Mechanics

Change your Flat

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The AIDS/LifeCycle is a fully supported ride. So, I don’t need to know how to change a flat, right? The Training Ride Leaders will do that for me, won’t they? Besides, I live in a city. There’s always some kind cyclist willing to lend a hand.

The answer is no. Just no. There’s so much wrong with that logic that the discussion has to start out from the basics. Before I help you learn to change a flat, lets learn about what goes into a road tire. (Skip to TL;DR for steps and a video.)

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Hot guy changing tire. (Source.)

A. Components

Just to get terminology straight: The big roundy thinks with the spokes is called a “wheel.” The rubber part that touches the road as you ride is called a “tire.” Inside the tire is a flimsy inflatable torus called a “tube.” When you “fix” a flat or “change” a flat, you’re most likely not changing the tire, but the tube.

Road bicycle tires are never solid. All of them have tubes. (Yes, there are tubeless kinds, but I don’t discuss those here. Tubeless are not a good choice for most cyclists.) Even the best tires (those with Kevlar linings and beads, such as the ubiquitous Gatorskins) can and will get punctured. And when the tire gets punctured, the tube is usually toast.

B. Mechanics

The wheels are attached to the bicycle at the “hub.” As you ride your bike, the hub bears the weight of the bike-body system. The tire, being a torus (doughnut-shaped thing) with the hub running though it, must be fully removed from the bike before a flat can be changed.

You may laugh or have skipped the above paragraph as obvious, but it is not. I have seen many stranded riders, their tire and tube dislodged from the wheel, looking perplexed about how to get the tube out to be changed. (Read my posts about bonking and eating for more on how a rational person could get to that point.)

C. Types of Flats

There are three broad categories of flats: puncture flats, pinch flats, and herniated flats (I have no idea if these are official names, but the names are instructive). Puncture flats mean that something (glass, a nail, a staple, a tiny shard of metal, a thorn) has embedded itself into the tire and put a hole in the tube. Avoid these by getting better tires, such as Gatorskins.

Pinch flats generally occur when there is insufficient tire inflation for the tire, and the cyclist has hit a rut or hole in the road causing the tube to wedge between the tire and the wheel’s rim causing a hole. Pinch flats can also result from improper tire installation (user error). Avoid these by learning how to install the tire and always re-inflate the tire when starting a ride.

Herniated flats occur from damaged or old tires. When the tire material rubs through or is cut in some way, the inflatable tube can poke out (herniate) through the opening due to tire inflation pressure. Avoid these by visually inspecting the tires before riding and replacing the tires often.

Flats may also occur if there is damage (either manufacturing or otherwise) to the inflation stem (the thingy on the tube that lets you put air into the tube).

D. Types of Tubes

Road tires are determined by two metrics: size and valve type. Typical tires are 700 cm in diameter and about 18 to 27 cm in thickness. You can tell what size tube to buy by reading the tire size off the sidewall of your tire. Most road wheels have holes for Presta values (the thin, pointy kind you have to unscrew to open up, while other kinds of wheels have Schrader valves (the kind used in automobile tires).

The only other thing you might want to know is the depth of the valve itself, if you’re using Presta. Do NOT get the shortest possible valve stem. If you do, there’s a chance your pump will not be able to connect to the value end and you won’t be able to inflate the tube. (Here’s a link to a tube buyer’s guide.)

E. What you need

To fix your flat, you will need the following:

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Tire Levers
  • Tire levers,
  • An un-damaged tube (either new or patched),
  • A pump or CO2 cartridge system.

Most wheels have quick release pins holding the wheel onto the bike by the hub. If your bike does not have quick release, you’ll also need a wrench.

These things you will need to carry with you at all times. Choose wisely. You should also

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Quick Release. Also show wheel, tire, and hub!

invest in a floor pump for your car or home. You’ll get better tire pressure with the floor pump.

F. Proper Tire Inflation

The proper inflation will be listed on the tire’s sidewall. Typical road tires need to be inflated from 90 to 120 psi. You don’t necessarily need to inflate to the full level for good riding. Try different inflation levels, but always stay within the manufacturer’s range.

