It sounds like you are doing some strength repeats where you go for a tough gear and grind it out. For these kind of intervals your heart rate should be lower because you are not trying to go for maximum speed but more for a "weights workout" done specifically on the bike.

If that is your _object_ive when doing the workout, your heart rate is not really important. That said, I don't know what 175 bpm is for you. For me that is still well in an aerobic zone. If 175bpm is your maximum heart rate then something is not right. Either you are pushing too many watts or not sticking to the cadence or both.

At this time of year you want to focus on building a solid foundation for higher intensity later in the year. You will probably be able to do a bit more riding because the intensity is lower. If you do too much volume with too much intensity, you can run into an overtraining situation. However, a bit of higher quality aerobic work is fine.

So ask yourself, is this still aerobic? You should be breathing hard (that is still aerobic) but it should feel "sort of hard" not "really, really hard".

If you have someone do a lactate step test on you, they can then help you to get a better handle on your perceived efforts and how they correlate with what your body is experiencing.