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| *Vultures Knob>>>Bike Pedals |
What do u think is the most efficcent pedaling RPM? |
on cars, usually, the higher RPM the better, but most people i know cant spin their legs quite at 18,000 RPM. although higher Rpms usually arent fuel efficcent and thats what we need on bikes. is there an ideal RPM? does it depend on distance from pedal to crank? does it differ for people with different leg strengths? i wanna see some deep thought answers, people It will vary from person to person. It will also vary depending on an individuals power output and leg strength. Generally power will peak around 90-110rpm. Power is a function of crank length, force and cadence. (Torque x Speed). Most riders will produce more torque at lower cadences. In terms of pure efficiency (power in v power out) there are less losses (friction/heat) at lower cadences. If you apply a torque (force x distance also = energy) to the pedal a greater percentage of this will be turned into motion at a lower cadence. Be aware that at lower cadence there will generally be less power. (power = energy x time) I usually aim for about 90 -100 rpm trying to stay below my aerobic threshold, But will increase the rating when I put the power on. If I am on a really long group ride I sometimes drop as low as 60 while in the bunch. Oh yeah..... had better supply some links or I'll be drowned in down thumbs. http://www.me.utexas.edu/~neptune/papers... http://anonymous.coward.free.fr/wattage/... It really depends on the rider. For example, both Jan Ullrich and Lance blast up the mountains, but look closer. Jan churns the butter, and Lance whips the cream. Find a gear ratio/RPM that fits you well, and go with it. Of course, it will change as you get more fit, but then you wont be noticing anyway, because you will be used to it. bicycling.com Good answers above. Like cars there are race and street cars - same in cycling. There are many human factors that go into the RPM equation. I would put the common non-racing, performace cadence range at 80 to 95. And during a ride with some medium hills my cadence would be between 70 (on some hills) to 90+(down hill) Generally on the flats I'm at about 80-85. When I was younger my cadence was maybe 5 rpms higher. I have a little bit of a gut now and find a higher cadence difficult; I also use a little longer crank arm - 172.5 - (I'm 5-8) which slowed my cadence down a little too. While you want to keep spinning up hills you will be actually slower in most cases (not all) if you try to maintain the same cadence as on the flats. Too slow and you bog down. Newbies are drilled to spin, then you see 'em emulating Armstrong's cadence. If training, it's important to vary you cadence too. I ride in a very high gear - for ten miles - 1 gear only, then I'll ride in a very low gear the entire time. Works you strenth and spinning. Since it's very individual you need to experiment with it. The experienced rides I ride with have varied cadence as I, newbies are counting their peddal strokes. Ultimately, when you have experienced many miles at various RPM your body tells you what it right. Of course when standing your RPMs have to drop, when sprinting they go up. When doing a TT keep RPMs to a very narrow band if it's flat. If you're racing a crit, you RPMs will be high, you need to react fast. Cadence variation helps to keep you fresh, allows flexability and improves your workout. There is a sweet spot for each rider, it's the balance between leg strenth/endurance and your cario capacity. Simply put you pedal too fast you be winded with little to show for it. Too low, and you will fry you legs. If you ride 10 miles very hard when you finish you should be heaving for breath AND you legs should be wasted. The Lance - Jan comparison (in another answer) is a perfect example of balance between legs and lungs. Lance used his superior lung capacity and Jan his leg strength. Hence the high and low cadence. I've paid enough attention over the years to both my own style (and how it's changed as I've aged), and to those who I've ridden with to be fairly convinced that "optimum" cadence is entirely dependent on a given rider. That being said, there are several factors that go into a specific rider's comfort zone, including: aerobic capacity (lungs), muscular capacity (legs), body geometry (leg length, hip/knee angles, natural 'gait', bike geometry, gearing, age, and terrain. Several of my riding buddies are of the 'Jan Ullrich' type; strong legs, relatively heavy body weights for their size, and/or have something of a tendency to be pigeon-toed or bow-legged. Even when they're on the bike ... which means they're more comfortable at slower (65-85 rpm) cadences, regardless of actual terrain adjustments. These guys would be sprinters or perhaps classics riders at the Pro Tour level. Several others, of course, fall into the 'Lance Armstrong' or 'Alberto Contador' category; relatively light body weight, great aerobic capacity, clean 'straight' lines when riding ... and correspondingly higher (85-95 on the flats) cadences. Myself, I tend toward the higher rpm choices, partially because of my gearing (I ride a compact crank) and partially because I've got a good power-to-weight ratio ... relatively high power, relatively low weight. As far as Pro Tour riders go, I'd be classed as a climber, or maybe an all-rounder. Since the combination of events leading up to 'comfort' are different for every indiivdual, there's no such thing as one perfect cadence. It changes for every rider, and can be somewhat dependent on terrain as well (slower cadences on longer, steeper climbs, for instance ... or faster cadences on descents). My advice is to know your body and do what works for you. You'll probably find that as your fitness level increases, your cadence will as well ... until age kicks into the equation and it might start to drop slightly once more. 90 ususally 53x19x 90rpm = 20 MPH This is always a question that has no 100% answer. You will find cyclist who will live and die by a particular cadence. Now I'll throw my two cents worth in. At different rpm's you use different muscle types consisting of fast or slow-twitch fibers. Each works differently (go to "www.performancetriathlete.com /cms/ article-detail.asp?articleid =433" for a detailed explanation.) Then you get into the issue of rpm vs. gearing. If you want to explore the math behind it go to "www.kenkifer.com/ bikepages/ touring/gears.htm" for a good read on how it all relates. Now depending on what type of riding you do it can make a world of difference. If you haven't guessed I'm a mountain biker and I mtn bike race, I'll be the first to tell you to develop the widest rpm range you can. When off road riding on a very technical rough area, a high rpm (100+) will probably cause you to bounce or stall when encountering rocks or roots, not a good thing when you need to maintain your momentum, and a low rpm will wear you out. Read the two articles and test what they say it may surprise you. |
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