It is important that you check tire inflation before every ride. So get a good floor pump for home or your car that has a gauge on it. If the inflation is low, put more air. If its too high, let some air out and check again.

G. Changing the Actual Tube (TL;DR)

Here are the steps you need to take to fix your tube. This post is already too long, so I’m only listing the steps and not going into excruciating detail. But you should watch the video which follows and then search YouTube for additional videos.

  1. Front or back tire? If you’re lucky, it was the front tire. If not…doh!
  2. If it was the rear tire, shift into the big chain ring in the front; small cog in the back. You’ll have to lift the rear tire to accomplish this. This will make the wheel much easier to install after you’ve removed it.
  3. Take the wheel off the bike. Lay the bike, chain side UP, on the ground in a safe location. If it was the rear wheel, be careful not to get dirt on the cassette!
  4. Visually inspect the wheel before proceeding. Is there any obvious damage? Can you see the pin or thorn which caused the flat? Is the tire severely damaged? If you can find the culprit, you can remove it easily and possibly patch the tube.
  5. Unscrew the valve and let out any remaining air.
  6. Using the tire levers, remove one side of the tire from the wheel. (If you remove the tire entirely, note that road tires are generally directional. So when you reinstall it, make sure its facing the right way.)
  7. Remove the tube from inside the tire. You may have to remove a small silver nut from the valve stem. That is used to make inflation easier, so if your new tube doesn’t have one, save it.
  8. If your visual inspection did not reveal the culprit, run your hands gently inside the tire, feeling for sharp objects. Be careful that you don’t get cut. If you find it, remove it and keep looking. If you don’t find it, keep looking until you get bored…it might have dislodged itself or you might have had a pinch flat.
  9. Unfurl the new tube. Open the valve and blow a little air into it with your mouth. Close the valve stem. This makes it easier to install.
  10. Put the new tube’s valve stem through the hole in the wheel, then nest the new tube inside the wheel.
  11. If you took the whole tire off, align the tire in the correct direction with the wheel. Holding the wheel and tire with one hand, lever the inside edge of the tire onto the wheel’s rim.
  12. Then, starting at the valve stem, using only your fingers and palms (not the levers), lever the outside edge of the tire onto the wheel. Make sure the tube does not get pinched between the tire and wheel (hence the air).
  13. When you get to having only a few inches left to lever on, you may want to let a little air out of the tube. That may help. But any way you slice it, those last few inches can be grueling. Using your palms, kneed each side of the remaining few inches until it pops on. Keep checking that the tube is not pinching!!
  14. Only if you absolutely cannot do it with your hands, lever ONLY the last couple inches onto the wheel. If you use the levers too early, you will certainly pinch the tube and have to do it all over again.
  15. Check that the tube is not sticking out anywhere by squeezing the tire and looking down into the wheel well. if you see any tube, it might pinch when you add air.
  16. Open the valve and using your pump or CO2 cartridge, put a little air into the tube until it is much firmer, but not hard. Close the valve. Check that none of the tube is poking out between the wheel and the tire. If it is, quickly deflate and try again.
  17. Once you are satisfied, put as much air into the tube as you can. If you’re using CO2, use the remaining bit of cartridge. If your pump as a meter, put the full amount of pressure you can, up to the pressure listed on your side wall. If your pump doesn’t have a meter, put as much air into the tire as you can…you probably cannot over fill it. If the ride is bouncy, stop and put more.
  18. Once you get back to civilization, find a floor pump. If you used CO2, remove it and put air. CO2 molecules are smaller than the pores in the tube and will deflate over time.

Watch this video, then Google more and watch them, too.


H. For the Love of the Goddess, Why do I need to know all this?

You need to know how to do this because some day you may find that your TRL’s are helping another rider elsewhere along the route. You’ll either have to wait, call an Uber Extreme (or whatever that’s called), or do it yourself. You’ll find that doing it yourself is faster, easier, and more gratifying. Then, when you see someone stranded on the side of the road, you can say, “Hey, let me help you with that.”

