Hot answers tagged

60

What really struck me though was that the average speeds really haven't changed much The chart ranges from about 25km/h to over 40km/h, and that is a big change. As others have mentioned, increasing your average speed requires a non-linear increase in power applied to the pedals. In other words, to increase average speed from 25km/h to 26km/h is easier ...


50

This is an interesting point of view. Let's unpack this a bit. Assume I have a ride that is 10 miles of flat, 10 miles of ascent, and 10 miles of descent. On the flat I maintain a constant 20 miles/hour. On the ascent I fall back to a constant 10 miles/hour. On the descent I maintain a constant 30 miles/hour. My average speed for this would be: (10 miles ...


46

The short answer is: not that difficult. The long answer requires some explanation. The equations of motion for a rider on a bicycle are well-understood if not always well-known. The power needed to propel a bicycle on firm flat ground (as on a velodrome) varies approximately with the cube of speed. Thus, to double your speed, you would need to increase ...


41

Having made the change myself, I can confirm that shock absorbers are actually detrimental to city riding. You lose a lot of power, especially when trying to stand on the pedals for acceleration. Road bikes are also typically much lighter, which in my experience not only helps you go uphill faster, but also makes it a lot easier to carry the bike when ...


38

It is really dangerous to follow a large vehicle closely. It is possible behind a directeur sportif in a passenger car which is smaller: you can see through it, and the driver is a cyclist who knows you and knows about you. You cannot see what is coming in front of the truck. If they choose to brake hard, watching the brake lights will be of no use; you have ...


30

Disclaimer: I am a fixie hater. I'll try to answer this as if I was impartial. Proper road bikes (Including the Moulton) are the machines for speed, and always have been (unless you're on a velodrome). Looking at it through a speed lens, a fixie has a slight weight, aero, and drivetrain efficiency advantage over a road bike, but this usually doesn't come ...


25

Always "riding your hardest" is called "junk miles" because it is not possible to always ride your hardest. The biggest performance gains come from more targeted and disciplined riding (as suggested by mattnz). To climb your steep hills (I assume these are relatively short, steep climbs, not a mountain pass) you need to work on developing high power over ...


24

I happen to be one of those who attract new riders into the sport, and have given the basic training to many people. Here is a brief of what I try to teach them: Riding position Be ready to react Have your bike properly tuned/fitted Scan the terrain(Look forward) Use a proper braking technique Never get to the extremes Grow progressively The most important: ...


22

Average speed is extremely dependant on: Your fitness (main factor) Weather (particularly wind) Road surface quality Interruptions like traffic lights, dog-walkers on bike-lanes Accumulated fatigue over multiple days How hilly the terrain is (although this can be balanced out by the faster descent) As you mentioned, best way to see is using a GPS and ...


20

I started commuting the same way about 8 months ago on a 29'er mountain bike, 2 things made the trip faster and more enjoyable. Firstly tyres, I changed from knobblies to slicks and it made a BIG difference both in feel and actual speed. Secondly I got a lot stronger from biking every day. I eventually got a lighter cheap touring bike which is faster, and ...


19

In "Epidemiology of bicycle injuries and risk factors for serious injury" by Frederick P Rivara, Diane C Thompson, and Robert S Thompson, the authors gave a questionnaire to 3,390 bicycle riders who had attended a hospital emergency department in the Seattle area. They found that cyclists involved in a crash at a speed greater than 15 miles per hour were 1....


19

In my younger foolish years I actually did this exact scenario, except at a slightly lower speed 85 kph (speed limit was 80 km/hr), but for a distance of nearly 10 km (between two suburbs). In my case I drafted a double trailer gravel truck which was very slow to accelerate making it easy to keep pace. This was only possible due to the massive low pressure ...


18

I've been a cycle commuter for 12 years. Here are the things that had the biggest impact on my speed: Smooth high pressure tires (80+ psi for road) Greatly decreases rolling resistance Clipless Pedals & Shoes - When you're clipped in you put energy into pedaling all the way around rather than just on the downstrokes Remove any suspension - suspension ...


17

The increased weight of the larger wheel (if indeed it does increase) will of course add weight to the bike, but additional weight adds very little rolling resistance (though it does of course affect hill climbing). It is a myth that "rotating mass slows you down". In terms of top speed there's no difference between weight on the wheel rim and weight ...


17

Who rides fixes? Roadies who have got bored with always being out the front? Maybe its someone wanting to make a statement to the "Freds" (look it up) in the group I once did a 160km ride where some guy on a MTB (with nobbiles, back in the mid 1990's steel, 26" etc) arrived home 00:04:35 behind the leading pack (About 4:10 hours). Some argued the only ...


