When David specifies a Redchilli FR2 for a mountain event, he starts by asking about the climbs. How long are they, where are the steepest sections, and what cadence feels comfortable when you’ve already been riding for several hours? Those answers help him choose the chainrings and cassette before the bike is hand assembled in Devon.
A mountain race rarely exposes a lack of fitness in just one way. It asks for repeatable climbing torque, sensible pacing, clean shifts when tired and enough useful gear on the road back down. To configure gearing for mountain races well, start with the event’s steepest sustained gradients and your own climbing cadence, not the chainset fitted to the bike in the showroom.
The right answer is personal. A strong, lighter rider racing short climbs may be entirely comfortable with a closer-ratio cassette and a 36-tooth inner chainring. Another rider tackling a long sportive-style mountain event, carrying more fatigue into the final pass, may gain far more from a lower bottom gear than from tightly spaced sprockets. Neither choice is automatically faster. The useful question is whether the gearing lets you ride your intended effort without forcing a cadence that breaks your rhythm.
Start with the course, not the catalogue
Look beyond the event’s total elevation figure. A race with 2,000 metres of climbing can feel very different depending on where that climbing sits, how steep it becomes, and whether the roads allow any recovery. Study the profile for the longest climbs, the steepest ramps, the number of ascents and the final hour of the course.
A steady Alpine-style climb at 7 or 8 per cent rewards a different set-up from a British mountain route that repeatedly pitches into double-digit gradients. In Devon, Dorset and the wider South West, short steep lanes can ask for low gears even when the overall elevation is modest. A route featuring 15 to 20 per cent sections also makes cadence changes more abrupt, particularly if the road surface is poor or the bend tightens at the steepest point.
Consider the descent as well. If the race has fast, open roads after each climb, a high top gear matters. But it should not be allowed to compromise the gearing you need for the climbs. Most riders spend longer ascending than pedalling hard downhill. On many technical descents, cornering, braking and positioning limit speed long before a 50×11 or 52×11 gear does.
The lowest gear is your pacing tool
Your easiest gear is not an admission that you expect to struggle. It is a way of protecting your effort when the road steepens and fatigue builds.
A useful starting point is to think in ratios. Divide the number of teeth on the small chainring by the largest cassette sprocket. A 34×34 is a 1:1 ratio. A 34×36 is lower at 0.94, while a 36×30 is higher at 1.20. The lower the number, the easier it is to turn the pedals for a given speed.
For many committed road riders, a compact 50/34 chainset with an 11-34 cassette gives a broad and sensible range for mountain races. Its 1:1 lowest gear is a useful reference when comparing setups. Check whether it lets you hold your preferred cadence on the steepest sustained climb at the effort you plan to ride. If you also spend time in fast groups, look at the spacing of the sprockets you use most on rolling roads.
That does not make 50/34 and 11-34 universal. A rider who naturally climbs at a lower cadence, has a high power-to-weight ratio and races smoother mountain roads may prefer a 52/36 with an 11-30 or 11-32 cassette. The steps between sprockets are closer, which can help when holding a precise rhythm on a steady gradient. The trade-off is clear: the lowest gear is meaningfully harder when a climb reaches its final steep ramps.
For long endurance races, multi-day events or riders who know that steep gradients force them below a sustainable cadence, a sub-compact chainset can be a very sensible choice. A 48/31 with an 11-34 cassette creates a notably easier climbing gear while retaining a top gear that is adequate for the vast majority of real roads. It is not simply a solution for inexperienced riders. It is a specification decision that can preserve legs for the decisive part of a long day. A sub-compact setup needs a compatible frame and drivetrain. Confirm chainline and front derailleur compatibility before choosing the chainset
Use cadence honestly
Many riders choose gearing based on what they can turn for two minutes when fresh. Mountain races are usually decided by what remains possible after several hours, at the top of the last climb, with your fuelling and pacing no longer perfect.
Look at your ride data if you have it. On sustained climbs, where does your cadence settle when you are riding well? If it regularly drops into the low 60s on steep sections and you are having to stand simply to keep the pedals moving, a lower gear may allow better pacing. If your lowest gear already covers the steepest sections comfortably but you keep finding yourself between gears on steadier climbs, compare the sprocket steps in the part of the cassette you use most.
