3 Fundamentals of Correct Bike Size - Bianchi Infinito CV

Road Bike Size / Fit Basics

Before you purchase your new road bike, you need to ensure the frame meets 3 basic size requirements: stand-over, reach, seat height. 

1. Stand-over

No dimension is more important than Stand-over. But what is stand-over you ask?

Stand-over is the measurement of the height of the bikes top-tube from the ground at its midpoint.

Ok, so why is it so important? Simply put, if you are travelling along on your bike and you need to stop in a hurry, you'll have to jump forward, landing on the ground, standing with your legs on each side of the top tube. Having the correct Stand-over will ensure you do not impact your groin area during this situation. 

How to test it.

When you stand-over the midpoint of the bike, with shoes on, you should be able to lift the bike up until there is a 2 cm gap between the tyres and the floor - without the frame coming in contact with your groin.

If you are looking at the best size option based on a geometry chart, measure from inner leg to floor (with shoes on), remove 2cm and test that measurement against the bikes geometry chart. 

2. Reach

Get this one wrong, and you may be in for a world of back pain. Whether that is upper or lower back pain will depend on whether you buy, or are sold, a bike that is too big or too small for you. Buy the correct size bike and your hours of saddle time will actually strengthen your core and back, not hinder it. 

The Reach is the distance your hands project forward to comfortably rest on bars and manipulate the brakes and gears. 

 

How to test it. 

The quickest test of correct reach is to sit in the correct riding position on the bike (a trainer is great for this or if that is available, take the bike for a quick ride or balance against a wall with someone's assistance). 

Sit on the bike in a neutral position with your hands resting on the hoods (illustrated above) and your head in a natural riding position - eyes looking forward. Now look down at the front wheel hub/axel. If the position is correct the bars should block your view of the hub/axel. If you can see the hub/axel in-front of the bars, the bike is too small. If you can see the hub/axel behind the bars, the bike is too large. 

Stem length obviously plays a role here. However, if you are buying a bike from a store, it should be equipped with the correct size stem for the frame. Ideally, you should only have to swap stems if you have a particularly long or short torso. 

Your saddle can be moved forward or back on the 'rails' to make small adjustments to your reach outcome. If the bike is the correct size for you, you should not have to move it all the way forward or all the way back. 

3. Seat Height

Seat height impacts on comfort and performance - correct seat height optimises both. Your seat needs to allow for an efficient and powerful pedal stroke while maintaining you in a balanced, static and comfortable seated position. 

It is also important to note that your seat needs to be in the correct position to properly determine your reach (above). 

How to test it.

This is a simple and quick way to ensure a powerful and efficient seat height position. Sitting on your bike, rest your heal on your pedal when it is in the lowest (6 O'clock) position.

You need to check two things now and you will need another person to assist with this. Check that your leg is fully and comfortably extended. At the same time, when viewed from behind, your hips should be level. If required, adjust the seat height to achieve the ideal balance of full leg extension and level hip placement. When this is resolved, returning you foot the usual cleated cycling position should achieve the correct amount of knee bend.

Extra - Bar Drop

The position of the bars relative to the seat. This is the bike fit positionings that can cause a lot of trouble and one that we recommend determining over time and with the assistance of a professional bike fitter.

If you are new to cycling with average fitness and flexibility, err on the side of positioning your bars at the top of the steerer with one spacer above the stem. This will allow options to lower the bars over time as your fitness, flexibility and riding continue to evolve. 

Does this position influence which size bike to purchase? That should be a secondary consideration after first determining which frame geometry is appropriate for you. If your flexibility is limited (or not what it used to be), you may be best to consider a frame with endurance geometry to ensure a higher front end and a more relaxed position on the bike. 

Size Chart

The following chart provides a rule of thumb approach to determine your bike size based on your height. This is a simple approach to a complex situation, but it is accurate in the majority of cases. Of course, the length of your limbs is not factored into the table below and long or short limbs or torso can play a big role in determining the right bike size for you. 

Bianchi women's sizes 44, 46/47

Bianchi Infinito sizes 50, 53, 55, 57, 59, 61

Your Imperial Height  Your Metric Height  Bike Size Guide

   5 feet 1 inches

   155 cm

    Size - 44

   5 feet 2 inches

   157 cm 

    Size – 44

   5 feet 3 inches

   160 cm

    Size – 44/46/47

   5 feet 4 inches

   163 cm

    Size – 44/47

   5 feet 5 inches

   165 cm

    Size – 47/50

   5 feet 6 inches

   168 cm

    Size – 50

   5 feet 7 inches

   170 cm

    Size – 50

   5 feet 8 inches

   173 cm

    Size – 50/53

   5 feet 9 inches

   175 cm

    Size – 53

   5 feet 10 inches

   178 cm

    Size - 53/55

   5 feet 11 inches

   180 cm

    Size – 55

   6 feet 0 inches

   183 cm

    Size – 55/57

   6 feet 1 inches

   185 cm

    Size – 57

   6 feet 2 inches

   188 cm

    Size – 57/59

   6 feet 3 inches

   191 cm

    Size – 59

   6 feet 4 inches

   193 cm

    Size - 59/61

   6 feet 5 inches

   196 cm

    Size – 61

   6 feet 6 inches

   199 cm

    Size – 61

   6 feet 8 inches

   203 cm

    Size - 63