bike gears - I Love Bicycling

What are Bike Gear Ratios?

January 14, 2020 by Sarah Lauzé

Over the years, the number of gears on bikes has steadily increased. Today’s normal, generally speaking, is 22 gears through two chainrings and 11 sprockets. However, not only has the number of gears increased, but also the range of sizes for the chainrings and sprockets. Yes, this has allowed riders to fine-tune the gearing on their bike, but bike gear ratios can also be really confusing.

First, you need to understand that the size of chainrings and sprockets define the gearing on a bike. You can determine the size by the number of teeth (T) involved, but more important is the ratio. The ratio speaks to the way that the sprockets multiply the effort made with the chainring.

The Basics

Bicycle gears began with the introduction of the train drive, making the bicycle a lot more efficient. Historically, bikes were fixed gear, meaning one revolution of the pedals was equal to one revolution of the back wheel, for a 1:1 ratio. With a train drive, however, a single turn of the chainring can produce multiple revolutions of the rear sprocket and wheel.

Example: A 39T chainring is paired with a 12T cog, giving us a ratio of 39:12 or 3.25. So, one complete rotation of the crank will make the rear wheel rotate 3.25 times.

Do bike gear ratios matter?

In short, yes. If your gears are too easy, you’ll get dropped on those flats as you spin out. On the other hand, if they’re too high you’re not going to be able to maintain an efficient cadence on steep climbs. Having the correct gears for you can impact the following:

Power Output – Your power output, measured in watts, is the most important factor in determining your speed. Bicycle gearing presents resistance, allowing you to transfer this power (through torque and cadence) from your legs into forward movement. Your gears should allow you to get the most from your power, which is varies from rider to rider.
Cadence – Cadence is the amount of times your foot completes a full pedal stroke in one minute (also known as rpm). First, you need to know what your preferred cadence range is. Do you like to spin in an easier gear, or push at a lower cadence but higher gear?

What are the choices?

As mentioned previously, gear ratios are determined at the crankset and the cassette. Essentially the lower the number of teeth on the chainrings results in an easier gear, and the lower the number of teeth on the cassette creates more resistance (harder gear).

Cranksets

Cranksets set the tone for bike gear ratios on your bicycle. In general, there are three size options that will dictate your gearing and also set your bike up for its intended use.

Standard (Double)- A standard crankset has a one hundred thirty millimeter bolt circle diameter (or BCD, Campagnolo cranks have a one hundred thirty five millimeter BCD). Almost always, the chainrings on standard cranks are 53 teeth and 39 teeth. Today it is still the choice for most cyclists, unless you will be tackling the steepest and longest of climbs consistently in your rides.
Compact – Compact cranksets allow a wider range of gearing options with their 110 millimeter BCD. Most often they will come with a 50 and 34 tooth pair of chainrings, but increasingly you will find 52 tooth and 36 tooth pairings. The former is a great all-around combination, especially if you are tackling significant climbs. The latter gives an easier gear for climbing and still has a big enough chainring to not lose very much top-end speed when compared to a standard crankset on the downhills and flat.
Triple – Until compact cranksets came out, triples were the only way to get a bike dedicated to climbing. The third chainring makes for a slightly heavier and more complicated shifting system. Today you will almost exclusively find them on touring bikes and mountain bikes.

Cassettes

Your cassette will fine tune the gearing of your crankset. The flatter your riding, the closer your gearing should be on your cassette. You will encounter fewer difficulties on your daily rides. With eleven speed cassettes, you could get an 11/25 (referring to the smallest and largest cogs) cassette and never be overgeared and never have more than a two tooth gap between cogs.

The biggest cog on a cassette you can use with a short cage rear derailleur is 28 tooth. Paired with a compact crankset, it is sufficient to ascend all but the longest and steepest climbs. If you need lower gearing, you can get a medium or long cage derailleur and get up to a 36 tooth cog. Note that you may have large gaps between cogs, although that is offset by your ability to get over serious difficulties with relative comfort.

