My Bikes
"Footnotes"
- Tyres
- Lights
- Recumbent Stability
Miscellaneous:-
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My Bikes
"Footnotes"
Miscellaneous:-
Built on an Apple iMac (Mac OS X 10.2.3 (Jaguar)) using PageSpinner, BBEdit Lite and Graphic Convertor. Uploaded with FTPeel.
Tyres are a compromise. Thin, narrow, light tyres are much faster, but have less grip and are more prone to punctures. Big heavy tyres are harder work because there is more rotating mass, but they are less prone to puncture and are more comfortable. You can save a lot of effort by fitting lightweight tyres, but be prepared for more punctures. You need to decide between a long-lasting, puncture-resistant tyre, or a faster, more puncture-prone tyre. There are exceptions of course, and there are light tyres which also have good puncture-proofing. Many tyres have a puncture-resistant band just under the tread, usually a harder rubber, occasionally kevlar. My own favourite tyres are by Schwalbe, in particular the Stelvio, though the Marathon is also very good. I have also started using Michelin's ProRace on the San Remo, and initially these also seem to have good puncture protection. I have had the Schwalbe Stelvios on the recumbent for over two years without a single puncture.
When you choose a tyre, the first consideration is the surface on which you'll be using them - Is the surface harder or softer than the rubber of the tyre? Grip works like this - the harder compound digs in to the softer compound (this is different from friction, which is how two surfaces stick together). If you are mainly going to be off-road on a mountain bike, then the earth or mud is softer than your tyre. The hard rubber of the tyre will dig into the soft ground. For this you need a good aggressive tread pattern. If you are cycling mainly on the road, then the imperfections on the hard surface of the tarmac will dig into the softer rubber. Here you don't need a tread pattern. You need as much rubber in contact with the tarmac as is possible. If you do have a tread pattern, then you have gaps in the rubber and so less contact with the tarmac. If you want more grip with the road, you need more rubber in contact - get a wider tyre.
The reason for tread pattern on a tyre is to provide a channel along which water can be displaced. If there is a layer of water between the tyre and the tamac, then you can aquaplane and the wheel will slide out. Let's get this straight - Bicycles DON'T Aquaplane. Cars and Motorcycles have a large contact patch where the tyre touches the road, and their weight is distributed over this so there is a low pressure applied. Bicycles have a very small contact patch, so the pressure applied is much greater. This pressure alone is enough to displce the water, avoiding the need for a tread pattern. If you do have a tread pattern, then you have less contact rubber. Instead of thinking "tread" think "gaps". Get a slick tyre and you'll have more rubber in contact with the road. If you want more grip, don't think "tread", think "wider"
There will be times, no matter how good the tyre is, when you will lose grip and the wheel will slide out. Loss of traction occurs when something intervenes between tyre and tarmac. Water on the roads obviously causes slippage in extreme circumstances, though rarely on its own. Water brings oil (and especially diesel spills) to the surface, and that reduces grip. White lines (and other road markings) and manhole covers are particularly slippy in the wet. There's no way of improving grip on such surfaces. The only solution is to avoid riding over such hazards in the first place.
I got a puncture on the Airnimal and replaced the tube as usual. I left the bike in the corner of the room and went off to do some work. Ready for a ride, I retrieved the Airnimal - and found a puncture. Replaced it again (fortunately I bulk-buy my inner tubes), and an hour later I have another puncture. Replaced it again and instead of putting the wheel back on the bike, I hung the wheel on a wall-hook. An hour later, another puncture.
In desperation I posted on the Cycling Plus web site forum looking for a solution. Within the hour, "pbiggs" had supplied the answer - check the rim tape.
Rim Tape is fitted around the inside of the wheelrim to protect the tube from the ends of the spokes. On most new wheels as supplied from the manufacturer, the rim tape is thin rubber, usually the same rubber as the inner tube. If the sharp end of the spoke can puncture the inner tube, then it can just as easily puncture rim tape made from an inner tube.
he first thing you should do when you get a new bike is to replace the cheap rim tape with a good quality tape. The best are cloth tapes, especially that made by Velox. Tapes are available in different widths, make sure the one you get is a suitable width for your rims. Do this one small job, and I promise that you will halve (at least) the number of punctures you will suffer.
It's very important to ensure that you are running the correct tyre pressure. The recommended tyre pressure is marked on the tyre wall. If you run too high a pressure, then you may suffer spoke punctures, no matter how good your rim tape is. If there is any imperfection in the tyre wall, then you may suffer a blow-out.
If you run too low a pressure, then you may suffer pinch punctures (snake-bite punctures). This happens if you hit an obstruction (like a rock for MTBers) or a pot-hole (for roadies). You don't get enough protection from the air-chamber in the tyre, and the rim is forced down towards the obstruction and the rim traps the tube, giving rise to a double puncture. For those who have used MTB, Hybrid or indeed car tyres, which run at around 30 psi, some road bike tyres might seem extraordinarily high - my road bike tyres have a recommended pressure of 110 to 125 psi. Take a regular pump, and you might have to work hard to get a pressure of 40 psi. The solution is, get a track pump. Track pumps make it very easy to get very high pressures. This is one 'accessory' which I think of as a necessity.
