“Will cycling make your thighs bigger?”

“Will cycling make me skinny?”

Spoiler alert: No! Cycling will not make you fat. It will make you fit and strong. Will it give you cycling legs with monster quads? Only if that’s what you’re after (but you’ll need to do a lot more than just ride). Or it might just give you some unique muscle tone, like that distinctive teardrop over your kneecap (otherwise known as your vastus medialis oblique or VMO) and impressive calves. If you ride (or do any exercise) regularly, your body adapts to help you be better at it. That’s how training works.

But remember: strong is different than “big,” and every person’s unique makeup will react differently to the stimulus of cycling.

“In general, cycling can help improve cardiovascular fitness and decrease fat mass,” says Jinger Gottschall, an associate professor of kinesiology at Penn State University. How it will otherwise shape your muscles and your mass depends on myriad factors, including how much you ride, the kind of riding you do, what training you do off the bike, what you eat, as well as your hormonal makeup. Here’s what you can expect.

Pro-level riding equals next-level quads.

If you ride 15 to 20 (or more) hours a week, you better believe you’ll have the cycling legs to show for it. “Professional cyclists have a larger thigh muscle cross-section than non-cyclists,” says Gottschall. Especially pronounced are the quadriceps muscles that push the pedals down, as well as the large hamstring muscles that help sweep the pedals up. That’s why brands such as Levi’s and Rapha make special jeans to fit cycling enthusiasts who have trim waists, but strong quads. But remember: strong is different than “big,” and every person’s unique makeup will react differently to the stimulus of cycling. Riding long, slower, steady-state rides will also put you in a fat-burning zone so your muscle mass may grow while fat decreases resulting in a different—but not necessarily bigger—body composition.

Casual riders don’t need special pants.

Recreational riders or indoor cyclists who spin two or three times a week for exercise don’t have bigger thighs than non-riders, says Gottschall. “If you ride to meet your physical activity requirements of 150 minutes a week, there’s no significant difference,” he says. But doing so is great for your overall health, so you shouldn’t let anything stop you.

You need to add weights to get seriously swole quads.

Big monster cycling legs don’t come easy: the track racers you see with Godzilla-sized quads push more than pedals to get that way. They also push heavy metal plates, says Gottschall. “The magnitude of muscle hypertrophy with cycling is one-third of the muscle hypertrophy you get from resistance training.” You’d have to completely overhaul your diet and training routine to mimic those results.

More testosterone means more muscle mass.

Men tend to be more muscular than women because they have higher levels of the hormone testosterone. The anabolic hormone regulates and stimulates protein synthesis, says Gottschall. The better your body is at taking protein and synthesizing it into your muscle cells, the bigger those muscle cells can become.

With big monster cycling legs, you may become a bit imbalanced.

Muscle activity is almost four times greater in the quadriceps than in the hamstrings during cycling, says Gottschall. “Knee flexion exercises can help maintain balance.” To prevent muscle imbalances, try a TRX hamstring curl:

Sit facing the anchor point and place both heels into the foot cradles. Lie down face up with legs extended straight, feet below anchor point, and arms at your sides. Keeping your core tight, lift hips off the floor, then pull heels in toward glutes in a smooth and controlled motion. Keep hips lifted as you straighten your legs back to the starting position. Repeat until fatigued.

Riding builds heart and lung strength, so you can get leaner.

High-intensity cycling increases your heart and lung capacity, says Gottschall. Better cardiovascular fitness makes you a better fat burner. It also means you can ride faster for longer, and burn more calories. “I recommend two high-intensity sessions a week that include 20 minutes of interval training above 85 percent of your maximum heart rate,” she says.

READ MORE 6 Ways To Train LessAnd Still Get Strong

Hills and sprints make stronger quads…and maybe bigger.

Hypertrophy only happens under heavy loads. That’s why sprinters, who routinely hammer monster gears, develop tree-trunk quads over time. Riding lots of hills can make you stronger and eventually build muscle, but the overall load tends to be lighter since we spin rather than mash our way up hills.