Caleb MorganBy Caleb Morgan

Updated November 2026

A felt tri bike size chart is the fastest starting point for finding a Felt triathlon frame that fits your body, but the chart only gets you partway. In this guide, you will learn how to read a Felt tri size chart, take the measurements that actually matter, confirm your fit with a few simple checks, and avoid the mistakes that send many first-time triathletes to the wrong frame. By the end, you should be able to narrow your choice to one or two sizes and know what to ask a shop before you buy.

What a Felt Tri Bike Size Chart Actually Tells You

Felt publishes size charts for its triathlon and time trial models that map rider height, and in many cases inseam, to a frame size such as XS, S, M, L or XL. Those ranges are the manufacturer’s best estimate for a typical rider with proportions close to the average. Because real riders vary in leg length, torso length and arm length, a height-based chart is a starting filter, not a final answer.

Shopping for one? See our guide: 5 Best Road Bike Shoe Size Charts (2026): Expert Picks.

Think of the chart as the first of three checks. The second is the geometry table for each model, which lists stack, reach, effective top tube and seat tube angle. The third is an in-person or video-assisted fit session. If you skip the geometry table, you may pick a frame that looks right on paper but puts you too far forward or too stretched out in the aero position.

Step 1: Measure Your Height and Inseam

Start with two numbers. Measure your height barefoot against a wall, with your heels together and your back straight. Then measure your inseam: stand against a wall with a hardcover book held firmly between your legs, spine snug against the book, and measure from the top of the book to the floor. Record both in centimeters, since most Felt charts list metric values alongside inches.

  • Height: measured barefoot, to the nearest millimeter
  • Inseam: measured from the floor to the crotch, with the book at the same height you would use for a flat measurement
  • Arm length (optional): from the center of your shoulder to your wrist with the arm extended

Take the inseam measurement twice. Small errors here shift your saddle height and your frame choice, so it is worth getting a consistent number.

Step 2: Find Your Starting Size on the Chart

Locate your height on the Felt chart for the specific model family you are considering. Tri and time trial frames often use a different chart than road bikes, so make sure you are reading the right table. If your height falls on a boundary between two sizes, use your inseam and arm length to break the tie.

Rider height (approx.) Typical starting frame size Things to check next
Under 160 cm (5’3″) XS Reach, saddle-to-bar drop
160–168 cm (5’3″–5’6″) S Inseam, stack
168–176 cm (5’6″–5’9″) M Reach, arm length
176–184 cm (5’9″–6’0″) L Torso length, aero position
Over 184 cm (6’0″) XL Stack, seat tube height

Treat this table as a general pattern, not a substitute for the chart published for the exact model you are considering. Felt updates geometry between model years, and the official chart always wins.

Step 3: Compare Geometry Numbers, Not Just Size Labels

Two riders of the same height can need different tri frames. Look at the geometry table for your candidate sizes and focus on four numbers:

  • Reach: the horizontal distance from the bottom bracket to the front of the head tube. Longer reach stretches you out; shorter reach brings you upright.
  • Stack: the vertical distance from the bottom bracket to the top of the head tube. Higher stack means a more upright position.
  • Effective top tube: a useful proxy for how far you reach to the aero bars.
  • Head tube and seat tube angles: these influence handling and how your hips sit over the pedals.

When you compare two adjacent sizes, you will usually see a few centimeters of difference in reach and stack. That gap matters for your back, shoulders and comfort over a long ride.

Step 4: Check Your Aero Position Fit

A tri frame has to fit in the aero position as well as on the hoods or the flat section of the bars. Before buying, check these points:

  1. Sit on a trainer or stationary bike and move into your planned aero position with your elbows on the pads and your hands relaxed.
  2. Confirm your back is flat or slightly rounded, not collapsed, and your hip angle stays open enough to breathe easily.
  3. Check that your knee does not hit the pads or the aero bar at the top of the pedal stroke.
  4. Make sure your elbows sit inside the pad width and your shoulders are not hunched.
  5. Reach down to the bars and back up; if you feel stretched or your hands slide off the pads, the frame may be too long.

If you can, ride the bike for 20 to 30 minutes before committing. Pay attention to numbness in the hands, neck tension and lower back fatigue, since those signals often indicate a size or setup problem.

Step 5: Dial in the Setup After You Choose a Size

Even the right frame size needs setup. Adjust these in order:

  1. Saddle height: set it so your knee has a slight bend, about 25 to 35 degrees, at the bottom of the pedal stroke with your heel on the pedal.
  2. Saddle fore-aft position: check that your front knee sits roughly over the pedal spindle when your crank is level.
  3. Aero pad position: move the pads forward or back to shorten or lengthen your reach without changing the frame.
  4. Stem spacers and stem length: adjust height and reach if your stack is slightly off.

