Gear ratio = chainring teeth ÷ cassette cog teeth. A compact crankset (50/34) paired with an 11-32 cassette gives the widest usable range for most amateur road cyclists -- enough top-end speed on flats and enough low-end relief on sustained climbs. The right gearing does not make you more powerful. It lets you apply the power you have at the cadence where your body works best. That distinction matters more than most riders realise.
Gearing is one of the cheapest changes you can make to a bike, and one of the most consequential. A new cassette costs less than a set of tyres. Yet most riders never question what came on the bike from the shop, and a surprising number are riding gears that actively work against them -- over-geared on every climb or spinning out on every descent.
What Gearing Actually Is
A bicycle drivetrain is a system of mechanical advantage. You push the pedals, the chain transfers that force to the rear wheel, and the ratio between the front chainring and the rear cassette cog determines how far the wheel travels for each pedal revolution.
The formula is simple:
Gear ratio = chainring teeth ÷ cassette cog teeth
A 50-tooth chainring paired with a 25-tooth cassette cog gives a gear ratio of 2.0. For every full turn of the pedals, the rear wheel turns twice.
A 34-tooth chainring paired with a 34-tooth cassette cog gives a gear ratio of 1.0. One pedal revolution, one wheel revolution. This is a very low gear -- the kind of gear that lets you crawl up a 15 % gradient without destroying your knees.
Higher gear ratios mean more wheel speed per pedal revolution but more resistance at the pedal. Lower ratios mean less resistance but less distance covered per stroke. Every gear choice is a trade-off between these two things. The complete gear ratio guide walks through the full maths and every common road and gravel combination.
The entire point of having multiple gears is to keep your pedalling cadence in a productive range across varying gradients and speeds. Without gears, you would either spin out on descents or grind to a halt on climbs. With gears, you can hold 80-95 RPM whether the road is flat, tilting up at 5 %, or dropping away at 8 %.
Chainrings: The Front Half of the Equation
The chainrings are the toothed rings attached to your cranks. Road bikes have two (a "double"), though single-chainring setups are increasingly common. The chainring sizes set the upper and lower boundaries of your gearing range.
Standard (53/39)
The traditional racing setup. A 53-tooth big ring and a 39-tooth small ring. This was the default for professional racing for decades and remains common on high-end road bikes sold to amateurs who will never need it.
A 53/11 top gear gives a ratio of 4.82. At 90 RPM, that puts you above 55 km/h. Most amateur cyclists will never sustain that speed on flat ground. On a 53/39, the lowest gear with an 11-28 cassette is 39/28 -- a ratio of 1.39. On a 10 % gradient, you would need to push roughly 3.5 W/kg just to maintain 60 RPM in that gear. For a 78 kg rider, that is 273 watts -- which is above threshold for most amateurs.
Standard gearing exists for flat criteriums, time trials, and professional racing. If your regular routes include climbs of any significance, standard gearing is almost certainly too high.
Compact (50/34)
The compact crankset dropped the big ring to 50 teeth and the small ring to 34. This remains the most versatile road gearing option for amateurs and the one I would recommend to the vast majority of riders.
A 50/11 top gear gives a ratio of 4.55. At 90 RPM, that is still above 51 km/h. You are not giving up meaningful top-end speed. But the bottom end changes significantly: a 34/32 combination gives a ratio of 1.06, and 34/34 drops to 1.0. These ratios let you spin at 80+ RPM on gradients where a standard crankset would have you grinding at 60.
The compact crankset is not a concession. It is a recognition that the riding most of us do -- sportives, club runs, training rides with 1,000+ metres of climbing -- demands a low gear that the standard setup cannot provide.
Semi-Compact (52/36)
The compromise option. A 52-tooth big ring and a 36-tooth small ring. Semi-compact has become increasingly popular with stronger club riders and age-group racers who want slightly more top-end than a compact without the punishing low-end of a standard.
The 52/36 works well paired with a wide-range cassette (11-32 or 11-34). The 36/32 combination gives a ratio of 1.13 -- not as low as a compact's 34/34, but workable for most climbs under 12 %. It is a solid choice if you are a strong rider who finds the compact's big ring too small for fast group rides but cannot manage the standard's small ring on climbs.
