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10

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 ...


8

The differences are quite significant from race to race - each track is different. Also events such as Rampage are not too much about speed. The top speed may vary between 55-65km/h on tracks such as Mount Sainte Anne up to around 80km/h in Pietermaritzburg which is known for high speeds achieved. Of course all assuming good weather. Also these speeds are ...


7

I'm not sure that anyone is going to be able to give you a definitive answer... especially since you are asking if your commute will improve by 30 seconds when the commute time you give has a range of 60 seconds. But 30 seconds out of 17.5 minutes is about a 2-3% improvement, which seems reasonable... The more interesting question would be "what can this ...


6

As you might expect, the exact down slope you would need for a full answer will depend on how much drag you and your bicycle produce. If you are very aerodynamically efficient and there are few losses through the bearings and tires, the slope can be shallower. If you create a lot of drag either via aerodynamic inefficiency or mechanical and rolling ...


6

Guy Martin is obviously a decent cyclist, but you should note that his record-breaking ride occurred under very special conditions. For starters, he built his own frame (or rather Jason Rourke built it for him). Next, he chose exactly where the run would take place - on sand flats. And not least he was towed in order to get up towards top speed, which ...


6

I want to use the bicycle for the 26-30mi commute that I do everyday and if it is a racing bike it could potentially save time A trained cyclist can definitely ride farther and faster on a road bike than on a hybrid bike, based solely on wind resistance and bicycle fit. However, the speeds you list are completely unrealistic. Bike speeds are based ...


5

I think this is kind of a non-question. You want the helmet that rides the fastest? For anything "fastest", either components or kit, just look at what the professional riders are using. This seems to imply that you either wear a regular-design lid (albeit one which is very light, very ventilated, and probably very expensive). Or, you go for a time-trial ...


4

The Varna, which was one of the best bikes in 2003 has speed + power graphs up from their Battle Mountain runs that year. At 80kph Sam was putting out about 225 watts, but accellerating. There's also a 0.5° slope to consider. This article suggests that the bike uses about 150W at 50mph/80kph. Sam weighs about 80kg, the bike about 25kg. Let's call it 110kg ...


4

Aerodynamics of a helmet cannot be considered in isolation but rather how it affects aerodynamics when on the rider. The fastest helmet choice for one rider won't necessarily be the fastest for another, it's quite an individual thing. I've done many, many aero tests of helmets on rider, and am often surprised at the combination that proves best. In general ...


3

Bigger tires, bigger chainrings and a smaller cassette all lead to a higher gearing (the crank arm lengths among other things also come into this, but that encapsulates into bike fit). Bigger tires are subject to frame clearance and feeling squirmy possibly. Bigger chain rings require front derailleur compatibility. Smaller cassette also requires ...


3

There are now "sprinters" helmets that are bit in between TT helmets and regular bike helmets. Giro Air Attack is a good example. There are even some pro riders using them in TT stages.


3

The factors that affect bike efficiency are: Weight Mechanical power train Losses Aerodynamic Drag Rolling resistance For a touring bike, the difference between a folding and regular bike are all lost in the noise. Smaller wheels tend to have higher rolling resistance and the bike might be a bit heavier, but for touring it just doesn't matter that much. ...


3

It's not about energy to accelerate the bike to speed, but the energy to keep it there. For bicycles the kinetic energy is a small part of the total power output of the rider (typically under 10m/s = 36km/hour and 100kg, and e=1/2 m v² = .5 * 100 * 10² = 5000J or watt-seconds. So a casual rider putting out 250W could reach 36kph in 20 seconds, assuming no ...


3

Usually, when you want to commute somewhere, you have to carry things (a rack+panniers are good for this, esp. if you carry laptops), you don't want to arrive in a pool of sweat (and you need a change of clothes on hand anyway) and you want to arrive comfortably (cause you should be productive at work). These are all the opposite of what a racing bike is ...


3

Most speedometers are accurate as long as you input/set the right wheel size! I have used very cheap ones, and they allow me to set the wheel size in milimeters, and after checking the same path with two different cars, the difference is minimal compared to what I had with the bicycle (in a 25Km ride the difference was only 10 meters compared to the cars). ...


