In my first post on the voluminous topic of cycling related soreness I covered saddle height. Next up is the fore/aft positioning of the saddle which can have a dramatic affect on how much power you can put to the pedals. Too far either way and you not only end up using the wrong muscles to pedal, you’re leverage will be blown. That’s only part of the equation though; you also have to consider how you fit in the “cockpit”, or the space between the bars and the saddle. Now, forgive me for being the broken record – normal cycling pain is muscular pain. If you hurt, structurally, more than likely it’s the bike or your gear. There are, however, a few ‘saddle time’ pains to watch out for – meaning the more time you put on the saddle, the more “used to” the bike you become, the less you hurt, but that’s for another post.
Let’s deal with the pedaling power first because it’s very simple. There’s a bone just under your kneecap that, if you’re thin enough, sticks out just a bit. If you drop a plumb-bob from the leading edge of that bone just below the kneecap, with the ball of your foot right over the spindle and the crank arms parallel to the ground, the point of the plumb-bob should end up directly in the middle of the pedal spindle (the shaft that screws into the crank arm). If the point is forward of the spindle, move your saddle back. If it’s behind the spindle, move the saddle forward. If you have your saddle at the right height, this is said to be the proper leg angle (though I’m sure there are rare instances where this is not the case – a professional fitting will flush that out). This gets your leg in the right location to really push down on the pedal. If you’re too far back, you’ll be pushing out. Too far forward and you’ll be trying to push back (I can only imagine how bad this is on the hamstrings!). Adjusting the saddle for fore and aft is that simple.
Now, there’s another item to look at as well, and this has to do with your stem length and the drop from your saddle to your bars (3-5 inches or 7.5-12 cm) is good for fairly efficient cycling (though you must be flexible enough to take this, if you’re not it will hurt). BUT, if your butt is too far forward you will have to hunch your back when you get down in the drops unless your stem is entirely too long – and we’ll get to all of that in a minute. Also, if your saddle is too far back you’ll have to stretch out too far, reaching for the hoods. What happens in this case is that the cyclist will typically choose to ride on the bar tops, away from the brakes. The main problem with the former is that when you’re crunched into the cockpit you will have trouble filling your lungs with air – your diaphragm won’t work as efficiently. Too far away and you’ll be limiting yourself the the bar tops (because it just feels “better” or more “natural” – it may, but it is wrong).
Finally, we get into the nooks and crannies of the problem, uh if you will. Saddles are funny, simple things. The idea is to place your two “sit bones“:
If you can’t sit on the proper part of the saddle, you will know pain intimately. If the saddle is too far forward, you’ll end up cycling on the nose of your saddle (the skinny front part). If you look at the diagrams above you’ll be able to see that this will create major problem. Hot spots aplenty! You’ll be blocking some very important blood flow. The same can be said if your saddle is too far up. In that case, your tendency will be to ride in a more upright position – meaning getting to the drops when you’re pulling the group at 24 mph into the wind will be near impossible for more than a few short seconds.
Now, and this will go to a later post, a very large key in this equation is the stem length. You’re wondering how that thing holding the handlebar could be such a big deal? Allow me: If the stem is too long, you’ll have to move your saddle forward to keep from stretching out too far which will cause your knees to be too far forward on your pedal stroke which will rob you of power. This is not something you can overcome by “practicing” or “getting used to”. Too stretched out is too stretched out. The same can be said of a stem that is too short – you’ll have to move the saddle too far back and you’ll be pushing at the pedals instead of down on them. This big rat’s nest of a paragraph explains exactly why a proper fitting is so important. To make it even more confusing, the parameters change for different types of cycling. You’re more upright for touring and mountain biking while road cycling and triathlons (at least with any speed) require more of the classic aerodynamic position on the bike. Everything on that bike has to work to get you in the proper position on the bar ends, hoods or in the drops and over the pedals. The classic injury here is numbness and “hot spots” in the nether-regions if you’re setup is off.
Now, to keep this simple, first you check saddle height and get that set. Then you check the for-aft position with the plumb-bob (or a 4′ level works in a pinch – against the outside edge of your knee and the outside edge of the pedal spindle – that leading foot should be plumb when the crank arms are parallel to the ground).
Once that is set, your stem is the rest of the equation. If you have to reach for the hoods (you’ll know it, riding on the bar top will be more comfortable than the hoods), shorten the stem. If you’re crammed into the cockpit, lengthen the stem. The length of the stem is easiest determined at a bike shop – I do not have the equations to figure out the stem length. The best I could do would be trail and error… “I’m too stretched out with a 120mm stem so I’ll get an 80 or 85mm…”
Now, there is a little bit of wiggle room with the saddle, but not much. Remember this though: if the saddle goes back, you will have to lower the saddle. If the saddle goes forward, you’ll have to raise it.