Bike Size Chart: What Size Do I Need?

Frame size is the only decision in this entire purchase you cannot undo. Components can be replaced, tires can be swapped, a saddle can be changed for twenty dollars. A frame that is the wrong size stays the wrong size forever, and it is the single most common reason a first bike ends up unridden.

Fifteen minutes here is the best-spent time in the whole process.

A real size chart

Below is Tommaso’s own published chart for the Imola, read directly from their product page. We are showing a specific manufacturer’s chart rather than a generic one on purpose: sizing is not standardized between brands, and a chart averaged across the industry would be a chart that is wrong for every individual bike.

Source: Tommaso Imola product page, read 23 July 2026. Standover height and frame reach are not published on that listing, so they are not shown here rather than estimated. Always check the chart for the specific model you are buying.

Why your inseam matters more than your height

Two people who are both 5’10” can have leg lengths that differ by two inches. Height gets you into the right region of the chart; inseam tells you which side of a boundary you fall on.

How to measure it properly

1. Stand with your back against a wall, in the shoes you will actually ride in.
2. Feet about six inches apart.
3. Put a hardcover book between your legs, spine upward, and pull it up firmly against your crotch — firmly, the way a saddle sits under your weight.
4. Have someone mark the wall at the top edge of the book.
5. Measure from that mark straight down to the floor.

Long legs for your height? Lean toward the smaller frame with the seat post raised. Short legs and a long torso? Lean toward the larger frame, or the smaller frame with a longer stem.

The between-sizes rule

When you fall between two sizes, size down. This is close to universal advice and the reason is mechanical rather than aesthetic.

A frame that is slightly small can be adjusted outward and upward:

• Raise the seat post — free.
• Fit a longer stem — around $25.
• Add spacers under the stem to raise the bars — usually already included.
• Slide the saddle back on its rails — free.

A frame that is too big cannot be adjusted the same way, because the fundamental distance from the saddle to the handlebars is built into the frame itself. You end up permanently over-stretched, which produces sore shoulders and a sore lower back and no amount of fiddling fixes it.

Notice that the Tommaso chart above fits a shorter 75mm stem to the two smallest frames and a 120mm stem to the two largest — that is the manufacturer doing exactly this adjustment for you at the factory.

What to check when the bike arrives

1. Standover. Straddle the bike, feet flat on the floor. You want an inch or two of clearance between you and the top tube on a road bike, and two to three on a gravel bike. Zero clearance is a genuine safety issue.
2. Saddle height. With your heel on the pedal at its lowest point, your leg should be almost straight. When you move to the ball of your foot, that gives roughly the right slight bend. This is the single adjustment that most affects comfort and power.
3. Reach.Hands on the brake hoods, elbows slightly bent, back at roughly 45 degrees. If you feel stretched out and your shoulders ache after twenty minutes, the frame may be too long — a shorter stem is the first fix.
4. Knee position. With the cranks horizontal, the front knee should sit roughly over the pedal axle. Adjust by sliding the saddle forward or back.

When to pay for a professional fit

Not immediately — give yourself a few weeks. Some initial discomfort is your body adapting to a new position and it resolves on its own.

Get a fitting if, after three or four weeks, you have: persistent knee pain (a genuine warning sign, do not ride through it), numbness in hands or feet that does not clear, or lower back pain that is worse after riding than before.

A basic fit runs $75 to $200 and is worth every dollar if something hurts. It is also not something this site can do for you — a fitting requires someone watching you pedal, and we would rather say that plainly than pretend a web page can substitute.

Buying online without trying it

Most first-time buyers do this, so: use the manufacturer’s chart rather than a generic one, measure your inseam properly rather than guessing, size down between sizes, check the return policy before ordering, and budget for a $25 stem swap as a normal part of the purchase rather than a failure.

And prefer bikes that publish a real frame measurement. Several bikes in our comparisons sell as “L” with no number attached, which cannot be checked against any chart — and we mark them down for it in the road comparison and the gravel one specifically because of this page.