With cassettes less than 11 speeds, you will not have all of the potential options available to you, but you can still find a cassette that will suit your needs. Large cogs are still available and so are cassettes with small gaps between cogs. The small sacrifice you make is not having both large cogs and smaller gaps.

At the end of the day, you want to find the right gear setup so that you can forget about gears altogether and enjoy the ride! Click here for more information and charts to help you find the right gear ratio.

When to Shift Gears on a Bike

December 28, 2018 by Sarah Lauzé

If you don’t know when to shift gears on a bike, it can cause a whole lot of frustration. Those unpleasant clunks or grinding noises at the wrong moment mark that you’re struggling when you don’t need to be! You don’t just need to know how to shift your gears (although that is important), but also when. Learning to use your gears efficiently can make all the difference in your cycling progress.

Not only will knowing when to shift gears on a bike make you a faster rider, but it can also prolong the life of your chain. Here’s what you need to know about finding that perfect gear for every terrain.

What are bike gears?

Bike gears are the aspect of the drivetrain that determine the speed (cadence) at which you’re pedaling and the rate at which the drive wheel turns. Some bikes are fixed gear, so there is only one gear. However, the most common combination is three chainrings with nine gears in the back, for a total of 27 gears. These gears determine how hard (or easy) it is to pedal, and therefore dictate your speed.

How to use your gears

If you are totally new to cycling and aren’t sure how to physically change the gears, check out our article on “How to shift gears on a bike.” This will walk you through different types of shifters, and how each system works.

The left-hand shifter or lever will control the front derailleur, guiding the chain over the chainring by your pedals. On this front end, the bigger the chainring, to more resistance you’ll have. You want to use these sparingly, keeping them for major changes in terrain.

The right-hand shifter or lever controls your rear derailleur, guiding the chain over the back gears or cogs. On these back gears, the bigger the cassette, the less resistance you’ll have. These are your fine-tuning gears that you will be using a lot more.

Using bike gears efficiently

The most common mistake beginners make is to grind away in too hard of a gear. This is not an efficient use of energy, and you’re legs will tire a lot more quickly. The general rule is to keep a steady pedal stroke that isn’t either too slow and hard, nor too easy and fast. Finding the right gear for what you’re comfortable with along with the type of terrain your riding will come with practice.

3 Benchmark Gears

Low Gear – Also referred to as your climbing gear, low gear is the easiest the gears can be on your bike. This means your front gear is on the small chairing, and your back gear is on the largest sprocket.
Middle Gear – This is your everyday gear for rolling terrain. There is enough resistance so you can cruise at a modest speed, but not too much as to slow down your cadence too much. This means being on the small chainring on a double or a compact, and the middle chainring on a triple. The back gear will be hovering around the middle sprockets, adjusted according to any changes in terrain.
High Gear – This is for the fun parts. This will keep your legs spinning and the bike accelerating as you descend, or for pushing yourself as fast as you can on flats. The front gear will be on the big chainring, and the back will be on the smallest sprocket.

Don’t Cross the Chain

Avoid using the large front chainring simultaneously as the largest rear sprocket as this can cause your chain to slip or not shift properly. This is referred to as “crossing the chain.” Try running through the majority of your rear gears before touching your front chainrings.

The first step towards using your gears efficiently is to take a look at your cadence. Once you get a feel for what a proper cadence range feels like, you will start to pick gears that will keep you within that. Keep your eyes ahead on the road so you have plenty of time to shift down before you hit a hill. If you don’t, you may not be able to shift gears in time and you’ll end up having to walk your bike.

Learning how and when to shift gears on a bike is one of those things that you learn when starting to ride and as you ride more, you will get good at it. Just make sure to practice in a safe area, say an empty parking lot or driveway, as your focus will be on the shifting, not and traffic or other hazards that may be around.

Bicycle Chainrings – A Guide

March 29, 2016 by Wade Shaddy

Chain ring, or chainring, is cyclist lingo for front gears. Bicycle chainrings optimize your power by utilizing gear ratios for different output on different terrain. Gear ratios are complicated and even engineers using complicated formulas don’t always agree on proper application of the chainring. For the average rider, it’s for the most part personal preference — within reason of course, cross-chaining is a no no and what works or doesn’t work for you is what’s really important.