3

Any half decent touring or racing bike can do the speeds you noted, however, a more practical value for commuting is ~10-20 mph, on flat terrain. I'd recommend a touring bike for the purpose, rather than a racing bike for all the reasons noted previously. They have slightly wider tires and sturdier frames. The first leads to a somewhat less bumpy ride, the ...


3

What is your "cadence" (number of pedal revolutions per minute)? A healthy young cyclist should be able to "cruise" at 80-90 rpm, and that would be considered your top speed. If at 80 rpm you're only getting 18kmph (11mph) in your fastest gear then your bike gearing is quite low and you probably need to change something. But many novice cyclists simply ...


2

I found driod support for these kinds of sensors to be patchy at best and not yet what I consider ready for prime time. Manufacturer provided software is often crap, third party often don't support the hardware. Many claims of features and devices suppported apply to the iPhone versions only. I current use Digifit iCardio on my driod phone with Scorche ...


2

I don't think accuracy is a problem, even with cheap ones. I tested my first one (cheap chinese) against Google Earth and the marks on the road (every 100 m) on a paved straight road over a 15 km ride, and the differences are minimal. Cheap models only let you specify the nominal wheel size in inches. Better ones present a list with all relevant wheel sizes ...


2

Other answer is good - I got pulled away before I could finish this post I have nice day bike and a rainy day bike and they have less difference than those two bikes and pick up more than 30 seconds on the about the same commute even rainy bike on a nice day Factors: Overall bike weight Aerodynamics The drop bars reduce wind resistance More efficient ...


2

From the web site that bike comes with 40T chainring and a 14-28T Freewheel. 17.94 kmph is a cadence of only 50. bikecalc.com You should be up at 80+. On a sprint you should go over 100. A folding bike is not as efficient as most full size bike but gearing is not what is holding you back at 18 kmph. Not going to give specific hybrids but there are many ...


1

But you don't have the same transmission as the wheels are part of the transmission. Smaller wheels are not as efficient - more rolling resistance. You also need to send more chain which is not as efficient. You don't have the same position and lack multiple positions offered by drop bars. The frame is not as rigid and absorbs pedal energy. In the end ...


1

The 'best' is fairly subjective and probably not compatible with lightest. For what it's worth I remember reading somewhere that the Edge 510 is widely used through the pro peloton. I use a Garmin Edge 810 and would recommend it in an instant but it is possibly bigger than it needs to be if you're very worried about weight and size (I chose it for its ...


1

Android can just about handle multiple BTLE sensors simultaneously but there are still some low level Android bugs that make it rather unreliable. The coding for is also a good bit more complex to get working than the single sensor case. I have support in my app IpBike via a beta version of IpSensorMan At this point in time if you were getting new then an ...


1

I assume we're not talking about some low-price, no-name thing from a Walmart sale but about one from one of the more common speedometer selling companies (cyclosport, sigma, garmin, to name a few). With those, I don't think that there will be significant differences in accuracy. Also wired vs. wireless should not make a difference by itself (unless the ...


1

In a practical sense, increased weight will make you go downhill faster, for the same reason decreasing weight will make you go uphill faster See this interactive calculator. If you set the gradient to "-10", set "Power P (watts)" to 0.001 (i.e almost zero): With rider weight set to 50kg you will go about 59.54km/h With rider weight set to 75kg you will ...


1

This may be half-remembered physics coming into play here, but I've raced (substantially heavier) friends down hills where they've been on bikes which should - be all accounts - be slower than my own, yet they've won. Could momentum come into play over rougher terrain? By that, I mean if a rider carrying a heavier weight were to hit a bump, or hole etc, they ...


1

The short answer is yes. See Chris's post for the long answer. The main reason for this "answer" is to encourage great caution. As a teenager (in the previous millennium), I grew up in hilly area. There were two descents we used to do regularly - a two mile run from my friends farm to home, and a steep hill of one mile. My best time to get home was 2:11, ...


1

If there were friction it'd be the exact same (remember the hammer and feather on the moon deal). However - your net drag isn't really going to be proportional to your mass. The air resistance isn't proportional at all to your mass (although the rolling drag is). Due to this, you'll have less drag per kilogram with more weight which will cause you to go ...


1

For the first question answer is «Not». The problem is air resistance, starting from 40-45 km/h it's like a wall. For every addition to you speed you'll spend more and more power. For the second — 50 km/h (and even more) is a normal speed for descents on a road bike. This bikes is pretty controllable on such speed.



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