A few years ago, bikers didn’t have many options regarding wheel sizes; 26-inch wheels were standard. Nowadays, 29” and 27.5” wheels are more common, with the 27.5” gaining popularity due to its playful, lightweight, and highly-maneuverable frame.
Many people with 29” bikes have started swapping wheel sizes for 27.5”. So the question is: what happens when you change wheels, and should you change them? Does this affect your riding experience and safety?
Let’s answer all those questions, so you have all the necessary info before taking your bike apart.
Wheel Size Compatibility
Bike wheel sizes vary, from 16-inch kids bike to 32-inch wheels for adults.
Wheel Size Standards
Wheel sizes are broken down according to their use and the type of bike you have.
For example, 16” wheels are mainly used in children’s bikes, while 20” wheels are very popular in BMX bikes. Most American adult bikes have 26” wheels as the standard wheel size.
Most adult mountain bikes have either 27.5” or 29” wheels. Anything bigger than that, like 32” and 36” bikes, is usually custom-made for people with larger and taller frames.
This begs the question: if 27.5” and 29” bikes are the standards for mountain bikes, how interchangeable or compatible are they?
27.5” and 29” Wheels Compatibility
Technically speaking, 27.5” wheels are compatible with a 29” bike assuming the bike and wheelset are designed for disc brakes. However, you can’t expect to mess with the laws of bike nature without ramifications.
You’ll get some benefits from swapping the wheels but also have to deal with some obstacles.
Replacing the wheels can lead to reduced frame and pedal clearance. That also means the geometry of the bike is altered. You’ll feel the bike sitting somewhat lower than before, meaning it could run up against obstacles which can be frustrating.
You might also experience frame and pedal strikes. However, some benefits make 27.5” wheels worth it.
Benefits of Using 27.5-Inch Wheels on a 29-Inch Bike
You’ll want to use a 27.5-inch wheel because of the following advantages:
- Improved Maneuverability
You get more maneuverability when you swap out your 29” wheels for 27.5” ones.
Normally, 29” bikes have a longer frame because of the larger wheel size, making them more flexible. That’s great when you’re pedaling down a straight path, but when you get to tight turns and twisty roads, you’ll experience some resistance with a 29” wheel.
The 27.5” wheels are more snappy and easier to maneuver when you’re riding non-linear trails with sharp twists and turns.
- Better Acceleration and Handling
The 27.5” wheels have greater acceleration than the 29” ones. This is partly due to the reduced weight of the smaller wheels, but there’s also a scientific component that makes smaller wheels rotate faster.
As bike wheels get bigger, most of the weight from the spokes, rims, tubes, and tires starts to shift away from the wheel’s center. In physics, this is called having greater rotational mass, which means it’s harder to rotate the wheel, thus reducing the acceleration speed.
The 27.5” wheels have better weight distribution and acceleration, which makes them feel faster, more snappy, and highly responsive.
- Ability to Use Wider Tires
One benefit to having 27.5” wheels is you can use wider tires. This can be a clever way to minimize the geometry changes caused when you swap out your 29” wheels for 27.5” ones.
Sure, you might still experience a slight bottom bracket drop, but the broader tires can make up for some of the size difference while maintaining the benefits of a smaller wheel.
Drawbacks of Using 27.5-Inch Wheels on a 29-Inch Bike
While using a 27.5” wheel is great, it has some downsides.
- Potential Impact on Bike Geometry and Handling
When you replace your 29” wheels with 27.5” ones, expect some changes in your bike geometry and handling.
You might notice a slight lowering in the bottom bracket, and the pedals might start hitting random obstacles more often, like rocks and roots. It usually isn’t that serious, but if you’ve been riding for some time, you’ll notice these small differences.
- Difficulty Finding Compatible Parts
When swapping wheels, keep in mind it can be difficult to find compatible parts.
For example, if you’re using 27.5” plus wheels, you’ll need boost hubs, which are much wider than standard hubs. You’ll need to make sure the hubs and other components are compatible when swapping your 29” wheels for 27.5” ones.
- Reduced Efficiency and Speed
While 27.5” wheels have faster acceleration, 29” wheels can give you more speed and efficiency overall if you’re going on long rides.
The 29” wheels have slower acceleration, but once they reach their top speed, they require less effort and momentum to keep going. They also have more traction due to a larger contact patch, making them more efficient when cycling on slippery roads.
Considerations for Changing Wheel Size
You might want to change your 29” wheels to 27.5” ones for several reasons.
It could be for better acceleration and maneuverability, or you could simply want a wheel size more suited for shorter individuals. The smaller wheel size lowers the bike’s center of gravity, which is excellent for cornering stability.
If you decide to swap wheels, remember that proper installation and maintenance are important.
If you feel like your bike is dragging or your wheels aren’t spinning freely, chances are you didn’t install them properly.
Factors to Consider Before Swapping Wheels
Before swapping your 29” wheel for a 27.5”, take note of these factors first:
Type of Roads (Maneuverability)
The 29” wheels are better for straight roads, while the 27.5” wheels are better for twisty trails.
Shorter individuals will be more comfortable with the 27.5” wheel.
Ground Traction & Stability
The 29” wheels offer more traction and grip, making them more stable and ideal for slippery roads.
Acceleration and Speed
While 27.5” wheels offer more acceleration, 29” ones provide more speed in the long run, making them ideal for long rides.
So is it okay to put 27.5” wheels on your 29” bike? The answer is yes.
While this might affect the geometry and handling of your bike, you’ll get more maneuverability and acceleration, which are perfect for twisty roads and sharp corners.
Even better, throw in a pair of wide tires, and you’ll barely notice the change in geometry.
Give the 27.5” wheels a try if you’re uncertain which size suits you best. As cyclists like to say, “when in doubt, pedal it out!”