Bike Size Chart – How To Choose?

The fastest way to find your size is to match your height to the frame chart for your discipline below, then confirm it with a quick inseam measurement. Most riders can pick the right Twitter frame in a couple of minutes this way, and our Find My Size tool does the math for you on every product page. This guide brings together the road, gravel, and mountain bike (MTB) size charts, the measure-yourself method, and how to compare Twitter sizing against other brands, so you can order with confidence.

These charts give you a reliable starting point. For racing, long-distance comfort, or if you fall between sizes, a professional bike fit is always worth it for the final adjustments.

How to measure yourself for the right bike size

There are two simple do-it-yourself methods. Use them together for the best result: the height chart gets you in the right ballpark, and the inseam formula confirms it.

Method one: height to bike size

The quickest approach is to match your height to a frame size using the chart for your discipline. Scroll down to the road, gravel, or MTB section below and read across from your height to the recommended frame size.

Method two: calculate size from your inseam

Your inseam (the length of your inner leg) is a more precise input than height alone, because leg length drives standover and reach. Here's how to measure and calculate:

• Take off your shoes and stand with your legs about 15–20 cm (6–8 in) apart.
• Measure the height from the ground to your crotch. That number, in centimeters, is your inseam.
• Decide which type of bike you want — road, gravel, mountain, or city — then apply the matching formula below.

Multiply your inseam in centimeters by the factor for your bike type to estimate your frame size:

• Road bike — inseam (cm) × 0.70 = your frame size
• Gravel / city bike — inseam (cm) × 0.685 = your frame size
• Mountain bike — inseam (cm) × 0.66 = your frame size

If the two methods point to different sizes — common if you have a long torso or long legs for your height — use it as a signal. Sizing down favors a more agile, aggressive fit; sizing up favors comfort and reach.

Road bike size chart

Road bikes are measured in millimeters and are designed for a stretched-out, efficient position. Use your height to find your starting frame size, then confirm with the inseam formula (inseam × 0.70). Because different brands measure frames differently, a Twitter road size will not always share the same number as another label — see the comparison section below before you assume two "size 54" bikes fit the same.

Ready to shop? Browse the full lineup of carbon road machines in our road bikes collection.

Gravel bike size chart

Gravel bikes sit between road and mountain geometry — a slightly more relaxed, stable position for mixed terrain and long days. Match your height to the gravel chart below, and use the 0.685 inseam factor to confirm.

Explore drop-bar, do-it-all gravel builds in our gravel bikes collection.

Mountain bike (MTB) size chart

Mountain bikes are usually described by wheel size in inches (like 29" or 27.5") as well as frame size, and they run a shorter effective reach for control on the trail. Use the 0.66 inseam factor here — MTB frames are intentionally smaller relative to your leg length so you get more standover clearance. Pick the chart that matches your wheel size.

29" mountain bikes

27.5" mountain bikes

See the full range of hardtail and full-suspension trail bikes in our mountain bikes collection, and pedal-assist options in the eMTB collection.

How to compare Twitter sizing with other brands

Different companies produce different bike geometries, and it varies by model and purpose. The geometry can even be expressed in different units — a mountain bike wheel might be listed in inches (29"), while a road frame is in millimeters. Some brands label frames with letters (S/M/L), others with numbers, and among the numbered brands, they may measure different parts of the frame entirely.

That's why you should never assume the same size label fits identically across brands. Compare the actual geometry numbers — stack, reach, top-tube length, and standover — not just the S/M/L or the number on the box.

As the example above shows, two brands can use completely different measuring patterns to describe "the same" size. If you have a size from another brand in mind, a free tool like geometrygeeks.bike lets you line up geometry charts side by side so you can find the closest Twitter match.

Still unsure? Use Find My Size

If you'd rather not do the math, the Find My Size tool on each Twitter product page turns your height and inseam into a recommended frame size in seconds, tuned to that specific model's geometry. It's the easiest way to be sure before you order — and if you're between sizes, our US support team can help you decide.

Every Twitter bike ships with free shipping and all import duties and taxes included to 35+ countries, so the price you see is the price you pay to your door. Learn more on our shipping, duties & taxes page. Prefer to build around an existing fit? Browse framesets and parts in our components collection.

Frequently asked questions

Should I size up or size down if I'm between sizes?

It depends on how you ride. Size down for sportier, more agile handling and a lower, more aggressive position; size up for more reach, comfort, and stability on long rides. Checking both the height chart and the inseam formula usually breaks the tie.

Why is my mountain bike frame "smaller" than my road bike frame?

Because MTB frames use a smaller inseam factor (0.66 versus 0.70 for road). Trail bikes are deliberately sized down relative to your legs to give you more standover clearance and control over rough terrain.

Can I use my size from another brand to pick a Twitter bike?

Not directly. Brands measure frames differently and may use letters or numbers, so the same label can fit differently. Compare the actual geometry numbers — reach, stack, and top-tube length — using a tool like geometrygeeks.bike, or use Find My Size on the product page.

Do I really need a professional bike fit?

Not to choose the right frame size — these charts and the inseam formula are enough to order confidently. A professional fit is recommended afterward for fine-tuning saddle height, reach, and cleat position, especially for racing or long-distance comfort.

Does Twitter Bikes USA help if I order the wrong size?

Yes. We're an authorized US distributor with a US-based support team and manufacturer warranty. Reach out before you order if you're unsure, and we'll help you confirm the right frame for your height and riding style.