In 1977 runners Hinda Miller and Lisa Lindahl sewed together two athletic supports or “jockstraps” and created the prototype of the modern-day sports bra. This “Jockbra” was later rebranded under the name Jogbra, for obvious reasons.

If you have small breasts that don’t move much while cycling, you’re unlikely to suffer from exercise-induced breast discomfort.

However, if your breasts move a lot when you’re cycling or mountain biking, or if you experience breast pain/discomfort, even if your breasts are small, a supportive bra is an absolute must and will make your ride even more enjoyable and relaxing.

FUN FACT: The first commercially available jogbra (1977) sold for $8.00, which is nearly equal to $35.00 today (2020).

• If you experience breast pain or discomfort from bouncing boobs, then you need to wear a sports bra. Breast bouncing during cycling and mountain biking should be minimized to increase comfort, performance, and pedal efficiency.

Cycling: Sports bra & efficiency

Sports bras work by allowing the breasts and trunk of the body to move as one unit, which is mimicking the motion of males.

Wearing a proper-fitting supportive bra reduces the activity of the “pec” muscles by 55%, which causes you to get fatigued quicker, especially while mountain biking.

The bigger the breasts, the heavier, for example, a size 34B (75B in EU) weighs about 7 ounces (200grams) and a size 38D (85D in EU) weighs about 1.5 pounds (700gram). The heavier the breasts, the more movement, which will cause you to use more energy without the right amount of chest support.

When breasts bounce during activities, they don’t bounce in unison nor do they bounce in coordination with your torso. In addition to this causing discomfort, it also is very inefficient and will require you to expend more energy to maintain the same power output while pedaling.

While no direct studies have been conducted that look specifically at cycling performance and breast support, several studies have researched running performance while wearing sports bras. The researchers found: 

• Significant reductions in “pec” muscles activity with reductions of over 60% during endurance events 

• Shoulder and deltoid activation was also significantly higher without adequate bra support (similar to “pec” activation) 

• Decreased efficiency through modifications in running mechanics and stride length and frequency 

While cycling and running are different, the increased activation of upper body muscles during cycling can lead to increased energy demands and fatigue. If you are out riding all day, wearing a sports bra can make you faster by not wasting precious calories and energy.

intensity, age, size, activity & extra support

Any activity that causes your bosoms to bounce, especially if they move excessively and frequently, then you should be wearing a sports bra for extra support.

All breasts sit on top of the pectoralis muscles (“pecs”) and are attached to your body only by the Cooper’s ligament and your skin. The heavier the breasts, the more movement.

The amount of breast support needed varies with age, bra size, type of exercise, and intensity:

• Age - As you age, your skin thins and its elasticity decreases. Breasts are only attached to the chest by the Cooper’s Ligament and skin, so more movement occurs as you age

• Size - Large breasts weigh 1.5 to 2+ pounds (700g to 1kg). Larger breasted women will need more support as larger breasts move more

• Activity - Any activities that cause vertical movements of the body cause more breast movement and require greater breast support

  • Vertical movement exercises = running, horseback riding, basketball, volleyball, and mountain biking

• Intensity - The more vigorous the intensity, the more support you will need. Going from a walk to a jog or a leisurely bike ride to intense cycling will require extra support.

Leisurely cycling & sports bra

Excessive breast movement during activities like jogging and jumping can cause breast discomfort.

However, leisurely cycling on a beach cruiser or commuter bike causes minimal breast movement or discomfort and generally doesn’t require the wearing of a sports bra.

• Leisurely cycling

  • Low impact

  • Minimal forward lean

  • Upright sitting posture: No forward lean as cruiser and commuter bikes are designed for maximum rider comfort and upright sitting

road cycling, exercise-induced breast pain, & sports bra

Road cycling, especially when getting “aero” or riding in the drops places you in a less supportive position. Also, going from seated pedaling to standing, high-speed cornering, and fast braking, all-cause excessive breast movement.

If you are a serious road cyclist or participate in vigorous indoor cycling, it’s recommended to wear a sports bra. 3D motion studies show that breasts move 30% more from a standing position to walking, with over triple the movement going from a walk to a run, with cycling falling in the middle of this range.

You should keep in mind, that for bike touring or long-distance road cycling, having extra support makes you more efficient, even if you don’t have any comfort issues.

Mountain biking & wearing a sports bra

Mountain biking, especially riding technical singletrack and downhilling steep MTB paths, causes large amounts of breast movement and a sports bra should be worn.

Cycling during hormonal changes

Throughout normal hormonal changes during your menstrual cycle, your breasts will be at their most sensitive, which could require extra support and even a different size bra.

Breast pain commonly increases from ovulation and will ease during menstruation. Being in rhythm with your cycles and utilizing the correct bra during the right time is important for your breast comfort and enjoyment of your pedal time. Keep in mind that breasts during this time can be larger and/or heavier, due to increased fluid retention.

Sports bra fit

It does not matter how supportive your bra is if it's not fitting right. Studies estimate that 85% of women are currently wearing the wrong size bra.

If you're currently wearing a sports bra and still experience discomfort, you might be part of the 85% club.

Also, keep in mind that bras have a used by date. Worn bras become stretched and have little elastic properties, which means not much support.

Dial in your ride with a DIY Professional BikeFitting

about the authors

Valentina is a guide for Pedal Chile and is our resident badass. Valentina was born and raised in La Patagonia, which probably explains her affinity for adventuring. When Valentina isn’t crushing some poor dude’s soul, you can find her shredding down Rucapillán. Favorite season: Austral Summer

Jesse is Director of Pedal Chile and lives in Valdivia, Chile. Jesse has a Master of Science in Health & Human Performance and a Bachelor of Science in Kinesiology. Hobbies: MTBing, snowboarding, reading, taster of craft beers, researcher, & compression sock wearer.

More articles from Pedal Chile

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