Bicycle Gears for Dummies? Click Thru This IN-DEPTH GUIDE
Don't let it happen to you! Get wise to bicycle gears right here... Oh, and Nathan's injuries weren't as horribly catastrophic as they appeared here #fullrecovery

Bicycle Gears for Dummies? Click Thru This IN-DEPTH GUIDE

Dummies? Fear not, that’s just the shape of me adding a few drops of levity! Gearing for Dummies, yes, but Gearing For Normal Riders, for the rest of us! Haha, and hello to you and welcome along, Dear Reader. It’s good to have you here for a journey into bicycle gears! Oooh, into the depths we go; the dark oily silence of transmission ratios, gear inches, derailleurs, internal-hub-gears, uphills and downhills, 1-bys, 2-bys and 3-bys… Are bicycle gears ready to give up their secrets? And are you ready to enter the esoteric world of cross chaining, narrow-wide chainrings and sprocket cassettes? And teeth! Teeth! Teeth, teeth everywhere! Oh no, it’s that recurring dream again… Quick, pass me the torque wrench!

I’ve collated here some info I’ve gathered regarding gearing over the last 50 years of cycling on singlespeeds and hub-geared bikes to 1-bys and multi-geared triple front ring setups. So if you’re ready, we’ll push off nice and easily with a diagram showing the bits and a brief glossary of the terms and go from there. It’s a large article we got ourselves here, and it’s jam-packed with goodies. While it’ll likely make most sense if you take your time to read right through and fully familiarize yourself with terms and ideas, still I wanted to give you some convenient shortcuts below to the main topics covered…

Bicycle Gears Diagram and Glossary of Terms

High level annotation of bicycle gears. For more detail, see below…

Brief glossary of terms to get us started:

  • Chainring: toothed chainrings are bolted to the right side crank arm spider. Crank spiders are five-, four- or three- branched bifurcations of the crank arm and match the number of bolt holes on the chainring. In the pic above, the chainrings are 5-bolt so the crank arm spider has five attachment points. Chainrings can have varying amounts of teeth. The varying teeth provide different gear ratios.
  • Crank arms: Crank arms are connected to each other at 180 degrees by being attached to a rotatable bottom bracket axle. Pedals are screwed at the other ends of the crank arms. A chainring or chainrings are bolted to the right crank arm.
  • Chainset: the chainset (aka crankset) comprises the crank arms, crank arm spider and chainrings (often sold as a set, hence chainset or crankset). Chainsets can be designed for singlespeed / fixed-gear and take one chainring only. They can also be designed for multiple chainrings, usually two or three.
  • Chain: chains can have a varying number of links depending upon the application. Many chains have a quick link that means the chain can be joined (or in many cases split) by hand. Chains come in different widths also. The width is usually taken from the width of the chain rollers (between the link plates). Singlespeed chains are currently normally 1/8 inch width while geared systems are normally 3/32 inch width.
  • Front derailleur: shifts the chain between front chainrings. Front derailleurs can be top-pull, where the cable run is routed from the shifter down the seat-tube and attaches to the front derailleur from its topside. They can also be bottom-pull, where the cable run is routed from the shifter down the downtube under the bottom bracket and attaches to the front derailleur from its underside. Front derailleurs are designed to be either used with a 2-by, two chainring chainset, or a 3-by, three chainring chainset, the latter having a wider cage.
  • Cassette (gear cassette or sprocket cassette): a collection of gear sprockets organised by number of teeth into a cassette. While cassettes can be simply loose sprockets separated by spacers, more often than not, besides the smallest few rings, they’re usually bolted together to help maintain integrity of the freehub body.
  • Rear derailleur: shifts the chain between sprockets on the rear gear cassette. Rear derailleurs are generally of a parallelogram design that pivot towards or away from the wheel hub. The chain is passed through two smaller guiding wheels, a jockey and a tension wheel. These wheels are on what’s called a cage. Rear derailleurs can have longer or shorter cages depending on the range of gears on the cassette and on the cassette’s largest sprocket.
  • Gear cables: usually a steel inner cable passes from the gear shifter through an outer, theoretically compressionless housing and is bolted to the derailleur. As the gear shifter is clicked or twisted, an amount of inner cable is pulled through or allowed to pass back depending on whether we’re shifting down or up. This moves the derailleur and nudges the chain to another sprocket or chainring.

Q: What’s a gear ratio? And what’s Gear inches?

A: Both gear ratio and gear inches are metrics for comparing different gears with each other. Simply put, a gear ratio is the ratio of the number of teeth on the front chainring to the number of teeth on the rear sprocket. A 32-tooth (32T) chainring driving a 16-tooth (16T) sprocket on the rear hub gives a 32:16, or 2:1 gear ratio. On a 2:1 ratio, for every rotation of the cranks, the wheel will rotate twice. If I reduce my rear sprocket to 14T I’ll have a 32:14 ratio which is a higher ratio than before. If I’m on my inner ring on my road bike, which is often 34T for a compact chainset, and I’m in my lowest rear gear (largest sprocket – see Q: Gear Shifting Terms: What way’s UP and what way’s DOWN? below), the lowest gear possibly being 34T then my gear ratio is 1:1

Both the chainring and the sprocket can be swapped out for differing sizes. Here a 32T ring and 16T sprocket = 2:1 gear ratio

Q: How can I compare gear ratios? Like so how do I know if one ratio is higher or lower than another?

