Hi! Great question. First, let me clarify that this is muscle activation work, which is focused first and foremost on strengthening the brain-muscle connection, which paves the way to increased strength/power through better motor patterns. For example, glutes serve as hip extensors (opposite of hip flexors) and as external rotators. On the bike, you don’t “need” external rotation, because you’re moving your legs in a single plane, and hamstrings/calves can easily compensate in the job of “extensor” in the limited range of angles your hip travels during a pedal stroke. BUT glutes are extremely powerful and – when strong – can contribute a lot of strength to the pedal stroke, in addition to hip stability and thus knee health on and off the bike.
Activation work is about reminding your brain to fire your glutes as part of a specific neuromuscular motor pattern (e.g. sequence of muscle contractions through an efficient pedal stroke). As such, activation work does NOT require the effortful type of muscle contractions you would do during a typical weight lifting routine. Consistency, however, helps a lot, as does doing this type of work before getting on the bike, so you’ve warmed up that brain-muscle connection and reminded your brain to fire those glutes on the bike.
Simple activations I like to do:
Lie face down on your stomach, with left leg straight and right leg bent with knee at ninety degrees, so your right quad is in contact with the ground, but your right foot is in the air. First, fire your transverse abdominus to stabilize your core, then fire your right glute, gently - just enough to engage the muscle. Do this for ten or so distinct pulses, but try to do so without activating your hamstring, without rocking your hips, and without using your back muscles: erector spinae or quadratus lumborum. (Again, this is a very subtle activation, so you might not even feel your leg/knee lift more than an inch off the ground; if you’re lifting your whole leg off the ground, you’re trying too hard and probably recruiting too many muscles.) This can be difficult, if you rely mostly on your hamstrings, and takes a lot of awareness and focus to know when you’re actually and truly isolating the glute. Focus on form for these! Only do as many reps as you can gently and correctly, isolating the glute. Repeat on the left side.
Lie on your back with your left leg out straight, and with a Swiss ball under your right leg, allowing you to rest the leg with your right hip and knee at 90-degree angles. Activate your transverse abdominus to stabilize your Coren, then activate the right glute with a gentle, isometric contraction. Again, try to do this without engaging the hamstring, or otherwise compensating with other muscles. This teaches your brain to access the glute when your hip is flexed, as it is on the bike. Do as many reps as you can with excellent form (up to 10), then repeat on the left side.
These two exercises are enough to do before a training session on the bike. When you’re on the bike, it can help to use proprioception to “remind” your brain to activate those glutes at the appropriate part of the pedal stroke. To do this, you can rest your hands on your glutes (yup, put your hands on your butt) and feel when they are or are not firing. You can do this during rest intervals as a quick reminder for your brain during your workout. Don’t worry if you’re not firing every pedal stroke; each time your forget is an opportunity to “remind” your brain and strengthen that motor pattern!
A couple of other exercises I like for this that move into more strength/stability work:
Dipping Bird (example video here) - uses the glutes as extensors - good for balance, core, hip stability and glute activation/strength.
Monster Walk - uses glutes as external rotators - good for core, balance, hip stability, knees.
Bridge (example here) & Single Leg Bridge - uses glutes as extensors, works rotational stability in isometric contraction
Clamshells (example here) - uses glutes as external rotators, really gets medial glutes
Standing 4-Way Hip with or without band - can do these without a band everyday while you brush your teeth! (example here)
Hope this helps!