Big Ring

Some cyclists like to push the big ring all the time but it’s often more an exhibit of bravado than its efficiency. If you have the muscle and power to cruise all day in your big ring, that’s your business and you have every right to do it.

Small Ring

On the other end of the scale, some riders scoff at the small ring, believing it’s there only to climb the steepest of hills. But there’s no reason why you shouldn’t use it whenever you feel like it, that’s what it’s there for.

Same Ratio

Pushing the big ring on a given gear in the back can have exactly the same ratio and effect as riding in a smaller ring on a different gear in back. It’s been proven by engineers and physics. So what’s the difference?

They Feel Different

Some cyclist contend that bigger gears just feel better. It could be that it’s spreading the chain load, thus reducing friction. However, spinning at a more moderate pace in smaller gears is probably done by the majority of cyclists and produces a better chain line that will invariably be nicer to your drivetrain, your legs, and prolong your bikes longevity, not to mention your own.

Leverage Ratio

Bicycle gears work on leverage ratios, pairing a chainring at the front with a cog in the cassette at the back. The wider the ratio, the more speed you can achieve at a given pedaling cadence. A smaller ratio means less leverage on the rear wheel and thus easier pedaling.

Obvious Differences

Its obvious to all cyclists that using different diameter gears results in a higher speed, lower speed, or a more pronounced effort from an inefficient cadence. Most cyclists don’t put a lot of thought into why this is so, probably because it’s so obvious when you switch gears.

It’s Reversed

Chainrings are bolted to your crankset, and the pedals attach at the end of the crank arms. The more teeth, the harder it is to pedal. All cyclists should know by now that smaller gears in the back allow the bike to go faster and larger gears make it to go slower with more power. It’s reversed for chainrings — bigger gears make you go faster, smaller gears make you go slower, with more power.

The Math

If you want to get techy about it, use this chart for fun a guide but be forewarned, it will likely make your eyes glaze over and be of no real practical use to you unless you’re an engineer, or good with algebra. Before cyclocomputers existed, the way to calculate your speed was to count the number of times you pedaled in a given period of time to determine your cadence. You then needed to know what gear you were in which you could then roughly calculate how fast you were going. You would need to memorize parts of this table first however.

Three Choices in Bicycle Chainrings

Today’s road bike typically has a choice of three chainring set-ups, with two of them dominating — the standard double and the compact-double. The third choice however — the triple — also has a very special place in the cycling world for those who wouldn’t ride with anything less.

The Double

Standard double chainrings usually come with 53 teeth on the big ring and 39 teeth on the small ring. The double has been used for years before anyone even thought of anything else.

Compact Chainrings

The compact is exactly what the name implies. The gear ratios have been compacted from a standard double. One of the most common chainring sizes for compacts are 50-tooth for the large ring and 34-tooth for the small ring. Other combinations are 50-36, 52-36 and 48-34 but these are less common.

The Triple

The triple generally has the benefit of lower gearing for more efficient climbing. Standard gearing for a triple might be 50-39-30.

Bottom Line

The bottom line is that compact cranks climb steeper hills better than standard double chainring configurations. Taking it a step further, triples offer even lower gears for climbing. However, compact chainrings are the lightest in weight of the three choices.

Can I Change Rings?

Can you change rings for personalized riding — yes and no. Crank arms have specific bolt circle diameters, or BCD, which must be matched up with the corresponding chainring BCD. Standard double cranks usually have a 130mm BCD and typically won’t work with anything smaller than a 38 small ring. Compact cranks on the other hand, have a 110mm BCD which can accommodate chainrings as small as 33-tooth.

The 52-36 Combination

You can put slightly larger chainrings on a compact crank. A 52-36 combination is particularly popular choice among some cyclists who want a happy medium between top-end speed and climbing ease.