A: Well – and if you know anything about gambling or betting odds, you’ll know this too – but we just divide the first number in the ratio by the second number in the ratio. This gives us a fractional or decimal number. This fractional or decimal representation of the ratio can then be compared. Taking the example above, I might have on my bike a 32T chainring at the front and either have a 16T sprocket at the rear, or be on the 16T sprocket on my rear cassette. Either way, the ratio is 32:16, or 2:1, right? Dividing the first by the second 2 divided by 1 = 2.00. If I swap out that 16T rear sprocket for a smaller 14T rear sprocket, keeping the chainring the same, now the ratio is 32:14. Dividing 32 by 14 = 2.29 (rounded). So you can now say this is a higher gear ratio. Do you think this higher 2.29 ratio will then be more difficult or easier to push than the easier 2.00 ratio? That’s right, it’ll be harder. Higher ratios require more energy to push at the same cadence – they’re harder, and lower ratios require less – they’re easier.

Gear inches is a measurement of how many inches forwards along a flat surface, your bicycle will travel for one full 360 degree revolution of the cranks when in a certain gear. It’s a slightly more quantitative metric than gear ratio, and perhaps more real world as the calculation includes the tire outer diameter, but essentially is utilized in the same way.

Using either of these metrics we can say one gear is higher or lower than another which is useful for comparing gears on different bikes or perhaps if we come to change our chainsets or cassettes, we want to know if our gearing will be equivalent or will it feel too easy or difficult to push by comparison. For example one bike might have a highest gear of 53:12 and the other 50:11, which one, for the same rate of pedaling (cadence) will have the fastest top speed? Do you know? Putting these values into my favourite gear calculator, we see on the 50:11 bike, pedalling at 90rpm, the speed will be 32mph 53:12 @90rpm will be 31.1mph. The same calculations apply for lowest gears when hill climbing, or more likely touring with a loaded bicycle where we might want to know which bike will have the easiest gearing or widest range of gearing.

A note on the number of gears. Even as a kid I knew other kids’ ten-speed bikes were probably better than my five-speed. Why? I didn’t know that. It wouldn’t have mattered back then. A higher number of rear sprockets is useful for one reason. That reason is to maintain a smooth pedaling rate. Imagine a rear cassette of sprockets goes from a small 11 tooth to a large 32 tooth. If I have an 8-speed cassette I’ll have six others between the two extremes. If I have a 12-speed rear cassette I’ll have 10 others between the two extremes. So what? Well, this means the jumps in gear ratio between each adjacent sprocket for the 8-speed are larger jumps than those for the 12-speed. This means when I upshift or downshift on my 8-speed bike I’ll have to adjust my cadence (pedalling rate) noticeably. Or at least more noticeably than on a 12-speed where the jump in gear ratio is smaller between sprockets. Make sense? So higher is better for road riding. For off-road riding or touring, the higher number of gears is more about the range of available gears. Touring bikes in particular need to have a gear for almost every eventuality 🙂

Q: Bicycle gearing systems: what are Single-Speed and Fixed Gear drivetrains?

A: These two are probably the simplest bicycle gearing systems, mechanically speaking. They’re the least aesthetically troublesome to the look of a sleek bicycle frame. There are no derailleurs, cables or shifters messing up the svelte lines of the bike! I’ve found, in comparison with my derailleur gears, my singlespeed was considerably quieter too because of the greater efficiency of the direct chain run rather than directing it to move through the convolutions of the derailleur cage, pulley and jockey wheels.

With singlespeed setups there’s no trying to figure out which gear to choose when on a ride. There’s no worry about chainslap (the smacking against the chainstay on a pitted or surface). There’s no worry about the chain dropping off the chainrings as everything is well tensioned. The system is remarkably efficient.

Q: What’s the difference between singlespeed gearing and fixed gearing (fixie)?

A: Simply put, a fixed gear means the sprocket on the rear wheel is fixed whereas single-speed is not fixed and allows “coasting”. With a fixed gear bicycle, it’s not possible to “coast” or to “freewheel” for example when on a descent. The sprocket is screw-threaded onto the rear hub shell. The pedals move the cranks, driving the chain around the chainring and the rear sprocket, rotating the wheel, all as expected. Once the bike is in motion, the rotation of the wheel can also drive the cranks and pedals. While this can have the effect of allowing the rider to feel more attached to the bike, can have advantages for leg strength, and can permit easier track stands at junctions and traffic lights! it can also require a period of learning how to handle the bike.

Track bikes (designed to be ridden in indoor velodromes) are always fixed-gear. You’ll notice the cyclist’s legs keep moving even when the race is complete – no coasting! One good thing about track bikes is that they don’t need brakes. The rider can if they choose to slow, resist the direction of movement of the cranks. Then again, slowing down isn’t a big issue on the velodrome track. However, one issue that, while rare, has still proved fatal and that’s the danger of riding fixed-gear bikes on the public roads without brakes. While fixie riders have a bunch of cool techniques for skid stopping, in an emergency like an oblivious pedestrian stepping out, there’s a much smaller chance of stopping quickly without brakes. But a bike is just a bike, and this is entirely an issue with irresponsible cyclists.