17

In terms of losing weight immediately, the obvious answer is to use whatever gear combo allows you to produce the greatest energy output. For most people this will likely be a hair lower than the "preferred" range of about 70-90 RPM -- maybe 50-60, and pedaling as hard as you can. However, if you want to KEEP losing weight by getting on the bike again ...


16

Speed is determined only by gearing, of which crank, cassette, wheel, and tire are components Any 2 bikes using, say, 42t cranks with a rear 32t cog and 25c tires on 700c wheels at 90rpm will be going the same speed. Bike type and size, rider/bike weight, and even front wheel/tire size and crank length don’t matter. These other factors only effect how much ...


16

Some representative values from http://bikecalculator.com/veloUS.html. It's a road-bike calculator, so it's not quite accurate. I simulated a hybrid/city bike by having the rider on a 30-lb road bike with MTB tires, and riding that "road bike" in the least aerodynamic position possible. Note that the difference between a road bike and an actual ...


15

I think this relates quite nicely to motorbikes where you corner at very high speeds and I'll give a run-down of the techniques, why they are useful and how they apply, and how they might apply to cycling. So when turning left: You shift your weight over on the seat and tilt the bike left. This allows the centre of gravity to be slightly lower, aiding in ...


14

Your average speed is always going to be a measure of distance over a period of time. What I think you're trying to get at is accounting for your grade losses (i.e. riding up a hill), but it would be equally pertinent to include losses for wind resistance and friction as well. This would allow you to determine the amount of work per distance (or per time) ...


14

According to BikeCalculator, assuming you drop 10 kg while everything else remains the same (power output, etc.), you would travel 0.3 km/hr faster over a 50 km ride, on the average. In other words, at 100 kg, assuming an average power output of 150 Watts, you'd average 27.54 km/hr over a 50km ride if you weighed 100 kg; doing the same ride at the same 150 ...


14

Not necessarily thinner tyres, but ones with less tread will make a difference. If you are commuting by road only, then putting on some 'slick' tyres will cut a lot of the wind resistance, and rid you of that whirring noise as the tread nobbles whiz through the air. I've had my rigid mountain bike up to 76 Km/h on slicks (but that was down hill). About the ...


14

The heavier person will present more area to the wind, but this is mitigated by two factors: The bicycle presents a fixed area to the wind and the area presented by the heavier person is not proportional because of the 2/3 power law. If you just scale up a rider by a factor in mass, the volume increases in proportion, but the frontal area scales up as the 2/...


14

Let's assume you are talking about speed on a non-inclined surface for a given level of effort. (When we talk about how 'fast' a bicycle is we can also mean how well it accelerates from a standstill or low speed, or how well it handles around turns or on a bumpy surface.) Constant speed is achieved when power applied to the pedals is equal to the power lost ...


13

TLDR - Weight training is the wrong activity for improving both your sustained speed (26-30kph) and your 1-minute speed (40kph). Read below to understand why. Background There are three main types of skeletal muscles: slow twitch (type 1), fast oxidative (type 2 a) and fast glycolytic (type 2 b). Your make up of the three types determined primarily by ...


13

As long as you are moving through the air, aerodynamic drag will account for some portion of total drag. Here is a plot that shows the relative contribution of aerodynamic drag vs. rolling drag on total drag for a rider at constant speed on a flat surface with the given CdA (drag area) and Crr (coefficient of rolling resistance). There is no magic threshold ...


13

Unfortunately, there is a fairly straight forward reason why you actually need to ride hills in order to get faster at them: crank inertial load. We have two main types of skeletal muscles. (Skeletal muscles are responsible for our locomotion and movements, cardiac and smooth muscles make up the other muscle types in our the body). The two main skeletal ...


13

It's all in the air resistance. Flat out is not much more than 50km/h for me on a deserted road. Even 10 metres behind a bus it's much easier (but you still have time to react to braking). I actually found this out when I changed lanes into the slipstream of a bus while riding quite fast and found myself seriously gaining on it. Entering the zone is quite ...


12

The following forces are acting on your bike as you roll downhill (in more or less decreasing order): Gravity The force of gravity is proportional to mass. If two riders have the same aerodynamic profile, the heavier rider will descend with a higher maximum speed. This is easily seen in the formula for terminal velocity. The intuitive explanation is that ...


12

The main thing you have to consider at speed is drag: The force F on you+bike (mass m) is: F = ma = mg sin Q - F_d - F_rr where a is your acceleration, g is the acceleration due to gravity and Q is the hill angle to the horizontal. F_d is the drag force which doesn't scale with mass. Try dropping a balloon and a (soccer) football of the same size and you'...


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