Getting the right bike size can become quite complicated if you’re in dogged pursuit of finding specific performance characteristics. You can’t just grope after a sleek carbon fiber mountain bike without taking into account its size configurations from the get-go. A mountain bike that is way off your ideal size will be more difficult to ride over trickier terrains and will bring numerous handling issues and back problems. Besides having more comfort and better control, a properly sized mountain bike goes a long way in bringing years of enjoyment and confidence on the trails.
For bike enthusiasts coming from other cycling backgrounds, it’s interesting to note that size varies greatly between a BMX size, a road bike, and a mountain bike. If you’re concerned about what to consider in terms of size, this guide will help you get a better grasp on what size mountain bike you need and save you from the hassle of going through different size charts to pick the right one for you.
Important MTB Sizing Measurements
It’s all too easy to choose a wrong-sized mountain bike. The problem is that frame sizes are all over the place and there is no consistency, not one that tallies with the manufacturer’s measurements at least. While using the rider’s height and the length of the seat tube are a useful benchmark to get a clearer picture of the frame size, they do not account for a good fit. Using height is only useful for ascertaining whether the frame is too short or too high.
Below you will find a few other key indicators that help you get a better idea of what your ideal mountain bike size is. Keep in mind that they will only get you close to your ideal size. Sizing will still vary depending on your riding style and personal preferences.
Effective top tube length (ETT)
Effective top tube length measures the horizontal distance from the top center of the head tube down to the center of the seat post. ETT is useful for determining how the bike fits while you’re seated on the saddle. It is a good indicator of the comfort, fit, and handling of your bike but it only affects your position while seated. This might be a useful measurement for enduro riders who prioritize pedaling power and get to be on the saddle more frequently. Other than that, ETT doesn’t always tell the whole story as frames have evolved beyond the conventional diamond-shaped hardtail.
Reach
Reach measures the horizontal length between the center of the head tube and the center of the bottom bracket. Reach is a deciding factor of how roomy the bike will feel and how it reflects on the cockpit length while you’re standing up on the pedals (common for downhill biking).
Reach is arguably the most reliable indication of a bike’s size without being affected by different shapes of seat tube angles, or taut head angles. A long reach would force you to lean over and stretch out, whereas a short reach would keep you cooped in in an overly upright position. Accordingly, identifying your perfect reach will put you in a better position to achieve a more suitable and strong riding position.
Standover height
While it’s difficult to gauge your bike size based solely on standover height, it is still a useful indicator to determine whether a bike fits or not. Standover height is the gap between the top tube and your crotch which is measured by standing right in front of the saddle. When measuring your standover height, it is important to leave a clearance of at least two inches between the top tube and your crotch. This will make it easier for you to comfortably dismount while on the trail and quickly hop off when needed. Unless you plan to ride shoeless, make sure to also wear your shoes when assessing your standover height as this will give you a more accurate overall leg length.
Seat Height
Setting your seat height correctly can have a large impact on the handling and pedaling efficiency. Seat height is especially important for beginners who need to frequently stop and take their feet on firm ground. For efficient pedaling, you’d want a seat angle that offers you a proper position over the bottom bracket. To raise or lower your seat you need to release the lever on the seatpost using a torque wrench or just push a button depending on your bike setup.
While you need to try out different seat heights until you find what fits best, we recommend lowering your seat to the point where you have a slightly bent knee. Don’t take it too far though, as a bent knee can become weak and more susceptible to injuries.
What Size Mountain Bike Do I Need?
Our size chart provided below is a good starting point to help you find your ideal mountain bike size. While height and frame size are a solid baseline, it is recommended to check other factors such as standover height and seat height. These measurements are pretty much the same for all disciplines and terrains of mountain biking. If you happen to be in between sizes, it’s best to opt for the smaller size as accommodations can be worked out later so you don’t get a painful experience.
Mountain bike size chart
| Height | Standover Height | Frame Size | Standard Sizing |
| 4’10” – 5’2″ | 25″ – 26″ | 13” – 15” | XS |
| 5’3″ – 5’8″ | 27″ – 30″ | 15” – 17” | S |
| 5’9″ – 5-11″ | 29″ – 32″ | 17” – 19” | M |
| 5’11” – 6’3″ | 31″ – 34″ | 19” – 22” | L |
| 6’4″ – 6’6″ | 33″ – 37″ | 21” – 24” | XL |
| 6’6″ and over | 35″ and over | 23” – and over | XL-XXL |
Choosing the appropriate mountain bike size is as crucial as choosing its design. It would be a big-time mistake to just pick an expensive carbon fiber mountain bike without taking into account its measurements. Unlike apparels, you can’t just alter a carbon fiber frame. Having said that, it’s crucial to get the right fit from the outset.
Another thing to consider is the type of riding you plan to do, as bike sizes vary greatly between types of bikes and riding styles. As mentioned earlier, riding in the mountains and riding on the road requires completely different bike sizes. We hope that our mountain bike size guide and chart will put you on the right track to find your perfect size bike.