Singlespeed – beautiful cycling efficiency and simplicity. Horizontal dropouts here take a chain tensioner to keep everything nice and tight

So a singlespeed gearing setup on the other hand, while similar in simplicity to a fixie setup, does permit coasting. The rear nub of a singlespeed setup can either be specifically designed for singlespeeds or can be a standard cassette-compatible hub with the cassette removed and replaced by a single cog and spacers either side. That’s what I ran for many years without issue.

Q: What’s appropriate gearing for a single-geared bike?

A: The choice of gearing is yours based on the riding you do. While the single geared bicycle is undoubtedly the simplest gearing system, it’s also the least flexible. You have one gear which has to suffice for all your riding. That’s why single speed setups are usually chosen for cruiser bikes which are designed for easy rides around a flat beach path. The problem is, if you have inclines, flats and descents on your rides, then what’s the most appropriate size of gear for all your riding?

Q: How do we alter the gearing on a single speed or fixed-gear bike?

A: Well if I find most of my ride I’m struggling to push a gear that feels too hard, then I need a higher gear ratio – see Gear Ratios section above. I can either install a smaller chainring on my crankset – one with fewer teeth, or I can install a larger rear sprocket at my rear hub – one with a greater number of teeth. I can swap out both actually if I’m looking for a very specific gear ratio. But usually one or the other will give me the best gear for my riding. And then contrary to the above scenario, if most of my riding has me spinning out at the pedals to the extent that I’m almost bounding on the saddle then I would benefit from a higher gear. This necessitates a larger chainring or smaller sprocket.

Changing out chainrings for different sizes isn’t complicated. Singlespeed rings like this have no need for ramping or different teeth profiles for hopping the chain on and off. The chain is on and stays put!

Personally I rode a 29er singlespeed mountain bike in a 32:16 or 32:15 ratio shown above, which were – with a bit of hard grinding on the steepest ascents – capable of getting me around fairly well. I’d spin out on paved descents too, but I was happy to freewheel down those for the most part. My flat speed was around 15/16mph (25kmh) at that time which was more than good enough for me. So it’s a personal choice which gear to choose. Ideally choosing a gear that allows a 90rpm cadence on most terrain that you’ll be covering (with the odd spinning out period and the odd stomping-on-the-pedals period) should be good. Let me know in the comments what gear you choose if you’re on the one only.

One other thing to mention and that’s Flip-flop hubs. These are rear hubs that can take a fixed sprocket on one side and a freewheel on the other, usually at the same time. For riders who want to ride fixed mostly but might want the flexibility of riding a freewheel singlespeed on some occasions.

Q: Are Geared-to-singlespeed Conversions possible?

A: Yes it’s entirely possible to convert between a geared bike and a single-speed bike by removing the sprocket cassette and replacing that with a single cog and spacers either side. The gear derailleur(s) and gear shifters can also be removed as those are now extraneous. The chain length may be difficult to get exact so it isn’t too long in particular. Half-link chains can help here, as can singlespeed chain devices. This isn’t a problem for bike frames that have horizontal (or sloping) dropouts or track ends, where the wheel will slot in the frame along a range of positions rather than from the underside in one position only.

Q: Bicycle gearing systems: what’s a “1-by” drivetrain?

A: Sometimes written 1×10 or 1×11, for example, a 1-by drivetrain is different from a singlespeed or fixed-gear bike because it will have a range of gears, usually on a cassette on the rear hub. The rear gears will usually be changed using a derailleur . The derailleur is operated by a shifter which is most conveniently mounted on the handlebars. While the shifter is usually cable operated, both Shimano and SRAM have wireless shifting options available in the Di2 and eTap systems at the tap of a button.

A wee bit o’ history 😀

As a kid, back in the day, (oh, here we go again…), I had a 5-speed race bike. Did I mention before? lol 😀 I didn’t call it a 1-by five. It was just a 5-speed. Didn’t stop it from being a 1×5 though! #trivia

An old 5-speed I once owned. Didn’t stop it from being a 1×5 though! #retrocool

For a good many years (oh, here we go again…) 1-by systems were a bit of a rarity barring the aforementioned kids bikes and very low end department store type bikes. Mountain biking showed us the way in tech terms with downhilling and Four Cross (4X) racing, the bikes for which often ditched the multiple front rings in favor of a single ring. But to prevent the chain dropping, chain devices were needed.