Small changes to pads and stem can fix a lot, but they cannot make a too-small frame feel large. If you are between sizes, a professional bike fit can help you decide.

Common Mistakes When Using a Felt Tri Size Chart

  • Using a road bike chart for a tri frame. Tri geometry differs, so read the chart for the specific tri model.
  • Relying on height alone. Long legs, a short torso or long arms can change your ideal size.
  • Ignoring stack and reach. Two frames labeled the same size can feel very different.
  • Buying the bigger frame to chase speed. A frame that is too long compromises comfort and control, and you may not be able to hold the aero position.
  • Skipping the test ride. A static check on a stand is useful, but the real test is how you feel after a longer session.
  • Assuming a used frame fits the same as a new one. Older geometry may differ from current Felt charts.

Tips for Choosing the Right Size

  • Measure twice and write the numbers down before you visit a shop or compare models.
  • If you are between sizes, consider which way you want to err: a slightly smaller frame with a longer stem is often easier to adjust than a frame that is too long.
  • Bring your riding shoes and any aero helmet you plan to use to the fit session, since they affect your position.
  • Ask the shop to show you the geometry chart for the exact model year you are buying.
  • Revisit your fit after a few weeks of riding, since flexibility and comfort change as you build fitness.

A few inexpensive items make the sizing process more accurate and help you check your position at home.

  • A rigid bike fit tool or a basic bike fit kit with a plumb line and angle gauge helps you check knee position and saddle height against the crank. View on Amazon
  • A bike trainer that holds the rear wheel steady lets you test your aero position safely before you ride outdoors. View on Amazon
  • A set of aero bar pads in a range of widths lets you refine your reach and elbow position without changing the frame. View on Amazon

If you want to compare sizing across different tri and road models, the Triathlon Bike Size Chart: How to Find Your Right Tri Frame Size guide covers a broader range of brands. For a step-by-step method that works across Felt models, see Felt Bike Size Chart: How to Find Your Right Frame Fit in 6 Steps. If you are also comparing road options, Felt Road Bike Size Chart: How to Find Your Right Frame Fit explains how the road geometry differs.

FAQ

Is a felt tri bike size chart accurate enough to buy from?

It is a reliable starting point, but it should be combined with the geometry table for the exact model and, ideally, a fit session. Height alone does not capture reach, torso length or arm length.

Should I size my tri bike the same way as my road bike?

Often not. Tri frames are usually designed with a more aggressive, stretched aero position, so the size you ride on a road bike may be different from your tri size. Check each model’s chart separately.

What if I am between two sizes?

Compare reach and stack for both sizes. If you are more comfortable in an upright position and want to keep the front end lower, the smaller frame with a longer stem is often easier to adjust. If you need more stretch, the larger frame may suit you, but make sure you can still control the bike comfortably.

Does saddle height change which size I should buy?

Saddle height matters for setup, but the frame size is mainly determined by reach and stack. You can adjust saddle height within a range, so it is more useful as a check than as a sizing factor.

Can I use aero pads and a stem to fix a fit problem?

Pads and stems can fine-tune reach and stack by a few centimeters. They cannot turn a frame that is significantly too large or too small into a good fit.

Do I need a professional bike fit?

It helps, especially if you have a history of back, neck or knee pain or if you are between sizes. A qualified fitter can measure your position and recommend changes. If you have an existing injury, consult a medical professional or physical therapist before making major changes.

How do I know if my tri frame is too big?

Common signs include overstretching to reach the aero bars, hands sliding off the pads, shoulders tensing, and difficulty controlling the bike at low speeds. If you notice these, check whether a smaller size would be more comfortable.

Are geometry charts different for women’s tri bikes?

Some manufacturers offer women-specific geometry or saddle options, so check whether Felt lists separate fit information for the model you want. Use the same measurement steps and compare the geometry numbers rather than relying on a label alone.

Conclusion

A felt tri bike size chart gives you a reliable first estimate, especially when you start with an accurate height and inseam measurement. Confirm your choice by comparing reach and stack in the model’s geometry table, then check the aero position in person or on a trainer. Small setup adjustments can refine the fit, and a professional fit is worth considering if you are between sizes or have existing discomfort.

Ready to choose one?

Caleb Morgan

About Caleb Morgan

Caleb Morgan is part of our editorial team and reviews and edits our cycling for beginners guides, checking product details against manufacturer specifications and owner feedback.