Hot answers tagged

87

I happened to do just that. I took an old hand pump and an inner tube to the bath tub. Submerged the pump and pre-filled the tube with water, complete with burping out any air bubbles. With the tube moderately full and free from air, I put it on the rim with the tire. Then the final pressure up. The first thing to notice is that the pump operates with ...


55

Is this a conspiracy of bike and wheel manufacturers, to maintain a steady demand for tubes and tires? No, because if it worked as well as you suspect, someone would have made it happen and taken all the money tube and tire companies are getting. The reason pneumatic tires continue to be used is because air itself is a great spring. Additionally, being a ...


48

To a racer, rolling resistance and handling top the list; durability is far down the list. The coefficient of rolling resistance (Crr) for a racing tire on typical French or Italian roads used during a Grand Tour is about .004, or even lower. The Crr of a puncture resistant tire can be > .01. Crr scales like gradient, so the difference between Crr's of .01 ...


48

Turbo trainers are notorious for quickly wearing out tires. Trainer tires are therefore made of a hard wearing compound. However, this compound may not provide enough traction for safe cycling. Traction is immensely important as it is usually the limiting factor to the maximum speed in curves. If one's rear wheel slides away while cornering recovery is ...


48

If you value your time at US\$20 an hour or higher, you’ll find you’ll quickly benefit by just getting a spare set of wheels, leaving the tires permanently mounted, and swapping wheel sets as needed. Otherwise, you have to clean sealant from the tubeless rims which make them a pain and buying a new bottle of sealant every now and again is going to start ...


41

They don't need them but they are good to have. I have an e-bike that I use as a daily commuter. Here are my thoughts: E-bikes are heavier than regular bikes and put considerably more power out at the rear wheel (my motor has 350 watts, I add maybe 60-80 watts at most) compared to a regular bike which only has 80 watts alone. if you have an ebike with a ...


41

Wet metal plates on the road have an astonishingly low grip, on par with a sheet of ice. There's very little you can practically change on your bike to improve this - changing to wider tyres at low pressure would help, but the rest of your commute will be like slogging through treacle, and highly unpleasant. What you can do - change your technique. Never ...


38

The "cement" used in tire tube patch kits (de)vulcanizes the rubber in the patch and of the tube. Which is a chemical process, usually using sulfur, where the rubbers bond and form a stronger bond than just an adhesive would do. Rubber cement is just a gooey adhesive. Usually latex with acetone and other chemicals to make it more pliant. You wouldn't want ...


36

It's quite common to deflate a tube for some valid reason, like you want to change a worn out tyre or replace a spoke. If your valve is a Schrader (a car style) then you remove the cap by twisting, then use a pokey object to depress the center pin in the valve to release the air slowly. A nail, or the end of a house key, or a Phillips-head screwdriver are ...


35

A car tyre has much thicker rubber than a tubeless bike tyre, thicker still than a tube. The steel wires in the belts of a car tyre are impermeable to gas and occupy a significant fraction of the area of that layer. So there is a material difference. In both cases the rim can be regarded as impermeable, and the sidewall more permeable than the tread. Car ...


32

TLDR answer: you ran over something Given the ding/cut in the rim itself that aligns with the cut in the tire, you ran over something metal that was sharp enough to cut your tire and even dig into your rim a bit. That looks like a deep carbon fiber rim - if so, I'd recommend doing a better job watching what you're riding over because the next bit of debris ...


30

Maximum tire width is dependent on two main factors, clearance at the frame/fork, and the width of the rim. As for the frame clearance this can usually be visually inspected and easily distinguished if a larger tire than the present tire will cause issues. Brakes such as V-brakes or cantilevers may also cause clearance problems with some tires so attention ...


30

It is an increasingly common practice for manufacturers to add tire wear indicators, which are little divots like the ones on your tire. Otherwise, there is no objective measure of when to change a tire apart from your mileage log (and riders of different weights should be expected to wear out tires at different rates). Basically, once you can no longer see ...


30

There are two good answers here already, I'll add the relevant physics. Any suspension has three key variables: Its spring constant, i.e. how quickly the force rises as the suspension is compressed. Its dampening, i.e. how much energy is lost in every compression/decompression cycle. Its unsuspended mass, i.e. the amount of material that needs to move ...