So once, many a year ago now (oh, here we go again…) I “converted” my 3×9 on my nice ball-burnished GT Zaskar LE that I commuted to work on. The fool I was, lol 😀 I made no other arrangements at the front besides removing the inner and outer rings, and the front derailleur, cable and shifter. Ah, that looked much cleaner. And I think it was about the look rather than the functionality, but the, isn’t so much in cycling! Well during some simple gear shift, my chain bounced at the front, causing it to drop at the smallest sprocket at the rear, catch in the gap between the cassette and the frame (and limit screws be damned), tear the derailleur off its hanger and snap three spokes on the rear wheel. Oh dear. I had to faff a “single speed” solution that day to get home at all lol. I’m sure there’s a moral in that story. I don’t think I ever learned it though 😀

So while you could always convert to your own 1-by system, since around 2012 / 2013, 1-by systems have been around more commercially, but it’s only within the last few years that they’ve made a name in all fields of cycling including on-road cycling. SRAM and Shimano have advanced the technology in 1-by gearing setups. Back in the day, I remember the chain had a tendency to bounce itself off the chainring. That doesn’t happen now with narrow-wide chainrings that grip the chain and “shadow” derailleurs with better pivoting geometry and clutch mechanisms to allow smooth changes and keep the chain in constant tension so it doesn’t bounce off over rough ground or when shifting (which I found) over a much greater range of rear gears.

On modern 1-By drivetrains, the chainring teeth are alternately narrow and wide to better hold the chain

The 1-by rear cassette now has to cover the range of gears facilitated by two or more chainrings. This has resulted in cassettes sporting larger lowest sprockets and, as mentioned, specially designed rear derailleurs to match. !-by setups now tend to center around an 11-42T cassette and a chainring whose size depends upon its application. For road 1-by setups a 42T chainring is common. For off-road chainrings are running at around 28-30T with the 11-42T cassette for XC/Enduro bikes and the higher gearing 36T with the 11-28T road-type cassette for downhill-only bikes.

And while it may be argued that a 1×11 can’t match a 2×11 particularly on road for gear range, don’t forget, we rarely use the inner half of the cassette when in the big ring at the front, and vice versa, so we rarely if ever fully utilize all gears in a multi-front-ring setup. I found on my 1×10 that I’d easily use all 10 gears and that cross-chaining was never an issue. At the minute, I’m riding a lowly 2×8 system on which I use at most 8 or 9 available gears before I get chain rasp on the front derailleur from crossing the chain too far.

I liked the simplicity of the 1-by system

… Yup, it was by far my favourite. So simple, if I want to spin faster or it’s too difficult to push at a decent cadence uphill, I change down, and vice versa. Change up, change down, no wondering if I change up on the front will I also have to change down at the back to keep a similar cadence. Less mentally confusing for a mentally confused soul like myself. But how about you? What are your thoughts on 1-by systems? Are they rightly the future of bicycle gearing?

Q: Bicycle gearing systems: what are internal hub gears?

A: This, from the outside is similar to a single-speed drivetrain insofar as a single chainring on the crank arm drives a single sprocket on the hub. The magick happens inside the hub shell. You’ll notice the hub shell is much larger in diameter than a regular rear hub. This, being in order to house the gearing cogs. Wikipedia has an interesting explanation of how it works, technically speaking, but I think that’s beyond the remit of our article here, we’re all dummies right? 😀 #kidding. Essentially, clicking the shifter pulls a gear selecting pin out from the hub’s hollow axle. This determines the gearing selection with which hub shell is driven around the fixed axle. Usually because of how the hub shell is indeed driven around the axle, the axle has to be braced against rotation to the frame. This is normally done with lock-washers / non-turn washers.

I rode a sturdy and dependable 3-speed Sturmey S-RK3 internal gear disc hub and I found the setup to perform really nicely on my commuter bike. With only three gears, expect the gearing to be rudimentary. But I found it perfectly adequate. The middle of the three was the direct gear where the front ring directly drives the hub via the rear sprocket. There’s plenty of choice in the Sturmey rear sprockets too. The retainer ring is a bit of a faff to install and take off, but once you know the dark secrets, it’s easy! lol 😀 There was one lower gear which was fairly spinny and one higher which was good for when the speed picked up. I found it required no maintenance at all over the two years that I rode it even through the wet Irish winters! I liked its simplicity. I had a nice little bar-mounted under-brake-lever thumb shifter.

My self-built 3-speed Sturmey Internal gear disc hub and the nice little trigger shifter. Not the lightest, but was nothing if not totally dependable and reliable #solid

Yes, there was a little extra weight over conventional rear hubs – though don’t forget this can be offset by not needing a derailleur. Because I’d gone from singlespeed to the three-speed Sturmey hub I was indeed adding weight. But it wasn’t a deal-breaker for me. I liked that setup.

I find myself at the minute currently sourcing an internal hub gear setup with more gears, maybe 8 for a vintage bike resurrection. I liked the Shimano Alfine 11-speed internal hub, but for my purposes and the vintage frame I’m setting up, I need a hub brake since it was originally a rod-brake bike. I like the Nexus roller brake. I don’t believe these are available for the Alfine though? Rohloff hubs are amazing too, if only I happened to have that much spare cash for the build #staytuned 🙂

Q: Bicycle gearing systems: what are “2-by” and “3-by” drivetrains?

A: Possibly the most complicated of the gearing systems, but in many ways, at least until we have maybe a 1×12 or 1×13, they’re possibly the most flexible bicycle gearing system. So we’ve taken a 1-by system and we’ve added another chainring to the chainset, or sometimes two chainrings. We add a front derailleur and place a shifter on the left side of the bars (or for vintage bicycles, on the left side of the downtube!) 2-by systems are common on road bikes while 3-by are more often utilized on modestly priced mountain bikes and on touring bikes in general where a larger range of gearing options is needed. Many “beginner” type bikes of all styles use 3-by systems.