Cadence is not a target to chase for its own sake. Some riders are efficient at 75rpm, others closer to 90rpm. What matters is avoiding repeated, unnecessary spikes in muscular load that leave the legs heavy later in the event.
Configure gearing for mountain races as a complete system
Chainrings and cassette sizes cannot be selected in isolation. The rear derailleur must have the capacity and maximum sprocket clearance for the cassette, while the chain length needs setting correctly. Some combinations are approved directly by the groupset manufacturer; others may work only with a particular derailleur cage or are not advisable at all. It is worth confirming this before buying parts rather than discovering compromised shift quality during race week.
The drivetrain also needs to work cleanly under pressure. A mountain race will expose a marginal set-up quickly: a hesitant shift to the largest sprocket, a chain that rubs when crossed over, or a front derailleur that struggles under load all disrupt momentum when it matters. Correct hanger alignment, a fresh chain, accurate indexing and appropriate chain length are small details with a very real effect on confidence.
Wheel and tyre choice influence the feeling of the gearing too. A larger-volume tyre at a lower, controlled pressure can improve traction and reduce fatigue on rough climbing roads. Its rolling radius may alter effective gearing very slightly, but the practical benefit is grip and composure. There is little value in choosing a high gear because it looks purposeful if the rear wheel slips whenever you try to apply it.
Do not overvalue the top gear
A 50×11 is already a substantial gear. At 100 rpm, a 50×11 gear gives about 57 km/h with a 2.10 m tyre rollout. A 52×11 extends that further, but many riders will only use it briefly in a mountain race. On a fast descent, the better decision is often to freewheel, recover, eat or focus on the road ahead. On a fast, technical descent, freewheeling can leave you more room to focus on braking and your line.
There are exceptions. A race with long, fast valley roads, head-to-head attacks after descents or a powerful rider who can sustain high speed on rolling terrain may justify a 52- or 54-tooth outer ring. For time trials and triathlon, where uninterrupted speed is more likely, that calculation changes again. But for a typical road mountain race, losing a little top-end gear is often a worthwhile exchange for having one more usable sprocket when the gradient bites.
Test the set-up before race day
A gearing choice should be proved on roads that resemble the event, ideally when you are carrying some fatigue. Find a climb with a sustained section and a steep ramp. Ride it at controlled race effort, using the gears you expect to use on the day. Notice whether you can remain seated when you want to, shift smoothly before the gradient changes, and bring your breathing back under control over the crest.
Avoid making the test artificially easy by riding it fresh every time. Include it near the end of a longer training ride, with the same tyres, bottles and nutrition plan you intend to use. You are testing the whole riding experience, not just whether the lowest gear turns.
If you are changing cassettes, chainrings or derailleur components, make the change early enough to ride several times with it. Different jumps between sprockets can take a little adaptation, especially when changing from an 11-28 to an 11-34. That familiarity is useful when you need to select a gear quickly before a steep corner.
Build for the rider, not the label
A race bike does not need a race-hard gear selection. The most effective gearing is the one that allows you to apply your fitness consistently, stay within your pacing plan and arrive at the final climb with something left to use.
Two riders can choose the same Redchilli FR2 and need different gearing. For a race with long, steady climbs and fast valley roads, David might prioritise closer steps through the gears the rider uses most. For an event with a steep final pass, the priority may be a lower bottom gear that helps the rider stay seated and keep turning the pedals late in the day. Those choices sit alongside fit, wheels, tyres, when specifying the complete bike.
Choose a range that gives you options when the day becomes harder than expected. Mountain races are demanding enough without asking your drivetrain to prove a point.
Your FR2, Geared for the Course
Tell David about the climb you’re preparing for and the gear you reach for when the gradient bites. Whether you’re racing on steep British roads or heading for a long Alpine pass, that conversation helps shape the gearing on your FR2. Each bike is individually specified and hand assembled in Devon, with ongoing support as you put miles on it.
Redchilli Bikes. Your Bike. Your Way.