26

16 km/h is so slow that even the worst tyres should keep you up, unless something like oil spills were involved. If something is so slippy that you fall without warning at such low speeds there is not much one could do. If you have a hunch this might happen tripodding corners or getting off the bike may help. The first drizzle after a long dry spell can ...


23

It should be perfectly safe to re-use the tyres. Many tyres are stored folded/twisted in their packaging to save space. I would however recommend carefully inspecting each tyre first, checking for damage to the tread area, sidewalls and tyre bead.


23

It’s an intentional wear indicator. There should be “TWI” (Tread Wear Indicator) and a small arrow printed on the sidewall where the dimple is. When the dimple is no longer visible your tread is almost gone and it’s about time to replace the tire.


22

If the bike has been hanging rather than sitting with weight on the tyres (and hence damaging the sidewalls), there is a good chance the tyres are still ok. You can check the tyres by going around and looking for hairline cracks in the rubber and feeling if the rubber is brittle/flaky. If they look ok then go ahead and inflate them and recheck the ...


22

I periodically check and pull out the street glass shards I have been doing the same for as long as I have a bike. Glass shards, small sharp stones, nails, drawing pins... name something I haven't pulled out of my tires! But I never worried of patching the tire, and never had problems because of that. My tires (even those which weren't puncture resistant) ...


22

Definitely a cut - the damage to the rim and the fact that the rubber and carcass fibers are clean cut through confirm that. If the tire burst from over pressure you'd see ragged edges. Also, from what I remember of mechanical engineering classes in college tubular shapes split along their axis when over pressured, not across. My first thought when looking ...


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 ...


21

You are correct that the type of puncture you're getting is caused by the rim "pinching" the inner tube. The root cause here is one of the following: pressure too low (most likely) You're not avoiding potholes carefully enough Weight is too high for the tires/terrain. This has nothing to do with fixies except perhaps that people on fixies tend to ...


21

According to Schwalbe at https://www.schwalbe.com/gb/e-bike.html For standard pedelecs with pedal assistance up to 25 km/h no specific tyres are stipulated by the legislators. But the loads and average speeds of these bicycles are also higher than in the case of normal bicycles. We therefore recommend only certain tyres as “E-Bike Ready 25”. ...


21

The real answer is you need inner tubes with longer valve stems. Tubes come with various length stems to accommodate deep section rims. There are screw-on valve stem extenders available for both Presta and Schrader that you could use to extend your stems. (I think some Schrader ones are actually for car tires, but they would still work for a bike.) With ...


21

Ideally, the brakes should be able strong enough to break traction otherwise you will not be able to brake maximally (i.e., just before the threshold of losing traction). Rim brakes can do this, even in wet weather, if set up correctly. The real advantage of disc brakes in wet weather is other aspects of how the brakes perform. From personal experience, ...


20

They are both types of rubber cement but not the same MSDS will tell you a lot One difference is tire uses a mainly naphtha as a solvent and the elmers does not. Park MSDS Elmers MSDS Looked up a couple other vulcanizing fluids and the commonality is the use naphtha as a solvent. According to this link naphtha is also rubber solvent. A bicycle tube ...


20

As usual, Sheldon's got the answers. ISO 622 is the unambiguous way of referring to the following rim sizes: 700c (you see this marketing on road, hybrids; this is from the French system; the c is often dropped, but there are rare a,b sizes) 29"x decimal (you see this on mountain bikes; usually only applied to wide rims) 28"x decimal (particularly in ...


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 ...


20

Puncture resistant tires are heavier relative to non-puncture resistant tires. They also have sloppier handling/less control/higher rolling resistance, and are typically harder to change (though professional racers will usually wheel swap). And you have the question of rider preference -- you're going to set the type of tire + pressures and what not, the way ...


20

While my initial attempt with lightly deflated tires was not a success (I could only bike 100 m before being exhausted) my second attempt went much better. Based on your helpful answers, comments and suggestions I deflated my rear tire to 1.5 bar, and my front tire to 2 bar and rode at the waterline without much problems at an average speed of 20 km/h. I was ...


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