The importance of bike fit can’t be overstated. You pedal thousand of revolutions per ride, putting thousands of pounds of pressure on the joints. If you aren’t aligned well the joints are getting loaded improperly which can lead to over use injuries. Cycling can be pretty kind to the body as it doesn’t have the impact of running but you can still hurt yourself if you are set up wrong.
You and your bike must work like a fine tuned machine. Think of you knee as a hinge. If a hinge isn’t side loaded it will eventually bind and wear prematurely. Your knees work the same way. If even one aspect of fit is misaligned you can hurt yourself. The good thing is that bike fit, while a little complicated due to all of the inter-relationships of machine and body, isn’t rocket science.
If you can’t get into see a professional bike fitter, these rules will help you improve your bike comfort and performance.
Rule 1: Everything is connected.
If you move your seat back you will need to lower your saddle and possibly shorten your stem. Everything on the body is interconnected so you can’t just move one piece without is affecting all the other adjustments to some degree. Remember that song about the shin bone being connected to the knee bone. When fitting a bike, I start with the cleat set up and work up from there. Cleats need to be anywhere from 5-15 mm behind the ball of the foot. Your saddle height needs to be high enough that you get a good extension at the bottom of the pedal stroke (around a 30 degree knee bend at the bottom) but no so high that the hips rock when pedaling. A slightly lower saddle will feel smoother pedaling at high cadence while a slightly higher position will maximize leverage when pushing bigger gears. Depending on your riding style this can influence where in the range you want to position the saddle.
Rule 2: Fit your bike to your body as you body won’t adapt to your bike
If you need a higher bar position or shorter reach, then make the changes as your body won’t adapt to a position that is much out of your comfort zone. In particular are side to side balance issues. If your hips sit twisted on the saddle you will need to adjust slightly to the opposite side of the forward hip. If one leg is longer than the other or just behaves that way on the bike, you should shim the shorter leg for half the difference. With road pedals, you can put a shim between you cleat and shoe. If you have mountain bike clipless pedals, then it’s best to fix build up the insole in the shoe of the shorter leg if you have the room within your shoe. If you shim the cleat on a mountain bike it can create instability as the cleats are so small.
Rule 3: Look for balance when riding
If any body part protests (hurts) when you are going hard then look to re-balance your position. If you get numb hand you may need to move your saddle back and down, shorten your reach or raise your bar. It’s often a combination of these to achieve a balanced position that lets you put out your maximum sustainable power with minimal body fatigue. By having your cleats back on your shoes, your saddle back and your bar position adjusted to match, the postural muscles will have the least amount of engagement making for a more comfortable ride. This combination will also tend to increase the involvement of the hamstrings and glute muscles there by increasing endurance as the load is spread over more muscles.
Bike fit is both an art and science. There are no magic formulas to get in the right position. It’s a combination of bio-mechanics, experience and understanding that the body works as a unit can help figure out how to fix discomfort and performance issues.