So we add another ring, or rings at the front, our derailleur to change between, and bingo! Now we’ve just doubled or even tripled the number of available gears, haven’t we?

Well, in theory we have indeed. In practice however, we might have a degree of gear ratio duplication where similar gear ratios are possible over two chainrings. In some ways we’re also prevented in our full utilization of all gears by the idea of cross-chaining.

Q: What does cross-chaining mean?

A: Cross chaining happens when the chain, when viewed from the seated position on the bike, leaves the outer, larger chainring at an angle and heads to the inner rear sprockets. It can similarly happen when the chain leaves the inner smaller chainring at an angle and heads for the outer rear sprockets. Ideally we want our chainline as straight as possible between the chainring and the rear sprocket. The greater the angle, the greater the wear on the components and potential risk of chain slippage. It’s not always the case, but it’s often the culprit. Cross chaining is inefficient, as demonstrated by energy lost to noise – it’s noisy! Cross chaining can also cause the chain to rasp on the poor front derailleur which can’t be trimmed to get out of the way of this diagonal horror scenario! lol 😀

Cross chaining isn’t the end of the world, but it’s inefficient (ie. noisy) and increases wear on chain link plates and sprocket teeth

So in practice, what this does is limit the choice of gears to pairing the outer chainring to the outer half of the rear cassette, and the inner chainring to the inner half of the rear cassette.

The ultimate advantage in multiple front ring setups is as stated in the number of gears available over a certain range of gearing. While that may not be double or triple the number of a singlespeed, it can still give a sufficient increase to allow, particularly in road cycling, for a smoother steadier pedalling rate (cadence) as the speed increases or decreases.

Q: Gear Shifting Terms: What way’s UP and what way’s DOWN?

A: I think there’s a natural confusion around what constitutes “up” and “down” when it comes to bicycle gears. Why do I think it’s natural? Because of the shape of the gear cassette on the rear hub. Were I a teeny tiny little mountaineer dude scaling that rear gear cassette, it’s plain which way I’d go if I were going up and which way would be down. Poor little dude, I hope he makes it! However… bicycle gear naming isn’t based on how anything looks! Especially true because the front and rear gearing work differently! So forget how the thing looks!

Because shifting up to a higher gear references the greater distance along the ground that is covered in that higher gear for one complete 360 degree rotation of the chainset. It also references the greater speed in that higher gear for the same energy input or pedalling rate. Don’t worry about looking down at the size of gear sprocket your chain is on. That’s just confusing. What it looks like is not important. What’s important to know is this…

When you shift UP to a HIGHER gear on your bike, you will cover GREATER distance along the ground for one complete 360 degree rotation of your chainset.

  1. If you pedal at the same rate (cadence) you will move at a GREATER speed than in a lower gear
  2. This gear will be harder to push than a lower gear

When you shift DOWN to a LOWER on your bike you will cover a LESSER distance along the ground for one complete 360 degree rotation of your chainset

  1. If you pedal at the same rate (cadence) you will move at a LESSER speed than in a higher gear
  2. This gear will be easier to push than a higher gear

Remember, it’s easy to understand the confusion, but up/higher and down/lower concern have nothing to do with the size of the gear sprocket on your cassette that your chain is on!

Remember, looks aren’t important! And I should know! 😛

Make sense? It’s more easily understood for drivers who can’t see their gear cogs because they’re hidden in the gearbox. First gear will be a proportionately larger cog inside that gearbox than fourth, fifth, sixth or what have you. It’s the same here. All good so far? 🙂 Okay, try this next…

Q: Gear Shifting Terms: Front gearing and rear gearing, what’s the difference?

This doesn’t apply to fixed-gear, singlespeed or most non-hybrid hub-gearing. It only applies to gear systems with multiple chainrings: the 2-by or 3-by we mentioned at the start.

A: Adding front gears is really an augmentation or magnification of the effect of the rear gears. How we explained above the shifting up and shifting down remains exactly the same. Though in this case shifting up will indeed actually shift your chain onto a larger chainring. But as before, that size of ring/sprocket idea is not important here. And so, pretty much exactly the same as above, but specifically for the front gearing, we can say…

If we remain in the same rear gear then:

When we shift the front UP to a HIGHER gear on our bike, we will cover an EVEN GREATER distance along the ground for one complete 360 degree rotation of our chainset.

  1. If we pedal at the same rate (cadence) we will move at an EVEN GREATER speed than in a lower front gear
  2. This front gear will be harder to push than a lower front gear

When we shift the front DOWN to a LOWER gear on our bike we will cover a LESSER distance along the ground for one complete 360 degree rotation of our chainset

  1. If we pedal at the same rate (cadence) we will move at an EVEN LESSER speed than in a higher front gear
  2. This front gear will be easier to push than a higher front gear

If that all makes sense and/or you’re fully au fait with drive systems then feel free to skip on.

Oh man, you’re talking motor vehicles? In a bicycle article, really?

