# Tag Info

32

Here's what you need! Lightweight and upright --

28

Consider trying a recumbent. They fail on your "light" requirement, with weights well above a diamond-frame. However for a crook back, sitting in a comfy armchair is magical compared to being on a road bike. There will be some acclimation time - don't expect to just get on and ride like normal.... OK you go back to being a complete noob who can't even ...

25

This research claims around walking 334 kilojoules of energy expended for a 1.6km walk Using the same 1.6km distance, if you cycled at 20km/h at 70watts (arbitrary but vaguely-plausible numbers), you would be involve around 20 kilojoules being "sent to the pedals". Assuming you are about 20% efficient, that would be 100kilojoules burned For that distance, ...

25

IMHO, it's not the weight that is hurting you the most. While weight makes a difference and a lighter bike would be much better, it's too common in cycling world for people to use weight as a proxy quality and performance. Any twit with scales can measure it. That said, there is no doubt more suitable bike would make longer trips faster, and a better ...

24

Breaking the rules with a kind-of non-answer and personal opinion, but... 1) Mountain bikes should be heavier than a cyclocross bike. It's got a suspension fork and frame and wheels need to be beefier to handle bigger loads and impacts. 2) Don't buy a bike with a plan replace major components. Just buy the bike that meets your needs in the first place (in ...

22

First things first: A belt is probably slightly less efficient than a properly installed clean chain. The test you link already indicates that. Probably with the tension Gates requires you'll loose a bit more power. On to your question: The chain is 200 grams heavier than the belt, of course with the chain you get gears, which you don't get with a belt ...

21

The ideal gas law (which is a good approximation in this case) says PV=nRT where P is pressure, V is volume, n is mols of gas, R is the ideal gas law constant, and T is temperature in Kelvin. Thus, solving for n, we see n = (PV)/(RT). Then, assuming air is made up of {gas1, gas2,...} with fractions {p1,p2,...} (so p1+p2+...=1) and corresponding molar ...

20

Most important - Well done in losing weight, what you are experiencing is very normal, don't let it put you off. A word of warning - despite the common perceptions, most people do not lose weight exercising. Their appetite increases to compensate for the the increased calorie demands, this could be what's happening to you. Personally I think focusing on ...

16

Obviously the prices seem to support the idea that aerodynamics matter more than a few hundred grams of weight, but at what point does the added weight offset the gain? An exact calculation will depend on the total mass of you and your bike, your speed, the wind, its angle, whether you're climbing, on the flat, or descending, and the speed you're going (...

16

Bonking occurs when your body cannot metabolise stored fat (and muscle protein) fast enough to replace the glycogen reserves, you deplete the reserves in your muscles and liver, and eventually you run out of glycogen. Fat conversion requires high levels of oxygen, and is slow, so once those reserves are gone, your blood sugar plummets. I suspect your body ...

15

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 ...

15

On a non-folding bike, I'd look at the wheels, and probably replace them with 36 spoke touring wheels and reasonably wide, tough tyres (e.g. 35mm). The tyres absorb some of the shock loads. However a folding bike has made some compromises affecting the structural strength, as well as introducing weak points. Two major ones are the main hinge and seat post. ...

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/...

13

In context of this kind of discussion - weight and cost are the same thing - the more you spend on a bike, the lighter it is (with diminishing returns) and you cannot talk about weight without talking about how much money you have and are prepared to spend (sometimes not the same). The context of this answer is a targeted weight of a 7-8kg MTB. No weight ...

13

Bontrager's Law states parts can be light weight, durable, or inexpensive you only get to pick two characteristics. The only time it makes monetary sense to replace a part with a lighter one is if the component has failed. If you think 3kg. will make a difference between winning and losing try this experiment. Ride a timed course while carrying 2 full water ...

12

There are generally two types of dropper seatposts, mechanical (e.g. GravityDropper) and hydraulic (e.g. RockShox Reverb). Mechanical dropper seatposts use a spring to move the seatpost and a bolt to keep it in place. This is a very simple design and there are few things that can break or jam, and the weight is also kept very reasonable since there are few ...