Oval Chainrings

Recent bicycle chainring designers have brought back the oval-shaped chainring, that was thought to have been discredited. The studies are mixed to say the least, but recent testing by professionals have revived the odd-shaped rings. Oval chainrings have been reported to improve the feel and smoothness of your pedaling action, reduce dead-spots, and improve the activation of your glutes and hamstrings. Claims were also made that non-round rings help to delay the onset of muscle fatigue in the quads. Experts agree that when set up properly, you can’t feel the oval shape. Aside from a tendency to drop the chain, oval-shaped chainrings may just be one of the next innovations in chainring technology.

Go For It

So the answer is yes, you can personalize your bicycle chainrings if the bolt patterns fit and the chain and derailleur will accommodate it. In most cases, if your chosen chainring combination won’t work, there’s always an alternative to it that will probably work just as well. Don’t be afraid to experiment with it. Changing bicycle chainrings is one of the easiest ways to change the performance, comfort, or efficiency of your bike. Go for it.

How To Use Bike Gears Properly

October 4, 2015 by Lee Agur

Bike Gears – How They Work

How To Use Bike Gears Properly — This bike is in the easiest gear possible. It is in the small chainring upfront, and it is in the largest gear in the back.

Bikes have anywhere from one front chainring to three chainrings these days, accompanied by seven to eleven gears in the back. The different combinations of these gears will determine how easy or difficult it is to pedal and will dictate your speed. If you are looking to make small adjustments in the speed/difficulty then you will want to change your back gears (also known as cogs).

If you are looking to make a big change in your effort or speed then you will likely want to change the front chainring. A great example would be when you are heading from a downhill in the big ring and then switching to the small chainring as you climb up the other side of the hill.

Shifting Bike Gears

Left Shifter – Changes the front chainring and makes the biggest shift change.

Right Shifter – Changes the rear cogs and makes the smallest incremental shift changes.

What Is the Proper Gear To Be In?

The appropriate gear to be in is a gear that allows you to have a good steady cadence without feeling like you are pedaling too hard or too gently.

If you select a gear that is too high for the conditions, it will force you into a slower cadence. Pedaling slower than your ideal cadence is wasteful of energy. You also run a higher risk of muscle strains and joint damage, particularly to the knees and hips. Pedaling faster than your ideal cadence can allow you to generate an extra burst of speed, but you will tire yourself out too soon if you try to maintain an excessively fast cadence.

Aim for a constant cadence of 75 – 95rpm.

What To Avoid When Changing Bike Gears

Cross chaining occurs when the chain is on a big slant. The chain should not go on the big ring up front and the big ring on the back simultaneously, nor should it go on the small ring upfront and the small ring in the back. Cross chaining wrecks your chain, decreases efficiency and it also gives you less options when trying to find a new gear.

Using Bike Gears

To begin with, start in your small chainring up front.
Get on your bike and become familiar with changing your back gears with your right shifter.
Get comfortable shifting through the gears (while avoiding cross chaining) before you start shifting with the front gears as well.
Attempt to maintain a smooth steady cadence of about 75 – 95 rpm while maintaining a moderate effort when pushing on the pedals. Change the gears appropriately to maintain this steady cadence and effort.

How To Use Bike Gears On a Hill

Use the small or middle chainring upfront and the bigger gears in the back. You will want to switch in to these gears early as you approach the climb allowing you to climb the hill slowly and with less effort.

How To Use Bike Gears On a Flat

Use the middle front chainring and the middle or small gears in the back. Focus on small adjustments with your back gear.

How To Use Bike Gears Descending

Use the large front chainring and the middle or small gears in the back.

How to Change Bike Gears

February 11, 2014 by U.M.

Changing your bike gears while cycling takes some practice in order to accomplish the change fluidly. Avid cyclists know that if you ride your bike off road or on any kind of terrain that isn’t flat you will need to change gears. Most bikes contain anywhere from ten to twenty-seven gears that are split between the front and back wheels. Knowing when and how to change them is an important part of cycling. [Read more…]