Mountain gears for road bikes: The right gear ratio for mountains
Frequency is everything when cycling uphill on a road bike: pedalling at a relaxed pace is easy on your legs and back and increases your range. Aim for a cadence of 75 to 85 revolutions per minute when cycling uphill to stay fresh even after several kilometres uphill. More Read tips on how to ride mountains better on a road bike here. Depending on the gradient and length of the climb, it may be necessary to use real uphill gears on the Road bike gears to be retrofitted. Most road bikes have gear ratios, i.e. the rear wheel always turns faster than the crank. However, a few entry-level racing bikes also have 34 teeth on both the rear sprocket and the small chainring at the front. In the lowest gear, the crank and rear wheel rotate synchronously. If the wheel is supposed to turn slower than the crank, this is referred to as a reduction. If you want to adjust the gear ratio on your road bike, in most cases you will have to replace the entire crankset including the chainrings.
Easier uphill gears on a road bike: larger sprockets or smaller chainrings
Almost all road or gravel bike gears can be upgraded, but there are limitations. The most favourable option is to change to a larger rear cassette, for example a sprocket with 32 or 34 teeth. But beware: With older groupsets, the rear derailleur usually also has to be replaced and the chain length adjusted! Smaller chainrings also make climbing over passes and long mountains easier: The new chainrings tested in TOUR 2/19 Sub-compact cranks (48-32 and 46-30 teeth) can even realise a reduction ratio in which the small chainring is smaller than the largest sprocket - this should make it possible to conquer any steep side road, even with luggage on the bike. A 50/34 compact crank at the front and a cassette with 30 or 32 teeth remains a good solution for trained road cyclists if you are orientated towards the flatter main routes.
Important tip for converting the road bike gear ratio
Lengthen the chain for larger sprockets and shorten it appropriately for smaller chainrings. Otherwise, in the worst case scenario, your rear derailleur or the frame could be destroyed!
Mountain transmission on a road bike: Larger sprockets
The rear derailleur capacity limits the sprocket size - longer cages create more teeth on the sprocket. Top road bike groupsets in particular are limited, smaller gears are often found in cheaper groupsets. The higher the quality of the cassettes, the lighter and more durable they are and the better the shifting behaviour.
Shimano gears
Up to ninefold
Road bike rear derailleurs usually manage a maximum of 28 teeth. MTB rear derailleurs and cassettes up to 34 teeth of the same model years fit here and are compatible with the road bike levers.
Ten-way circuits
Dura-Ace rear derailleurs are limited to a maximum of 28 teeth. The first Di2 generation must be converted with an Ultegra cage to create a maximum of 32 teeth. For other Shimano groupsets, long Ultegra rear derailleurs (mechanical or Di2) of the last generation offer up to 32 teeth, current Tiagra rear derailleurs up to 34.
Eleven-way circuits
The Dura-Ace can manage 28 teeth, then 30 teeth from 2016. Younger Shimano rear derailleurs from the Ultegra or 105 series can manage up to 34 teeth in the long version (called "GS" by Shimano), while the short cage ("SS") stops at 28 teeth.
SRAM gearsticks
Sram offers so-called WiFli derailleurs for all ten- and eleven-speed gear generations, which can manage a maximum of 32 teeth. The Sram 12-speed derailleurs are available with short and long cages, with the short cage already working up to 36 teeth. The new electronic 1x12 XPLR eTap AXS groups can be combined with cassettes with a bandwidth of 10-44 teeth.
Campagnolo gears
All Campagnolo derailleurs up to ten-speed are limited to a maximum of 29 teeth, while newer rear derailleurs from 2011 onwards (Centaur, Veloce) can still manage 30 teeth. Eleven-speed drivetrains can be brought up to 32 teeth with Potenza rear derailleurs.
Road bike cranks: compact cranks for smaller gears
Standard crank
53/39 teeth - gear ratio for professionals and strong amateur road cyclists who mainly ride on flat terrain
Semi-compact crank (or mid-compact)
52/36 teeth - for trained hobby road cyclists who cycle on flat to hilly terrain
Compact crank
50/34 - typical and sensible combination for hobby riders, in combination with large sprockets on the rear wheel also suitable for high mountains or difficult mountain bike marathons such as the Ötztaler
Sub-compact crank
48/32 or 46/30 - ideal for less trained road cyclists, in the mountains or on a touring bike with luggage
What you need to consider with new chainrings
The bolt hole circles of the mounting bolts determine which chainrings can be mounted on the crank. With very small chainrings, it can happen that the front derailleur cannot be mounted deep enough. In this case, front derailleurs from more modern, cheaper derailleur groupsets often help.
All manufacturers
Conversion to compact cranks (50/34) is possible from eight-speed upwards in most cases, all suppliers have the gradation in various qualities in their programme. Attention: Older cranks with 53/39 (up to approx. 2012) have larger bolt circles - smaller chainrings can therefore not simply be fitted, the entire crank must then be replaced. Suppliers such as Stronglight or TA Specialités also have single chainrings with 38 (standard bolt circle) or 33 teeth (compact bolt circle) for nine-, ten- or eleven-speed. Triple cranks (e.g. 52/42/30) are also common with Shimano (up to ten-speed) and Campagnolo (up to eleven-speed), but the conversion to compact usually requires a suitable front derailleur and shifting lever, which is complex and expensive.
Elf compartment
Younger cranks from Shimano and Campagnolo (recognisable by four instead of five chainring bolts) can easily be converted to compact chainrings. The oval rings from AbsoluteBlack also allow 48/32 on modern Shimano cranks. Other manufacturers offer smaller gradations up to 46/30 as complete compact cranks. You can download the test below. But be careful: Before you buy your dream crankset, you should definitely check the compatibility with your mounted front derailleur and the bottom bracket standard of your road bike frame!
TOUR tested these compact cranks with mountain gear ratio
Brand Model / Price in Euro (crank / bottom bracket) / Crank gradation
- Easton EC90 SL / 630 Euro/70 Euro - 47/32 teeth
- FSA Energy Modular / 289/60 Euro - 48/32 teeth
- FSA K-Force Modular / 669/60 Euro - 48/32 teeth
- FSASL-K Modular / 379/60 Euro - 46/30 teeth
- Praxis Works Alba M30 / 175/45 Euro - 48/32 teeth
- Praxis Works Zayante Carbon M30 / 325/45 Euro - 48/32 teeth
- Praxis Works Zayante M30 / 240/45 Euro- 48/32 teeth
- Rotor Vegast / 355/50 Euro - 46/30 teeth
- Rotor Aldhu/ 355/50 Euro - 46/30 teeth
With the smaller chainrings, the road bike gearbox can be better adapted to the needs of less trained hobby riders: They enable easier uphill gears or smaller gear jumps than with the standard gears. This is at the expense of really fast gears, which many road cyclists don't need anyway. They are therefore also a good option for gravel bikes and touring bikes. All models were convincing in terms of shifting behaviour, but there are big differences in the weight of the sets and the price.
You can find detailed information on available blade gradations, bearing standards and crank lengths together with grades, weights and hardness measurement data for the material in the download for €1.99.
Why not free of charge? Because quality journalism has its price. That's why we guarantee independence and objectivity. The TOUR tests are based on standardised and reproducible test procedures, which we always disclose. TOUR articles can be bought - TOUR test victories cannot!
