A quick note: the formula used in this piece might look a little daunting but it’s a lot simpler than it seems. I’ve been climbing ok latelly, but at the same time having difficult to follow some heavier guys (who climbs with me) on the flats. I’ve long been aware of the relative unimportance of bike weight (lose 10% off the bike, and bike + rider is only ~1% lighter) but it’s nice to see the numbers for climbing. That … Comix Some skip up like mountain goats. Awesome article Matt! I love it. Your equation states: Power required to overcome rolling resistance, P = krMs. So, how does the required power change depending on the gradient, assuming we’re talking about a constant speed? Power = Work / Time = Force * Displacement / Time = (Mass * Acceleration *Displacement) / Time. bike speed â headwind or + tailwind), v = speed of the bike through the air (i.e. Also, as Jules alluded to, there is a Psychological side to is as well. Iâve found personally people really need to get a grip on snacking and knowing when they are truly hungry. (6.8/22.9) x 60 = 17.8 minutes = 17 minutes 48 seconds. Here are five DC bikes that I like. This is why really good climbers are generally skinnier or smaller than average riders. I’ve gone through and calculated the required wattage for the whole number gradients from 0% (a flat road) to 20% (ouch), assuming that I want to maintain a speed of 20km/h on each of those grades. Each of these bikes will work to get you out on a ride, though they vary in intended use, levels of performance, and versatility. Thanks for posting this info. Itâs also a calculation that most Grand Tour teams place huge importance upon. 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. google_ad_client = "ca-pub-2062310126166513"; The additional power is proportional to the grade or slope of the road and the speed of the rider along the slope (or along the level line). The Zwift Concept Z1 (Tron) bike is 32 seconds faster than the stock Zwift Aero+32mm Carbon setup in our Alpe climb tests. As a result our rider might be able to stay with the bunch for the entire 20-minute climb. 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. Site Map, KOM: A Guide to Downhill performance is composed and impressive, especially considering its short, 115mm of rear-wheel travel. About 2 years ago I went from 170 down to 145-150. For this calculation we’ll also need the average gradient of the 1 in 20 which is more or less 4% (not 5% as the climb’s name would suggest). If the total ascent is 4000m, and the weight of the bike and rider is 90kg (I wish! seconds) which is where the speed term comes in (i.e. Road Bikes. The chainstay is 17 inches which is long enough to make the ride more comfortable and improve the gripping power. And how long will that average speed take Rider B to finish the climb? But it will happen in the more mountainous parts of the world. It’s this dedication of yours that rewarded you with some huge PBs recently. My take: 2000m climbing on a 100km ride is a big day in the saddle, and is something I very rarely do. That said, the Tron bike is still one of the fastest on flat/mixed routes. Mass times speed is (kg)*(m/s), which does not produce Watts. The good news is that losing five pounds is a fairly attainable goal for most people that will translate to some gainsâplus, your cycling kit will fit a bit better. Well done for putting it all together and particularly explaining why my calculations on the 1 in 20 never work out… i.e. 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). POWER-to-Weight Ratio. I’ve been working to lose weight watching what I eat and pushing myself on rides. Let’s take the formula we used above and reverse-engineer it: You’ll recall that 326W is the required wattage when considering a drivetrain efficiency of 95%, which correlates with 310W on the road — the power we need to use in this calculation. Cheers. If you’re lighter, you’ve got less mass to haul uphill and therefore less power required to ride at the target speed. Fortunately, a new class of bikes, Downcountry, have recently gained some traction. Required fields are marked *. And because that part of the equation factors in the rider’s weight — as discussed above — the lower the weight, the lower the required power to climb at a certain speed. Find out here: http://goo.gl/ZUNu5. In the previous section we learnt that a 90kg bike + rider combo needs to produce 326W of power to climb at 20km/h on a 5% hill. And maybe I've left some factors out. He might be able to push 330W for 15 minutes, for example, but as the wattage increases, the length of time he’s able to maintain that wattage for decreases. Ted is 61 years old, 6â 1â tall and weighs 167 lbs. Thanks a lot! POWER is time specific so you need to divide through by a time term (i.e. Science of climbing: why power-to-weight ratios matter, New climb added to the site: Buckland Gap, http://cyclingtips.com.au/2013/09/climbing-and-time-trialling-how-power-outputs-are-affected/, Lose weight — you won’t need to produce as much power to haul yourself and your bike uphill, Increase the amount of power you can produce, For the sake of approximation, we can use the climb’s percentage gradient/100 for the variable “i” in this equation. I’m too tired from my bike ride up a 10 mile hill at the moment to be certain your formula could be used to get the answer to the problem I pose. Most would go for a mountain bike at 28 to 29 pounds. 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…. The twelve extra pounds required about 10% more power output. This keeps the bikeâs weight more centered because the front tire is closer in toward the rider. the other measure i like to reference when assessing climbing performance is VAM, or rate of vertical ascent (the principle is dead simple, but its use was pioneered by none other than Dr Michele Ferrari). As the weight came off climbing ability really increased. So youâll want to think through your strengths as a rider when choosing your frames and wheels for races. Maybe you have thought of it. google_ad_width = 300; This means itâs possible to express the effect of weight on climbing, with a fair degree of accuracy, by dividing one weight with another using the following formula: Letâs take a typical, relatively sprightly bike of 25lbs / 12kg as a demonstrator. Breaking the 1 in 20 down into three sections — 3.3km at 4.5%, 1.1km at 1.9% and 2.4km at 4.5% — and running the calculations again returns a slightly different result: 17 minutes 30 seconds versus 18 minutes 7 seconds. If the total ascent is 4000m, and the weight of the bike and rider is 90kg (I wish! Could someone explain this in terms of energy instead of power? 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. So that is, the overall weight of his bicycle climbing is the amount! But at least I ’ ll definitely look into the energy expenditure issue that the windspeed signs be! Heavier bike is 32 seconds faster than the stock Zwift Aero+32mm Carbon setup in Alpe... What ’ s just as powerful as rider B, but things have moved on from... 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