1x Systems (Single Chainring)
Single-chainring drivetrains eliminate the front derailleur entirely and use a single chainring (typically 38-44T on road, 38-42T on gravel) with a wide-range rear cassette (10-44 or similar). The appeal is simplicity. The trade-off is significant -- more on that below.
Cassettes: Where the Range Really Lives
If chainrings set the boundaries, cassettes fill in the detail. The rear cassette is a stack of cogs, described by the smallest and largest: an 11-28 has an 11-tooth high cog and a 28-tooth low cog. The numbers between describe the steps.
Common Road Cassettes
11-28: The traditional road racing cassette. Tight spacing between gears (often single-tooth jumps in the middle range), which gives smooth shifts and fine cadence control. The 28-tooth low gear is adequate for moderate climbs if you have decent power, but it will leave you grinding on anything steep.
11-30: A small step up from 11-28 that adds a meaningful low gear without sacrificing much spacing. Increasingly the default on mid-range to high-end road bikes. A sensible choice for moderately hilly terrain.
11-32: The sweet spot for most amateur riders in hilly terrain. The 32-tooth cog provides a genuine bailout gear when paired with a compact crankset (34/32 = 1.06 ratio). You lose one or two closely-spaced middle gears compared to an 11-28, but the security at the bottom end is worth it.
11-34: Maximum range for standard road derailleurs (some Shimano and SRAM road derailleurs now accommodate 34-tooth cogs). The 34/34 = 1.0 ratio is an extremely low gear that can get you up almost anything. The trade-off: bigger jumps between gears in the middle range, which means less precise cadence control on rolling terrain.
11-36 and wider: Available with some groupsets (particularly SRAM AXS) and increasingly common on endurance and gravel-oriented road bikes. These push the low end even further but introduce spacing gaps that purists find objectionable. For touring and long-distance sportives with major climbing, the low gear is worth the trade-off.
Which Cassette Do You Actually Need?
The answer depends on one question: what is the steepest gradient you ride regularly, and can you hold 75+ RPM on it with your current gearing?
If the answer is no, you need a bigger cassette. It really is that simple. An 11-32 or 11-34 paired with a compact crankset covers the vast majority of road cycling terrain in the UK, Ireland, and continental Europe. If you are riding Alpine or Pyrenean cols with sustained gradients above 10 %, the 34-tooth cog is not optional -- it is the difference between riding the climb and walking it.
Gear Inches and Development: The Numbers That Actually Matter
Raw gear ratios are useful for comparison, but they do not tell you how far the bike travels per pedal revolution. For that, you need development.
Development (in metres) = gear ratio x wheel circumference. For a standard 700c wheel with a 25 mm tyre, circumference is approximately 2.1 metres. A gear ratio of 2.0 gives 4.2 m of forward travel per pedal revolution.
This matters because it connects gearing to speed:
Speed (km/h) = development (m) x cadence (RPM) x 60 / 1,000
A 50/25 gear (development = 4.2 m) at 90 RPM gives: 4.2 x 90 x 60 / 1,000 = 22.7 km/h. That is a solid endurance pace on flat ground.
You can work out the development for every gear combination on your bike using the Gear Ratio Calculator. It gives you the actual speed for a given cadence -- the number that matters when planning pacing or deciding whether to change cassettes before a race.
Choosing Gearing for Your Terrain
Flat Racing and Criteriums
For flat-terrain racing, top-end speed matters and climbing relief does not. A semi-compact (52/36) or standard (53/39) with an 11-25 or 11-28 cassette gives tight gear spacing for fine-tuning cadence in a bunch. Most crit racers spend the entire race in the big ring and the middle third of the cassette. The small ring is insurance. An 11-25 gives the tightest possible spacing in that middle range.
Rolling Sportives and Club Rides
This is where compact (50/34) with an 11-32 cassette earns its keep. You get enough top-end for descents and fast group sections (50/11 at 90 RPM = 51+ km/h), tight-enough spacing in the middle range for rolling terrain, and a genuine low gear for the steepest sections.
For riders in hilly regions, this is the default setup. There is no shame in it. There is also no performance penalty -- the professionals are not riding 53/39 anymore either, as we will see.