Yes, but just for the motor vehicle drivers! If that ain’t you, or if you find yourself horribly offended, skip this! lol, just kidding! 😀 Otherwise you’ll have to indulge me because I thought an analogy might help to further clarify and not confuse things further! Because for front gears I’d think in terms of motor vehicles, be they motorcycles, cars, trucks or whatever.

In a motor vehicle we have an engine that spins (revs) at a variable rate and drives the wheel or wheels which also spin at a rate that can vary according to the engine revs and also the gears. Without wanting to sound facile, on a bicycle, we can kind of equate the motor engine to our legs. And changing gears on a motor vehicle is akin to changing REAR gears on our bike. We can adjust the revs of our legs, which is our pedalling rate or cadence the same as happens when we use the accelerator on a motor vehicle.

Make yourself comfortable. We could be here for some time…

However, changing front gears on a bike is different. It wouldn’t so much be like changing gears in the motor vehicle, as much as selecting a whole other gearbox altogether. You’d have your lower gearbox (granny ring on your chainset), sometimes a middle gearbox (middle ring on your chainset), and higher gearbox (big ring on your chainset).

So here’s me tootling around town in my car with my lower gearbox selected. Man this is a complicated car! If only I had a bike. Or a horse! But anyway, where was I? With my lower gearbox selected, I can zip around the tight streets, changing gear as normal (rear gears on a bike). I can accelerate fairly quickly, but I seem to hit high revs at fairly low speeds. Still, for start-stop driving and zipping around like a gnat, this lower gearbox is the job.

Say I take my car out of town onto more open highway

… Now I find my engine is spinning out even in my highest (rear) gear. What do I do? Aha, my complicated car has another gearbox. Fortunately I select it at the click of a gear switch. Now I’ve selected my higher gearbox, man the speed increases. But it does so at a slow rate of increase! Also, trying to sustain high engine revving (rate of pedalling or cadence) I’m noticing that fuel gauge dropping kinda quickly as burning through a lot of energy. But I can top out on speed in this higher gearbox and in my highest (rear) gear. And it’s fun to go fast sometimes.

Okay so now I’m starting to climb into the mountain roads, my higher gearbox seems to be making my car labour. It feels as if I need to downshift. But I’m already in my lowest (rear) gear? So I just click the gearbox selector and bingo, I select my lowest gearbox. Now my revs (cadence) pick up even though my speed has slowed. I can select the most appropriate (rear) gear to keep the engine revving (pedalling) at the most favourable rate. And it’s a nice drive up into the hills!

And THAT is my epic analogy, I need to go lie down for a bit now, and I’d advise you to do the same! lol 😀 Did that explain anything or just waste lots of scarce words? Let me know 🙂

Q: Gear Shifting Basics: How does bicycle gear shifting work?

A: I think we grasp the simple idea that pedals, crank and chainring(s) at the front, via a chain, drive a sprocket or group of sprockets (assembled as a cassette) at the rear, but how does gear shifting work?

There are different kinds of gear shifters from vintage thumb shifters or downtube levers, to twist shifters, trigger shifters and combined brake and gear shifters…

All kindsa tasty gear shifters: thumb, trigger, twist or grip shift, downtube, and drop-bar brake/gear shifters

However it doesn’t matter what kind of shifter is on your bike. They all do the same job. And what is that job?

By clicking or twisting our gear shifter, we’re either pulling a tiny amount of gear cable inner towards the shifter through the fixed gear cable outer, or we’re allowing that cable to be pulled back towards the derailleur. This cable movement will articulate the derailleur on its pivots and nudge the chain across to the adjacent sprocket or chainring. The derailleur keeps the cable tension via a spring. Just enough cable is moved to shift the chain the short distance between sprockets or chainrings.

The action is similar for internal hub gears. Clicking or twisting the shifter pulls a gear selecting pin out from the hub’s hollow axle. This determines the speed with which the hub shell is driven around the axle.

Q: Gear Shifting Basics: How do I shift gears?

A: It’s particularly important when climbing or riding under load that you BACK OFF THE GAS but KEEP PEDALLING! If you drive a manual transmission car, you’ll know this as well. When changing gear in the car: foot off the accelerator momentarily > de-clutch > select gear > engage clutch and simultaneously foot on the gas again. Same on the bicycle. When climbing say and feeling the cadence rate slow or the pedalling become difficult, keep pedalling. What I do is try to push ahead of myself more than I need. This affords me a slight moment of “gearchange breathing space” ie. backing off the power without slowing my speed noticeably.

…aahhh, sweet, sweet gearchange breathing space 😀

The steeper the incline, the more “gearchange breathing space” is needed . It’s this backing off releases some of the tension on the chain. And this allows it to slip more easily onto another sprocket without crunching and grinding. Then you can power on again. This whole thing only takes a fraction second.

If you don’t ease off on the pedals for that split second, the poor derailleur has to wrench off a chain under your tension and try to wrangle it onto another sprocket. What you’ll find then is a noisy change and potential for momentary slippage. So, remember, ease off for that momentary change!

Likewise, if you change gear while stationary and not pedaling, the derailleur will have moved, but the chain will be caught in limbo between sprockets (or chainrings) Pushing off will be a clunky moment, again with potential for slipping!

