Just got a basic computer for my bike that has a cadence sensor with it. What does cadence help you with? I know it has something to do with RPM's....i think but when does it come handy?

any details would be great and yes i am a new to road biking

it's like a rev meter in a car.
too high overtaxes your cardio and too low is no good for your knees.
cadence display will allow you to find your regular rhythm from which you can work on improving your technique or form.

aim for at least 80rpm.
most people average somewhere between 90 and 100rpm.
120rpm, and you might want to switch gears to the next one up.

don't bother looking at it until you've warmed up and found a nice stretch of road to maintain a comfortable cruising speed to find your normal cadence. If it's below 80rpm, you will want to work on spinning faster.

alright i see. so if im below 80rpms then i should pedal faster or go to a lower gear. also for hills should i aim for at least 80 rpms?

Most people around here average about 40. They also ride the wrong way on the street and do a bunch of other bad things.

hills you should aim for around 10rpm less than what you get on flats, but it all depends on personal preference and muscle make up.
unless you've ran out of gears.
in the context of road cycling

Cadence = Revs. With a 4:1 gear ratio, every rev of the crank = 4 revs of the wheel.

Car engines idle around 800 RPM and can redline up to 8000+ RPM. Humans can't quite match cars, but if you can crank at a modest 4,000 RPM, you will achieve 16,000 RPM with the wheel. Using 2100 mm circumference tires (typical 700-23C road bike tires), that's:

.0013 miles per revolution * 16,000 RPM * 60 minutes per hour = 1,252 miles per hour, close to twice the speed of sound.

I know I'm nit picking but you do realize you divide to find mph, not multiply. That's why you might sometimes see mi/h, as in, division.
(Also, according to you you'd end up going 0.34 mph)

wow desuism, great math skills you got there! maybe you should write out what colombo's saying in words and see what units cross out, and then get back to us on the answer!

No, the calculation by colombo is correct and if you look at the units you'll see that the revs and minutes cancel out since they appear in both numerator and denominator and the only units left are miles in the numerator and hours in the denominator; i.e. miles/hour. Of course actually achieving a cadence of 4000 rpm is likely to prove rather difficult - and especially so in a 4:1 gear ratio (108 gear inches). Good luck with that.

Well that's rather embarrassing. Should probably double check my own critique...

(Then again, the more you know, etc.)

If you're new to road biking then cadence has essentially no importance: it simply tells you how fast your feet are turning the cranks, in rpm, and if you're new to road biking you don't yet have enough experience to put that into context and to know how to evaluate it. OTOH, if you're experienced at road biking then cadence also has essentially no importance. It's shown on bike computers because it's easy to measure. People like to think if it's easy to measure it must be good for something. It's not. Some people will tell you to pedal at some magic cadence number, like 80 or above. Cadence depends on your terrain, your gearing, and especially your physical condition so if random guys on the internet who don't know you or your terrain or your bike prescribe a particular cadence range (and they will) you should ignore 'em. Cadence is a red herring. Just find the right combination of cadence and gearing that lets you ride comfortably. If you feel like you're bogging down, change gears; if you feel like you're spinning too fast, change gears.

Cadence has many purposes on the bike when you're training. Lower cadence stesses musculoskeletal system more. Higher candence stresses aerobic system more. I typically stress aerobic system early in the week and hit musculoskeletal later in the week. On the weekends with no intervals I find my own sweet spot of 85-95 rpm. My training program moves me in and out of these ranges all the time.

Cadence measurement is important. But maybe not for the same reasons for all the times. New riders need to take cadence into a broader context. More important to a new rider is the pedal stroke.

With a high cadence, you train your body's cardio and pulmonary system to adjust to the fast spinning even with an easy gear. Your muscular system will eventually get accustomed to the spinning and your heart rate will adjust as well.

At the beginning the heart rate will go up and you will want to quit doing this. When you achieve a certain proficiency at this, you can ratchet up the gears, meaning pushing harder gears. At those higher gear ratios, your spinning range from low rpm to higher rpm has already materialized. You're a better rider with the ability to spin at different ranges under different circumstances.

The cadence measurement will display your spinning effort but take it into context as to your process of conditioning. Riders take the same routes year after year, so as you become familiar with the effort it takes to go 30 mph on a sprint, then you will know what the spin should be as well. Same goes for climbing.