Mountain Stages and Major Cols
If your rides regularly include sustained gradients above 8 %, your low gear becomes critical. A 34/34 combination (gear ratio 1.0) lets a 75 kg rider hold 80 RPM on a 12 % gradient at roughly 270 watts. That is still a significant effort, but it is sustainable for a well-trained amateur. The same rider on a 39/28 (ratio 1.39) would need to push 60 RPM at the same power -- which moves into the territory of muscular fatigue, knee strain, and premature bonking.
For serious mountain riding, compact chainring (50/34) plus 11-34 cassette is the pragmatic choice. Yes, you lose some spacing. No, it does not matter when the alternative is walking.
Touring and Ultra-Distance
Loaded touring demands the lowest possible gears. A triple crankset (48/36/26) or a compact with a mountain bike cassette (11-40 or wider, via a derailleur adapter) gives ratios below 1.0 for spinning up steep gradients with 15-20 kg of luggage. Speed is not the priority. Sustainability is. A gear that forces you to stand on every climb will end the trip faster than any mechanical failure.
The 1x Debate
Single-chainring drivetrains have taken over mountain biking and gravel racing. On the road, adoption has been slower, and for good reason.
Where 1x Works
Gravel, MTB, and cyclocross. A single chainring with a clutch derailleur means fewer dropped chains, no cross-chaining, and one less mechanism to clog with mud. A 40T chainring with a 10-44 cassette provides a range from 0.91 to 4.0 -- wider than most 2x road setups. For off-road disciplines where simplicity and reliability matter more than close gear spacing, 1x is the clear winner.
Where 1x Falls Short
Road riding with variable terrain. The problem with 1x on the road is not range -- modern 1x cassettes cover enough range. The problem is spacing. A 12-speed cassette spanning 10-36 distributes 12 cogs across a much wider range than a 2x system using those same 12 cogs across a narrower band. The result: bigger jumps between gears, often 3-4 teeth in the middle range, which translates to 5-8 RPM swings per shift.
On the road, where you spend long periods at steady cadence and small gradient changes require small gear adjustments, those jumps matter. You end up never quite in the right gear. Over 5 hours, that adds up.
Flat-terrain efficiency. With a 1x, the chainring is sized for climbing (38-42T). On flat ground at high speed, you run out of gearing earlier. A 42/10 top gear gives a ratio of 4.2; a 50/11 gives 4.55. That costs 2-3 km/h at the same cadence.
The Verdict
If your riding is primarily gravel, mixed-terrain, or you value simplicity above all else, 1x is a strong option. If you ride mostly road, a 2x system with a wide-range cassette gives better cadence control and more usable top-end. The industry would love you to buy 1x for the road. The physics says 2x is still the better tool for the job.
Cadence and Gearing: The Connection Most Riders Miss
Gearing and cadence are two sides of the same coin. Your gearing determines the cadence range available to you at a given speed on a given gradient.
If you are climbing a 7 % gradient at 12 km/h and your lowest gear is 34/28 (development = 2.55 m), your cadence is:
12,000 / 60 / 2.55 = 78 RPM
That is workable. Now imagine the same climb with a lowest gear of 39/25 (development = 3.28 m):
12,000 / 60 / 3.28 = 61 RPM
At 61 RPM, you are grinding. Each pedal stroke requires significantly more force. Your Type II muscle fibres -- the ones that fatigue fastest -- take more of the load. Your knees absorb more stress. You arrive at the top with less in the tank, and the next climb hits harder.
This is why gearing and cadence cannot be discussed in isolation. The "right" cadence is meaningless if your gearing will not let you achieve it. The cadence calculator lets you model this directly — plug in your speed and gear ratio to see whether your setup can hold the RPM you want. If your target climbing cadence is 80+ RPM and you regularly ride 8 % gradients, work backwards from those numbers to find out what gear ratio you need. Then check whether your current setup provides it. If it does not, swap cassettes.
Use the Gear Ratio Calculator to model this for your own weight, power, and terrain. Combine it with the Power-Speed Calculator to see what speed a given power output produces on a given gradient in a given gear.
Common Gearing Mistakes
Over-Gearing
The most common mistake in amateur cycling. Riders buy a bike with a 53/39 crankset because it came specced that way, then grind up every climb at 55 RPM and wonder why their knees ache.