I. Final Word

Practice. That’s it. You won’t know how to do it, so do it. Take your tire off your bike and go for it. If you’ve never done it before, give yourself two whole hours. You can do it. I know you can. Plus, if you do it now, you’ll have the safety of being able to go the bike shop if you abjectly fail! 🙂

Love,
Your Bear

PS: Writing these posts takes a lot of time and effort. If you found this useful, consider donating to my ride at: Bear’s Donation Page.

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Climbing, Descending, and Flats TLDR: Pedal

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I’ve written several posts on how to climb, how to descend, nutrition and climbing, and related safety issues. Please review them because this post doesn’t discuss the mechanics. Instead, I want to reiterate something I’ve said in many prior posts: to get anywhere on your bike, you have to move your legs. The prior two posts about cadence were leading up to this conclusion: the only way to keep yourself moving forward efficiently is to pedal your bike.

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Image Credit.

If you’re not pedaling on a climb, you’ll fall over. If you’re not pedaling on a flat, you’ll slow down fast and fall over. “Duh,” you say, “but what about descents? It will be much more efficient for me to use the descent as an opportunity to let my tired legs rest.” The answer is no, you should be pedaling.

There are two issues to unpack from that: (1) You’re too tired, and (2) You haven’t fully grocked the mechanics of moving your bike forward.

If you’re too tired to pedal on a descent, you’re probably working on the challenge of the ride you’re on. That does not meant it is too challenging for you, but it does mean you should consider pacing yourself. Check with your doctor to make sure the exercise you’re planning is right for you. Then read my blog posts on nutrition. 90% of problems like this can be solved by eating and drinking more.

Otherwise, the issue may be a mechanical one. (First, after 5 or so serious rides, are you still in pain or numb in the feet, knees, back, arms, or butt? You likely need a bike fit (remind me to do a post on this issue).) That means you’re not using the lessons in cadence we discussed the last two weeks; review them.

If fitness and mechanics are not the issue, then you just have to trust me on this: on your descents, PEDAL YOUR BIKE. On climbs (obviously). On flats (less obvious than you’d think). On descents. YES, on descents…always pedal.

The reason is simple. So long as your pedal strokes are engaging the wheel, you’re gaining momentum. On a descent, you have a huge advantage: gravity. If you don’t pedal, friction (road and wind) will slow you down. If you do pedal, you can partially or wholly overcome friction. The only real exception is if you’re descending too fast for your skill level, or your speed is so high that even on your hardest gear you’re not adding to momentum

The advantages are huge. Not only will you go faster on the descent you’re on, but you will gain momentum to pull you over the next, inevitable hill. And you’ll exhaust yourself less gaining that momentum to push you over the hill than waiting for the climb to pedal.

So the take away is this: learn to use your gears, use them, and pedal your bike on every inch of every mile that you possibly can.

Love,
Your Bear

Efficient Riding: Cadence and Exhaustion

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iStock_000041000650_FullbOne of the many new things you may need to relearn about cycling is where your power comes from. Your thighs pump your legs to turn the pedals; your core acts like a wall for the thighs to push against. So at first glance it seems pushing your muscles to the limit is the best way to move those pedals faster. But the food you’ve eaten powers those muscles. So, pushing them too hard will exhaust your energy which will inevitably slow you down. How do you ride, then, without constantly exhausting yourself?

The answer is cadence. Cadence is the rhythm of your feet as they turn to push the pedals. A good rider will balance cadence power output. Given a flat smooth road and a windless, generally, a very fast cadence (say 120 revolutions per minute) may help to avoid exhaustion, but won’t move your bike very far forward for the effort you’re putting out. A very slow cadence (say 50 rpm) will likely involve pushing hard on the pedals with each downstroke, and pulling up hard on the upstroke — it might move your bike forward faster, but it will definitely exhaust you. (Read my prior article on why higher cadence is better.) The answer is to modulate your cadence based on road conditions and your fitness level. How do you modulate your cadence?

And that answer is effective use of gearing and fitness. The first and easiest step is to learn to use your gears. Assuming you have a road bike with two front cogs (together, “the chainring”) and ten or eleven rear cogs (together “the cassette”) — a very common set —  practice using  your front gear as a macro adjustment and your rear gear as a micro adjustment:

  1. When descending, be sure the front gear is in the large chain ring.
  2. When on flat or rolling hills, use large front chain ring if you have a tailwind (wind aiding you by pushing you in the direction of travel).
  3. When on flat or rolling hills, use the small front chain ring if you have a headwind (wind hindering your by pushing you backwards).
  4. When climbing, be sure the front gear is in the small chain ring.

