binding pedals to shoes. Cleats are only one part, but each manufacturer has its own characteristics and differences. They are actually important parts that are linked to usability and their merits and demerits.
Advantages and disadvantages of putting sealant in road bike and MTB tires and how to choose
This section summarizes what sealants are for road bikes and MTBs, their advantages and disadvantages, and how to select sealants.
Types of valve extenders and how to select one
A valve extender, which extends the valve, is an essential item for operating deep-rim wheels on road bikes and other vehicles. The following is a summary of the different types of valve extenders, their differences, and how to select one.
Summary of brake shoes for carbon rim and wheel
When using rim brakes on carbon rim/wheels, it is essential to use special brake shoes to reduce braking force and damage to the rim. In this issue, we introduce a collection of brake shoes for carbon rim wheels.
Advantages and disadvantages of front single
The "front single" without front shifting is being increasingly adopted in MTB and gravel road bikes. This section summarizes the advantages and disadvantages of the front single.