There is one tyre which is completely immune to punctures, and that is the solid tyre. Don't even think about fitting solid tyres. Here's Mike Burrows on the subject, taken from the book Bicycle Design:
A tyre that won't puncture seems like a jolly good idea. In fact, of all the bad things that you could do to a bike, this is just about the worst.
They increase rolling resistance enormously, allow you and your bicycle to feel every bump and ripple in the road, have a much smaller contact area than pneumatics which, coupled with their hardness, means less grip. Their excessive weight gives any bike a leaden feel, and worst of all - they don't puncture.
The best thing bout cycling is the variety it brings to your life, for you cannot enjoy the good days without bad days to act as a contrast. So when you are struggling along into a headwind and driving rain, slowly realinsing that the occasional bump from the back is the valve bottoming out on the road, then remember that you forgot to mend the spare tube… remember, tomorrow will be great.
Latex Tubes. Most Inner Tubes are made from butyl rubber. Some lightweight tubes are made from latex rubber. These are designed mainly for racers, as they have a lower weight and so less rotating mass, which makes for a faster wheel. The latex tube also offers some puncture protection - being lighter and more flexible, any shard portrusion deflects the tube, rather than puncturing through the tube. Scaled up, imagine jumping onto a sheet of glass - you'll go straight through it. Jump onto a trampoline, and it will deflect under you.
The disadvantage of the latex tube is that they don't hold air so well, and you have to pump up the tyres far more often. The choice is for example, pump up the tyres every two or three days, and repair a puncture once a year OR pump up the tyres once a month and repair a puncture once every three months. You pick your preference. I go with the butyl tubes.
Slime. Slime is a gooey mess which goes inside your inner tube. If you have a tube where you can dismantle the valve, then you can insert the slime yourself. Messy, though, so I couldn't recommend it. You can also get pre-slimed tubes which are much easier.
Slime is a rubber compound which coats the inside of the tube. If you puncture, then the slime works its way into the hole and sets, so sealing the hole. Personally, I don't like the stuff. For one thing, when you leave the bike overnight, all the slime pools in the bottom of the tube. When you set off in the morning, it takes a while for the slime to distribute itself around the tube. Until then, the wheel is going to be out of balance. When the slime does its job, then there's a good chance that it will also seal itself to the inside of the tyre casin. When you remove the tyre to do a proper repair, then there's a good chance that it will rip a chunk out of the tube. If it doesn't, then the puncture is going to be much harder to find.
Everyone should be able to fix a puncture in a bicycle tyre. Even if you don't ride a bike regularly, think of the brownie points when you fix the puncture on your nephew's bike.
Sooner or later you will get a puncture when commuting, and you'll do exactly the same on the bike as you would do in the car. Sort out the problem. You wouldn't sit at the side of the road trying to find and repair the puncture in a car's tyre. You'd fit the spare wheel. You shouldn't mess around trying to repair a bicycle tyre either. You won't be carrying a spare wheel around with you, but you can carry a spare tube. One thing you don't want is two consecutive punctures; you've fixed your puncture, get on the bike and ride off again - only to puncture again straight away. The first thing you should do when you're fixing a flat is to check the tyre casing for whatever it was that caused the original puncture. A thorn, piece of glass, sharp stone, if it punctured the tyre casing then there's a good chance it is still lodged in the casing. Check the inside of the tyre by running your fingers around the inside of the casing, feeling for anything sharp, and remove what you find. Then check again in case there was more than one object. And if you find something else, check again. And keep checking until you can work your fingers all the way round the casing without finding anything. Don't bother trying to find and repair the puncture at the roadside. Take a spare tube with you, and once you've checked the casing, you can fit the new tube, pump it up, and away you go. Once you get to your destination you can then fix the punctured tube, in your lunch break or before your dinner. Don't mess around with that old method of plunging an inflated tube into a bowl of water looking for air bubbles. Inflate the tyre so that the rubber is really stretched, then cup your hand around the tube and run it around the tyre - you'll be able to feel the air seeping out. Mark the spot where the hole is. Don't bother with traditional puncture repair kits - use pre-glued patches such as Park Tools' Super-Patch. Let all the air out of the tube again, roughen the tube around the hole with a bit of sandpaper, peel the the backing paper off the patch and apply to the tube. Press down firmly. Tube is ready for use again. Do this before you begin your next journey, just in case you have another puncture.
If you're familiar with Principia, or if the mention of Newton's name sends you into a coma, then you may want to skip this. An object will remain at rest or in motion until a force is applied. Travelling along at a constant speed, you need to apply only as much force as is needed to overcome air resistance and internal friction. When you need to apply considerably more energy is when you want to accelerate. Cycling along at a constant speed, there is one part of the bike which is still accelerating - the wheels. The rotation of the wheels is a continuous acceleration. The point on the wheel which is in contact with the ground (at six c'clock) is at rest. The points at three and nine o'clock are travelling at the same speed as the bike. The point at the top of the wheel, at twelve o'clock is travelling at twice the speed of the bike. Any pont on the circumference of the wheel has to accelerate from rest to twice the speed of the bike, and then decelerate to rest again on every single revolution of the wheel. The more mass there is on the wheel, the harder you have to work to accelerate the wheel. If you want to use less effort, then make the wheels lighter. An ounce off the wheels is worth a pound off the frame.
Clones Are People Two!