Another advantage of internal hub gears is that they don’t require that you pedal to change gear. This is handy if you have to make an unexpected stop at a junction, say, and aren’t in the correct gear for starting off. A quick click or twist and the internal gear is selected without needing to engage drive, ie. pedal!

Q: Gear Shifting Basics: When do I shift gears?

A: There’s usually an appropriate moment to change gear in order to maintain your cadence. If you find your pedaling rate drops so you no longer feel as if you’re spinning as much as pushing, ie. below 80rpm, I would change to a lower gear. If your pedaling rate drops such that you’re grinding or stomping on the pedals, either change down a gear or two or stand up to pedal.

I’ve elaborated on how and when to gear shift on your bike in another article that might give some further information 🙂

It comes down to individual preference and fitness, but I find when it comes to an incline, particularly a sudden steep one, I find there is a section of that incline at the bottom where I’ll have to choose one of two courses of action. Either I push hard at 50-60rpm in the gear I’ve arrived at that incline in, or, change to a lower gear and spin, possibly more than I wanted to, before the speed drops and that spinny gear is the right gear. In this section at the bottom of the incline, I usually change to a lower gear and spin sooner rather than later. I’ve found this maintains as much speed as possible. But then if you’ve bigger legs, it’s possibly better that you push out the watts than change sooner #preference

Is the terrain rolling? Will you have to change to a higher gear only for a short period and then change back to the lower gear? Here, I prefer to stay in the lower gear for the incline, and spin where necessary on the flat or the descent. Of course if the ascents and descents are long, well obviously change to the appropriate gear to maintain cadence. I’m only referring here to terrain which is a succession of short (maybe 100yd/100m) peaks and troughs.

Q: Gear Selection: What gear do I choose on hills or when climbing?

A: It would be imprudent of me to suggest any actual gear combination or ratio. Why? Because we’re all such different individuals, which gear to be in depends on a few things:

  • Your ride fitness. While professionals can spin up hills in fairly high gears, most of us need lower gears to facilitate a decent cadence without resorting to stomping the pedals.
  • The length of the climb. Short climbs can almost be powered up in higher gears. Climbs that are long drags need to be not attacked too hard at the bottom but paced; settled into at a maintainable rate with the view to powering up and over the top for the plateau or descent. Again, the gear choice will largely depend on your level of ride fitness as above!
  • The gradient of the climb. Steeper climbs > lower gears, shallower climbs, higher gears
  • Your ride goals. Maybe your hill is a way to strengthen your legs. In which case your gear can be higher resulting in a lower cadence. Maybe your goals are for developing your cadence, in which case a lower gear is better. Maybe your goals are to be able to have a conversation on the incline so the gear choice is one that allows you to ride in a lower training zone where your oxygen requirement is also lower. So, yeah, it depends!
  • Your cadence preferences. Some people prefer a lower cadence > higher gear choice than, other folk who prefer a higher cadence > lower gear choice. What can I say. It’s preference again!
Which gear for climbing? There isn’t a right one, but there’s a right one for you for the climb you’re on and for how you’re feeling at that moment!

Just for me personally, I try to keep spinning at 70-90rpm if possible. Anything below that and I’d usually select a gear one higher and stand for a bit, then change back to one lower and sit, and alternate like that. Then again, I’m not so great at short, sharp inclines. I prefer the ones that I can settle into and let my heartrate adjust itself!

Q: Gear Selection: What gear do I choose on flat roads?

A: What’s your goal? If you’re going for as much speed as possible, then stay in as high a gear as you can maintain around 90rpm cadence at, or just below your threshold training zone. If you don’t have a heart-rate monitor, your threshold training zone is probably going to be a 16 or 17 on the Rate of Perceived Effort (RPE) scale And if you don’t have a cadence monitor, maybe you’re like me and might find having a song in your brainhole is helpful. I like this song bpm site because it gives ideas for songs with a beats per minute rate that matches your desired revolutions per minute pedalling rate.

If distance or endurance is your goal, you’d be in whichever gear, or gears allow you to ride steadily at a 7-8 on the RPE scale above.

Other than that, truth is, there really is no “best” gear to be in. It’s as simple as just picking a gear that suits your own riding enjoyment!

Q: Gear Selection: What gear do I choose on descents?

A: It depends on whether you’re freewheeling or whether you want to pedal to maintain or increase your speed.

If you’re pedalling on the descent, as above, keep in the gear that gives you the most appropriate cadence and speed for your own riding goal.

Personally speaking, when I’m freewheeling on a descent I’ll usually stay in the big ring at the front and a sprocket or two up the cassette at the rear. The only reason for this is to minimize chain slap on the chainstay. I don’t need to, but it just feels better and less distracting to me on a descent if it’s quiet than if the chain’s rattling everywhere #personalpreference 🙂

For more hands-on information on using your bike’s gear shifters, check out my beginner’s guide to gear shifting.

Q: Gear Shifting Problems: Why is my gear not changing smoothly?

Q: Gear Shifting Problems: Why do my gears slip under load or uphill?

Q: Gear Shifting Problems: How do I stop my gears from jumping, slipping and clicking?

A: Man, your gears are really troublesome aren’t they? Okay, I’ve grouped all three of these questions under one answer. Why? Because the chances are they essentially point to the same thing – a maladjusted derailleur. I’m going out on a limb here and assuming we’re talking about the rear derailleur, but the principles are the same front or rear.