A 53/11 top gear lets you pedal at 90 RPM above 55 km/h. Unless you are sprinting downhill in a professional peloton, you will never use it. The fix is honest self-assessment: look at your ride data. If your max flat speed is 40 km/h and your climbing cadence drops below 70 RPM, you are over-geared. A compact crankset and a wider cassette will make every ride more enjoyable.
Under-Gearing
Less common but worth mentioning. If your lowest gear is so low that you never use the last three cogs on your cassette, you are carrying gears you do not need at the cost of closer spacing in the range you use most. The other form: spinning out on descents, maxing out your biggest gear while the group pedals away. Rare with 2x setups but common with 1x systems using smaller chainrings.
Ignoring the Cassette
Many riders obsess over chainring size and ignore the cassette, which is easier and cheaper to change. Swapping from an 11-28 to an 11-32 gives you a meaningful low gear without touching the crankset. Check your rear derailleur capacity (most modern road derailleurs handle 32 teeth), fit a longer chain if needed, and you are done in 20 minutes for a fraction of a crankset swap.
What the Pros Actually Run
Professional gearing has changed dramatically in the past decade. The days of every rider on a 53/39 with an 11-25 cassette are gone.
Mountain Stages
On major Grand Tour climbs, most World Tour riders now use a 52/36 semi-compact with an 11-34 cassette -- or even a compact 50/34 for the hardest mountain stages. Pogacar has been spotted on a 36/34 lowest gear on Alpine stages. Vingegaard ran similar configurations on the long Pyrenean cols. The reasoning is the same as for amateurs: holding cadence on steep gradients preserves muscle function for the later stages of a race.
Flat Stages and Time Trials
On flat stages and TTs, 54- and 56-tooth chainrings are common, paired with 11-25 or 11-23 cassettes. The key insight: professionals change their gearing to match the stage. They do not ride the same setup on Alpe d'Huez that they ride on the Champs-Elysees. If the best riders in the world adjust gearing for terrain, the idea that amateurs should ride the same setup everywhere is absurd.
The Trend Toward Wider Range
The broader trend is toward wider cassette ranges with closer chainring spacing. A 52/36 with an 11-34 gives a similar overall range to the old 53/39 with an 11-28, but distributes it differently -- more range on the cassette, less gap between chainrings. SRAM's AXS groupsets push this further with 48/35 chainrings and 10-36 cassettes. Smaller chainring gap means smoother front shifts; wider cassette range means you always have a gear for the gradient.
How to Decide: A Quick Framework
If you are unsure, answer two questions. First: what is the steepest gradient you ride regularly? Under 5 % -- almost any road gearing works. 5-8 % -- compact (50/34) with 11-30 or 11-32. 8-12 % -- compact with 11-32 or 11-34. Above 12 % regularly -- compact with 11-34, no discussion.
Second: what cadence do you hold on your steepest climb? Check your ride data. If it drops below 70 RPM, you need a lower gear. A bigger cassette or smaller chainring is cheaper than physiotherapy.
Key Takeaways
- Gear ratio = chainring teeth / cassette cog teeth. Higher ratios mean more speed per pedal stroke but more resistance. Lower ratios mean less resistance but less distance per stroke.
- Compact cranksets (50/34) suit the vast majority of amateur road cyclists. Standard (53/39) is overkill for anyone who rides hills.
- Cassette range is easier and cheaper to change than chainrings. Moving from 11-28 to 11-32 gives you a meaningful low gear for less than the cost of a decent pair of gloves.
- Your lowest gear should let you hold 75+ RPM on the steepest gradient you ride regularly. If it does not, change your gearing before your next event.
- 1x drivetrains work well for gravel and MTB. On the road, the gear spacing penalty is real and costs you cadence control where it matters.
- Professionals change gearing to match the terrain. You should too -- or at least set up your bike for the hardest terrain you ride, not the flattest.
- Use the Gear Ratio Calculator and Power-Speed Calculator to model your specific setup against your terrain and target cadence
- For more on the cadence side of this equation, read the cadence guide
- If climbing is the problem, the five fixable reasons you get dropped on climbs covers the broader picture
- Low-cadence training remains a valid tool -- but the gearing has to support it
- Want this dialled for your specific terrain and fitness? NDY coaching builds the equipment conversation into the training plan. The application is where it starts.