Rider A’s mate, Rider B, is also able to hold 326W for 20 minutes, but he and his bike combined only weigh 85kg. It’s worth noting here that the 1 in 20 probably isn’t the best hill to use as an example as there are two significant gradient changes: from the first section into the false-flat, and from the false-flat into the final section of the climb. Some skip up like mountain goats. Like many things, it depends. There are three ways to improve your climbing: Increase threshold power, lose weight, or a combination of the two. Of course, a difference of just a few watts can make a massive difference in a race situation too, or even if you’re just trying to beat your mates up a hill. While not skinny his weight won’t hold him back. As can aerodynamics. If a rider keeps losing weight, and presumably some lean muscle mass (i.e., power), will he still climb faster? The best lightweight wheels for cycling typically feature shallow-section rims built to save weight and climb fast. Accounting for drivetrain efficiency of 95%, I’d actually need to produce 326W to travel at 20km/h up the hill. A lighter bike is not necessarily faster. Could someone explain this in terms of energy instead of power? POWER is time specific so you need to divide through by a time term (i.e. I was guessing the other way i.e. I’d like to say a huge thank you to Josh Goodall for his help in checking and revising this article. The bike should now be leaning toward the unweighted foot and your body should be in a straight line above the weighted foot. I’ve been working to lose weight watching what I eat and pushing myself on rides. If there is a tail wind, this number will be less than 0. This number will be different for every rider,  and depends on many factors. can be found on almost every bicycle related message board. Sorry Dave, but I think you have misunderstood the equation. A related topic I’ve been wanting to satisfy is that of Energy Expended. Here are five DC bikes that I like. I surprised myself. For example, a 5% hill has, Riding on heavier, wider tyres and/or riding on rough roads will increase the rolling resistance coefficient, meaning you’ll have to produce more power than you would on a smoother road, with thin tyres, for a given speed. I know the the maths makes perfect sense, but why does a steeper hill feel like it takes SO MUCH MORE effort? great article Matt. $9500 for this bike which is a lot but not extreme considering it has a full wireless AXS group. A lightweight bike will help you sail up the climbs and accelerate out of the bends. Required fields are marked *. A steep and sustained climb is the ideal environment to illustrate the power-to-weight concept, but not all (perhaps even most) races have hilltop finishes. Plus you also wobble a fair bit when it gets super steep, the riding position isn’t comfortable and you have to expend energy to stop the front wheel from lifting and the back to have enough grip to stop spinning…. At a sustained output of 200W (200 Joules/sec) it would need 4.9 hours just to provide that energy. More than that, any bike frame on the list above can beat the Tron up the Alpe, using any wheelset on our list of top climbing wheelsets. 1. Your equation states: Power required to overcome rolling resistance, P = krMs. Most other expressions found while googling have an extra g product with similar values for the coefficient as you have here. May 29, 2013 • 53 comments, The formula used in this article is derived from the formula discussed. Comix So Rider B wins by 30 seconds. If someone tried hard to minimize the weight of their bike and equipment then t… But, in order to lose weight, you need to know how to approach your biking workouts the right way. The giMs part of the equation. We showed that, everything else being equal, the lighter rider will be faster on a given climb because they weigh less. BMX Bikes But how big is the weight penalty? On a flat surface the power to overcome gravity is zero. /* bottom text banner, created 2/9/09 */ strava will produce this for you – although the error margin is inversely proportional to the length of the climb, i.e. If the climb goes for, say, 20 minutes, our rider is going to get dropped from the bunch about 5 minutes before the summit — he will have reached the limit of his ability to hold that wattage. It feels efficient with excellent climbing abilities despite its 31-pound weight and is plenty capable for any length of ride. When you're hours into a ride and you're climbing a steep hill, it may feel like the weight of the bike underneath you is seriously slowing you down. Lighter items perfor… Let’s assume I want to work out how much power (in watts) I need to produce to get up a hill of 5% gradient at a speed of 10km/h (not very fast). I require a lot more than 2 watts to propel my bike at 20km/h on a flat road even in a vacuum 🙂. Your email address will not be published. While I’d need to deliver 132W to the back wheel in order to keep moving at 10km/h, the road bike isn’t a perfect machine and the power I push through the pedals isn’t the same amount that’s delivered to the wheel. Weight training” by riding a heavier bike is classic. We can estimate that a well-maintained bike has a drivetrain efficiency of roughly 95% though, so: So, at 90kg (me + my bike), on a hill of 5% gradient, with no wind and on a decent road surface, I need to produce roughly 139W of power to travel at 10km/h. 1) can produce more power, I really like your analysis of power and climbing. It simply depends on how much weight is lost and how much less powerful the cyclist is. If you lose weight at the expense of rigidity and strength, the gains may be lose. Add rolling resistance and air resistance…. But even when programmed with correct resting & max HR, both are skewed by fatigue drift, skin & core temperature, elevation, and cardiac response delay. The heavier a rider is, the greater his energy requirements will be 2. If a rider can put out those thirty extra watts but has to exceed his threshold power to do so, then the increased power output comes at significant cost. your weight to be around 70kilos. mass * g. This would mean multiplying the rolling resistance by 9.8 . They are practical for those looking for full-suspension confidence and comfort without sacrificing efficiency. You guys are thorough bike nerds. But when the road turns up, gravity kicks in and weight matters. The fastest setups available (Specialized Tarmac Pro or Cannondale EVO with Lightweight Meilenstein wheels) turn in a time ~17 seconds faster than the Tron bike over our ~49-minute test.. Determining Ideal Bike Weight. Downhill performance is composed and impressive, especially considering its short, 115mm of rear-wheel travel. So riders will want to think through their frame and wheelset options when racing on climbing … I usually find Strava’s estimates, which are based on their power estimates, to be substantially over the real energy expenditure (especially for bunch rides); Garmin Connect, which I believe uses the Firstbeat algorithm, comes closer. If an athlete can lose weight without compromising power output, there is almost always an increase in performance, regardless of the course profile. Each of these bikes will work to get you out on a ride, though they vary in intended use, levels of performance, and versatility. The values I need are: You’ll recall that the formula looks like this: So plugging in the various values we get: P = (0.005 x 90 x 2.78) + (0.5 x 0.6 x 2.78 x 2.78² x 1.226) + (9.8 x 0.05 x 90 x 2.78). The cyclist is lists component & bike weights the day enjoying this incredible experience,... 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