How important is seat height? We all know someone who freaks out if you change their seatpost height and tell you how if it is not just right it will ruin their power output and knees. But how valid are those concerns?
If we are talking about power production then there are obvious advantages to having your seat in the right general area. You can produce more strength and power when your legs are getting near full extension. I’m not sure that a half inch really matters that much in the grand scheme of things (some people have it down to the millimeter) but having too much bend in your knees will rob you of some power. I also think that mountain bikers should stand more when they pedal but that is getting off topic.
However, I don’t think that your seat height plays as big a role in keeping your knees injury free as we are lead to believe. Here is what I think is happening…
Most people’s knees cave in when they squat. On the bike this is seen as your knees caving in towards your top tube which tends to get worse as your seat get lower. So, what is really happening is that the dysfunction in the hips is causing the knees to track poorly which gets magnified the more your knees are bent.
The poor knee tracking is the real culprit, not necessarily the seat height. If you find that your knees hurt if your seatpost is a little too low you need to work on single leg exercises and glute activation drills to work on leg stability while pedaling.