Description of the Situation:
You’re wondering whether 26-inch wheels will fit on a 24-inch frame and fork that you already have.
Condensed answer: Most 24-inch bikes are too small and narrow to accommodate a 26-inch wheel unless the model is specifically designed for multiple wheel sizes.
To know with certainty, check the manufacturer’s website or measure the radius and width of the 26-inch wheel that you want to install and compare the findings to the clearance offered by the frame and fork.
Requirements to Fit a 26-inch Wheel On a 24-inch Frame
To know if your current wheel will fit, measure the radius of the wheel and the width of the tire pumped to the desired air pressure. Then, measure the fork and frame clearance as follows:
Fork – measure the distance from the dropouts to the lower wall of the crown as well as the narrowest gap between the fork’s legs.
Frame – measure the distance from the dropouts to the chainstay bridge + the narrowest gap between the chainstays. If there isn’t a chainstay bridge, measure the distance to the seat tube.
Divide at least 5-8mm from each measurement to ensure that the wheels won’t rub. Compare the final numbers to the radius and width of the wheel.
If the size of the wheels exceeds the findings, you won’t be able to install your current 26-inch wheels.
The only option left would be to use a narrower tire such as 1″ (the smaller the tire, the smaller the wheel) and try again.
If that’s not an option, you will have to continue riding with 24″ wheels or change the frame.
The Problems with Installing 26-inch Wheels on a 24-inch Bike
Even if the frame and fork are large enough to accept a 26-inch wheel, the combination still creates some issues listed below:
1. Most Rim Brakes Won’t Work
Cantilever, V-brakes, and Mini V-brakes attach to brake bosses on the seat stays and fork.
The position of the bosses is dependent on the wheel size because the brakes have to grab the rim.
A 24-inch frame and fork have lower brake mounts than 26-inch models because 24-inch wheels have smaller rims.
When you put a 26-inch wheel inside a 24-inch fork or frame, the rim ends up far above the brake bosses making it impossible to use the original brakes.
There are some solutions, but none qualify as super convenient.
The options are:
- V-brake Mount Risers
It’s possible to install V-brake risers – special adapters that mount to the existing braze-ons and provide their own elevated brake spots. The downside of this solution is the extra point of failure introduced to the brake system.
- V-brake Clamp Adapters
Another option would be to install V-brake clamp adapters and place them at an appropriate level.
The con of this method is the price. Some clamp adapters are expensive. If you need four, you may end up paying USD 80-100. For the same money, you can source a second-hand 26-inch rigid frame.
– Cut and re-weld the mounts
Experienced frame builders can remove the existing brake mounts and re-weld them higher on the frame and fork so that the pads can grab the rim of a 26-inch wheel.
In practice, this solution isn’t optimal because the procedure may cost a decent chunk of money. For the same sum plus a little extra, you may be able to find a legit 26-inch frame on the second-hand market.
– Switch to Caliper Brakes
If the frame and fork permit the installation of caliper (road) brakes, you may be able to get a pair working.
The downside? You will need 26-inch road wheels and tires which aren’t readily available because most road wheels are 700c or 29-inches in MTB sizes.
Additionally, if the frame is originally an MTB one, the distance between the rear dropouts is probably 135mm. Meanwhile, the O.L.D. of rear road wheels is 130mm.
Therefore, you would have to cold set the frame to 130mm or buy a custom 135mm wheel.
Note: A frame can be cold set only if it’s made of steel. Other materials don’t handle cold setting well due to their lack of elasticity.
FAQ: What’s O.L.D.?
The term Over Locknut Dimension (O.L.D.) refers to the usable part of the hub or the distance between the outer sides of the two locknuts.
FAQ: What About Disc Brakes?
Disc brakes do not create the above issues because there is no need to move the mounts for the calipers. The brake should work just fine as long as the fork and frame can accept the wheel.
2. Raised Bottom Bracket
26-inch wheels will elevate the bottom bracket of the bike and potentially create instability issues. The chances of experiencing this downside are greater with an MTB frame because mountain bikes have taller bottom brackets for extra clearance by default.
3. Severe Toe Overlap
24-inch bikes are compact and have shorter cranks and frames. When you add bigger wheels, the chances of hitting the tire with your toes during turns a.k.a. toe overlap increase greatly.
4. No Fender Clearance
You would have a hard time installing full fenders because there won’t be enough space for them.
5. Unpleasant Geometry
Bigger wheels would make the bike look larger, but the frame will remain the same. The rider may still find the geometry limiting/compressing.
Some Bikes Are Designed to Support 24-inch and 26-inch Wheels
Some 24-inch children’s bikes are engineered to accept multiple tire sizes to eliminate the need for a new bike as the child grows.
Below is a list of models with that feature:
|Model||Wheel Size Support|
|Rocky Mountain Reaper||24”, 26”|
|Scott Ransom 400||24”, 26”|
|Spawn Rokk||24”, 26”|
|Slater Mobster||24”, 26”|
|Mondraker Factor 24||24”, 26”|
|Propain Yuma||24”, 26”|
|The Flow Drifter||24”, 26”|
FAQ: Can you put 24-inch wheels on a 26-inch bike?
The reverse exercise (24-inch wheels on a 26-inch bike) is easier. If a bike has clearance for 26”, it can obviously accept 24” wheels.
However, the problem with rim brakes would still manifest because the braze-ons would be at the wrong place. If the bike uses disc brakes, this won’t be an issue.
For that reason, some people future-proof a bike by buying a 26-inch model and putting a 24-inch wheel on it. When the kid is large enough for a 26-inch bike, the original rims are installed.
Summary: What You Need to Know
1. Very few dedicated 24-inch frames have clearance for 26-inch wheels.
2. The frame may have clearance for 26-inch wheels, but the conversion would still create problems (brake mounts at the wrong place, unnaturally high bottom bracket…etc.)
3. There are mountain bike frames and forks designed to support both 24 and 26-inch wheels.