This post is for my friend, Sandra.
One of the tougher things to grasp for slower cyclists who want to get fast is the 90 revolutions per minute cadence. Why is it preached to pedal so fast? There are a few ways to explain this but I like to make the attempt to keep things simple…
First, here is the poetry in motion, one of the coolest and most colorful cyclists in the last generation or two, Jens Voigt breaking the world 1 hr. record, riding about 31-3/4 mph in that hour to do it – at 43 years-old:
At any place in that video, take a stop watch and count his pedal strokes over ten seconds and multiply that by six. What you’re looking for is one count every time one foot bottoms out (count the right or the left, not both), you’ll come up with 100-108 rpm. Now keep in mind, Jens is one hell of a strong cyclist. He’s known for putting a hurting on the peloton when he’s racing… In that challenge, he chose that cadence and set up his gearing to it. He’s on a single-speed track bike – there is no coasting on that bike. If you’re moving you must pedal. And guessing, he was using a 53 tooth front chain ring and a 13 tooth rear cog. If I use Sheldon Brown’s gear calculator I can see that a 53/13 combo at 100 rpm works out to 31.6 mph so it’s fairly simple to glean from this that at 100-108 rpm he’d be right at his 31-3/4 mph average speed. [Ed. The guys at the shop said he did it with a 55/14 setup]
With “How it’s done” out of the way, let’s look at the important part, “why” – or more to the point, why cycling with a high cadence is so important to generating and maintaining speed. There is a simple way to look at this, we can simplify the concept. If you take weight lifting and doing curls with a 30 pound weight, how many single arm curls could you do? 10? 20? 30? Now, how many could you do with a 5 pound weight? You could go all day. Cycling with an easier gear works on the same principle. Unfortunately, if you’re going to use an easy gear, to go fast you have to pedal that gear at a faster cadence to generate the speed. Why 90? Well this is fairly simple. First, getting up to 100-110 is a bit difficult to sustain but more importantly, if you’re riding in a group and pushing 90, you have a little gear left to respond to a sudden surge, it’s that simple. At 90 you have enough gear to accelerate. At 110, it’s too hard to get your legs to spin faster without a massive amount of training. So let’s look at this, using the gear calculator again, in that light.
Let’s say a typical cyclist uses a 60 rpm cadence. Here are the results of a 52/36 chain ring combo with a 11-28 cog cassette (11 sp.):
Now, if you want to average 20 mph you have to push the second hardest gear on the cassette at 60 rpm (I use that gear to hit 31 by the way). That’s a lot of pressure on the pedals to move so slowly. Let’s look at the same gearing at 90:
To hold 20 mph you can use the sixth or seventh cog on the cassette. It’s as simple as going back to that 30 lb. vs. 5 lb. weight for curls.
Now that we’ve established that you can push less weight if you can pedal a little faster, training to do so isn’t exactly as easy as just doing it. First, gone are the standard platform pedals. In order to keep your feet on the pedals at 90 rpm, you almost have to lock your feet onto them. I tried to ride in a group on platform pedals one time and I’ll never do that again. The problem is trying to keep your feet in the proper location on the pedals at speed – it’s not easy. So you’ll either need the pedals with the straps on them (called toe clips interestingly enough) or go with the shoes that have cleats that lock into the pedals. Once we’ve got the pedals and shoes sorted, it’s a matter of training the body to operate smoothly with a 90 rpm cadence. The easiest way would have to be on a trainer or spin bike where you don’t have to worry about balance and can work a stop watch and count your revolutions out as you go. I rode for several months before I started concentrating on cadence… I learned how to pedal faster out on the road. I fine tuned that on the trainer over the winter. Another way, albeit a little more risky, is to ride in a group and match the cadence of those in front of you. If you work at it, training your body to use a higher cadence should only take a few weeks at the most.
Now let’s look at the benefits of the higher cadence – beyond being able to ride faster and hold more speed for a longer period of time. First and foremost is acceleration. Jumping from a 90 cadence to 110 in the sixth gear is a hell of a lot faster and easier than going from a 60 to a 70 cadence in the second to the last gear. Folks, it’s not even close. I can accelerate on a dime (well maybe a quarter) in the easier gear but I’ll labor to pick up the speed, maybe even have to do so out of the saddle, in a harder gear. It’s not even close. Second would be climbing. When I’ve got that 90 cadence wound up and I hit a hill with it, selecting gears to maintain that cadence is very simple and again with the acceleration – the difference is even more profound when you’re going up a hill. Finally, and it might take a while to realize this for yourself, you’ll find that once you get used to that cadence, it’s easier to hold a certain speed once you get into that happy zone between 85 and 95 rpm. Now this will go by feel so it’ll be tricky to grasp at first but if you look at the 90 rpm chart above, you’ll see in the big ring (52) column, the 15 tooth cog is good for 24.4 mph at 90 rpm. In that gear I can hold 24.2 mph easier than I can hold 23 mph. In other words, I can go faster with less effort. Don’t take my word for it, try it for yourself. Just give yourself a few months to get used to the cadence first.
When it comes down to it, if you still have doubts, look at it this way: Who’s right, you or every professional who has clipped into a pedal in the last 40 years or so? Learn to push the easier gear with a higher cadence. If you’re looking for the “easier, softer way”, that’s it.
UPDATE 2016: James Smith dropped in to comment that there isn’t really a “one size fits all” approach to cadence and he’s right. You’ve gotta ride your ride. If you’re constantly leaving gaps in the pace line and can’t react to a surge within the group, chances are you need to downshift and pedal a little faster though. Call it a safe bet.