How you do this is dependent on what kind of components your bike has. (See REI’s article explaining gears.) But the front controls on most road bikes are on the left side. Usually, you have to force the derailleur to push the gear UP onto the large ring, so the “faster” gears are achieved with a bit more effort on the gear lever, while to gear DOWN you are releasing the pressure, so the shift is more like a click.

Once you’re in the correct front cog, use the rear cogs to micro adjust your performance. If you find yourself sweating, huffing, and using too much muscle power, you may want to push the rear gear UP into a larger (higher) cog. If you find your legs spinning like mad while all the world passes you, you may want to RAISE the gear by pushing the rear gear DOWN into a smaller cog.

Gaining a basic understanding of the mechanics is important, but the only way to do it is to try it out. (See this article for an explanation of how to shift.) Don’t be shy to play with your gears. Try riding on flats first in the big chain ring (front gear). Then try the same ride later in the small chain ring. Then micro adjust with the rear to keep your legs spinning.

You may notice a subtle difference in how you ride and the difficulty. This is, in part, because there is a big overlap in the “gearing ratio” (see prior link) — some of the same gears are represented by different combinations of chain ring/cassette gearing.

Here’s a quick list of common gear combinations which may help gel the whole thing in your brain:

  • The “easiest” gear combination for climbing is the chain is all the way TOWARD the bike (small chain ring, largest cassette cog);
  • The “hardest” gear for descending is the chain all the way AWAY FROM the bike (large chain ring, smallest cassette cog).

There are two combinations which you should avoid: largest chain ring and largest cog; smallest chain ring and smallest cog. This is called cross chaining. In these configurations, you put the most stress on the chain. Better components can do this no problem, but if you’re dropping your chain a lot, check to see if you’re doing this.

The takeaways are this:

  1. Big front chain ring: climbing — Small front, descending.
  2. Large rear cassette: easier — Small rear, more power.
  3. Maintain a cadence which does not exhaust you, but moves you forward at the desired pace.
  4. Don’t be afraid to experiment.

Next week, I’m going to write about fitness and cadence and give you some target cadences which should help with your understanding. Also, you can get a good cadence meter for your  bike pretty cheap — apart from your speed, cadence is a good metric to help gauge your cycling (though I’d invest in a heart rate monitor first).

Love,
Your Bear

Absolute Beginners: Pedals and Pedaling

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Bicycles typically come with three basic types of pedals, but pedals can always be upgraded or replaced (this is usually the first upgrade most riders make). The types are:

  1. Plain or “Platform” Pedals (figure 1).
  2. Pedals with “toe clips” (figure 3).
  3. Clip-less Pedals (figures 4a–4c).
Figure 1: Platform pedals

Pedals are affixed to a crank on either side of the bike, each arm 180º from the other. The pedals are attached to the crank by a variable length arm; length determined by bike size, rider size and proportions, and type of crank installed. If you ever have a bike fit, the fitter may well replace the crank arms with longer or shorter arms to accommodate your particular mechanics (that will likely require a whole new crank, by the way, because the crank is usually built in to the front chain ring). (Figure 2.)
The pedals are one of three basic interfaces you have with your bike: the handlebars (for stability and control), the saddle (for your butt, but also for stability and control), and the pedals (for power, stability, and also for control). As you can see, all three interfaces provide control over the bike. As the Absolute Beginners series continues, I’ll describe how bicycle steering is generated from the pedals and saddle as much as or more than the handlebars.
To generate power and to keep the bike upright, the rider must keep the chainring moving with the chain engaged, thus powering the rear wheel. The rider generates this power by turning the crank by means of the crank arm. In turn, the crank arm is moved by pressure on the pedals with the feet.
And the primary difference between the pedal types is the efficiency with which you move the crank arm by means of your foot: the more affixed your foot is to the pedal, the more power you get for your effort.
Figure 2: Parts of a crank. Image Credit. Click to enlarge.

