![]() ![]() ![]() To summarize, the lowest ratio needed for most people when doing typical self-supported, ultra-distance cycling events will be somewhere in the range from 0.8:1 to 1.0:1. Personally, I prefer to have a lowest gear ratio of around 0.83:1 when doing ultra-distance rides and I also appreciate having that gear available on local shorter, hilly rides. Having an even lower gear ratio than 0.92:1 may therefore be advisable for many people. To keep things simpler, I only present gear ratios on this page and ignore the very minor effect of tire size, but you can include this when doing your own calculations. Tire diameters from as small as 650B x 35mm up to 700C x 40mm are common but wouldn’t change the result by more than about +/-2 rpm. In addition, I assumed a tire size of 700C x 25mm. Being able to sustain 200 watts (or 800 vertical m/h) even when fatigued and having a total weight with bike and equipment of 85 kg are rough values and may be over-estimates for typical ultra-distance cyclists. This result of needing a 0.92:1 gear ratio only applies to this one specific example and the values that I’ve assumed. ![]() If the rider wants to maintain a more comfortable cadence of 60 rpm on such a climb then the chainrings, cassette or both should be changed to have a lowest ratio of no more than 0.92:1. They show that the cadence when riding at 7 km/h with this gearing would be 52 rpm, which is worryingly low. There are useful tools for turning speed into cadence when using a certain gear ratio here and here. How Low Should You Go?īased on your anticipated speed and minimum tolerable cadence, are the gear ratios on your bike sufficient?Ī common setup on a road bike adapted for climbing is a compact road crankset with 50-34 chainrings and an 11-32 cassette, which gives a lowest gear of 34:32 or a ratio of 1.06:1. However, most experts agree that using a cadence lower than about 60 rpm for an extended period puts extra strain on the muscles, thereby causing unnecessary fatigue and increasing the chance of injuries developing.Īlthough cadence information generally isn’t very useful when riding, it’s a good idea to use a cadence sensor occasionally to be aware what different values feel like and to know what is the minimum that you can comfortably maintain, which may depend partly on your Crank Length. Research shows that what cadence a cyclist prefers to use doesn’t have a massive or consistent effect on their power or fatigue as long as it is within a reasonably broad range. The revised estimates for these specific Alpine climbs are therefore 720 m/h and 180 watts, which translate to 7.2 or 7.0 km/h. Taking the same values as in the What Determines Cycling Speed? section (weight = 85 kg for rider+bike+equipment, C d A = 0.43, C rr = 0.004 and drivetrain losses = 5%) then a power of 200 watts on a 10% gradient equates to a speed of 7.8 km/h.Īt an elevation of 1500 meters, a cyclist’s available power is generally reduced by about 10% compared to sea level due to the reduced oxygen (see the Environmental Effects on Cycling Speed: Wind, Elevation & Air Temperature page). Sustainable power can be turned into speed at a certain gradient using this calculator. Using the numbers from the 2016 TCR route gives: 800 / (10 * 10) = 8 km/h. VAM (in vertical meters per hour) can be turned into cycling speed (km/h) at a certain gradient (in %) using this formula: Second, what are the average gradients for the steepest long climbs on the route that you’re preparing for? For instance, two of the climbs on the 2016 Transcontinental Race (TCR) route had sustained sections of 10% gradient at elevations above 1500 meters. Sustainable Climbing Speedįirst, you need to either know the rate of climbing you can sustain, known as VAM and measured in vertical meters per hour (e.g., 800 m/h, as shown on many bike computers or activity tracking websites) or your sustainable power in watts (e.g., 200 watts, measured using a power meter or estimated on activity tracking websites). To calculate the size of the lowest gear you need, you should begin by determining what speed you can maintain on a certain climb and what pedaling cadence is tolerable. Bike Gear Shifting Systems & Derailleurs.Avoiding Bike Crashes & What To Do If You Crash. ![]()
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