Cadence sensors are good for teaching you how to adjust cadence sensors. Seems most of the folks I ride with are constantly wrestling with their cadence sensor trying to get it to pick up. T he things seem pretty finicky.

I have a Shimano flightdeck computer with virtual cadence. I like having cadence info available, and I think it's really useful for new riders. Like others have said, on the flats try to keep your cadence above 80. On the hills just try to keep your legs from burning to a crisp and your heart from ripping out of your chest and turn whatever revs you can.

too low a cadence in too high a gear and it's like you're lifting weights with every rotation of the pedal. too high a cadence and you're wasting energy and loosing power.

find the sweet spot and you keep maximize your effort for the best speed you can achieve and maintain. My 2 cents.

I like how you assume you even have a choice. I turn whatever I can without hacking up a lung. sometimes it drops so low i might as well walk.

I was referring to "road cyclists". Toronto is the poseur capital of Canada, you must see a lot of Pinarellos and Cervelos going really slow the wrong way down the street. My wife points them out for me when we're in the car.

true, lots of clubs here, and plenty of people wearing team replica kits

I question your manhood and suggest a triple

One other way to look at it, for a given pedal force, the faster the pedal is moving with that force applied, the higher your power. Conversely, if your power output is ok, you can reduce the muscular force needed to maintain that power by pedaling at a higher cadence.

"One other way to look at it?" Dude, that's the only way to look at it. Don't look at cadence in isolation: the context we're talking about is the context of cadence, pedal force (or crank torque) and/or power. Since inexperienced cyclists don't know what either their pedal force and power are, they don't have any way to evaluate their cadence. That's why chasing cadence without knowing at least one of the other two is a red herring.

the units cancel out, his math is good.

I dont agree that its a "red herring". You do have an "internal power meter". After all your legs are connected to your brain and you can tell how (relatively speaking) much force you are applying to your feet, how tired you feel, how hard you are breathing etc.

You dont need to spend $1000's on power meters, head units and all of that stuff imho. If it helps you great but you can make improvements and measure your performance over time simply by using a cyclocomputer with cadance. An HRM would be the next step after that if you have $50 to spend. I bought a very nice Nike women's specific model for my wife for that price at Nashbar over the winter. It was 50% off.

Over the last year I have added Catyeye Astrale 8s to our bikes. I use my cadence as a shift up/down indicator. Over a 22 mile hilly route I have been +/- .2 mph avg day to day and I have been able to track my overall gain in performance.

btw I think that this is the best deal going for a cyclocomputer with cadence: $19.99 + shipping at Nashbar

then riddle me this: when people try to break the hour record on the track, why do they maintain a cadence of 95-100 rpm? in case you don't know (and i can't assume you do given the horrible advice you posted), it's because it allows the athletes to utilize as much aerobic power as possible. everyone's optimal pedaling rpm is different, but the higher it is, the more sustainable it is (get too high, and your overall efficiency goes down). it is the very same reason why you should keep your cadence up at the cost of a bit slower speed when you are on the front end of a time trial as this would ensure that you'll have something left in the tank for the latter part. and just fyi, not everyone can give a good estimate of their cadence, which is why it's important to have something to measure it.

I like that image because that's what I do whenever the cadence nazis bring up your exact point.
First, go take a look: none of the recent hour records were done at 95-100 rpm. Fail. Not a single one. In case you don't know (and I assume you don't since this was so hilariously wrong) of the recent hour record holders, only Obree was below 100 rpm and even he wasn't in that range. You have to go back to Oscar Egg to find a record holder in your range and that was in 1912. In case you don't know (and judging from what you've written, I can assume you don't) this is 2010 so that's almost a century.

Second, as far as what the cadence was for hour record attempts is a red herring for new road riders. You can point to their cadence but I can point to their crank torque. As everyone but you now knows, hour records have been set at cadences from 90ish on up. They were also set at average pedal force in excess of 200N. Every single one of them. The average pedal force of hour record attempts is exactly as relevant as their average cadence is to new road riders.

Try again.

[Edit:] BTW, are you also posting under the name "desuism?" Cuz you're both as embarrassingly wrong.

rchung sounds allot like another **chung we have around here whom is all enamored with Power Taps as well.

sock ? I wonder