1. Platform Pedals
When you first purchase your bike, its likely to be equipped with plain pedals. A rider uses platform pedals the old fashioned way: you simply place the balls of your feet on the top of the pedal and push down with the upper foot, allowing the lower foot to rise with the motion of the crank arm.
Plain pedals represent a low-end in a progression of efficiency. When you cycle with only plain pedals, you get power only when your foot is pressing down on the pedal, not during any other part of the stroke. So any effort made to move your other foot (back and forth and up in the circle representing one bicycle pedal stroke) does not go into your forward momentum.
2. Pedals with Toe Clips
“Toe clips” are cages which affix to the pedal. Special pedals are usually required to install the toe clips.
Figure 3: Toe clips. Image Credit.
Pedals with toe clips represent a step up in the progression of efficiency. They provide two main purposes: first, they position your foot roughly in the best position (ball of foot over the pedal), and second, they affix your foot more firmly to the pedal. Thus, you get power from pushing down on the pedal, pulling up on the pedal, and from the forward motion of your foot in the pedal stroke. So, with toe clips, you’ll get power on 3/4 of the pedal stroke over the 1/4 with platform pedals only.
Reason tells us that if you pull your foot back during the pedal stroke, you’ll pull out of the clip. Usually, your shoes will have some kind of ridges which will keep your foot on the pedal when you pull back. This final 1/4 of the pedal stroke will not provide as good an adherence to the pedal as the other 3/4. Still, this is light years better than the pedal alone.
Toe-clip pedals have several drawbacks. They are heavier than “clipless” pedals. They provide for a LOT of foot movement during the pedal stroke, decreasing efficiency. They are cumbersome to operate. They are harder to get into and out of than “clipless” pedals. And, believe it or not, they are more dangerous to operate than clipless pedals.
If you chose toe clips, remember: you cannot safely ride with your foot on the non-toeclip side! The toe clip may catch on road debris or surface features, and may cause you to crash.

3. Clipless Pedals
Yes, even though you “clip into” them and “clip out” of them, these babies are “clipless.” That is because they do away with the toe clips. And these are the most efficient pedals for cycling. Your foot is fully affixed to the pedal, so you are most likely to get full efficiency out of each pedal stroke.

Here are some different types. SPD offer a smaller interface with your shoe, and are often used for mountain biking. SPD SL offers an easier clip along with a nylon cleat and are often used for road biking:

Figure 4a: Shimano SPD Clipless Pedals. Image credit.
Figure 4b: Shimano SPD SL Pedals and Road Bike Shoes. Image credit.

Figure 4c: Shimano SPD SL Cleats. Image credit.
I can’t deny it, clipless pedals are intimidating. But they are also awesome. When you get them dialed-in, you and your bike become one. You are the bike. With clipless pedals comes the maximum possible efficiency. You can get power from 100% of the pedal stroke. And you can feel the difference.
Thus, you will see very few road cyclists riding with anything but clipless pedals. As you progress, you’ll want to upgrade to clipless pedals for sure. In fact, most dedicated riders will skip toe clips entirely and jump right to clipless pedals.
Once you decide to take the plunge, there are many manufacturers looking for your business: Shimano, Look, Crank Bros, and Speed Play are all more-or-less common brands. Which you choose is a matter of personal choice. Ask other cyclists which they prefer — you will often find near religious adherence to a brand. Here’s a useful buying guide.
You need to practice with these. Ask your sales person or training ride leader to demonstrate how to clip in and clip out. You usually get in by aligning the cleat to the edge of the pedal and pressing with the ball of your foot. You usually get out by twisting your foot and stepping off the pedal. Here’s a useful video. You can search YouTube for many other similar videos.
This was a lot of information about a seemingly innocuous part of your bike. But pedals are very important and worth the time thinking about them.

Love,
Your Bear

By the way: Over the next couple months, I’m going to write a few articles with the lead-in title “Absolute Beginners,” explaining some of the basic principles of cycling. Most of the information is stuff I’ve learned from other cyclists, bike shop mechanics, classes I’ve taken, and Google searches. Please help me out and comment with corrections, additions, or supplements which will help my readers learn about how to operate their bikes!