If by “slip” we’re referring to the chain slipping onto a smaller rear sprocket on the cassette, then this is because, for that particular gear (and the other gears too) the rear derailleur isn’t set so that its jockey pulley and tension pulley are not directly underneath that sprocket. Rather, they’re slightly towards the higher gear (next smallest sprocket). While cycling not under load, this discrepancy is within the derailleur’s tolerance. But when the load increases, for example when you start climbing, the extra tension in the chain taughtens the system trying to right itself as much as it can into a straight line. This moves the derailleur and shifts the gear, causing the slipping.

The rear derailleur barrel adjuster is designed to be quickly and easily turned by hand to adjust the rear derailleur’s position, ensuring the chain is correctly on its correct sprocket

To remedy this problem, all we have to do is to turn the barrel adjuster on the derailleur anticlockwise by a quarter or half a turn. Actually you can reasonably sight for a straight line, when standing or crouching behind your cassette. The line should run down the sprocket that the chain is on and down through the jockey wheel and tension wheel on your derailleur. It’s most likely that your derailleur will be slightly to the right of the sprocket when viewed from behind. Turn the barrel adjuster anticlockwise until it’s directly below the sprocket. If you have your bike on a workstand (or upside down) and can spin the cranks, you would turn the barrel adjuster on the derailleur anticlockwise until the chain begins to make a noise against the next largest sprocket. Then back it off until the noise just stops. This should set the shift for all gears. Try it to see if it works.

Adjust the static position of the derailleur by turning the barrel adjuster clockwise (moves the derailleur outwards) or anticlockwise (moves the derailleur towards the hub)

The other causes of chain slip or skipping might be:

Chain is actually slipping around sprocket teeth? This means your derailleur is so out of line that the chain is riding around the outside of the rear sprocket rather than settling over its teeth. Simply adjust exactly as above.

If the chain is slipping when riding over rough ground it could be that the derailleur isn’t keeping the chain in tension well enough. This could be the result of a weakened, or seized spring in the jockey wheel cage. A run through with GT85, WD-40 or penetrating oil should loosen things up there.

Actual sprocket wear. This is fairly rare as rear cassettes last for thousands of miles. However it is certainly possible, if, for example, the bicycle has suffered from poor maintenance and perhaps has been exclusively ridden in the one gear? #scratcheshead 😀 I dunno, but if that’s the case, only a new cassette will fix that one.

Other investigations. Potentially beyond our “dummies” remit of this article, however, I do like to give the extra info, in the interests of thoroughness soooo…

  • The cassette lockring can come loose. This can cause the cassette to “wobble” on the freehub and make both changing gear and staying in gear difficult.
  • The derailleur hanger itself can become bent. This can happen due to the derailleur taking a knock during a ride, or more likely when the bike is either parked or being stored or moved. The derailleur hanger can be easily straightened if you have the Park Derailleur Alignment Gauge (or one of the other similar options) or, interestingly, it’s actually possible because of the same 10mm threading, you can actually carefully thread a solid-axle wheel in there! It makes a great visual representation of which direction your hanger is bent in.
  • The derailleur limit screws may require re-adjusting. Limit screws do as their name implies, and stop the derailleur from accidentally flipping the chain right off the cassette at either end. This misalignment should only impact upon changes to either the highest or lowest gears. If this is the problem, it should only be noticeable there. Remembering our directions of high and low gearing, usually the high gear (smallest rear sprocket) limit screw is above and the low gear limit screw is below. Moving these limit screws can cause damage both to the bike and to you! so do so with caution. Clockwise limits the derailleur – moves it towards the center of the cassette. Counter-clockwise (which is possibly what needs to happen if this is the issue) moves the derailleur towards the edges of the cassette. Remember though, too far and the chain can be shifted off the cassette altogether! Make small adjustments, watch from behind what’s happening to the derailleur when you do #dangerwillrobinson! 😀
  • The B-Tension screw may require re-adjusting. The B-Tension screw on many derailleurs sets the verticaldistance from the upper tension wheel on the rear derailleur to the sprocket. If the distance is too small, the chain can have too tight a squeeze as it passes that point. This can lead to audible rubbing that you can potentially feel through the pedals too. If the distance is too far, shifting can be sluggish. It’s not a critical operation here – clockwise increases the distance between derailleur and sprocket and counter-clockwise brings the two together.
  • Cycling-Questions-Limit-Screws-and-B-Tension-Adjuster
    Showing the B-Tension screw. (Where present) this pushes against the derailleur hanger. Also, high and low limit screws. Take care adjusting these two!

Soooo… That’s about us all done. A lot of words. Do you remember when we started out, we knew nothing. Now we’ve learned gears together! #seemssolongago 😀

I’ve tried to cover everything in a level of detail appropriate to those of us who – while we ain’t no dummies, we might not be experts. Yes, I have my hand up! As ever, if you’ve any further questions, please ask in the section below, or leave a comment. I’m keen to hear what you folk are up to in the land of sprockets and chainrings. But whatever gear ratios you ride, do it safely and have fun meantime! David.


Leave a Reply

Close Menu