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1d
comment Calorie Burn Meter Bicycle
Calories are related to joules and to watts. There are power meters that measure watts, which can then be translated to calories. See this bike.SE question and answer that describes how various power meters work.
Apr
11
comment Constant / maximum set load bike? Does it exist?
I can track stand -- but most people can't. Your design would essentially require that riders have your level of skill. I'm explaining why your design, although possible from an engineering point of view, hasn't already been done: its characteristics are not what most riders want. I can stand up from sitting on the floor without any additional stabilization from my hands -- but most people do use their hands (as do I, most of the time). Calculate the pedal force needed to start up while on the grass or gravel and you'll see that starting up would indeed require a crawler gear.
Apr
11
comment Constant / maximum set load bike? Does it exist?
Right, in your design, from a full stop the bike would simply shift to a (very) low gear to limit pedal load. This is exactly the feeling when one first begins on rollers -- most people have far more difficulty learning to start up on rollers than to maintain speed on rollers because the resistance is so low when starting out. They fall over before they can balance. You've observed how resistance varies when you go from pavement onto the grass. In most cases, riders will "muscle up," not to go faster but to use that pedal resistance to attain balance. Your design removes that.
Apr
11
comment Constant / maximum set load bike? Does it exist?
Right, resistance also increases when you climb a hill at constant speed. This was a simple illustration of the design challenges you face. In fact, the bigger issue when you ride outdoors is acceleration (which you can see in that answer I linked to). In order to accelerate as you might do from a stop light, you have to increase load while still balancing on the bike. If you limit pedal load at a constant maximum your system will have to respond by gearing down very quickly. It's possible from an engineering standpoint but it will be hard to modulate it quickly enough.
Mar
12
comment Identify this shaft driven bike for me
If it's a fixed gear, why does it have both front and rear brakes?
Feb
25
comment Buy TT BIke or Convert Road bike
What kind of tri? Short-course, long-course, draft-legal? Are you hoping to be a contender, or MOP? Can you afford two bikes, or only one?
Feb
25
comment Power to weight, FTP and Terrain Profile
Here are some links to references that show the relationship between size and CdA. The short summary is as I said above: as a reasonable rule of thumb, CdA scales less than proportionally with size. So the larger rider will have the same power/kg but higher power/CdA.
Feb
25
comment Power to weight, FTP and Terrain Profile
As a rough rule of thumb, CdA scales roughly with the 2/3rd power of mass, so although the larger rider has more area, it's less than proportionally more. An additional but smaller effect is that if they ride a bike meeting UCI rules, bikes have a minimum weight (currently, 6.8 kg) so the lighter rider bears a larger percentage increase in total mass compared to body mass.
Feb
17
comment What is the best aero position in a mountain bike?
Sorry, my question may not have been clear. Can you ask the person who wrote your training program what the goal of this particular training is? Are you training for a TT? Why are you doing this on a MTB, and does the person who wrote your training program know that is what you're using? Are you trying to adapt an existing training plan to that situation?
Feb
17
comment What is the best aero position in a mountain bike?
Can you ask the person who wrote your training program what he or she wants you to do?
Feb
8
comment What speed of wind gust will cause a cyclist to swerve by 1m or more?
Yesterday's Volta a Marina in Benidorm Spain had to be cancelled because of wind. You can see riders getting blown off their bikes here.
Feb
8
comment What speed of wind gust will cause a cyclist to swerve by 1m or more?
There is not enough information given to answer this specific question, nor is there likely to be. The same cross wind will affect a large slab-sided lorry differently than a small car; the same cross wind will affect a thrown ping pong ball differently than a speeding bullet. From this you can see that it's not so much about the wind as about the characteristics of the object, and we would need much more information about the object (in this case, a cyclist) than simply the speed of the wind.
Feb
2
comment Riding into a headwind faster than my top speed - how is it possible?
@ChrisH The reference you're looking for is Equation (2) in this document.
Jan
29
comment Riding into a headwind faster than my top speed - how is it possible?
Ah, I think I'm beginning to understand. Is your question, "if I can ride a maximum speed of X in calm wind, why can I still move forward when faced with a headwind of X?"
Jan
29
comment Riding into a headwind faster than my top speed - how is it possible?
The equation for bicycle drag is well understood though not always well known. In particular, the aerodynamic drag component of total drag includes airspeed as you're well aware -- but it also depends on air density. The reason why you can cycle into a strong headwind is because air isn't very dense. You would have a much harder time moving against a water current of 5 mph than an air current of 30 mph.
Jan
28
comment Why is a steady cadence so important? Or is it?
Have you read the answers to this question? bicycles.stackexchange.com/questions/12518/… In any event, if you examine what riders actually do, it is natural for cadence to vary. Riders rarely ride at a fixed cadence unless the conditions are also fixed (that is, same speed, same slope, same wind, same power).
Jan
14
comment Why does hunger have a much more drastic effect in cycling than in other endurance activities?
Your last sentence is unclear. It's not clear that less trained individuals can last longer before bonking while running than they do when cycling.
Jan
14
comment Why does hunger have a much more drastic effect in cycling than in other endurance activities?
@PeteH, a partial answer to how many calories a runner will burn per hour is given half-way down in this answer.
Jan
7
comment Does gear ratio affect Power?
@ChrisH One might think so, but empirically not. Many riders can produce > 1 kW for a few seconds in a narrow range of cadence but they might climb a nontrivial hill at, say, 200 - 250 watts. Empirical analysis of their cadence choices show that at a lower level of output they can and generally do produce fixed power over a wide range of cadence and crank torque.
Jan
7
comment Does gear ratio affect Power?
Welcome to bicycles.stackexchange. Your answer applies only instantaneously. For climbs of nontrivial duration, power is limited by metabolic processes (mostly, aerobic). That is, what you've written is true for maximal instantaneous power but when climbing any nontrivial hill your power output will be decidedly submaximal. There are still boundary values on gearing that will limit power production but and long as you are reasonably far from those boundaries your limitation is metabolic, not either force-limited nor limited by the speed of msucular contractions.