12

The spokes and gears are likely unrelated issues. You have done 2000km on the bike - have you replaced the chain and rear cluster yet? At you weight and those hill climbs, I would not be surprised if they are just worn out. It is also possible that at your weight and that distance the spokes have come out of adjustment, and/or now have fatiguied to the ...

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'...

12

I have carried a laptop on my commute bike for closing in on 15 years now. Mainly in panniers (saddle bags). For a little while in a courier bag when when I was young and dumb. For what it is worth (aka the dangers of anecdotal evidence) I didn't have any laptop failures directly related to a bike trip. I even toured with a 17inch laptop across 800 km of ...

12

While Criggie's answer explains the reasoning behind the limit, the reason why the official limit is almost always exactly 22kg is simple: that's the standard. The 22kg limit comes from the European standard EN 14344:2004: This document specifies requirements for child seats for cycles, which are intended to be mounted on pedal cycles and electrically ...

12

I would recommend you wait for one reason Covid. In most parts of the world bikes are in limited supply. Prices even on used bikes are 50% to 75% higher than comparable bikes a year ago. I think you may wind up overpaying and settling. By settling I mean selecting a bike because it is available. Maybe not the best fit, or the correct type(road, gravel, ...

11

To calculate the weight of a gas you need the volume, pressure and temperature. A bike tyre is a torus (doughnut) with volume given by the formula: V=(πr^2)(2πR) where R is the radius of the wheel and r is the radius of the tyre. For a 700c25 tyre, R will be 311mm and r will be 12.5mm that gives a volume of 9.59×10^5 cubic millimetres or 0.000959 cubic ...

10

According to Wikipedia, Gold has an "ultimate tensile strength" of 100 MPa, while steel runs from 400 to 5000. (Carbon fiber laminate is 1600.) Gold has a specific gravity of about 19, while steel has a specific gravity of about 7.8. So it would take about 4 times as much pure gold by volume, or about 9.7 times as much gold by weight. A 15 pound steel ...

10

According to the Weight Weenies.com web site listed weight can differ from actual weight by as much as 10-13%. One thing you should be aware of is there is some variations between identical frames due to manufacturing tolerances. Most weights listed in advertising literature are not for large frame sizes. Looking at the listings on the site it appears that ...

9

I am continuously amazed at the overemphasis placed on the weight of bikes. Yes it is important, but relative to other factors in deciding which bike to buy it is not that significant. Lets compare a 20lb bike to a 24lb bike. If your budget is \$1000 for a new bike, would you choose a 20lb bike with very good components and a so-so feel/fit, or a 24lb bike ...

9

The rational side of me says that over the short distance you're talking about, walking would cost more energy than cycling. The caveat here of course is how fast you walk. However when I first got back on my bike (and I was pretty overweight), I started off cycling between the train station and my office. It was something like 2 miles each way, and used to ...

9

'Bulk' is mostly about whether all of your luggage will fit in your bags. ie is the volume of your luggage less than the capacity of your bags. So it depends on how much stuff you want to take, and how big your panniers are. Aerodynamics doesn't really matter for touring. Unless you are cycling rather fast, or it is very windy. Usually the weight of your ...

9

The important thing to remember is that on a modern road bike, the frame is actually a small percentage of the overall weight of the bike. This frame, including the fork, is advertised at 3 pounds, while a bike built on the frame weighs in at 16.69 pounds. The frame is only 18% of the weight of the bike. Even if the frame which was a bigger size weighed 20%...

9

The physics model of cycling power and speed has been validated in the real world. Two examples are this and this. The model embedded in Analyticcyling.com's online calculator is based on these two papers. Whether the amount of difference calculated by the validated models is worth it to Joe and Billy is a question that can't be answered by the physics.

9

Many of the (continental?) European "every-day" bikes have a relatively upright and straight back position (you basically get a continuum there from sportive strongly forward tilted position to upright or even slightly back tilted.) Typical features of such a bike with more upright/straight back position are U (or M) shaped handle bars (the ends are ...

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