About Bicycle Gearing for a Good Pedaling Cadence
A previous Savvy Cyclist post describes bicycle gearing, and how to accelerate. This post gets to how your legs can produce power for a day’s ride without getting sore – and for a lifetime without wearing out.
Pistons, not pendulums
When you walk, your legs are like pendulums. Stand on one leg and swing the other forward and back. It has a natural, easy swing. Swinging it either faster or slower takes effort. Here’s a one-minute video illustrating the point:
But when you are riding your bicycle, your legs do not work as pendulums. Neither do they support your weight. They are pistons in an engine, connected to cranks. Because the cranks keep your legs turning, they can easily go faster. Let’s look at how this works out.
From one-speeds to bicycles with gears
I rode single speed coaster-brake bicycles as a kid. I got my first bicycle at age 7. Its small wheels had me spinning the pedals.
The next bike was big and heavy. I quit bicycling because I couldn’t ride it up the hill to my elementary school.
I first rode a bicycle with gears at age 17. It felt like flying. As is well known, the Wright brothers studied the flight of birds, helping them design their airplanes. But also, let’s remember that the Wright brothers were bicycle builders first. A bicycle, like an airplane, banks into turns. No earlier vehicle had done that.
Still, English three-speeds were geared too high to suit me. My career modifying gearing began with my installing a larger rear sprocket on my three-speed, so it would cruise along nicely in top gear and climb smartly in low gear. Really, a three- speed, so modified, is fine for urban riding if hills aren’t super steep.
From bicycles with gears to bicycles with more gears
After ten years riding on three-speeds, I got my first derailleur-equipped bicycle. I almost immediately modified it to get smaller steps between top gears and a lower bottom gear.
I’ll grant that gearing options have improved considerably over the years. Any mountain bike has a nice, wide gear range. Road bikes tend to have more gears but a narrow range: a racer mentality prevails, and these bicycles often need modification to work for ordinary people. Here’s the drivetrain of the road bike I use for recreational riding: It gets me up the hills!
Now, 7- and 8-speed internally-geared hubs are common. 11 and 14 speeds are available, too, though expensive.
What is the comfortable swing?
My legs are nearly as long as the grandfather clock’s pendulum in my video, but they swing twice as fast, because most of the weight isn’t at the bottom. It’s march tempo in music, no coincidence.: If you wear heavy hiking boots, your gait will slow down. But again, your legs are pistons, not pendulums when you ride a bicycle. The faster your legs turn, the less hard they have to push to produce the same power – so you can ride all day without getting sore, and for a lifetime without wearing out your knees.
A good pedaling cadence is quite a bit faster than a walking pace. With an optimal cadence, your oxygen-carrying capacity sets the limit of sustained power production. Your lungs don’t get sore by breathing hard, and your heart doesn’t get sore by beating faster. You can ride all day this way. .
Building muscle strength is something else entirely
Here’s another way to look at the issue: muscle-building exercise stresses muscles to their limit. The usual advice is for three sets of ten repetitions, to exhaustion, twice a week. More repetitions than that won’t build muscles any faster, they make you sore, and in the long run, can cause permanent damage. But, in an hour’s bicycle ride, your legs turn around thousands of times.
Certainly though, you can apply full muscle power for short bursts of power. Keep it in reserve for when you need it, because it fades quickly, and then you have to return to spinning.
Where to turn for more information about bicycle gearing
Getting the right gearing is simplest if it is original equipment on a bicycle you buy. But if your bicycle’s gears do not allow you to climb hills at a comfortable cadence, answers are as close as the nearest bike shop. Every kind of bicycle, even one-speeds, allows modifications.
For more details on modifying gearing with an internal-gear hub, you might look here:
https://www.sheldonbrown.com/internal-gears.html#sprockets
and for derailleur gears, here:
https://www.sheldonbrown.com/gear-theory.html .
Next article
In the next article in this series, John Brooking describes emergency maneuvers.
OK. So what is it about 90rpm that makes it historically “optimal”? Are there any ideas why going to higher and higher RPM wouldn’t be even better?
Regarding hills. I’m bringing back into service a bike that suffered a broken fork some years ago. Since I have choice over all components, I’ve equipped it with a inner chainring/inner cog combo that gives me a “19-inch” low gear. I expect to spin much more easily up a challenging climb nearby. But will I likely be going slower in mph than during the trips I’ve “chugged” on up?
Hi, Gary. I have never raced or tried to outdo other cyclists on speed, so I am perhaps not the best person to answer your question. Rather, I have been riding to spare my knees, since developing a loose piece of cartilage in one in 1982, as well as chondromalacia (wear of the surface of the patellar cartilage) and needing arthroscopic surgery. So I have chosen to shift down and spin, and geared my bicycles accordingly. I can tell you that Tyler Hamilton and Lance Armstrong won on the mountain passes in the Tour de France by using lower gears. Now, they had some, uh, chemical assistance, but so did the other racers. If I push hard more than briefly, I can feel the tenderness under my kneecaps and it tells my that I need to back off, or it will get worse.
The upper limit on cadence is set by coordination. It is different for different people. I rode tandem once with my niece, and she complained that I was pedaling too fast, though i was probably only doing 75 RPM. 90 RPM might be a bit high for recreational riding, except for 30 seconds or so when accelerating.
There is no penalty for having low gears, and they are there if you need them. You have some serious climbs where you live. I remember with some fondness climbing Beverly Hills Road in Coopersburg. I did that in a 22-inch gear and I was much younger then! My best bike for climbing now is my Bike Friday, and the low gear is 12 inches. It gets me up the continual 12% grade on Mt. Wachusett, here in Massachusetts, spinning at 3 mph.
I ride road and MTBs. I also ride a singlespeed MTB. I don’t personally believe that 85-90 rpm is the “optimal” cadence for all riders. If you have great aerobic capacity, that is fine. For me, I choose to push a higher gear at a slower cadence. When road riding, I rarely exceed 90 rpm. I’m usually around 70-75 rpm. Same with a geared MTB. Not so with the singlespeed MTB. I can ride at 12-14 mph with my gearing at about 90 rpm. On climbs, I am less than 40 rpm and sometimes even slower when the trail tilts skywards. On a singlespeed, you are only in the correct gear about 10% of the time. So, when I train riders, I tell them to find a cadence that is manageable. I have them start at 60 rpm and work up from there.
Randy — in his comment, Gary Madine introduced the idea of 90 RPM as optimal. I did not prescribe a specific cadence, only saying that spinning faster than a walking pace avoids soreness — technically, exhaustion of energy reserves in the muscles and lactic acid buildup — and is easier on the knees. YMMV — mine does. I’ll cadence at 90 for acceleration, more usually 75 when cruising along.
For the same road speed, using a lower gear equates to lower forces exerted over the longer distances which the pedals travel per second when turned at a higher cadence. It’s my impression that at some point the higher forces of lower cadence (road speed being equal) can lead to knee damage. Additionally, it’s been my understanding that higher cadences result in a greater percentage (ideally nearly all) of the work being done aerobically, i.e. much more sustainably, and lower cadences result in anaerobic work (fast twitch fibers), fueled by stored glycogen which runs out fairly quickly. I also speculate that at higher cadences the large muscles of the thighs are more fully and efficiently employed, and at lower cadences, calves are a limiting factor in the amount of work that can be done by the legs.
Of course, if you can’t pedal smooth circles at higher speeds, these advantages don’t result. My understanding is that racers concentrate on spinning at fairly high speeds in their training season because coordination is paramount, as is staying aerobic to the extent possible when you are riding 4+ hours per day.